Abstract 1881: Association of New-Onset Left Bundle Branch Block with Cardiovascular Morbidity and Mortality in Hypertensive Patients with Left Ventricular Hypertrophy: The LIFE study
Background: Whether new-onset left bundle branch block (LBBB) is associated with increased cardiovascular morbidity and mortality in treated hypertensive patients is unknown.
Object: To assess cardiovascular morbidity and mortality associated with new-onset LBBB in the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study among hypertensive patients with electrocardiographic left ventricular hypertrophy (LVH).
Methods: Hypertensive patients with LVH by Cornell voltage-duration product or Sokolow-Lyon voltage criteria on screening electrocardiograms were randomized to a mean of 4.8 years of losartan- or atenolol-based treatment. electrocardiograms were read at a central laboratory; Minnesota code 7.1 identified LBBB. Only participants without LBBB on LIFE study baseline electrocardiograms were included in the current study.
Results: The electrocardiograms in LIFE study annual follow-up evaluations identified 296 patients (143 or 48.3% women) with and 8277 patients (4458 or 53.9% women) without new-onset LBBB. New-onset LBBB was associated with older age (70.0±6.2 vs. 67.3±7.0 years), higher sex-adjusted Cornell voltage (30.7±7.9 vs. 27.2±7.1) and higher prevalence of cardiovascular disease (35.8% vs. 24.2%)(all p<0.005). During LIFE study follow-up, new-onset LBBB was associated with higher rates of the composite endpoint (18.2% vs. 11.6%), myocardial infarction (7.8% vs. 4.1%), congestive heart failure (33.6% vs. 11.8%) and cardiovascular mortality (7.4% vs. 4.4%) (all p<0.05). After adjusted for significant confounders, Cox regression analyses showed that hypertensive patients with new-onset LBBB had significantly greater risk of developing congestive heart failure (hazard ratio:2.33, 95% confidence interval:1.59–3.40, p<0.001) and myocardial infarction (hazard ratio:1.62, 95% confidence interval:1.03–2.56, p<0.05).
Conclusion: Among hypertensive patients with electrocardiographic LVH, new-onset LBBB independently identifies those at increased risk of developing subsequent congestive heart failure and myocardial infarction.