Ischemic Heart Disease – Session 1

Friday, September 29, 2023, 5:15pm – 6:15pm

122-01Changes in the Clinical Profile of Patients Undergoing PET Myocardial Perfusion Imaging: A Single-Center Experience Over 20 Years Dominik C. Benz, MD 1, Dominik F. Sager, MD1, Chrysoula Garefa, MD1, Susanne Markendorf, MD1, Aju P. Pazhenkottil, MD1, Andreas A. Giannopoulos, MD1, Ronny Buechel, MD2, Philipp A. Kaufmann, MD1; 1University Hospital Zurich, Zurich, Switzerland, 2University Hospital, Zurich, Switzerland.

Introduction:PET/CT myocardial perfusion imaging (MPI) is changing the management of patients with suspected or known coronary artery disease (CAD). Its clinical dissemination but also restrictions to reimbursement might have changed the profile of referred patients. The aim of the present study was to investigate temporal trends in the clinical profile and imaging findings.

Methods: In this cross-sectional cohort study, 3291 patients who underwent PET/CT between 1995 and 2020 were retrospectively included. Patients were grouped into 4 groups: 1) initial experience (<1999), 2) early clinical access with insurance coverage (2000-2007), 3) limited clinical access due to re-evaluation of insurance coverage (2008-2014), and 4) full insurance coverage (2014-2020). Clinical profile as well as PET findings were assessed.

Results: The number of scans is illustrated in Figure A and Table. Over time, age and BMI increased while prevalence of typical angina decreased (P < 0.001). The small number of patients during the initial experience represented a younger, more female population without known CAD and low prevalence of ischemia and scar (Table). During early clinical access and re-evaluation of insurance coverage (2000-2013), the majority of patients had more than two risk factors, prior acute coronary syndrome (ACS) and myocardial scar (Table). After insurance coverage (2013-2020), the clinical profile shifted towards less cardiovascular risk factors, prior ACS or coronary artery bypass grafting (Table). However, the yield of PET MPI remained high, with ischemia and scar in 38% and 49% of patients, respectively. This evolution is mirrored by the temporal changes of median MFR per year (Figure B).

Conclusion: The clinical profile of patients undergoing PET/CT MPI has continuously changed over the 20 years. While insurance coverage played a major role, referring physicians remained selective in their referrals to keep the yield of PET/CT MPI high.

122-02Comparison Between Regadenoson and Adenosine on Myocardial Blood Flow Quantification using Rubidium-82 PET Joris D. van Dijk, MSc., PhD, MBA, Mandy Kamerman, MD, Jorn A. van Dalen, PhD, Pieter L. Jager, MD, PhD, Mohamed Mouden, Phd, MD; Isala hospital, Zwolle, Netherlands.

Introduction: Multiple factors influence myocardial blood flow (MBF) quantification using PET: the type of tracer that is used, the infusion profile of the tracer, the PET-scanner, reconstruction techniques, and temporal sampling protocols. However, the influence of the pharmacological stress agent is fairly unknown. In particular, it is unknown whether the same MBF thresholds can be used to obtain the optimal diagnostic and prognostic value when shifting between regadenoson and adenosine. Hence, our aim was to compare the myocardial blood flow (MBF) quantification between these two agents using Rubidium-82 PET.

Methods: We performed a retrospectively cohort study including732 consecutive symptomatic patients who underwent rest-stress Rubidium-82 PET MPI using either regadenoson (n = 368) or adenosine (n = 364). None of the patients suffered from COPD or asthma. Regadenoson was administered as bolus whereas a six-minute infusion protocol was used for adenosine. Baseline characteristics, visual and semi-quantitative scan results, ejection fraction (EF) in both rest and stress, stress MBF values and myocardial flow reserves (MFR) were compared between both groups.

Results: Baseline characteristics did not differ between both groups (p≥0.62) besides a slightly higher prevalence of a positive family history in the adenosine group (66% vs. 55%, P = 0.005). The percentage of normal scans did not differ between the adenosine and regadenoson group (67% vs. 69%, respectively, P = 0.59). Summed stress and summed difference scores also did not differ between both groups (p≥0.84), just like the EF in rest and stress (p≥0.63). However, the global MBF in stress was slightly higher using adenosine (2.30 ml/g/min) than using regadenoson (2.18 ml/g/min, P = 0.04). Similarly, the MBF in the RCA and LCX territories were higher using adenosine (0.15 and 0.11 ml/g/min, respectively, p≤0.043). However, MFR did not differ for any of the three territories or globally when comparing adenosine with regadenoson.

Conclusion: Although the use of adenosine resulted in a slightly higher stress MBF compared to regadenoson, this was within the reproducibility range of PET Rb-82 and could therefore be regarded as not clinically relevant. Moreover, as the myocardial flow reserve remained unaffected, the influence of pharmacological stress agent on MBF PET Rb-82 quantification is limited.

122-03 13N-NH3Cardiac PET derived Myocardial Flow Reserve in Assessment of Coronary Microvascular Dysfunction in Symptomatic Non-Obstructive Coronary Artery Disease Patients Harpreet Singh, MBBS, MD (Nuclear Medicine) 1, Vinisha Gunasekaran, MBBS1, Prashant Panda, MD, DM1, Ashwani Sood, MD2, Bhagwant Rai Mittal, MD1; 1Post Graduate Institute of Medical Education and Research (PGIMER), Chandigarh, India, 2PGIMER, Chandigarh, India.

Introduction: Approximately 30-50% of the patients with symptoms of myocardial ischemia do not have obstructive coronary artery disease at angiography (NOCAD). Nearly 2/3rd of them may have coronary microvascular dysfunction (CMD). Intracoronary guidewire-based measurements of CFR or IMR are the currently recommended techniques for diagnosing CMD but are invasive. Alternatively, coronary slow flow (defined as TIMI frame count >25) in angiographically normal coronary arteries is considered a CMD marker. This study was conducted with the aim to non-invasively quantify myocardial flow reserve (MFR) using 13N-NH3 PET in patients with suspected CMD and to correlate MFR values with flow grades (TIMI and TMPG).

Methods:  Symptomatic patients with NOCAD were prospectively enrolled. Only patients with the coronary slow flow in ≥1 major epicardial vessel were included. Patients with a past history of angioplasty/CABG and patients unfit for vasodilator stress were excluded. Absolute quantification of myocardial blood flow (MBF) in ml/min/gm was obtained, using a dynamic rest and stress protocol with intravenous adenosine as a hyperaemic agent and 13N-NH3 as a PET perfusion tracer. The reconstructed data were processed using “Corridor 4DM” software.

