Brain natriuretic peptide based strategy to detect left ventricular dysfunction in Chagas disease: a comparison with the conventional approach.
BACKGROUND
Left ventricular dysfunction (LVd) is the main predictor of mortality in Chagas disease (ChD).


OBJECTIVE
To 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.


METHODS
Consecutive 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.


RESULTS
The prevalence of LVd (ejection fraction <or=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 x 36.4%, 95% CI: 29.4-43.9, p < 0.001). Similar results were obtained for the sample 2.


CONCLUSIONS
The 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.
Ribeiro
Antonio Luiz P
AL
Postgraduate Course of Tropical Medicine, Internal Medicine Department, School of Medicine, Federal University of Minas Gerais, Av. Alfredo Balena, 190-Campus Saúde, 30130-100, Belo Horizonte, Brazil. tom@hc.ufmg.br
Teixeira
Mauro M
MM
Reis
Adelina M
AM
Talvani
Andre
A
Perez
Amanda A
AA
Barros
Márcio Vinicius L
MV
Rocha
Manoel Otávio C
MO
D000328:Adult; D000368:Aged; D014355:Chagas Disease / Q000453:epidemiology* / Q000401:mortality / Q000503:physiopathology*; D004562:Electrocardiography; D006801:Humans; D008297:Male; D008875:Middle Aged; D020097:Natriuretic Peptide, Brain / Q000097:blood*; D011237:Predictive Value of Tests; D012680:Sensitivity and Specificity; D018487:Ventricular Dysfunction, Left / Q000097:blood / Q000175:diagnosis* / Q000453:epidemiology
D020097:Natriuretic Peptide, Brain