Association of persistent or worsened echocardiographic dyssynchrony with unfavourable clinical outcomes in heart failure patients with narrow QRS width: a subgroup analysis of the EchoCRT trial.

Aims: EchoCRT was a randomized trial of cardiac resynchronization therapy (CRT) in severely symptomatic heart failure (HF) patients with narrow QRS width <130 ms, ejection fraction ≤35%, and echocardiographic dyssynchrony. All received CRT implants which were then randomized to CRT-On or CRT-Off. While the trial showed no benefit of CRT to these patients, the aim of this subgroup analysis was to test the hypothesis that persistent or worsening dyssynchrony is associated with unfavourable clinical outcomes.

Methods And Results: We studied 614 EchoCRT patients with baseline and 6-month echocardiograms. Baseline dyssynchrony required for study inclusion was either tissue Doppler imaging longitudinal velocity delay ≥80 ms or speckle-tracking radial strain delay ≥130 ms. Persistent dyssynchrony at 6 months was observed similarly in both groups (77% in CRT-On; 76% in CRT-Off). Persistent dyssynchrony was associated with a significantly higher primary end point of death or HF hospitalization (HR = 1.54, 95% CI 1.03-2.30, P = 0.03), and in particular secondary endpoint of HF hospitalization (HR = 1.66, 95% CI 1.07-2.57, P = 0.02). HF hospitalizations were also associated with worsening longitudinal dyssynchrony (HR = 1.45, 95% CI 1.02-2.05, P = 0.037), and worsening radial dyssynchrony (HR = 1.81, 95% CI 1.16-2.81, P = 0.008). Associations of persistent or worsening dyssynchrony with outcomes were similar in CRT-Off and CRT-On groups.

Conclusions: Persistent or worsening echocardiographic dyssynchrony in HF patients with narrow QRS width was a marker for unfavourable clinical outcomes unaffected by CRT. In particular, echocardiographic dyssynchrony on follow-up was strongly associated with HF hospitalizations and appears to be a prognostic marker of disease severity.