Background: Left ventricular dysfunction(LVd) is the main predictor of mortali ty in Chagas disease(ChD). Aims: To compare the diagnostic performance of the co nventional 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. Meth ods: Consecutive ChD patients recruited at an Outpatient Reference Center in Bel o Horizonte, Brazil, without other systemic diseases, in 1998-99(sample 1, n=16 5) and in 2001-02(sample 2, n=62) underwent ECG, chest X-ray, BNP measurement and echocardiography. Results: The prevalence of LVd(ejection fraction ≤0.40) w as 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%CI: 7.7-19.6). The BNP/ECG strategy showed significantly better speci ficity(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. Conclusions: The BNP-based stra tegy was more accurate than the conventional approach in the detection of LVd in ChD patients and should be considered as a valid option.
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