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ORIGINAL ARTICLE
Year : 2023 | Volume
: 24
| Issue : 2 | Page : 98-103
Left ventricular global longitudinal strain following acute ST-elevation myocardial infarction – A comparison of primary coronary angioplasty and tenecteplase-based pharmacological reperfusion strategy
Mosaad Abushabana1, Mahmoud Korashy2, Kamaleldin Al-Tahmody3
1 Department of Cardiology, Dubai Health Authority, Dubai Hospital, Dubai, UAE
2 Department of Cardiology, The Ministry of Health and Prevention, Fujairah Hospital, Fujairah, UAE
3 Department of Cardiology, Dubai Health Authority, Dubai Hospital, Dubai, UAE; Department of Cardiology, Faculty of Medicine, Tanta University, Tanta, Egypt
Correspondence Address:
Dr. Mosaad Abushabana
Department of Cardiology, Dubai Hospital, Al Khaleej Street, Al Baraha, P. O. Box 7272, Dubai
UAE
Source of Support: None, Conflict of Interest: None
CheckDOI: 10.4103/heartviews.heartviews_103_22
Abstract
Objective: In the setting of acute ST-elevation myocardial infarction (STEMI), reperfusion therapy with primary percutaneous coronary intervention (PCI) performed by an experienced team or pharmacological reperfusion with thrombolytic therapy is highly recommended. Standard echocardiographic measurement of the left ventricular ejection fraction (LVEF) is widely used to assess left ventricular global systolic function. This study was designed to compare the assessment of global left ventricular function by standard LVEF and global longitudinal strain (GLS) in the two well-known reperfusion strategies.
Materials and Methods: We conducted a retrospective single-center observational study in 50 patients with acute STEMI who underwent primary PCI (n = 25) and Tenecteplase (TNK)-based pharmacological reperfusion therapy (n = 25). The primary outcome was left ventricle (LV) systolic function after primary PCI, as assessed by two-dimensional (2D) GLS using speckle-tracking echocardiography (STE), as well as LVEF using standard 2D echocardiogram using Simpson's biplane method.
Results: Overall mean age was 53.7 ± 6.9 years with 88% male gender. The mean door-to-needle time was 29.8 ± 4.2 min in the TNK-based pharmacological reperfusion therapy arm, and the mean door-to-balloon time was 72.9 ± 15.4 min in the primary PCI arm. LV systolic function was significantly better in the primary PCI arm as compared to the TNK-based pharmacological reperfusion therapy, both by 2D STE (mean GLS: −13.6 ± 1.4 vs. −10.3 ± 1.2, P ≤ 0.001) and LVEF (mean LVEF: 42.2 ± 2.9 vs. 39.9 ± 2.7, P = 0.006). There were no significant differences in mortality and inhospital complications in both groups.
Conclusion: Global LV systolic function is significantly better after primary coronary angioplasty as compared to TNK-based pharmacological reperfusion therapy when assessed by routine LVEF and 2D GLS in the setting of acute STEMI.
Keywords: Acute myocardial infarction, global longitudinal strain, left ventricular ejection fraction, primary percutaneous coronary intervention, thrombolysis
Introduction 
ST-elevation myocardial infarction (STEMI) is the most serious complication of coronary artery disease (CAD). Reperfusion therapy with primary percutaneous coronary intervention (PCI) performed by an experienced team or pharmacological reperfusion with thrombolytic therapy in an acute setting is highly recommended.[1]
Expansion in the infarct region, hypertrophy, and progressive ventricular dilation in the noninfarct region is the characteristics of the left ventricle (LV) remodeling after STEMI. This complex process of the LV and abnormal LV geometry and function indicate an augmented risk for morbidity and mortality following high-risk acute myocardial infarction (AMI).[2],[3]
Standard echocardiographic measurement of the left ventricular ejection fraction (LVEF) is the most widely used routine prognostic parameter of LV global systolic function to predict clinical outcomes including total mortality, death, or hospitalization for heart failure, death, or any cardiovascular event after AMI.[4] However, while the simple estimation of global LV function using LVEF is quick and adequate for screening, it also provides suboptimal data in many situations and it has several important limitations such as image quality, the geometry of the dilated heart, the presence of left bundle branch block, preload, and afterload dependency, intraobserver and inter-observer variability, the influence of heart rate.
The calculation of ejection fraction is usually performed using a variety of LV geometric assumptions.[5],[6],[7]
Two-dimensional (2D) speckle-tracking echocardiography (STE) has emerged as a robust, cheap, safe, and more accessible noninvasive imaging tool to accurately measure the various parameters of myocardial mechanics, including longitudinal, circumferential, and radial shortening and torsion.[6],[8] On the other hand, speckle-tracking-based measures of LV strain are less affected by loading conditions, in addition, relatively less operator dependent and more reproducible than LVEF when performed by trained operators.[9]
Since strain analysis by speckle-tracking technology precisely assesses the deformation of every myocardial segment by tracking groups of intramyocardial speckles, it correlates to myocardial performance.[8] Ersbøll et al.[10] reported that myocardial global longitudinal function evaluated by global longitudinal strain (GLS) is significantly reduced in patients with heart failure in the setting of AMI, and the analysis suggests that impaired GLS is an indicator of new onset of heart failure in the acute stage of myocardial infarction.[10] STE-derived measurements of myocardial mechanics components and deformation have been validated against sonomicrometry and magnetic resonance imaging.[8]
This study is comparing the LV function in patients with acute STEMI who were managed with primary PCI against those who were treated with thrombolysis using tenecteplase (TNK). The primary outcome studied was the assessment of LV systolic function following primary PCI when measured by 2D GLS and conventional LVEF.
