A Randomized Trial of Carvedilol in Chronic Chagas Cardiomyopathy

Overview

Chronic Chagas cardiomyopathy causes substantial morbidity and mortality in Latin America. Whether RAS inhibitors and beta-blockers are safe and beneficial has been challenged because of the lack of formal trials. Hence, the objective of this study was to determine the safety and efficacy of renin-angiotensin system (RAS) inhibitors and beta-blockers in chronic Chagas cardiomyopathy. This way, the investigators conducted a double-blind, placebo-controlled, and randomized trial in 42 patients with Trypanosoma cruzi infection and cardiomyopathy. All patients received enalapril (up-titrated to 20 mg BID) and spironolactone (25 mg QD). Subsequently, the patients were randomly assigned to receive placebo (n = 20) or carvedilol up-titrated to 25 mg BID (n = 19). The primary end points were change in left ventricular ejection fraction (LVEF) after RAS inhibition and that after the addition of carvedilol. The secondary end points were changes in other echocardiographic parameters, Framingham score, quality of life (36-item Short-Form Health Survey), New York Heart Association class, radiographic indices, brain natriuretic peptide levels, and chemokines as well as safety end points.

Chronic Chagas cardiomyopathy (CCC) is an important cause of heart failure (HF) and sudden death in Latin America.1 According to recent estimates, 13 million people worldwide are infected with Trypanosoma cruzi, of whom 3.0 to 3.3 million are symptomatic.2 The incidence rate is 200000 cases per year. Among those infected, 30% have clinical features of CCC and 15% ultimately develop overt left ventricular (LV) insufficiency-the main prognostic determinant of the disease. In Chagas cardiomyopathy, the hemodynamic and neurohormonal responses do not differ from those in other cardiomyopathies. This common pathophysiology suggests that treatments shown to be effective by classic HF trials should be beneficial in CCC. However, CCC has several specific characteristics, such as early cardiac denervation, frequent ventricular arrhythmias, and several forms as well as grades of conduction disturbances, including sinus bradycardia, complete atrioventricular block, and right bundle-branch block. Morphologically, hypertrophy, dilatation, and severe fibrosis are prominent. In 20% to 40% of cases, an apical ventricular aneurysm is present.1 These peculiarities in combination lead to a high incidence of sudden death (60% of all deaths), cardiac insufficiency, and ventricular remodeling. The responses of patients to the usual drugs prescribed in HF could be different, and this perception has led to the suboptimal dosing or lack of initiation of medical treatments that are of proven efficacy in patients with other etiologies of HF. The underlying problem is that therapies that are effective in patients with HF caused by non-chagasic cardiomyopathies, such as those with renin-angiotensin system inhibitors (RASis) and h-blockers, have yet to be formally tested in CCC. There are few clinical trials and no randomized study on this subject. Consequently, the investigators evaluated the effects of optimizing treatment with enalapril and spironolactone and then undertook a randomized trial of adding a h-blocker in the treatment of patients with CCC.