Results: A total of 29 patients with a mean age of 51.9 ± 9.8 years were recruited. Of the total 87 vascular territories assessed, the majority had TIMI and TMPG grade 2 (n = 60 and 74, respectively). The mean global stress MBF and MFR were 2.55 ± 0.73 ml/min/gm and 2.95 ± 0.81, respectively. Seven patients had reduced global MFR <2.3 (mean 1.80 ± 0.36). The majority of vascular territories with reduced MFR had a reduced TMP grade 2. However, only 7 (10%) of the 66 vascular territories with normal MFR, had a normal TMP grade 3, and the remaining 59 (89%) territories had reduced TMP grade 2 (n = 56) and 1 (n = 3). Thus, no statistically significant correlation existed between MFR and TMPG (P = 0.558). (Table 2) Relative perfusion abnormality was seen in 15 of 29 patients but only 6 (40%) of them had reduced MFR, remaining 9 patients had normal MFR. Additionally, in one patient with reduced MFR, there was no perfusion defect. Thus, there was no statistically significant association between the presence of perfusion defects and reduced MFR (P = 0.564).

Conclusion: 1.PET is an excellent non-invasive modality for diagnosing CMD due to its ability to quantify reductions in hyperaemic MBF and MFR. 2.The majority of the patients with reduced angiographic flow grades had a normal MFR (suggesting no significant CMD). Further, few patients with reduced MFR had normal TIMI & TMP grades. Thus, according to this study, slow flow on coronary angiography is a poor predictor of CMD. 3.In patients with normal coronaries, the presence or absence of perfusion defects alone does not rule in or rule out CMD and these defects should be interpreted in light of dynamic PET parameters such as MFR.

122-04Cardiac PET in Daily Practice for Risk Assessment in Patients With and Without Coronary Artery Disease Liyan Obeidat, MD 1, Kartik Gupta, MD1, Aakash Srikanth, MD1, Ayman Alsaadi, MD1, Arvind Karthikeyan, Student1, Ali Ghandour, MD1, Ahmad Alkhatib, MBBS1, Karthikeyan Ananthasubramaniam, MD, FASNC2; 1Henry Ford Hospital, Detroit, MI, USA, 2Henry Ford West Bloomfield Hospital, Detroit, MI, USA.

Introduction: The use of positron emission tomography (PET) has steadily increased in coronary and non-coronary applications. PET is superior SPECT for the detection of multivessel coronary artery disease (CAD) especially with its capacity to quantify rest and peak stress left ventricular systolic function as well as coronary flow reserve. We present our initial experience with utilization of PET in unselected patients with and without known CAD and demonstrate the utility of key parameters in PET applicable widely in daily practice.

Methods: We retrospectively reviewed patients who underwent cardiac PET between October 2019 and June 2021. Two groups were defined based on the presence or absence of CAD. Categorical variables are presented as frequencies (%) and compared with Chi-square while numerical variables are presented as Median (IQR) and compared with Mann-Whitney U test. Major cardiac events (MCE) included undergoing revascularization (PCI or CABG) and cardiovascular related deaths. Univariate and multivariate analysis were done for predictors of MCE.

Results: Of 271 patients undergoing cardiac PET, 130 had no prior CAD (Grp 1) while 141 had CAD (Grp 2). Of the study population, 12.5% developed MCE, with the majority (8%) being from Grp 2. In both groups, patients who developed MCE had no statistically significant difference in age (median 67.5 vs 72.5), race, history of diabetes or baseline medications such as statins and beta blockers. In Grp 1, patients who developed MCE were more likely to be males (83.3% vs 16.7%, P = 0.008), had lower resting EF (42.5-55%, median 52%, P = 0.034) and at stress (51.5-58%, median 55%, P = 0.016), larger area of ischemia (41.7% with ischemic area > = 10, P < 0.001), higher SSS (0-10, median of 6, P < 0.001) and higher SDS (0-10, median of 6 , P < 0.001). In Grp 2 patients who developed MCE were more likely to have hypertension (68.2% vs 31.8%, P < 0.001), had lower EF at stress (36-58%, median 55%, P = 0.008), larger area of ischemia (59.1% with ischemic area > = 10, P < 0.001), higher SSS (4-14, median of 8, P < 0.001) and higher SDS (0-11, median of 7, P < 0.001). There was no statistically significant difference in presence or absence of an infarction or transient ischemic dilation (TID) on PET in predicting MCE in both groups. SSS remained an independent predictor for MCE (P = <0.0001).

Conclusion: Our study highlights that the use of PET carries a substantial value in predicting outcomes in patients with and without prior known CAD. Using PET derived data points helps identify patients at risk for MCE and should be factored into risk estimations and management decisions.

122-05Studying the Impact of Reconstruction Parameters for a Modern SiPM PET System on Myocardial Blood Flow Ian S. Armstrong, PhD, Parthiban Arumugam, MB BS; Manchester University NHS Foundation Trust, Manchester, United Kingdom.

Introduction. As scanner and reconstruction technology advances, it is important to assess the impact of various reconstruction parameters and improvements on Myocardial Blood Flow. This study evaluates features such as point spread function (PSF) and metal artifact reduction (MAR) as well as standard variables such filters and iterations on a modern SiPM PET-CT system.

Methods. Resting dynamic data from 24 Rb-82 patients acquired on a Biograph Vision 600 were included. Data were divided into three equal subgroups based on cavity volume using EDV: large (>140ml), medium (80-140ml) and small (<80ml). The reference reconstruction was TOF using 4 iterations (i), 5 subsets, 6mm Gaussian filter and isotropic 1.6mm voxels. Seven variant reconstructions were produced, adjusting a single parameter to the reference: 1, post-filter (3mm, 9mm, 12mm); 2, iterations (2i, 6i) and 3, algorithm (TOF+PSF, TOF+MAR). Global MBF (gMBF) and regional MBF (rMBF) together will regional spill-over (rSO) were measured in Cedars Sinai QPET and expressed as the mean and standard deviation relative differences to reference values.

Results. Global MBF values from the reference reconstruction were 0.99±0.32, 1.30±0.24, 1.37±0.23 ml/g/min for large, medium and small cavity volumes, respectively, while rSO values were 0.32±0.03, 0.32±0.02 and 0.34±0.02, respectively. Apart from 3mm filter, TOF+PSF and TOF+MAR variants, differences in gMBF were significant, albeit small, for variant reconstructions. Variants with 9mm and 12mm filters were the only ones where gMBF changes showed a dependency on cavity size due to increases in rSO of +5.7%±1.8 and +13%±5.0 with 9mm and 12mm filters in the small cavity sub-group. Across all images, differences in gMBF were +0.9%±2.4, -1.1%±1.9 and -2.7%±3.5 for 3mm, 9mm and 12mm filter variants, respectively, with all rMBF values falling within ±8%. Differences in rSO were -1.9%±2.3, +3.4%±2.6 and +8.4%±5.7, respectively. For iteration variants, differences in gMBF were -1.0%±1.2, and +0.5%±0.7 for 2i and 6i, respectively, with all rMBF values falling within ±5%. Differences in rSO were +1.9%±2.3, and -0.4%±1.8, respectively. For TOF+PSF and TOF+MAR, differences in gMBF were +0.4%±1.4, and +0.2%±1.4 respectively with all rMBF values falling within ±4%. Differences in rSO were -0.9%±1.6, and -0.5%±1.6, respectively.

