Evaluate if benznidazole, an antiparasite drug, given at a dose calculated as 5mg/kg/day for 60 days, now administered as a fixed daily dose of 300mg during 40 to 80 days of treatment - period adjusted according to the patient's body weight to a total minimum dose of 12g (corresponding to 40kg) and a total maximum dose of 24g (corresponding to 80kg) - reduces morbidity and mortality in patients with Chronic Chagas' Cardiomyopathy (CCC).

The BENEFIT study is being conducted by the Population Health Research Institute (in Hamilton, Canada) and the Institute Dante Pazzanese de Cardiologia (Sao Paulo, Brazil) together with a Steering Committee, and an independent Safety Monitoring Board.

A randomized double-blind controlled clinical trial investigating the role of benznidazole in patients with chronic Chagas' heart disease.

Chagas disease has 3 phases: acute, undetermined and chronic phases. There are no clinical trials up to date that have investigated the use of antiparasitic drugs in patients that are in the chronic phase.

This study will evaluate the efficacy and safety of benznidazole (an antiparasitic drug) in patients with chronic Chagas' heart disease. Evaluate if benznidazole, an antiparasite drug, given at a dose calculated as 5mg/kg/day for 60 days, now administered as a fixed daily dose of 300mg during 40 to 80 days of treatment - period adjusted according to the patient's body weight to a total minimum dose of 12g (corresponding to 40kg) and a total maximum dose of 24g (corresponding to 80kg) - reduces morbidity and mortality in patients with Chronic Chagas' Cardiomyopathy (CCC). It will be developed in 49 study centres in Argentina, Bolivia,Brazil,Colombia, and El Salvador - countries with high incidence of Chagas Disease.

The Pilot study is evaluating if benznidazole is effective in producing parasitic cure (PCR negativization or reducing parasitic load) in chronic Chagas Disease as well as assessing the feasibility of conducting a large trial in chronic Chagas Disease in South America.

Inclusion Criteria:

• Consenting patients (between 18 and 75 years of age) with serological evidence of Chagas infection (any combination of 2 positive tests) and that have one or more of the following:
• Abnormal electrocardiogram with at least two components (complete RBBB or LBBB; left anterior or posterior fascicular block; ventricular premature beat; first degree atrioventricular [AV] block; Mobitz type I AV block; sinus bradycardia; primary ST-T changes; abnormal Q waves; low voltage QRS; or atrial fibrillation);
• Abnormal ECG (Mobitz type II, advanced or third degree AV block);
• Increased cardiothoracic ratio (> 0.50);
• Complex ventricular arrythmias on 24 hour ambulatory ECG monitoring;
• Evidence of regional wall motion abnormality or reduced global left ventricular systolic function or increased left ventricular and diastolic diameter on 2D-Echo.

Exclusion Criteria:

Patients will be excluded if having:

• NYHA heart failure class IV or decompensated heart failure
• Evidence of concomitant coronary artery disease (CAD) or other etiology of dilated cardiomyopathy
• Previous treatment with antitrypanosomal agents or an accepted indication for antiparasitic therapy
• Inability to comply with follow-up visits
• History of severe alcohol abuse within 2 years
• Known chronic renal or hepatic insufficiency or hepatic insufficiency
• Pregnancy or breast feeding
• Megaesophagus with swallowing impairment
• Other severe disease significantly curtailing life expectancy