Temporal changes in plasma brain natriuretic peptide levels during exercise stress-echocardiography in patients with dilated cardiomyopathy.

Abstract

The aim of this study was to evaluate temporal changes in brain natriuretic petide (BNP) levels during exercise stress-echocardiography in patients with dilated cardiomyopathy with respect to the left ventricular contractile reserve. We studied 55 consecutive patients with dilated cardiomyopathy (mean age, 55 ± 10 years, 49 (89.1%) male). All patients underwent exercise stress-echocardiography on a treadmill using the modified Bruce protocol. Contractile reserve was assessed by measuring changes in the wall motion score index (ΔWMSI) at rest and and at peak exercise. Levels of BNP were measured at rest, in the first minute, and after 20 minutes following termination of the stress test. Thirty-six patients had preserved left ventricular contractile reserve and 19 patients did not. Patients with preserved left ventricular contractile reserve showed a continuous rise in BNP levels from baseline to peak exercise and to 20 minutes following exertion (83.95 ± 108.51 versus 105.89 ± 116.00 versus 110.95 ± 119.70 ng/L, P < 0.001, respectively). On the other hand, patients without preserved left ventricular contractile reserve showed a decline in BNP levels at peak exercise as compared to baseline (335.49 ± 693.11 versus 320.08 ± 562.60 P = 0.031). ΔBNP was positively correlated with preserved contractile reserve (r = 0.46, P = 0.03) and lower NYHA class (r = -0.65, P = 0.001) in patients in whom baseline LVEF was lower than 20%. Multivariate analysis identified only WMSI at rest (beta -3.365, P = 0.008, 95 CI 0.03 to 0.411) as an independent predictor of left ventricular contractile reserve.The increase in BNP levels during exercise stress-echocardiography is associated with preserved left ventricular contractile reserve in patients with dilated cardiomyopathy.