Conclusions. Despite some statistically significant variations, all MBF differences were small and within an expected test-retest of ±15% based on published data. On the Biograph Vision, the use of PSF and MAR was shown to have no impact on MBF. These reconstruction options have been shown to provide additional benefits of improved signal-to-noise and reduced attenuation correction artifacts. Hence this work suggests that, for convenience, these options can be applied routinely on the Vision system.

122-06Comparison of Functional Values from Gated Rubidium-82 data using Data-Driven Motion Correction with CardioFreeze Ian S. Armstrong, PhD 1, Sarah Sargant, MSc1, Charles Hayden, MSc2, Bruce Spottiswoode, PhD2, Parthiban Arumugam, MB BS1; 1Manchester University NHS Foundation Trust, Manchester, United Kingdom, 2Siemens Medical Solutions, Knoxville, TN, USA.

Introduction: Multiple studies have shown image quality improvements in from the use of Siemens prototype data-driven motion correction (DDMC) in static Rb-82 PET images. This work extends the evaluation to ECG-gated data and CardioFreeze (CF) gating.

Methods: Stress and rest images for 49 patients acquired on a Biograph Vision 600 following 20mCi of Rb-82 were included in this work. 8-bin standard ECG-gated and CF gated reconstructions (PSF+TOF, 4 iterations, 5 subsets, 6mm Gaussian filter) were created from RAW and DDMC data, producing 4 comparison datasets. EDV, ESV, LVEF and EF augmentation (EFaug), defined as sLVEF - rLVEF, were measured in Cedars Sinai QPET.

Results: With motion and reduced edge sharpness in uncorrected images (neither DDMC nor CF used), the apparent volume of the LV cavity was reduced. This was more pronounced at ESV, leading to an overestimation of LVEF and worse in stress images, causing a greater overestimation of sLVEF than rLVEF and hence an overestimation of EFaug. For both standard and CF gating, rEDV and rESV increased by mean of 7% and 8% (P < 0.05) respectively with DDMC compared with RAW data, resulting in no significant difference in rLVEF. At stress, sEDV and sESV increased by 7% and 14% (P < 0.05) respectively with DDMC, resulting in a mean decrease in sLVEF of -1.4 percentage points (P < 0.05) due to reduced motion blurring of the cavity. This difference of impact on rest and stress images resulted in a mean reduction of EFaug of -1 percentage point when DDMC was applied. Compared with standard gating, CF gating increased ESV by a mean of 6.6%, 6.8%, 8.0%, 7.3% (all P < 0.05) for rRAW, sRAW, rDDMC and sDDMC respectively but reduced EDV by a mean of -1.2%, -1.8%, -1.3% and -1.8% (all P < 0.05) for rRAW, sRAW, rDDMC and sDDMC. This resulted in mean reductions of LVEF -2.5±1.6, -2.5±1.4, -3.0±1.1 and -2.7±1.3 percentage points for rRAW, sRAW, rDDMC and sDDMC, respectively. No significant differences between the reduction of sLVEF and rLVEF were observed and so EFaug was conserved for CF and standard gating.

Conclusions: DDMC has been shown to compensate for motion blurring, and hence correct for overestimation of LVEF, which is more pronounced during stress due to more prevalent motion. Use of DDMC may compensate for an overestimation in EFaug seen in uncorrected images. DDMC and CF led to a clear improvement in image quality, with sharper edge definition, leading to increases in cavity volume measurements. CF gating appears to reduce LVEF consistently for rest and stress despite this increase in volume, which results in calculations of EFaug that are comparable with standard gating techniques.

122-07Absence of Coronary Calcium with pharmacologic stress SPECT is associated with excellent outcomes Andrew K. Geissler, DO 1, Laura Onderko, MD1, Jared Tobolski, MD1, Timothy L. Dunn, CNMT2, Jeffrey A. Rosenblatt, MD, FASNC3; 1Maine Medical Center, Portland, ME, USA, 2MaineHealth Cardiology, Scarborough, ME, USA, 3VA Healthcare System, Augusta, ME, USA.

Introduction: While pharmacologic stress SPECT myocardial perfusion imaging (MPI) carries similar sensitivity and specificity for the presence of CAD, the inability to exercise carries a higher risk for adverse events, and patients are assigned a minimum a priori intermediate risk. Coronary artery calcium scoring (CACS) is a strong predictor of future cardiovascular (CV) events. CACS of 0 has been associated with CV event rates of <1%. Its absence has also been shown to re-stratify patients into a lower-risk group. Patients undergoing MPI often receive non-gated cardiac CT imaging for the purpose of attenuation correction (CTAC). A reliable correlation has been noted between standard gated CT and CTAC acquisitions. Incorporating the presence of coronary calcium (Ca+) to further stratify patients undergoing pharmacologic nuclear stress could represent a novel change in management strategies.

Methods: A retrospective natural history study was conducted on patients aged ≥ 18 years who underwent MPI with SPECT at a single institution between January 2015 - January 2018. MACE was defined as subsequent hospitalization for UA, NSTEMI or STEMI, coronary angiography demonstrating the presence of CAD, and sudden cardiac death within 3 years. Patients with prior CABG, absent CT data, initiation of a statin after the index stress test, or known history of heart failure were excluded. Studies were interpreted by a board-certified nuclear cardiologist and then subsequently independently reviewed in a blinded fashion by a board-certified nuclear cardiologist for the presence or absence of coronary Ca+.

Findings: Of the 465 studies reviewed, 177 were identified as having no Ca+ on CTAC slices. 56 patients were male (31.6%), average age: 63.6, 48 (21.7%) had diabetes, and 111 (62.7%) had hypertension. Of the 177 subjects without coronary Ca+, MACE was 0. Two patients died from non-cardiac causes and one patient had an ischemic CVA.

Conclusion: The inability to exercise during stress SPECT studies portends an intermediate risk in the presence of normal perfusion. Prior studies have demonstrated that a CACS of 0 is associated with a CV risk of <1%. The current study suggests that the absence of coronary calcium on CTAC slices during pharmacologic stress SPECT may allow reassignment to a low-risk category.

