Ergometric Findings in Asymptomatic Chagasic Patients, With Normal ECG and Without Evident Heart Disease

pp 471-477

Abstract

Background
Dysautonomia and QT interval dispersion are one of the earliest manifestations of Chagas disease which have proved to be predictors of increased morbi-mortality. New diagnostic technologies revealing earlier endothelial or dysautonomic disorders should provide better diagnostic and treatment strategies for the premature detection of patients with risk of developing chronic chagasic cardiomyopathy or sudden death.

Objectives
The aims of this study were: 1) To investigate clinical, electrocardiographic and ergometric characteristics in asymptomatic chagasic patients with normal electrocardiogram and no clinical evidence of the pathology. 2) To compare graded exercise testing results between chagasic patients and subjects with similar clinical characteristics but negative serological tests for Chagas.

Methods
This retrospective, observational study included 74 chagasic patients and 28 healthy subjects who underwent exercise testing during clinical check-up between March 2009 and September 2011.

Results
Chagasic patients often presented baseline heart rate £ 60 bpm (27.0% vs. 7.1%, p=0.02), lower maximal heart rate (129.5±22.8 vs. 145.2±16.5 bpm; p=0.002), prevalence of chronotropic incompetence, with maximum heart rate <80% pre-established value (47.3% vs. 14.3%; p=0.001) and higher rate of ventricular arrhythmias during exercise and recovery (25.7% vs. 0%; p=0.003). While in the control group patients the QTc interval shortened normally during exercise, in most chagasic patients it was noticeably prolonged (Chagas group: 412.1 to 432.8 ms; p = 0.0005; control group: 412.4 to 385.8 ms; p<0.0001).

Conclusions
Asymptomatic chagasic patients without verifiable heart disease showed a high prevalence of dysautonomia, such as chronotropic incompetence and QTc interval prolongation during exercise. Stress testing is a noninvasive, reliable and relatively inexpensive diagnostic method that can contribute to the early diagnosis of dysautonomic and ventricular repolarization disorders and thus identify patients with Chagas disease who are at increased risk of arrhythmogenic sudden death.