Abstract 11932: Mechanical Dispersion Predicts Ventricular Arrhythmias After Myocardial Infarction
Introduction Prediction of ventricular arrhythmias after myocardial infarction (MI) is still insufficient. LV ejection fraction (EF) <35% serves as the main criterion for selecting patients for ICD therapy. However, the majority of patients dying suddenly after MI have EF >35%. Mechanical dispersion by strain echocardiography reflects inhomogeneous timing in myocardial contraction and has been shown to predict ventricular arrhythmias. We hypothesized that mechanical dispersion may improve arrhythmic risk stratification in post MI patients.
Methods In this prospective multi center study we included 177 post MI patients (114 ST elevation and 63 non-ST elevation). Echocardiography was performed minimum 40 days post MI. Time from ECG R to peak negative strain was assessed in 16 longitudinal LV segments. Mechanical dispersion was assessed as the standard deviation from these 16 time intervals, reflecting contraction heterogeneity.
Results Ventricular arrhythmias defined as sustained VT, VF or sudden death during 33(14-76) months of follow up occurred in 8 (4.5%) patients. Mechanical dispersion was higher in patients with arrhythmic events (68±18ms vs. 38±18ms, p<0.001) and, as expected, EF was lower (47±15% vs. 55±9%, p=0.03). In those with EF>35% (n=172), mechanical dispersion was higher in those with arrhythmic events (63±19ms vs. 38±18ms, p=0.001) while EF did not differ (54±9% vs. 55±8%, p=0.76). By logistic regression, mechanical dispersion predicted arrhythmic events independently of EF (OR 2.1(95%CI 1.3-3.4) per 10ms increase (p=0.001). By ROC analyses, mechanical dispersion was superior to EF in identifying arrhythmic events (Figure).
Conclusions Mechanical dispersion by strain echocardiography predicted arrhythmic events independently of EF in post MI patients. Mechanical dispersion can identify patients for ICD therapy who do not fulfill current indications for primary ICD (EF>35%).
- © 2011 by American Heart Association, Inc.