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Maximal functional capacity in patients with Chagas' cardiomyopathy without congestive heart failure
Insights
Asymptomatic Chagas' disease patients with normal heart function show significantly reduced exercise capacity. This impairment in functional capacity is evident despite preserved resting left ventricular function.
Area of Science:
- Cardiology
- Infectious Diseases
- Exercise Physiology
Background:
- Chagas' disease is a known cause of cardiomyopathy.
- Many patients exhibit electrocardiographic (ECG) changes but maintain normal ventricular dimensions and remain asymptomatic.
- Objective characterization of functional capacity in asymptomatic Chagas' disease patients with normal left ventricular function is needed.
Purpose of the Study:
- To objectively characterize the exercise functional capacity of asymptomatic patients with Chagas' disease who have normal left ventricular function at rest.
Main Methods:
- Eighteen asymptomatic male patients with Chagas' disease (age 33±6) and normal left ventricular fractional shortening (LVFS > 0.30) were studied.
- Twenty sedentary healthy males served as controls.
- Both groups underwent ergoespirometry testing to assess exercise functional capacity.
Main Results:
- Chagas' disease patients exhibited significantly lower maximal O2 consumption (VO2max), O2 pulse (PO2max), maximal ventilation (VEmax), anaerobic threshold (VO2-AT), and maximal heart rate (HRmax) compared to controls.
- These differences were statistically significant (P < .001).
Conclusions:
- Asymptomatic individuals with Chagas' disease, despite normal resting left ventricular systolic function, demonstrate considerable impairment in their exercise functional capacity.
- This suggests subclinical functional limitations in early-stage Chagas' disease cardiomyopathy.
Background:
Chagas' disease is a known dilated form of cardiomyopathy. However, a great number of patients, although showing electrocardiographic (ECG) well-recognized changes, maintain normal ventricular chamber dimensions and are asymptomatic. The aim of the present study was to objectively characterize functional capacity in asymptomatic patients with Chagas' disease and normal left ventricular function.
Methods And Results:
Eighteen asymptomatic male patients with Chagas' disease, aged 33+/-6 years, were selected for the study. All showed ECG changes typical of the disease, as well as left ventricular fractional shortening (LVFS) greater than 0.30 on M-mode 2-dimensionally guided echocardiography. Twenty sedentary normal male patients, aged 29+/-6 years, served as controls. Both groups were submitted to ergoespirometry testing for assessment of exercise functional capacity. Patients with Chagas' disease, when compared with controls, showed lower (P < .001) maximal O2 consumption (VO2max, 24.3+/-4.2 v 37.0+/-5.4 mL x kg(-1) x min(-1) respectively); O2 pulse rate (PO2max, 10.5+/-1.4 v 15.1+/-2.5 mL/beat, respectively); maximal ventilation (VEmax, 50.1+/-13.5 v 113.0+/-17.6 L x min(-1), respectively); anaerobic threshold of maximal O2 consumption (VO2-AT, 15.8+/-3.6 v 24.6+/-4.7 mL x kg(-1) x min(-1), respectively); and maximal heart rate (HRmax, 154+/-21 v 186+/-7 beat x min(-1), respectively).
Conclusions:
Asymptomatic patients with Chagas' disease, although presenting normal left ventricular systolic function at rest, display a substantial impairment of exercise functional capacity.