122-08Machine Learning to Predict Hemodynamically Significant CAD Based on Traditional Risk Factors, Coronary Artery Calcium and Epicardial Fat VolumeWenji Yu, MD, Yuetao Wang, MD; The Third Affiliated Hospital of Soochow University, Changzhou, China.

Aims: We sought to conduct a machine learning (ML) model to screen for hemodynamically significant coronary artery disease (CAD) based on traditional risk factors, as well as coronary artery calcium (CAC) and epicardial fat volume (EFV) measured from non-contrast CT scans.

Methods: 184 symptomatic inpatients who underwent Single Photon Emission Computed Tomography/Myocardial Perfusion Imaging (SPECT/MPI) and invasive coronary angiography (ICA) were enrolled. Clinical features and imaging features (CAC and EFV) were collected. Hemodynamically significant CAD was defined when coronary stenosis severity ≥50% with a matched reversible perfusion defects in SPECT/MPI. Data were randomly split into a training cohort (70%) on which fivefold cross-validation was done and a test cohort (30%). The normalized training phase was preceded by the selection of features using recursive feature elimination (RFE). Three ML classifiers (LR, SVM, and XGBoost) were used to construct the predictive models for hemodynamically significant CAD by incorporating the key clinical variables, CAC, and EFV. Area under curve (AUC) of ML was compared and the best predictive model was chosen for further analysis and validation.

Results In the training cohort, hemodynamically significant CAD patients had significantly higher age, BMI and EFV, higher proportions of hypertension and CAC comparing with controls (P all<0.05). In the test cohorts, hemodynamically significant CAD patients had significantly higher EFV and higher proportions of CAC. EFV, CAC, hypertension, hyperlipidemia and diabetes mellitus (DM) were the highest ranking features by RFE. XGBoost produced better performance (AUC of 0.88) compared with traditional LR model (AUC of 0.82) and SVM (AUC of 0.82) in the training cohort. Decision Curve Analysis (DCA) demonstrated that XGBoost model had the highest Net Benefit index. Validation of the model also yielded a favorable discriminatory ability with the AUC, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy of 0.89 (95%CI: 0.82-0.97), 68.0%, 96.8%, 94.4%, 79.0% and 83.9% in the XGBoost model.

Conclusion: A XGBoost model based on EFV, CAC, hypertension, hyperlipidemia and DM to assess hemodynamically significant CAD was constructed and validated, which showed favorable predictive value. The data-driven approach may support clinicians in the identification of hemodynamically significant CAD and be applied early for risk stratification.

122-09Epicardial Fat Volume Was an Independent Risk Factor for Major Adverse Cardiovascular Events and Had Incremental Prognostic Value to Myocardial Perfusion Imaging in Chinese Suspected or Known Coronary Artery Disease Populations with Normal Left Ventricular Ejection FractionLe Yang, MD, Wenji Yu, MD, Yuetao Wang, MD; The Third Affiliated Hospital of Soochow University, Changzhou, China.

Background: A large number of coronary artery disease (CAD) patients with normal left ventricular ejection fraction (LVEF) also had poor prognosis. As a routine examination, Single-photon emission computerized tomography myocardial perfusion imaging (SPECT-MPI) is useful for risk stratification and predicting the occurrence of major adverse cardiovascular events (MACE) in suspected or known CAD populations, but there were false negatives. SPECT/CT is an “one-stop shop” examination, which through non-contrast CT can product attenuation correction for MPI and obtain information of coronary artery calcium (CAC) and epicardial fat volume (EFV) simultaneously. This study aimed to investigate the predictive and incremental value of EFV to MPI for MACE in Chinese suspected or known CAD populations with normal LVEF.

Methods: We retrospectively studied 290 suspected or known CAD inpatients with normal LVEF who underwent SPECT/CT from February 2014 to December 2017. Abnormal MPI was defined as SSS ≥ 4 or SDS ≥ 2.EFV and CAC was calculated by non-contrast CT. .The end of follow-up was February 2022. The follow-up information came from patient clinical case notes or telephone reviewing, and MACE was defined as cardiac death, late coronary revascularization ≥ 3 months after MPI, nonfatal myocardial infarction, angina-related rehospitalization, heart failure, and stroke. During the 76-month follow-up, the event-rate was 32.0% (93/290). Univariate and multivariate Cox regression analysis concluded that high EFV (>102.4 cm3) (HR: 3.2, 95% CI: 2.1, 5.2 P < 0.0001) and abnormal MPI (HR: 1.9, 95% CI: 1.2, 3.0 P = 0.005) were independent risk factors of MACE. By K-M survival curve, the event-free survival rate of patients with high EFV was significantly lower than low EFV group (log-rank test P < 0.001). In the subgroup with normal MPI, high EFV was associated with reduced event free survival (log-rank P < 0.01), with higher annualized event rate (8.3% vs 1.9%). Addition of high EFV to MPI could predict MACEs more effectively, with larger concordance index (0.57 to 0.69, P < 0.01),higher Global Chi-square (7.2to 41.4, P < 0.01), positive integrated discrimination improvement (0.10, P < 0.01) and net reclassification index (0.37, P < 0.01).

Conclusions: In Chinese suspected or known CAD populations with normal LVEF, high EFV was the independent risk factor for MACE after adjusting for traditional risk factors, CAC and MPI. In subgroups with normal MPI, EFV could also improve risk stratification. Addition of EFV to MPI had incremental value for predicting MACE.

122-10Clinical Usefulness of Myocardial Wall Strain Analysis by PET Feature Tracking: Direct Comparison With Conventional Tagging-Cine Image Using PETMR System Kenji Fukushima, MD,PhD 1, Masataka Katahira, MD1, Keiichiro Endo, MD,PhD1, Masateru Kawakubo, PhD2, Ryo Yamakuni, MD1, Naoyuki Ukon, PhD1, Takatoyo Kiko, MD,PhD1, Takeshi Shimizu, MD,PhD1, Shiro Ishii, MD,PhD1, Takayoshi Yamaki, MD,PhD1, Michinobu Nagao, MD,PhD3, Hiroshi Ito, MD,PhD1, Yasuchika Takeishi, MD,PhD1; 1Fukushima Medical University, Fukushima, Japan, 2Kyushu University, Kyushu, Japan, 3Tokyo Women's Medical University, Tokyo, Japan.

Introduction: Myocardial wall strain analysis has emerged as a useful imaging technique to detect subtle wall deformity in ischemic heart disease. We have developed a method for PET-derived strain analysis using endomyocardial feature tracking (PETFT) from gated PET images. We aimed to evaluate the clinical utility of PETFT by comparing with conventional tagging-cine cardiac magnetic resonance (TAG) using an integrated PETMR system.

