Mechanical dispersion is associated with poor outcome in heart failure with a severely depressed left ventricular function and bundle branch blocks

Objectives: Bundle branch blocks (BBB)-related mechanical dyssynchrony and dispersion may improve patient selection for device therapy, but their effect on the natural history of this patient population is unknown.Methods: A total of 155 patients with LVEF ≤ 35% and BBB, not treated with device therapy, were included. Mechanical dyssynchrony was defined as the presence of either septal flash or apical rocking. Contraction duration was assessed as time interval from the electrocardiographic R-(Q-)wave to peak longitudinal strain in each of 17 left ventricular segments. Mechanical dispersion was defined as either the standard deviation of all time intervals (dispersionSD) or as the difference between the longest and shortest time intervals (dispersiondelta). Patients were followed for cardiac mortality during a median period of 33 months.Results: Mechanical dyssynchrony was not associated with survival. More pronounced mechanical dispersiondelta was found in patients with dyssynchrony than in those without. In the multivariate regression analysis, patients’ functional class, diabetes mellitus and dispersiondelta were independently associated with mortality.Conclusions: Mechanical dispersion, but not dyssynchrony, was independently associated with mortality and it may be useful for risk stratification of patients with heart failure (HF) and BBB.Key MessagesMechanical dispersion, measured by strain echocardiography, is associated with poor outcome in heart failure with a severely depressed left ventricular function and bundle branch blocks.Mechanical dispersion may be useful for risk stratification of patients with heart failure and bundle branch blocks.