Background: In survivors of myocardial infarction (MI), new left bundle branch block (LBBB) is associated with adverse outcomes, but its impact is not well described in post-MI patients with left ventricular (LV) systolic dysfunction and/or heart failure (HF).
Objectives: The aim of this study was to determine if new LBBB is an independent predictor of long-term fatal and nonfatal outcomes in high-risk survivors of MI by reviewing data from the VALsartan In Acute myocardial iNfarcTion (VALIANT) trial.
Methods: In VALIANT, 14,703 patients with LV systolic dysfunction and/or HF were randomized to valsartan, captopril, or both a mean of 5 days after MI. Baseline ECG data were available from 14,259 patients. We assessed the predictive value of new LBBB for death and major cardiovascular outcomes after 3 years, adjusting for multiple baseline covariates including LV ejection fraction.
Results: At follow-up, patients with new LBBB (608 [4.2%]) compared with patients without new LBBB had more comorbidities and increased adjusted risk of death (hazard ratio [HR] 1.3, 95% confidence interval [CI] 1.2-1.6), cardiovascular death (HR 1.4, 95% CI 1.2-1.7), HF (HR 1.3, 95% CI 1.1-1.6), MI (HR 1.5, 95% CI 1.2-1.9), and the composite of death, HF, or MI (HR 1.4, 95% CI 1.2-1.6).
Conclusion: In post-MI survivors with LV systolic dysfunction and/or HF, new LBBB was an independent predictor of all major adverse cardiovascular outcomes during long-term follow-up. This readily available ECG marker should be considered a major risk factor for long-term cardiovascular complications in high-risk patients after MI.