Background-Chagas disease is a major cause of morbidity and mortality in Latin America. Knowledge of the predictors of prognosis can help clinical decision making by identifying patients' level of risk. Methods and Results-We reviewed the published literature on prognostic factors in patients with Chagas disease by performing a PubMed search for articles published in any language between 1985 and February 2006 and hand searches of the reference lists of retrieved articles. Studies were selected if they included patients in the chronic phase of Chagas disease, analyzed a clearly defined outcome (all-cause mortality, sudden cardiac deaths, and/or cardiovascular deaths), and used multivariable regression models of prognosis. From 606 potentially relevant studies, 12 met the inclusion criteria: 8 clinic-based studies including 3928 patients and 4 hospital-based studies including 349 patients. Impaired left ventricular function by echocardiogram or cineventriculogram was found to be the most common and consistent independent predictor of death. New York Heart Association functional class III/IV and cardiomegaly on the chest radiography also were independently associated with higher mortality. More recently, strong evidence was found that nonsustained ventricular tachycardia on 24-hour Holter monitoring indicated an adverse prognosis. The typical ECG abnormalities showed limited additional prognostic value. Other often-mentioned risk factors, advanced age and male sex, showed inconsistent results. A formal meta-analysis was not feasible because of the heterogeneity of published studies and the lack of minimal standards in reporting results.
Conclusions-A systematic review of published studies indicates that impaired left ventricular function, New York HeartAssociation class III/IV, cardiomegaly, and nonsustained ventricular tachycardia indicate a poor prognosis in patients with chronic Chagas disease.
Thirty-five individuals from endemic areas of Central Brazil (age range, 18-64 years; 19 women) in the chronic phase of Chagas disease, with positive serology and presence of circulating parasites detected by one or more recent positive xenodiagnosis, were selected for this study. Allopurinol (900 mg/d) or placebo was administered in a double-blind clinical trial for 60 days. After codes were broken, 23 had been allocated to the intervention group and 12 to the placebo group. Side effects were observed in 11 patients in the intervention group and in 1 in the placebo group. Seventeen patients in the intervention group and 10 in the placebo group completed the trial. Follow-up was performed by monthly xenodiagnosis and serologic tests every 3 months during the first year and at the end of the trial. Xenodiagnosis remained positive in all 17 of the treated group and in all 10 of the placebo group. Serologic tests were persistently positive in both groups after treatment. We concluded that, at the doses used, allopurinol was not effective to clear, in our region, Trypanosoma cruzi from peripheral blood of infected individuals.
Maternal transmission of Trypanosoma cruzi from 278 children of 145 mothers, chronically infected with this protozoan, to their offspring was investigated. This study was based upon serological tests. In only two cases (2/278 = 0.70%), such mode of transmission was demonstrated to have occurred. However, as according to extant records both patients had also been breast-fed, and the contribution of this factor could not be ruled out. In any case, maternal transmission, an alternative mode of acquiring the infection with Trypanosoma cruzi, was demonstrated. The methodology used is a further contribution to the evaluation of the prevalence of this propagating mechanism of T. cruzi; in addition to those aimed at the main objective of the investigation, records were kept about pregnancy, parturition, puerperium, abortion, prematurity, perinatal deaths and breast-feeding, which might contribute to a better interpretation of the subject.
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