Reduced left ventricular mechanical dispersion at 6 months follow-up after cardiac resynchronization therapy is associated with superior long-term outcome

Abstract

Background: In heart failure (HF) patients, left ventricular mechanical dispersion (LVMD) reflects heterogeneous mechanical activation of the left ventricle. In HF patients, LVMD can be reduced after CRT. Whether lesser LVMD is associated with improved outcome is unknown.

Objective: The purpose of this study was to relate LVMD to long-term prognosis in a large cohort of HF patients after 6 months of cardiac resynchronization therapy (CRT).

Methods: Clinical, echocardiographic, and ventricular arrhythmia (VA) data were analyzed from an ongoing registry of HF recipients of CRT. Baseline (before CRT) and 6-month echocardiograms were evaluated. LVMD was calculated as the standard deviation of the time from onset of the QRS complex to the peak longitudinal strain in a 17-segment model. Patients were divided into 2 groups according to the median LVMD (84 ms) at 6 months post-CRT.

Results: Of 1185 patients (mean age 65 ± 10 years; 76% male), 343 (29%) died during a mean follow-up of 55 ± 36 months. Baseline LVMD was not associated with all-cause mortality and VA at follow-up. In contrast, patients with less LVMD (≤84 ms) at 6 months post-CRT had lower event rates (VA and mortality) compared to those with LVMD >84 ms. On multivariable analysis, greater LVMD at 6 months after CRT was independently associated with an increased risk of mortality (hazard ratio 1.002; P = .037) and VA (hazard ratio 1.003; P = .026).

Conclusion: Larger LVMD at 6 months after CRT is independently associated with all-cause mortality and VA. LVMD may be valuable in identifying patients who remain at high mortality risk after CRT implantation.

Keywords: Cardiac resynchronization therapy; Heart failure; Mechanical dispersion; Prognosis; Speckle tracking.