Impact of QRS duration on left ventricular remodelling and survival in patients with chronic heart failure

Background In patients with chronic heart failure, QRS duration is a consistent predictor of poor outcomes. It has been suggested that for indicated patients, cardiac resynchronisation therapy (CRT) could come sooner in the treatment algorithm, perhaps in parallel with the attainment of optimal guideline-directed medical therapy (GDMT). We investigated differences in left ventricular (LV) remodelling in those with narrow QRS (NQRS) compared to wide QRS (WQRS) in the absence of CRT, whether an early CRT strategy resulted in unnecessary implants and the effect of early CRT on outcomes. Methods and results Our cohort consisted of 214 consecutive patients with LV ejection fraction (LVEF) ≤35% who underwent repeat echocardiography 1-year after enrolment. Of these, 116 patients had NQRS, and 98 had WQRS of whom 40 received CRT within 1-year and 58 did not. In the absence of CRT patients with WQRS had less LV reverse remodelling compared to those with NQRS, with differences in ΔLVEF (+9% vs 2 %, p<0.001), ΔLV end-diastolic diameter (-2mm vs -1mm, p=0.095) and ΔLV end-systolic diameter (-4.5mm vs -2mm, p=0.038). LVEF was more likely to improve by ≥10% if patients had NQRS or received CRT (p=0.08). Thirteen (24%) patients with WQRS achieved an LVEF >35% in the absence of CRT, however none achieved >50%. Conclusions A strictly linear approach to HF therapy might lead to delays to optimal treatment in those patients with the most to gain from CRT and the least to gain from GDMT.