Methods: PETFT and TAG data were obtained from 23 patients (mean 66±17.9 ys, male 14) who underwent 13N ammonia PETMR study. Gated PET cine images were obtained from list-mode acquisition with free-breathing, followed by breath-hold tagging-cine MR acquisition in the rest study. PETFT derived global longitudinal, and short-axis circumferential strain (GLS and GCS) were calculated using semi-automatic endocardium contour tracking. The strain values were compared to those of TAG based strain analysis. Perfusion defect in rest image was visually graded, and total perfusion defect (TPD) was generated.

Results: The mean GLS and GCS were -14.1±6.6 and -11.3±5.7 for PETFT, and -12.4±11.2 and -15.0±5.4 for TAG, respectively. PETFT showed significant and moderate correlation with TAG (r2 = 0.5, P = 0.0004; r2 = 0.4, P = 0.002 for GLS and GCS, respectively). The Brand-Altman plot demonstrated an acceptable agreement between the two methods, while a systematic error was detected (the limit of agreement was -7.7 to 11.2, and -12.6 to 21.1; the bias was 1.7, and 4.3 for GLS and GCS, respectively). In patients with perfusion defects (TPD>10%, n = 7), a significant correlation was still observed (r2 = 0.7, P = 0.02; r2 = 0.7, P = 0.04 for GLS and GCS, respectively).

Conclusion: PET feature tracking derived myocardial wall strain analysis demonstrated a significant correlation with conventional tagging-cine MRI. PETFT has the potential to become a valuable tool in the evaluation of subtle myocardial wall dysfunction.

122-11Simultaneous Assessment of Coronary Sinus Flow and Myocardial Flow Reserve Under Pharmacological Stress Using Hybrid 13N-ammonia PETMR System in Patients with Ischemic Heart Disease Kenji Fukushima, MD,PhD, Masataka Katahira, MD, Keiichiro Endo, MD,PhD, Naoyuki Ukon, PhD, Ryo Yamakuni, MD, Takatoyo Kiko, MD,PhD, Takeshi Shimizu, MD,PhD, Shiro Ishii, MD,PhD, Takayoshi Yamaki, MD,PhD, Hiroshi Ito, MD,PhD, Yasuchika Takeishi, MD,PhD; Fukushima Medical University, Fukushima, Japan.

Introduction: Myocardial flow reserve (MFR) measured by PET is an established diagnostic and prognostic marker for ischemic heart disease (IHD). Recently, coronary sinus flow (CSF) measurement using cardiac magnetic resonance has emerged as an alternative technique for evaluating coronary artery vasoreactivity. While both imaging techniques can be used to assess coronary endothelial function, there are fundamental differences in methodology between them. We aimed to investigate the correlation between MFR and CSF, and to assess the usefulness of simultaneous assessment for the severity of IHD.

Methods: Consecutive 47 patients (mean 66±17ys, male 41) who underwent rest-pharmacological stress 13N ammonia PETMR were enrolled. Rest and stress myocardial blood flow (MBF), and reserve (MFR) were obtained from list-mode acquisition. Myocardial perfusion defect was visually graded, and summed rest and diff scores (SRS, SDS) were calculated. CSF (mL/min/g) was obtained by phase-contrast magnetic resonance and corrected by left ventricular mass. CSF reserve (CFR) was calculated as the ratio of stress to rest.

Results: Rest and stress CSF showed significant but weak correlation to MBF (r2 = 0.1 and 0.2; P = 0.03, and 0.005 for rest and stress, respectively), while the correlation between CFR and MFR was not significant (P = 0.1). CFR and MFR showed a significant but weak correlation in patients with normal rest perfusion (r2 = 0.2, P = 0.04, for SRS<3, n = 19), while the correlation was not observed in patients with abnormal perfusion (P = 0.8, for SRS≧3, n = 28).

Conclusion: In patients with IHD, hybrid PETMR is feasible to perform simultaneous assessment of MFR and CSF reserve, and the discrepancy is likely caused by the perfusion abnormalities in the myocardium.

122-12The Value of Gated SPECT Myocardial Perfusion Imaging for Persistent or Recurrent Chest Pain after PCI in Patients with Coronary Artery Disease Zhimin Yang, MD, Jianfeng Wang, MD, Yuetao Wang, MD; Department of Nuclear Medicine, The Third Affiliated Hospital of Soochow University, Changzhou, Jiangsu Province, China.

Introduction: We aimed to evaluate the influencing factors of persistent or recurrent chest pain in patients with coronary artery disease after percutaneous coronary intervention (PCI) using gated myocardial perfusion imaging (GMPI).

Methods: This study prospectively enrolled 201 patients with coronary artery disease who underwent PCI. All subjects underwent GMPI within 1-2 months after PCI, and were followed up by telephone or medical record system at 1 year after PCI for persistent or recurrent chest pain. The clinical characteristics, cardiac Doppler ultrasound, electrocardiogram, GMPI, coronary angiography findings and PCI procedural factors were collected. PCI treatment methods are divided into complete revascularization and incomplete revascularization (incomplete revascularization due to technical reasons such as small coronary artery or preoperative non-culprit vascular functional evaluation). Multivariate logistic regression analysis was performed to define the independent risk factors of persistent or recurrent chest pain after PCI in patients with coronary artery disease.

Results: Persistent or recurrent chest pain after PCI occurred in 59 (29.4%) out of 201 patients. The symptomatic group was significantly older than the asymptomatic group (63.0±9.6 years vs. 59.7±10.4 years, t = 2.074, P = 0.039). Compared with patients in the asymptomatic group, patients in the symptomatic group had a higher proportion of patients with residual myocardial ischemia and incomplete revascularization (66.1% vs. 49.3%, χ2 = 4.743, P = 0.029 and 54.2% vs. 35.2%, χ2 = 6.247, P = 0.012). However, there were no statistically significant differences between the symptomatic group and the asymptomatic group in terms of coronary artery disease type, highest troponin, left ventricular ejection fraction (LVEF), arrhythmia, Gensini score, and coronary collateral circulation (all P>0.05). Multivariate logistic regression analysis showed that residual myocardial ischemia (OR = 2.237, 95%CI: 1.140-4.389, P = 0.019) and incomplete revascularization (OR = 2.117, 95%CI: 1.112-4.031, P = 0.022) were independent risk factors for persistent or recurrent chest pain after PCI.

Conclusion: Residual myocardial ischemia and incomplete revascularization are independent risk factors for persistent or recurrent chest pain after PCI. GMPI assessment of residual myocardial ischemia and the therapeutic strategy of complete revascularization have important clinical significance in predicting persistent or recurrent chest pain after PCI.

