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.