Materials and Methods Patients and study design
The study was conducted as a retrospective single-center observational study among the patients who presented with acute STEMI to our center. The study proposal was approved by the Dubai Scientific Research Ethics Committee (DSREC), Reference number: DSREC–01/2020_07.
Primary PCI was performed on the patients with acute STEMI if they presented to the emergency department within working hours. Otherwise, they have received pharmacological reperfusion therapy with TNK according to the international and (ASSENT)-3 PLUS trial protocol.[11] TNK was administered over 5–10 s according to the body weight with enoxaparin co-therapy as an intravenous bolus of 30 mg followed by 1 mg/kg subcutaneously twice daily for a maximum of 7 days.
Electrocardiogram (ECG) finding of STEMI was defined as new persistent ST-segment elevation of ≥0.1 mV in ≥2 limb leads or ≥0.2 mV in ≥2 contiguous precordial leads, or new left bundle branch block. LV systolic function was assessed within 72 h following coronary angioplasty by the independent operators using 2D STE as well as 2D LVEF estimated using the Simpsons biplane method. GLS was estimated by 2D STE using EchoPAC Software and Vivid E95 cardiac ultrasound scanner. Baseline data including patients' demographic profiles, past medical history and cardiovascular risk factor profile, ECG findings, laboratory data, clinical outcomes, and complications were collected from patient's electronic records.
The primary outcome studied was the assessment of LV systolic function following primary PCI when measured by 2D GLS and conventional LVEF.
Statistical analysis
The normal distribution of variables was verified with Kolmogorov–Smirnov and Shapiro–Wilk test. The categorical variables are presented as count and percentages (%), whereas the numerical variables are presented as mean ± standard deviations (SD). An independent-sample t-test of significance was used when comparing two means for continuous variables, whereas the Chi-square test or Fisher's exact test was used for categorical variables. The confidence interval was set to 95%. The P < 0.05 was considered to be statistically significant. Recorded data were analyzed using the statistical package for social sciences, version 23.0 software (SPSS Inc., Chicago, Illinois, USA).
Results The study included a total of 50 patients (mean age 53.7 years, 88% male) who presented with an acute STEMI to our department, and all of them received a form of reperfusion therapy either mechanical as primary PCI or TNK-based pharmacological reperfusion therapy. There were 25 patients in each arm; primary PCI and TNK arm. Overall, both groups were well-balanced in terms of their demographic and risk factor profile as shown in [Table 1]. At the time of presentation, although the majority (38%) presented with a thrombolysis in myocardial infarction (TIMI) risk score of two, Killip score of one (72%), and ECG changes suggestive of anterior wall STEMI (68%), there were no significant differences between two groups [Table 1]. The mean door-to-needle time was 29.8 ± 4.2 min in the TNK group, and the mean door-to-balloon time was 72.9 ± 15.4 min in the primary PCI group.
Coronary angiograms for the patients of the primary PCI group showed that the majority (52%) of the patients had single CAD and the minority (8%) had three-vessel disease [Table 2]. [Table 2] also shows that the left anterior descending artery was the most common culprit artery (68%) and 92% of the patient had a TIMI flow score of zero to one. Most of the patients (80%) had a TIMI flow score of three after coronary angioplasty and none had a TIMI flow score of zero to one [Table 2].
Table 2: Coronary angiogram findings for the primary percutaneous coronary intervention groupThe primary outcome of both LVEF (mean 42.2 ± 2.9 vs. 39.9 ± 2.7, P = 0.006) and GLS with 2D speckle-tracking (mean − 13.6 ± 1.4 vs. −10.3 ± 1.2, P ≤ 0.001) were significantly better in the primary PCI group as compared to the TNK group, respectively [Figure 1].
Figure 1: (a) Mean left ventricular ejection fraction between a PPCI and TNK groups. (b) Mean GLS between the PPCI and TNK groups. PPCI: Primary percutaneous coronary intervention, TNK: Tenecteplase, GLS: Global longitudinal strain. LVEF: Left ventricular ejection fractionAlthough the most common overall inhospital complications were heart failure (16%) and minor bleeding (10%), there were no significant differences between the two groups. There were no significant differences in other inhospital complications including death, arrhythmia, major bleeding, and stroke in both groups [Table 3].
Discussion This study is comparing the LV function among patients presenting with acute STEMI who were treated by primary PCI against those who were treated with medical reperfusion therapy using TNK. The primary outcome studied was the left ventricular systolic function following PCI, as assessed by 2D GLS and LVEF.
