Exercise-induced ventricular arrhythmias and vagal dysfunction in Chagas disease patients with no apparent cardiac involvement

INTRODUCTION : Exercise-induced ventricular arrhythmia (EIVA) and autonomic imbalance are considered as early markers of heart disease in Chagas disease (ChD) patients. The objective of the present study was to verify the differences in the occurrence of EIVA and autonomic maneuver indexes between healthy individuals and ChD patients with no apparent cardiac involvement. METHODS : A total of 75 ChD patients with no apparent cardiac involvement, aged 44.7 (8.5) years, and 38 healthy individuals, aged 44.0 (9.2) years, were evaluated using echocardiography, symptom-limited treadmill exercise testing and autonomic function tests. RESULTS : The occurrence of EIVA was higher in the chagasic group (48%) than in the control group (23.7%) during both the effort and the recovery phases. Frequent ventricular contractions occurred only in the patient group. Additionally, the respiratory sinus arrhythmia index was significantly lower in the chagasic individuals compared with the control group. CONCLUSIONS : ChD patients with no apparent cardiac involvement had a higher frequency of EIVA as well as more vagal dysfunction by respiratory sinus arrhythmia. These results suggest that even when asymptomatic, ChD patients possess important arrhythmogenic substrates and subclinical disease. .

Relação entre a fração de ejeção do ventrículo esquerdo e razão e/e' com a capacidade funcional na cardiopatia chagásica / Relationship between left ventricular ejection fraction and e /e' ratiowith functional capacity in chagas heart disease

Introdução: disfunção ventricular e capacidade funcional são importantes marcadores de morbimortalidade na cardiopatia chagásica (CCh). Objetivos: verificar a associação entre a capacidade funcional e funções sistólica e diastólica do ventrículo esquerdo na CCh. Metodologia: foram submetidos 35 pacientes com CCh (47,11±8,15 anos) a avaliação clínica, ecocardiograma e teste de esforço cardiopulmonar (TECP), sendo classificados em dois grupos: dilatado (com cardiomiopatia dilatada) e não dilatado (função sistólica preservada). Foram consideradas as variáveis fração de ejeção do ventrículo esquerdo (FEVE), razão E/e' e o pico do consumo de oxigênio (VO2pico). Na análise estatística foram realizados os testes de Pearson ou Spearman e a análise de regressão linear múltipla avaliou o efeito da FEVE e E/e' no VO2pico. Resultados: na amostra total houve correlação significativa entre o VO2pico e a FEVE (r=0,536, p=0,001) e correlação negativa e significativa entre o VO2pico e razão E/e' (r=-0,399; p=0,022). No grupo dilatado (n=16), correlação significativa foi observada entre o VO2pico com a FEVE (r=0,611, p=0,016) e a razão E/e' (r=-0,601, p=0,018). A análise multivariada das variáveis identificou a FEVE e a razão E/e' como fortes preditores do VO2pico (r=0,850; r2 =0,723).Não houve correlação significativa entre o VO2pico e a FEVE (r=0,393, p=0,107) e a razão E/e' (r=0,102, p=0,687) no grupo não dilatado (n=19). Conclusão: a capacidade funcional avaliada pelo VO2pico relaciona-se à função sistólica e diastólica em pacientes com cardiomiopatia dilatada chagásica.

Background: Left ventricular dysfunction and functional capacity (FC) are important markers of morbidity and mortality in Chagas heart disease (CHD), however, the relationship between these clinical parameters remains controversial. Objective: To verify the association between FC and systolic and diastolic functions of the left ventricle in CHD patients. Methods: Thirty-five CHD patients (47.11±8.15 years) underwent clinical evaluation, echocardiography and Cardiopulmonary Exercise Testing (CPET) and were classified into two groups: dilated group (dilated cardiomyopathy) and non-dilated group (preserved systolic function). The left ventricular ejection fraction (LVEF), E/e' ratio and peak oxygenuptake (VO2peak)were considered. Statistical analysis was carried outwith Pearson or Spearman correlation tests and backward multivariate linear regression analysis was performed to assess the effect of LVEF and E/e' ratio on VO2peak. Results: In the overall study population, there was a significant correlation between VO2peak and LVEF (r=0.536; p=0.001) and a significant negative correlation between VO2peak and E/e' ratio (r=-0.399;p=0.022). In the dilated group (n=16), a significant correlation was also observed between VO2peak and both LVEF(r=0.611; p=0.016) and E/e' ratio (r=-0.601; p=0.018). The multivariate analysis of these variables identified the LVEF and E/e' ratio as strong predictors of VO2peak (r=0.850; r2=0.723). In contrast, in the non-dilated group (n=19), there was no significant correlation between VO- 2peak and LVEF (r=0.393; p=0.107) and E/e' ratio (r=0.102; p=0.687). Conclusion: Functional capacity assessed by VO2peak was related to systolic and diastolic function in CHD patients with dilated cardiomyopathy.