Ventricular conduction abnormalities and associated outcome among reduced ejection fraction to mid-range heart failure patients

Abstract

Intra-ventricular conduction blocks can impair prognosis of heart failure (HF), but their specific impact is not well established, sometimes even controversial. This study aimed to analyse the clinical profile and outcomes of HF patients with left bundle branch block (LBBB), right bundle branch block (RBBB), IVCD (intra-ventricular conduction delay) and left anterior fascicular block (LAFB). A total of 187 patients with reduced ejection fraction to mid-range HF, were enrolled in this study. They were sub grouped within their electrical morphology into respectively: LBBB (24%), RBBB (7.5%), IVCD (8%), LAFB (10.5%) and narrow QRS (< 110ms; 43.5%). We analyzed their baseline clinical variables and outcomes after a median follow-up of 22 months [IQR:10–33]. Survival was assessed using multiple Cox regression analysis. LBBB was associated with more marked LV dilation ( P = 0.018). Patients with RBBB, presented overt signs of congestive HF ( P = 0.045) and depressed right ventricular motion ( P = 0.019). Those with IVCD, had intermediate echocardiographic characteristics between LBBB an RBBB. The LAFB group reported more history of coronary heart disease ( P = 0.029). Death occurred in 57 patients. Univariate survival analyses, showed that patients with RBBB had higher risk of cardiac death and pump failure readmissions in comparison to LBBB ( P = 0.023); and narrow QRS (all-cause mortality: P = 0.01; pump failure readmissions: P = 0.009). After multiple covariate adjustment, RBBB was an independent risk factor for all-cause mortality ( P = 0.047). HF patients presenting with intra-ventricular conduction blocks had significantly different clinical profiles. RBBB had greater clinical severity and was associated with higher risk of mortality and pump failure re-hospitalization and was an independent predictor of all-cause mortality. LBBB had more severe echocardiographic characteristics but in contrast, did not predict worse outcome.