Hyponatremia in Chagas disease heart failure: Prevalence, clinical characteristics, and prognostic importance

BackgroundThe prevalence, the clinical characteristics and the impact of hyponatremia on the prognosis of patients with chronic heart failure secondary to Chagas cardiomyopathy is unknown.MethodsAll patients with positive serology for Chagas disease and a left ventricular ejection fraction < 55% on echocardiography routinely followed at the cardiomyopathy service of the university hospital from January, 2000 to December, 2008 were screened. The work-up consisted of anamnesis, physical examination, standard laboratory tests, 12-lead resting ECG, and 2-D echocardiography. Hyponatremia was defined as serum sodium levels < 135 mEq/L.Results246 patients were entered in the study; 30 (12%) patients were found to have hyponatremia. A multivariate stepwise logistic regression analysis revealed that the need of inotropic support [hazard ratio (HR) = 2.97; 95% Confidence Interval (CI) 1.24 to 7,18; p = 0.01], left ventricular systolic diameter (HR = 1.05; 95% CI 1.0 to 1.1, p = 0.03), and diastolic blood pressure (HR: 0,96; 95% CI 0,92 to 0,99; p = 0.04) were independent predictors of hyponatremia. A Cox regression analysis showed that the need of inotropic support (HR = 1,84; 95% CI 1,24 to 2,72; p = 0,0002), hyponatremia (HR = 2,05; 95% CI 1,25 to 3,38; p = 0.005), Betablocker therapy (hazard ratio = 0,33; 95% Confidence Interval 0,22 to 0,50; p < 0,0005), and digoxin use (HR = 2,79; 95% CI 1,42 to 5,46; p = 0003) were independent predictors of all-cause mortality.ConclusionHyponatremia is an independent predictor of all-cause mortality of patients with chronic heart failure secondary to Chagas cardiomyopathy in the contemporary era of syndrome management. Hyponatremia can be predicted by variables consistent with syndrome severity.