Although the number of patients in our study was relatively small, the results strikingly showed that they were rather young with male dominance and more than half of them have CAD risk factors such as diabetes mellitus, hypertension, dyslipidemia, and current smoking.
It is possible that the potential benefits of thrombolysis were obtained as the mean door-to-needle time was 29.8 ± 4.2 min in the TNK group, between symptom onset and administration of thrombolytic therapy. Similarly, the mean door-to-balloon time was 72.9 ± 15.4 min in the primary PCI group, which could have equally impacted the primary outcome. Despite that, the findings of our study have no impact on short-term mortality and inhospital complications, and that is probably due to the small number of patients. However, we demonstrated that the primary outcome of LV function measure by LVEF and GLS following primary PCI is better than successful thrombolysis with TNK. A broadly similar point has also been made by Paul and George.,[12] who showed that in patients with STEMI, the pharmacoinvasive strategy failed to determine the equivalence of efficacy with primary angioplasty in terms of the impact on LV function measured by GLS.
The noninvasive assessment of ventricular function remains central to modern cardiology. Estimation of LV systolic function is the core of risk assessment and therapeutic decisions that are related to the myocardial performance of patients with acute AMI. Hence, it is recommended that the LVEF is identified before hospital discharge in all STEMI patients.[1] Although its potential limitations in certain circumstances, routine echocardiography after primary PCI is recommended to assess resting LV function and to exclude early postinfarction mechanical complications and LV thrombus.[1]
Segmental myocardial deformation of the LV in a 16-segment model can be measured directly with speckle-tracking strain. The average deformation of LV is expressed as GLS.[8]
A study by Karlsen et al.[13] demonstrates that GLS is a more reproducible method for the evaluation of LV systolic function than LVEF regardless of echocardiographic training.[13] These results reflect those of Negishi et al.[14] who also found a favorable interobserver agreement of GLS among various readers. The findings of these studies support the feasibility of the clinical use of GLS as a supplementary and incremental diagnostic tool in specific myocardial diseases. Furthermore, make GLS more agreeable than LVEF for follow-up of LV function by multiple observers.
When performed at rest, 2D strain echocardiography is capable to predict CAD in patients with stable angina pictures, and both lesion-specific regional longitudinal peak systolic strain and GLS are reduced.[15] Furthermore, relative apical sparing has been noticed in the left main stenosis compared with one or two-vessel CAD despite similar GLS.[15] This also accords with earlier observation, which showed that peak systolic longitudinal strain is significantly lower in patients with severe CAD including left main or three CAD.[16]
The addition of resting GLS to stress electrocardiography and conventional echocardiographic clues in patients with stable CAD improves the prediction of severe CAD.[15]
Non-ST-segment elevation acute coronary syndromes stay a diagnostic challenge because occluded vessels, especially in the posterior circulation, may not produce typical ST-segment elevation in resting ECG, and cardiac biomarkers could not accurately identify patients with acute coronary artery occlusions. A prior study has noted the importance of LV strain study by STE as a technique to identify an acute coronary occlusion in the patients suspected to have non-ST-segment elevation acute coronary syndromes, although ECG and cardiac markers failed to do so.[17] In addition, GLS was found to be better than routine echocardiogram parameters in excluding significant CAD in patients with non-ST-segment elevation acute coronary syndrome with a negative predicted value of 92%, with excellent feasibility of the strain measurements.[18] It is possible, therefore, that the measurement of myocardial strain by STE may assist clinicians in excluding substantial coronary artery stenosis and thereby permit early discharge.
Prognosis after AMI is mostly determined by the LV infarction area and subsequent LV function. Compared with LVEF, GLS has several advantages in the evaluation of LV function, prediction of infarct size, and ability to act as an indicator of residual segmental myocardial viability after AMI.[19],[20] These results seem to be consistent with other earlier research which found reduced GLS independently predicts LV infarct mass with sensitivity and specificity of 83% and 93%, respectively, when assessed by contrast-enhanced magnetic resonance imaging.[21] GLS showed prognostic benefit over traditional LV function assessment after AMI. Following AMI, a strong significant relationship between GLS and outcomes including all-cause mortality and cardiovascular composite endpoints, namely, nonfatal reinfarction, coronary revascularization, and hospitalization for heart failure have been reported in the literature.[22] Moreover, GLS can expect the recovery of LV function at a 1-year follow-up.[20] Hence, GLS with 2D speckle-tracking preferable and recommended GLS to be measured before hospital discharge after AMI.
Limitations
This study is a single-center experience with relatively a small sample size and only showed GLS analysis using an automatic functional imaging method.
Conclusion Global LV systolic function is significantly better after primary coronary angioplasty as compared to TNK -based pharmacological reperfusion therapy when assessed by routine LVEF and 2D GLS. The study demonstrates that GLS is a more reproducible method for the evaluation of LV systolic function than LVEF and probably could add more value to the traditional LVEF for the assessment of LV function in the setting of AMI.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
References 
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