122-13Assessment of Left Ventricular Systolic Dyssynchrony after PCI in Patients with Acute Myocardial Infarction Using Gated Myocardial Perfusion Imaging: an Analysis of Influencing Factors Jianfeng Wang, MD, Yuetao Wang, MD; Department of Nuclear Medicine, The Third Affiliated Hospital of Soochow University, Changzhou,Jiangsu Province, China.

Introduction: To clarify whether left ventricular systolic dyssynchrony(LVSD) occurs after percutaneous coronary intervention (PCI) in patients with acute myocardial infarction(AMI) and its associated factors by gated myocardial perfusion imaging (GMPI).

Methods: The patients with AMI who underwent PCI in the third affiliated Hospital of Soochow University from January 2020 to December 2021 were prospectively enrolled (registration number: ChiCTR2000038729). All patients underwent rest + stress GMPI, electrocardiogram and echocardiography within 1-2 months after PCI. After GMPI image reconstruction, Cedars-Sinai QGS quantitative analysis was used to obtain the LVSD parameters of resting GMPI: phase histogram bandwidth (BW) and phase standard deviation (SD). QPS quantitative analysis was used to obtain the quantitative index of resting GMPI to evaluate myocardial infarction size: myocardial perfusion defect size (Extent, %). The abnormal critical threshold (BW: 60.6°; SD: 22.62°) was taken as the mean ± 2 standard deviations of the BW and SD values of the normal population, and any index greater than the threshold was defined as LVSD.

Results: A total of 175 AMI patients undergoing PCI were included. There was no significant difference in sex, age, body mass index, previous drinking and smoking history, hypertension, diabetes and hyperlipidemia between the Non-LVSD group (n = 91) and the LVSD group (n = 84) (all P > 0.05). Compared with the Non-LVSD group, the ECG QTc interval of the Non-LVSD group was significantly prolonged (416.26ms ± 49.74ms vs. 402.37ms ± 25.76ms), and left ventricular ejection fraction (LVEF) is significantly lower (56.89% ± 6.84% vs. 59.71% ± 5.08%) (all P < 0.05). The proportion of multi-vessel coronary artery disease, the proportion of MPI residual myocardial ischemia and the extent of myocardial perfusion defect (Extent) in the LVSD group were significantly higher than those in the Non-LVSD group (76.19% vs. 59.34%; 52.38% vs. 28.57%; 11% vs. 3%). Multivariate Logistic regression analysis showed that coronary multi-vessel disease (OR = 3.526, 95%CI:1.346~9.238, P = 0.010) and Extent (OR = 1.144, 95%CI:1.070~1.222, P = 0.000) were independent risk factors for LVSD after PCI in patients with AMI.

Conclusion: LVSD still exists in about half of the patients with AMI after PCI, and multi-vessel coronary artery disease and myocardial perfusion defect extent (Extent) are independent risk factors for LVSD after PCI in AMI patients, indicating that the higher the probability of LVSD after PCI is in AMI patients with multi-vessel coronary artery disease and / or myocardial perfusion defect extent (Extent).

122-14Prognostic Value of Left Ventricular Systolic Dyssynchrony after PCI Based on Gated Myocardial Perfusion Imaging in Patients with Acute Myocardial Infarction Jianfeng Wang, MD, Yuetao Wang, MD; Department of Nuclear Medicine, The Third Affiliated Hospital of Soochow University, Changzhou,Jiangsu Province, China.

Introduction: To explore the prognostic value of left ventricular systolic dyssynchrony(LVSD) in acute myocardial infarction(AMI) patients with adverse cardiac events after percutaneous coronary intervention(PCI).

Methods: A prospective study (registration number: ChiCTR2000038729) included 175 patients with AMI who underwent coronary intervention, including 150 males (85.71%), age (60.61±10.59) years old, all subjects underwent rest + stress GMPI examination, electrocardiogram, cardiac ultrasound within 1-2 months after PCI. GMPI obtained the LVSD indexes: phase histogram bandwidth (BW) and phase standard deviation (SD), and obtained the index to evaluate the extent of myocardial infarction: myocardial perfusion defect extent (Extent, %). After PCI, AMI patients were followed up every 6 months by telephone and/or inquiring hospital medical records, the follow-up endpoint was the occurrence of major adverse cardiac events (MACE).

Results: The mean follow-up was (18.66±7.84) months, and 2 patients were lost to follow-up. During the follow-up period, a total of 31 patients (17.91%, 31/173) developed MACE, including 1 central-caused death, 12 hospitalized patients with recurrent unstable angina, 12 patients undergoing PCI stent implantation or balloon dilation again, there were 6 cases of in-stent restenosis and 142 cases of patients without MACE. Cox multivariate regression analysis showed that residual myocardial ischemia (HR = 2.277, 95%CI: 0.989-5.241, P = 0.049), myocardial perfusion defect extent (Extent) (HR = 1.048, 95%CI: 1.020-1.076, P = 0.001) and LVSD (HR = 3.489, 95%CI: 1.099-11.054, P = 0.034) were independent influencing factors of cardiac adverse events in patients with AMI after PCI. The Kaplan-Meier survival analysis showed that the incidence of cardiac adverse events in the AMI patients with LVSD after PCI was significantly higher than that in Non-LVSD group [32.53% (27/83) vs. 4.44% (4/90)], χ2 = 21.023, P < 0.001]. The area under the curve of residual myocardial ischemia combined with LVSD to predict the occurrence of MACE in patients with AMI after PCI was significantly higher than that of residual myocardial ischemia alone (AUC: 0.799 vs. 0.670, P < 0.05), and its predictive sensitivity was 86.43%, the specificity was 61.30%. The C-index of the combined prediction model increased from 0.698 (95%CI: 0.618-0.779) in the single residual myocardial ischemia model to 0.745 (95%CI: 0.666-0.824) (P < 0.05).

Conclusion: Residual myocardial ischemia, extent of myocardial perfusion defect (Extent) and LVSD are independent influencing factors of major adverse cardiac events after PCI in patients with AMI. LVSD has a significant gain in residual myocardial ischemia in predicting the occurrence of MACE in AMI patients after PCI.

