STI Assessment of Left Ventricular Function in Patients With Previous Myocardial Infarction and Recurrent Ventricular Arrhythmias

Purpose. Our aim was to compare strain parameters of patients with structural heart disease with and without ventricular tachycardia (VT) in order to identify high-risk patients that could have been missed by left ventricular ejection fraction (LVEF) criteria. Methods. We studied 86 patients (pts) with previous myocardial infarction (age, 59±14 years) scheduled for cardioverter-defibrillator (ICD) implantation. Forty-three pts had documented VT and 43 pts presented with no VT. Left ventricular (LV) function and volumes and score index were determined by two-dimensional echocardiography. Longitudinal LV strain was defined as the average of negative longitudinal strains of 6 segments of the septal and lateral walls in the apical 4-chamber view. Average radial and circumferential strain of 6 mid-LV segments was determined in the mid-short-axis view. Global strain was obtained by averaging the maximum systolic shortening in a 16-segment model. The analysis of strain parameters was performed offline using customized computer software (EchoPAC BT09, GE Ultrasound). Results. There were no differences in LVEF, LV volumes, QRS and QTc duration between pts with or without VT occurring during follow-up. Multivariate analysis revealed that global (p=0.018) and posterior wall circumferential strain (p=0.007) were strong and independent predictors of the occurrence of arrhythmic events. The area under the curve (AUC) for posterior wall circumferential strain was 0.79 and the optimal cutoff value -6.2% for a sensitivity of 71% and a specificity of 89% in predicting arrhythmic events. AUC for QTc was 0.32 yielding a sensitivity and specificity of, respectively, 49% and 65% to predict arrhythmias and AUC for EF was 0.51 yielding a sensitivity and specificity of, respectively, 56% and 70%. Conclusions. Circumferential strain was the strongest predictor of spontaneous ventricular arrhythmias among other clinical and echocardiographic variables such as score index and LV function and volumes in patients with previous myocardial infarction scheduled for ICD therapy.