Narrowing filtered QRS duration on signal-averaged electrocardiogram predicts outcomes in cardiac resynchronization therapy patients with nonischemic heart failure.

Abstract

To evaluate the impact of changes in the filtered QRS duration (fQRS) on signal-averaged electrocardiograms (SAECGs) from pre- to postimplantation on the clinical outcomes in nonischemic heart failure (HF) patients under cardiac resynchronization therapy (CRT). We studied 103 patients with nonischemic HF and sinus rhythm who underwent CRT implantation. SAECGs were obtained within 1week before and 1week after implantation and narrowing fQRS was defined as a decrease in fQRS from pre- to postimplantation. Echocardiography was performed before and 6months after CRT implantation. The primary outcome was death from any cause. The secondary outcomes were hospitalization due to worsened HF and occurrence of ventricular tachyarrhythmias. Of the 103 CRT patients, 53 (51%) showed narrowing fQRS. Left ventricular end-diastolic volume and end-systolic volume were significantly reduced (both p<.001), and the left ventricular ejection fraction was significantly increased (p<.001) after CRT in patients with narrowing fQRS, but not in patients with nonnarrowing fQRS. During a median follow-up period of 33months, patients with narrowing fQRS exhibited better survival than patients with nonnarrowing fQRS (p=.007). A lower incidence of hospitalization due to worsened HF (p<.001) and a lower occurrence of ventricular tachyarrhythmias (p=.071) were obtained in patients with narrowing fQRS. After adjusting for confounding variables, narrowing fQRS was associated with a low risk of mortality (HR 0.27, p=.006). Our results suggested that narrowing fQRS on SAECG after CRT implantation predicts LV reverse remodeling and long-term outcomes in nonischemic HF patients.