Utility of a novel risk score for prediction of ventricular tachycardia and cardiac death in chronic Chagas disease - the SEARCH-RIO study

• Published in: Brazilian journal of medical and biological research Vol. 46; no. 11; pp. 974 - 984
• Main Authors: Benchimol-Barbosa, P R, Tura, B R, Barbosa, E C, Kantharia, B K
• Format: Journal Article
• Language: English; Portuguese
• Published: Brazil Associacao Brasileira de Divulgacao Cientifica (ABDC) 01.11.2013; Associação Brasileira de Divulgação Científica
• Subjects: BIOLOGY; Cardiac death; Chagas heart disease; Chagas' disease; Clinical Investigation; Diagnosis; Electric properties; Electrocardiogram; Electrocardiography; Investigations; MEDICINE, RESEARCH & EXPERIMENTAL; Noninvasive electrocardiography; Prognostic score; Risk factors; Ventricular tachycardia; Brazil; United States; Noninvasive electrocardiography; Ventricular tachycardia; Chagas heart disease; Cardiac death; Prognostic score
• ISSN: 0100-879X; 1414-431X; 1414-431X; 0100-879X
• DOI: 10.1590/1414-431X20133141

The SEARCH-RIO study prospectively investigated electrocardiogram (ECG)-derived variables in chronic Chagas disease (CCD) as predictors of cardiac death and new onset ventricular tachycardia (VT). Cardiac arrhythmia is a major cause of death in CCD, and electrical markers may play a significant role in risk stratification. One hundred clinically stable outpatients with CCD were enrolled in this study. They initially underwent a 12-lead resting ECG, signal-averaged ECG, and 24-h ambulatory ECG. Abnormal Q-waves, filtered QRS duration, intraventricular electrical transients (IVET), 24-h standard deviation of normal RR intervals (SDNN), and VT were assessed. Echocardiograms assessed left ventricular ejection fraction. Predictors of cardiac death and new onset VT were identified in a Cox proportional hazard model. During a mean follow-up of 95.3 months, 36 patients had adverse events: 22 new onset VT (mean±SD, 18.4±4/year) and 20 deaths (26.4±1.8/year). In multivariate analysis, only Q-wave (hazard ratio, HR=6.7; P<0.001), VT (HR=5.3; P<0.001), SDNN<100 ms (HR=4.0; P=0.006), and IVET+ (HR=3.0; P=0.04) were independent predictors of the composite endpoint of cardiac death and new onset VT. A prognostic score was developed by weighting points proportional to beta coefficients and summing-up: Q-wave=2; VT=2; SDNN<100 ms=1; IVET+ =1. Receiver operating characteristic curve analysis optimized the cutoff value at >1. In 10,000 bootstraps, the C-statistic of this novel score was non-inferior to a previously validated (Rassi) score (0.89±0.03 and 0.80±0.05, respectively; test for non-inferiority: P<0.001). In CCD, surface ECG-derived variables are predictors of cardiac death and new onset VT.