Introduction
Randomized controlled trials supports the clinical efficacy and safety of cardiac resynchronization therapy (CRT) in patients with moderate or severe heart failure and ventricular dyssynchrony.1-2Guidelines from international cardiology societies provide strong recommendations for CRT specially in symptomatic patients with left bundle branch block (LBBB) and a QRS duration >150ms.3 However, some questions remain about its effectiveness in specific etiologies, such as Chagas Cardiomyopathy (CC), since most of the published trials about on the subject did not include a significant number of this population.
Upgrade for a CRT from a conventional pacemaker have become increasingly common in HF patients, since right ventricular pacing may aggravate left ventricular function.4 Despite this, there are still concerns about this practice, considering that the decision to proceed to upgrade is supported by small observational studies. Recent studies suggest that clinical response and survival are impaired in patients undergoing CRT upgrade compared to de novo implantations.5-6
Thus, the aim of this study is to compare the short-term mortality between upgrade and de Novo CRT implantation in a population with heart failure and clinical indication for this device, comparing its results between individuals with Chagas Cardiomyopathy and not.