Chagas disease is endemic to South and Central America and frequently affects patients in their most productive working years. As a result, the disease is very costly for governments and societies.1 Chronic cardiomyopathy is the most severe manifestation of human Chagas disease and can cause chronic heart failure (CHF), arrhythmia, heart block and sudden death.2
Exercise capacity has been shown to be related to poor survival in patients with Chagas disease. Previous studies have demonstrated that patients with Chagas infection present a poorer prognosis compared to patients with other causes of CHF.3 Despite these findings, data describing exercise training in CHF patients with Chagas disease are rare, especially regarding the use of the new and promising exercise training method known as neuromuscular electrostimulation (NMEE).
Case reportA 65-year-old sedentary male patient with 10 years of CHF symptoms due to Chagas disease was referred to the Department of Cardiac Rehabilitation of the Ana Neri Hospital - UFBA in August of 2009. The diagnosis of Chagas disease was defined by the positive result of two serological tests [indirect immunofluorescence and enzyme-linked immunosorbent assay (ELISA)]. To exclude the possibility of an ischemic heart disease, the patient underwent cardiac catheterization, followed by angiography. The studied patient was in New York Heart Association (NYHA) functional class IV and had a left ventricular ejection fraction of 40%. An evaluation of patient exercise capacity by a cardiopulmonary exercise test was initially attempted; however, the patient could not tolerate the testing because of excessive fatigue in the first minute of the exam. Instead, a six-minute walking test in a 30-m corridor was performed to evaluate the patient's exercise capacity. For this test, previously standardized instructions were followed.4 In addition, the Minnesota Living With Heart Failure Questionnaire was administered (Table 1).5
Patient data before and after NMEE treatment.
| Before | After | |
|---|---|---|
| NYHA functional class | IV | III |
| Body Mass Index (kg/m2) | 19.1 | 19.4 |
| Resting SBP (mmHg) | 100 | 110 |
| Resting DBP (mmHg) | 80 | 80 |
| Resting HR (bpm) | 54 | 57 |
| SBP during 6WT (mmHg) | 110 | 130 |
| DBP during 6WT (mmHg) | 80 | 80 |
| HR during 6WT (bpm) | 75 | 68 |
| Distance 6WT (meters) | 120 | 500 |
| MLHFQ Score | 65 | 50 |
| Borg Scale during 6WT | 19 | 13 |
| SpO2 during 6WT (%) | 95 | 97 |
NYHA, New York Heart Association Functional Class; SBP, Systolic blood pressure; DBP, Diastolic blood pressure; HR, heart rate; MLHFQ, Minnesota Living with Heart Failure Questionnaire; 6WT, 6-minute walking test.
After the initial assessment, the physiotherapy team chose the NMEE protocol for rehabilitation because of the patient's significant functional impairment and his inability to undergo conventional exercise training (Table 1).6 NMEE was performed on the right and left quadriceps for 60 minutes three times a week during for four weeks. NMEE was applied via an electrostimulator (Phisiotonus II, Bioset) on functional electrical stimulation (FES) mode. The carrier wave frequency was modulated at 50 Hz, with a pulse duration of 40 μs. The stimulator was set to deliver 20 seconds of contraction and 4 seconds of relaxation. Adhesive surface electrodes 3 cm in diameter were used for electrostimulation. The current intensity was adjusted according to the sensitivity threshold of the patient.
The patient's current medication (carvedilol 12.5 mg/day, captopril 75 mg/day and furosemide 40 mg/day) was not changed during the protocol. This protocol was approved by the Ethical Committee of our institution, and the patient provided informed consent prior to participation.
DISCUSSIONThe NMEE protocol was well tolerated by the patient, and no adverse events occurred.7 After the protocol, the patient performed another six-minute walking test and answered the Minnesota Living With Heart Failure Questionnaire. This reevaluation indicated a 380-meter increase in walked distance and a decrease of 15 points on the quality of life questionnaire score (Table 1).
In patients with Chagas disease, exercise training is an important aspect of cardiovascular rehabilitation; however, there are a minimum of controlled trials regarding this subject in the literature. The lack of trials may be related to the small prevalence of Chagas disease in developed countries or the high Chagas disease-associated incidence of malignant arrhythmia, sudden death and a consequent poor prognosis.2,3
Despite a recent upsurge in the interest regarding the use of NMEE for treatment of CHF patients, there are only a modest number of small trials. Moreover, these trials do not examine the etiology of Chagas disease. In CHF populations with left ventricular systolic dysfunction, NMEE appears to produce the same benefits as conventional physical exercise training by increasing both exercise capacity and quality of life.8,9 NMEE appears to be particularly useful in patients unable to perform conventional exercises, such as those in NYHA functional class IV.10
In the current report, the studied patient demonstrated severe functional impairment prior to treatment, which may have contributed to the large functional improvement observed in the relatively short intervention time. The functional capacity of patients in the initial phase of chronic Chagas heart disease is higher than those in advanced phases.11
CONCLUSIONIn the present report, NMEE was demonstrated to be a safe and efficient tool for improving exercise capacity during cardiac rehabilitation in a CHF patient with Chagas disease. Further studies are necessary to better elucidate the risks, benefits and indications of NMEE.