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, important questions still remain about the clinical application of this therapy in specific populations.
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, concerns persist as this conduct is supported by small and observational studies. In this sense, recent evidences suggest that clinical response and survival are impaired in patients undergoing CRT upgrade compared to de novo implantations.5,6
Chagas disease (CD) cardiomyopathy remains a prevalent cause of HF in Latin America, despite this, it is underrepresented in most CRT-trials. It is well established that CD patients had a worse prognosis compared to other HF etiologies, and recent studies suggests that these patients also have a higher short-term mortality rate after CRT.7,8 As the need for a pacemaker implantation is common in the course of CD cardiomyopathy, and since LBBB is relatively rare in this patients, an expected higher incidence of upgrade-CRT implantation in this population might play a role in worsening the outcomes.
Thus, the aim of this study is to compare the short-term mortality between upgrade and de Novo-CRT implantation in a heart failure population where Chagas disease is endemic.