ABSTRACT
Background: Cardiac resynchronization therapy (CRT) improves
outcomes in heart failure (HF) patients with left bundle branch block
(LBBB). However, the benefits of CRT in patients with previous pacing
are still uncertain. The aim is to compare the short-term mortality
between upgrade and De novo-CRT implantation.
Methods: Prospective cohort study that included HF patients
indicated for CRT with left ventricular ejection fraction (LVEF) of less
than 35%. Data were collected to investigate mortality predictors after
1 year. The overall survival was calculated by the Kaplan-Meier method
and multivariate analysis using Cox’s regression model was performed. A
value of p<0.05 was considered as significant.
Results: 93 patients were evaluated with a mean follow-up of
1.0±0.6year. Of these, 22 (23.7%) were upgraded from right ventricular
pacing. Chagas Disease (CD) was the most prevalent cause of HF with 29
(31.2%) individuals. LVEF at 6 months increased after CRT: 24,0%±7.8
to 30.3%±11.5, p=0.007, and there was no difference between upgraded
patients and De novo CRT, p=0.26. Overall mortality at 1-year was 30.1%
(28 patients). In univariate analysis, CD and upgraded therapy were
associated with high mortality, HR: 3.9, CI 1.8-8.4, p=0.001 and HR:
4.7, CI: 2.2-9.9, p<0.001, respectively. In the multivariate
model, only upgraded therapy remained independently associated with the
outcome, adjusted HR: 2.9, CI 1.2-7.2, p=0.02.
Conclusion: In this specific HF population, with a high
prevalence of chagas cardiomyopathy, upgraded therapy was independently
associated with worsened 1-year survival after CRT implantation.
Key words: implantable cardioverter-defibrillator,
resynchronization therapy, heart failure, left bundle branch block,
Chagas’s cardiomyopathy.