122-15Relationship Between Improvement of Perfusion and Myocardial Blood Flow With Revascularization and Patient Symptoms, Function and Quality of LifeTimothy M. Bateman, MD, MASNC1, James A. Case, PhD, MASNC2, Staci A. Courter, MA2, Brett W. Sperry, MD3, A. Iain McGhie, MD4, Kevin Bybee, MD5, Eric V. Burgett, CNMT, NCT6, Randall C. Thompson, MD, MASNC7, James O'Keefe, MD1, Krishna K. Patel, MD, MSc 8; 1Mid America Heart Institute, Kansas City, MO, USA, 2Cardiovascular Imaging Technologies, Kansas City, MO, USA, 3Saint Luke's Mid America Heart Institute, Kansas City, MO, USA, 4St. Luke's Mid America Heart Institute, Kansas City, MO, USA, 5St. Lukes Mid America Heart Institute, Kansas City, MO, USA, 6St. Luke's Hospital, Kansas City, MO, USA, 7Saint Luke's Cardiovascular Consultants, Inc., Kansas City, MO, USA, 8Icahn School of Medicine at Mount Sinai, New York, NY, USA.

Introduction: A key goal of percutaneous coronary intervention (PCI) is improvement of symptoms, function and quality of life (health status). While myocardial perfusion imaging (MPI) is amongst the most common means of identifying patients who may benefit from PCI, the relationship between changes in MPI findings and patients’ health status are not well understood. In this investigation, we employed Rb-82 PET MPI with flow measurements before and after PCI to address this gap in knowledge.

Methods: A total of 74 patients who had ischemia on a clinically indicated Rb-82 PET MPI (index test), reported symptoms on a Seattle Angina Questionnaire (SAQ), and who underwent a successful PCI, agreed to undergo a research Rb-82 PET 8 - 12 weeks later using the same camera, protocol, and stressor, and also to complete the same health status assessment at follow-up. Perfusion was assessed using the standard 17-segment model. Global myocardial blood flow reserve (MBFR) was quantified both times using standard commercial software (ImagenQ, Kansas City).

Results: Mean age was 70+-9 years, mean BMI was 31+/-6 kg/m2, and 69% were men. Diabetes was present in 39%, hypertension in 87% and dyslipidemia in 87%. Average time from PET to PCI was 11+/-9 days and from PCI to follow-up PET was 68+/-8 days. Overall, mean SAQ angina frequency (AF) scores improved from 78.4+/-16.1 to 91.8+/-13.6, SAQ Summary scores from 75.4+/-16.9 to 85.2+/-17.5, and MBFR from 1.86+/-0.49 to 1.97+/-0.55. In 40 patients the ischemia resolved while in 34 patients ischemic defects persisted on the follow-up scans. Despite similar baseline SDS and angina at baseline, those with residual ischemia fared worse post PCI and had no significant improvement in blood flow reserve. (Table).

Conclusion: Improved health status post PCI is closely correlated with improvement in MBFR. Residual ischemia and impairment of MBFR is associated with persistent symptoms, functional limitation and poor quality of life post PCI.

122-16Prognostic Interplay of Global Myocardial Flow Reserve and Ejection Fraction in Patients With History of Coronary Artery Bypass Grafting Mahmoud Al Rifai, MD MPH 1, Ahmed Ahmed, Post doctoral fellow1, Malek Nayfeh, MD1, Yushui Han, MS2, Moath Said Alfawara, MBBS3, Jean Michel Saad, MD1, Fares Alahdab, MD, MSc4, Faisal Nabi, MD5, Mouaz H. Al-Mallah, MD, MSc, FASNC6; 1Houston Methodist DeBakey Heart & Vascular Center, Houston, TX, USA, 2Houston Methodist DeBakey Heart and Vascular Center, Houston, TX, USA, 3houston methodist, houston, TX, USA, 4Houston Methodist, Houston, TX, USA, 5Houston Methodist DeBakey, Houston, TX, USA, 6Houston Methodist Hospital, Houston, TX, USA.

Introduction: The prognostic role of positron emission tomography (PET)-derived myocardial flow reserve (MFR) among patients with prior coronary artery bypass grafting (CABG) remains unclear, especially according to ejection fraction (EF).

Methods: Consecutive patients with prior CABG and a clinical indication for PET were enrolled in the Houston Methodist DeBakey Heart and Vascular Center PET registry and followed prospectively for incident outcomes. The primary outcome was a composite of all-cause death, myocardial infarction(MI)/unplanned revascularization(UR), and heart failure (HF) admissions. Multivariable Cox proportional hazards models were used to study the association between MFR (<2 vs ≥2) and incident events stratified by EF (≤50 vs > 50%).

Results: The study population consisted of 836 patients; mean (SD) age 68 (10) years, 53% females, 79% Caucasian, 36% non-Hispanic, and 66% with MFR <2. Over a median (IQR) follow up time of 17 (9-28) months, there were 166 incident events (62 HF, 70 all-cause deaths, 36 MI, 50 PCI/5 repeat CABG 90 days after imaging). In adjusted analyses, impaired MFR was associated with higher risk of the primary outcome among patients with low EF (EF<50%: hazard ratio [HR] 2.36; 95% CI 1.20-4.65, P = 0.013; EF> 50%: HR 1.10, 95% CI 0.62 - 1.93, P = 0.747; p for interactio n = 0.087).

Conclusion: Among patients with history of CABG, PET-derived global MFR <2 may identify those at increased risk of subsequent cardiovascular events, particularly in those with reduced EF.

122-17Increased Diagnostic Performance for the Detection of Coronary Artery Disease in Women with 18F flurpiridaz PET Myocardial Perfusion Imaging: A Prespecified Subgroup Analysis of the 18F flurpiridaz 303 Phase 3 Study Stephen Horgan, M.B., B.Ch., Ph.D. 1, Gary V. Heller, MD, PhD, MASNC2, DENIS AGOSTINI, MD, PhD3, Timothy M. Bateman, MD, MASNC4, Jeroen J. Bax, MD, PhD, MASNC5, Rob S.B. Beanlands, MD, MASNC6, Daniel S. Berman, MD, MASNC7, Sharmila Dorbala, MD, MPH, MASNC8, Ernest V. Garcia, PhD, MASNC9, Juhani Knuuti, MD, PhD10, Nagara Tamaki, MD, PhD, FASNC11, Francois Tranquart, MD, PhD12, James E. Udelson, MD, MASNC13, Jamshid Maddahi, MD, FASNC14; 1Morristown Medical Center, Morristown, NJ, USA, 2Morristown Medical Center, New Haven, CT, USA, 3UNIVERSITY HOSPITAL, CAEN, France, 4St. Luke''s Cardiovascular Consultants, Inc., Kansas City, MO, USA, 5Leiden University Medical Center, Leiden, Netherlands, 6University of Ottawa Heart Institute, Ottawa, ON, Canada, 7Cedars-Sinai Medical Center, Los Angeles, CA, USA, 8Brigham and Women's Hospital, Boston, MA, USA, 9Emory University Hospital, Atlanta, GA, USA, 10University of Turku, Turku, Finland, 11Hokkaido University School of Medicine, Kita-ku, Sapporo, Japan, 12GE Healthcare, Chalfont St Giles, United Kingdom, 13Tufts Medical Center, Boston, MA, USA, 14David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.

