New-onset left bundle branch block independently predicts long-term mortality in patients with idiopathic dilated cardiomyopathy: data from the Trieste Heart Muscle Disease Registry.

AIMS: Left bundle branch block (LBBB) is commonly associated with heart failure. We evaluated the prevalence, incidence, and impact of LBBB on long-term outcome in young patients with heart failure affected by idiopathic dilated cardiomyopathy (DCM).

METHODS AND

RESULTS

We included 608 patients with DCM from the Heart Muscle Disease Registry of Trieste in this retrospective analysis. At baseline electrocardiogram (ECG), 189 patients (31.1%) had LBBB. The patients with baseline LBBB had a significantly higher mortality rate than the patients without LBBB (38.6 vs. 27.9%, P = 0.002) at the univariate analysis. After a multiple covariate adjustment, the baseline LBBB was not associated with a significantly increased risk of death [hazard ratio (HR) 1.27, 95% confidence interval (CI): 0.88-1.81, P = 0.2]. Forty-seven (11.2%) patients without LBBB at baseline ECG developed LBBB during follow-up. Among these, the mortality rate was 49 vs. 25% in patients without new-onset LBBB (P = 0.001). New-onset LBBB was a strong and independent predictor of all-cause mortality (HR 3.18, 95% CI: 1.90-5.31, P < 0.001) at multivariate analysis.

CONCLUSION

After correcting for potential confounders, new-onset LBBB was found to be associated with an increased risk of all-cause mortality. The management of patients with new-onset LBBB may need to be more aggressive, possibly including early cardiac resynchronization therapy/implantable cardioverter-defibrillator therapy.