Brain natriuretic peptide based strategy to detect left ventricular dysfunction in Chagas disease: A comparison with the conventional approach

BackgroundLeft ventricular dysfunction (LVd) is the main predictor of mortality in Chagas disease (ChD).AimsTo compare the diagnostic performance of the conventional approach (ECG and chest X-ray) in the recognition of LVd in ChD, with a new strategy, in which BNP is measured in patients with an abnormal ECG.MethodsConsecutive ChD patients recruited at an Outpatient Reference Center in Belo Horizonte, Brazil, without other systemic diseases, in 1998–99 (sample 1, n = 165) and in 2001–02 (sample 2, n = 62) underwent ECG, chest X-ray, BNP measurement and echocardiography.ResultsThe prevalence of LVd (ejection fraction ≤ 0.40) was 9.1% in the sample 1. The conventional strategy recognized all patients with LVd (sensitivity: 100%, 95% CI: 79.6–100% and negative predictive value − PV 100%, 92.1–100%), but with low specificity (30%, 95% CI: 23.2–37.8) and + PV (12.5%, 95% IC: I7.7–19.6). The BNP/ECG strategy showed significantly better specificity (96.0%, 95% CI: 91.5–98.2, p < 0.001) and + PV (66.7%, 95% CI: 43.7–83.7, p < 0.001), and non-significantly lower sensitivity (80.0%, 95% CI: 54.8–93.0, p = 0.25) and − PV (98.0%,95% CI: 94.2–99.3, p = 0.08). Overall accuracy was improved with the new strategy. (94.5%,95% CI: 90.0–97.1 × 36.4%, 95% CI: 29.4–43.9, p < 0.001). Similar results were obtained for the sample 2.ConclusionsThe BNP-based strategy was more accurate than the conventional approach in the detection of LVd in ChD patients and should be considered as a valid option.