QT interval dispersion in patients with chronic heart failure secondary to Chagas' cardiomyopathy: correlation with clinical variables of prognostic significance

Cardiac involvement in African and American trypanosomiasis

American trypanosomiasis (Chagas disease) and human African trypanosomiasis (HAT; sleeping sickness) are both caused by single-celled flagellates that are transmitted by arthropods. Cardiac problems are the main cause of morbidity in chronic Chagas disease, but neurological problems dominate in HAT. Physicians need to be aware of Chagas disease and HAT in patients living in or returning from endemic regions, even if they left those regions long ago. Chagas heart disease has to be taken into account in the differential diagnosis of cardiomyopathy, primarily in patients with pathological electrocardiographic (ECG) findings, such as right bundle branch block or left anterior hemiblock, with segmental wall motion abnormalities or aneurysms on echocardiography, and in young patients with stroke in the absence of arterial hypertension. In HAT patients, cardiac involvement as seen by ECG alterations, such as repolarisation changes and low voltage, is frequent. HAT cardiopathy in general is benign and does not cause relevant congestive heart failure and subsides with treatment. We review the differences between the American and African trypanosomiasis with the main focus on the heart.

Assessment of QTc interval dispersion in patients with chronic heart failure secondary to Chagas-Hypertensive cardiomyopathy

No previous study has examined the association of clinical variables and QTc interval dispersion in patients with Chagas-Hypertensive cardiomyopathy. Sixty-four patients with Chagas-Hypertensive cardiomyopathy were entered for the study. Seventy-one chronic Chagas' disease heart failure patients and 68 patients with Hypertensive cardiomyopathy heart failure were used in the comparison of QTc interval dispersion. The QTc interval dispersion was defined as the difference between maximum and minimum QTc. Median QTc interval dispersion was 75 (55) ms in patients with Chagas' cardiomyopathy, (56) 73 ms in patients with Hypertensive cardiomyopathy, and (87.3) 98 ms in patients with Chagas-Hypertensive cardiomyopathy (p>0.05). In patients with Chagas-Hypertensive cardiomyopathy, median QTc interval was (134) 100 ms in survivors and (87) 96 ms in nonsurvivors (p>0.05). Thus, QTc interval dispersion values in patients with Chagas-Hypertensive cardiomyopathy are not associated with mortality and similar to those found in patients with Chagas' cardiomyopathy and in patients with Hypertensive cardiomyopathy.

Predictors of Mortality in Chronic Chagas Disease

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 Heart Association class III/IV, cardiomegaly, and nonsustained ventricular tachycardia indicate a poor prognosis in patients with chronic Chagas disease.