The prevalence and incidence of left bundle branch block in ambulant patients with chronic heart failure

Abstract Background Approximately one third of patients with chronic heart failure have left bundle branch block (LBBB) on their 12‐lead ECG. Methods and results 1418 consecutive patients (average (SD) age 70.5 (10.4) years; 74% male) first seen in a community heart failure clinic between December 2001 and June 2006 had a 12 lead electrocardiogram (ECG). 485 (34%) had a QRS duration ≥ 120ms. Patients with a broad QRS were older (72.2 v 69.3years), had worse left ventricular systolic function, were on a higher daily dose of diuretic and were more likely to be on amiodarone (14.4 v 7.1%). 12 lead ECG was available for 734 patients (52%) at 1year follow up. The QRS interval increased from 115.1ms at baseline to 117.6 ( P <0.0001). There were 52 incident cases of LBBB, an incidence of 10.9%. The only predictors of incident LBBB were QRS duration at baseline and amiodarone use at baseline. The proportion of patients with LBBB increased from 34.0% at baseline to 36.7%, 37.7% and 42.3% at 1, 2 and 3 years follow up, respectively. Baseline LBBB was associated with a worse outcome (HR 1.25 (95% CI 1.01–1.55). New LBBB was an independent adverse prognostic feature (HR 2.09 (95% CI 1.17–3.73); P =0.013). Conclusions The crude incidence of LBBB is 10.9% in the first year of follow up in an unselected population of ambulatory outpatients with chronic stable heart failure. Ongoing care of patients with chronic heart failure should include a regular 12 lead electrocardiogram.