Myocardial Deformation Imaging Meta-Analysis in Two Cohorts of Patients from UAE and Heart Hospital Hamadmedical Corporation: A Potential Role in Assessment of Coronary Artery Disease Severity and Myocardial Viability

Abstract

Introduction: The increasing prevalence of heart failure (HF) in coronary artery disease (CAD) urgently requires the establishment of new imaging techniques for early diagnosis and also to guide treatment of patients presented with acute coronary syndromes (ACS). Conventional echocardiography (CE) and electrocardiogram (ECG) are the gold standard methods in assessing myocardial ischemia (MI) and the function of the heart in patients with coronary artery disease (CAD). The lack of ST elevation by ECG and regional wall motion abnormalities by CE in non-ST segment elevation myocardial infarction (NSTEACS) in ACS patients reflect limited sensitivity of ECG and CE in identifying patients with acute coronary occlusion (ACO) and proper assessment of myocardial viability.
Aim of this study: This study now evaluates the ability of strain parameters in grading the severity of CAD to detect myocardial viability in ACS through a comparative meta-analysis in two cohorts of patients living in the UAE and Qatar. The study investigates the diagnostic accuracy of left ventricular longitudinal systolic strain function (GLS) by 2D-speckle tracking echocardiography (2D-STE), Territorial Longitudinal Strain (TLS) analysis and post systolic strain (PSS) in ACS patients admitted at the emergency departments. All the patients had acute chest pain which is highly suggestive of NSTEACS along with coronary angiography (CA).
Methods: The study recruited two groups, comprising of 347 patients, who were presented with acute coronary syndrome (NSTEACS) at the emergency department. The first group had 214 consecutive patients who had acute chest pain and high-risk profile and they were admitted to the emergency department at Eastern Emirates Hospitals, El-Fujairah-Dibba (EEEH), UAE. The second group consisted of 133 from emergency department at Heart Hospital- Hamad Medical Corporation (HHHMC), Qatar. In both groups, 85% of the patients were men with ages from 32 to 65 years (mean ± SD: 49.4 ± 9.5 years). Significant CAD was defined as having at least one epicardial vessel with ≥ 70% or left main>50% stenosis. All patients enrolled in this study underwent basic echocardiography, speckle tracking analysis, and coronary angiography. In 70 patients, PSS was calculated and myocardial perfusion imaging (MPI) was utilized as gold standards for the assessment of myocardial viability in patients with documented NSTEACS.
The sensitivity, specificity, positive and negative predictive values of peak longitudinal systolic strain (2D-STE) and PSS were calculated. Left ventricular systolic strain was displayed as bull’s eye plot and territorial longitudinal strain (TLS) in the territory of the infarct-related artery. They were obtained within 24 hours from admission. Coronary angiography (CA) was performed within 24 hours from admission and used as a reference tests to assess the severity of CAD.
Results: Echocardiogram obtained from the patients showed any no wall motion abnormalities at rest, although speckle tracking analysis was abnormal in 167 patients. In the first group of patients from the UAE, GLS showed a high sensitivity of 80% and a very high specificity of 93% for detection of significant CAD. In addition, PSS demonstrated a high sensitivity of 80% with an average specificity of 57%. The combination of GLS and PSS showed a further increase in sensitivity, specificity with positive and negative predictive values of 98%, 91%, 99% and 97%, respectively. Therefore, a very high correlation of GLS and PSS with coronary angiography was demonstrated: =0.90, p<0.0001 and R=0.88, p<0.0001, respectively. Furthermore, PSS showed a very high concordance with MPI scan (stress-rest-re injection studies) in detection of ischemic viable myocardium with very high sensitivity of 85%, r=0.79. In the Qatari (HHHMC) patients, a multi-vessel disease or left main disease (MV) was documented in 53.6%, and those with single vessel disease (SV) in 46.4%. LAD, circumflex and RCA lesions were found in 65, 50 and 39 patients, respectively. A control group of 129 cases was selected from outpatients referred to the echocardiography unit. The results showed that in comparison to CA, GLS sensitivity and specificity were 84% and 70%, respectively in all the patients. The sensitivity of GLS was 87% in MV and 80% in SV. Territorial strain sensitivity was 50%, 74% and 84.6% for the left anterior descending artery (LAD), circumflex and right coronary artery (RCA), respectively compared to specificity values of 64%, 65% and 61.7%, respectively.
Conclusion: It is concluded that GLS by speckle tracking analysis is definitely an accurate method in early diagnosis of the severity of CAD in patients presenting with NSTE ACS. The combined use of GLS and PSS showed very high diagnostic accuracy for the identification of significant CAD in these patients. Strain imaging by STE may be applied to diagnose the severity of myocardial ischemia by showing reduction in peak systolic strain. Moreover, it is equally important to demonstrate post-systolic shortening which is a characteristic feature of ischemic viable myocardium after ACS requiring revascularization.