Association between ventricular arrhythmias and myocardial mechanical dispersion assessed by strain analysis in patients with nonischemic cardiomyopathy.

Background: Mechanical dispersion (MD), defined as the standard deviation of time to maximum myocardial shortening assessed by 2D speckle tracking echocardiographic strain imaging (2DS), has been recently proposed as a predictor for ventricular tachycardia or fibrillation (VT/VF) in patients with ischemic cardiomyopathy and long QT syndrome. However, the role of MD in patients with non-ischemic cardiomyopathy (NICM) has not yet been studied. Methods and results: In 20 patients with NICM (mean age 62 ± 11 years, 75 % male, mean EF 32 ± 6 %, mean QRS duration 102 ± 14 ms), we measured longitudinal strain by 2DS in a 16-segment left ventricular model and calculated the MD. Patients were divided into two groups, defined by the presence or absence of documented VT/VF. In 11 patients (55 %), VT/VF was documented. The median time from VT/VF to echocardiographic examination was 26 (IQR 15-58) months. There were no significant differences in baseline characteristics between patients with and without index events. MD was significantly greater in patients with VT/VF as compared to those without arrhythmias (84 ± 31 ms vs. 53 ± 16 ms, p = 0.017). The analysis of the ROC curve (AUC 0.81, 95 % CI 0.63-1.00, p = 0.017) revealed that dispersion >50 ms is associated with twelve times higher risk of VT/VF in patients with NICM (OR 12.5, 95 % CI 1.1-143.4, p = 0.024). Conclusions: In this small cohort of NICM patients, greater MD was associated with a higher incidence of VT/VF. [ABSTRACT FROM AUTHOR]