Introduction: SPECT in women with known/suspected CAD has only moderate accuracy due to attenuation artifact and suboptimal sensitivity. In a recent phase 3 study, a novel PET tracer 18F flurpiridaz with MPI met the primary endpoint of sensitivity and specificity for the diagnosis of CAD as well as the secondary endpoint of improved performance when compared to 99mTc-SPECT MPI. This study reports a pre-specified subgroup analysis to examine the diagnostic performance of 18F flurpiridaz in female patients.

Methods: A total of 604 patients with suspected CAD were enrolled and underwent both 1 day rest-stress 18F flurpiridaz PET and 1- or 2- day rest-stress 99mTc-SPECT MPI before invasive coronary angiography (ICA) across 48 sites in US, Canada and Europe. Sensitivity, specificity and overall diagnostic performance (ROC AUC) with 95% confidence intervals were evaluated using majority rule blinded visual reads. The reference standard was % stenosis by blinded quantitative invasive coronary angiography. Significant CAD was defined as ≥ 50% stenosis in ≥ 1 epicardial artery. Sensitivity and specificity comparisons were performed using 1-sided z-tests with a significance level of 0.025. The hypothesis tests were 1-sided McNemar's tests with a significance level of 0.025 for sensitivity, and Nam's restricted maximum likelihood estimation method with a significance level of 0.025 of noninferiority for specificity (margi n = 0.1). The differences in ROC AUC were performed by χ2 analyses. A P-value <0.05 was considered significant.

Results: Of 578 subjects with evaluable studies, 188 (32.5%) were women with a mean age of 64.3 (SD) years. Mean BMI was 31.6 (SD) kg/m2 and 37% had a history of diabetes mellitus. 41 (22%) female subjects had CAD on ICA. 18F flurpiridaz PET MPI met the pre-specified primary endpoint of sensitivity [82.9% (95% CI: 71.4, 94.4), P = 0.0014] and specificity [72.8% (95%CI: 65.6, 80), P = 0.0008] by the majority rule assessment. 18F flurpiridaz sensitivity was significantly higher that SPECT [82.9% vs.65.9%, difference: 17.1% (-1.5%, 35.6%), P = 0.0448] and its specificity was non-inferior vs SPECT [72.8% vs. 66%, difference:6.8% (-3.4%, 17.0%) P = 0.0004]. ROC analysis showed significantly higher area under the curve (AUC) for 18F flurpiridaz vs SPECT in both women and men (0.84 vs 0.70, P = 0.0091 in women and 0.78 vs 0.67, P = 0.0001 in men). AUC for 18F flurpiridaz PET was comparable among women and men (0.84 vs. 0.78, p>0.05). 18F flurpiridaz PET MPI had significantly lower radiation exposure compared to 99mTc-SPECT (6.2 ± 0.7 mSv PET vs 9.9 ± 2.7 mSv for tetrofosmin and 12.4 ± 2.4 mSv for sestamibi SPECT), P < 0.0001), a finding consistent in men and women.

Conclusion: This pre-specified secondary analysis of the second Phase 3 multicenter trial demonstrates a higher diagnostic performance of 18F flurpiridaz PET vs. SPECT for the detection of CAD in women.

122-18Congenital Absence Of The Pericardium: A Rare Condition Diagnosed By Cardiac PET/CT Isha Verma, MD, Dean Marella, MD, Omar Safdar, MD, Michelle Sayad, MD, Stephen Horgan, MD; Morristown Medical Center, Morristown, NJ, USA.

Patient presentation: 45-year-old man with exertional dyspnea undergoing preoperative evaluation for bariatric surgery. Prior history of hypertension, paroxysmal atrial fibrillation, ESRD s/p renal transplant and obesity (BMI 36). EKG showed sinus rhythm with right axis deviation and non-specific T-wave abnormalities. Nuclear stress test was nondiagnostic due to increased RV and bowel uptake/artifact (outside study). Patient subsequently referred for cardiac PET MPI.

Diagnostic imaging and important Findings: PET/CT MPI was performed with rubidium (30mCi for both rest and stress ). Standard short-lived symptoms experienced with regadenoson during stress without any EKG changes. CT demonstrated marked leftward displacement of the heart with RV touching the left chest wall. CT attenuation correction required considerable adjustment to accurately fuse the emission and transmission images. Pericardium was not identified with interposition of the lung between the aortic arch and pulmonary trunk consistent with complete absence of the pericardium. There was homogenous uptake of radiotracer and no evidence of vasodilator induced myocardial ischemia. LV size and systolic function were normal. Myocardial flow reserve was also normal.

Follow up: The patient was cleared for surgery without any perioperative complications. Echocardiogram did not reveal any other congenital cardiac abnormalities.

Teaching points: Cardiac PET/CT MPI is a highly accurate imaging modality particularly in obese patients. There case highlights the added value of CT for the evaluation of the extra coronary cardiac and extra cardiac findings. Congenital absence of the pericardium is rare and is found incidentally during surgery or at autopsy. The hallmarks of complete absence of the pericardium include leftward displacement of the heart and interposition of the lung between the aortic arch and pulmonary trunk (figure).

122-19Machine Learning to Predict Major Adverse Cardiovascular Events from Positron Emission Tomography Fares Alahdab, MD, MSc 1, Radwa El Shawi, PhD2, Ahmed Ibrahim Ahmed, MD MPH1, Mahmoud Al Rifai, MD MPH1, Mouaz H. Al-Mallah, MD, MSc, FASNC3; 1Houston Methodist, Houston, TX, USA, 2University of Tartu, Tartu, Estonia, 3Houston Methodist Hospital, Houston, TX, USA.

Machine Learning to Predict Major Adverse Cardiovascular Events from Positron Emission Tomography

Fares Alahdab, Radwa El Shawi, Ahmed Ibrahim Ahmed, Mahmoud Al Rifai, Mouaz Al-Mallah

Background: We developed a machine learning (ML) model to improve the prognostic risk assessment of major cardiovascular adverse events (MACE) from positron emission tomography (PET) myocardial perfusion imaging (MPI). In this study, we aimed to evaluate its performance and accuracy in patients with coronary artery disease (CAD) and those suspected of CAD.

Methods: We included consecutive patients who had undergone clinically indicated PET MPI. The ML model was derived using automated machine learning (AutoML), a framework that automatically selects and tunes machine learning modelling pipelines (comprising data imputation, feature preprocessing, and classification algorithms). Through nested cross-validation, we used a combination of clinical variables including age, sex, body mass index and PET imaging variables to train and optim