174 Is Left Ventricular Longitudinal Function a Determinant of Plasma Brain Natriuretic Peptide during Exercise in Patients with Organic Mitral Regurgitation?

Abstract

Plasma brain natriuretic peptide (BNP) may be used for risk stratification in patients with organic mitral regurgitation (OMR). Whether exercise can induce changes in BNP in patients with OMR has never been investigated. Resting and exercise transthoracic echocardiography including Doppler, tissue Doppler imaging (TDI) and 2-D speckle-tracking (2DSt) quantification were performed in 56 consecutive patients (61±15 yrs, 54% of male) with moderate to severe OMR. Peak velocity and time-to-peak velocity (TP) were measured using TDI for Ea-, Aa- and Sa-wave. 2DSt was use to evaluate global LV longitudinal strain (GLS). Blood samples were drawn at rest and 5 min after peak exercise to measure plasma BNP level. BNP increases during exercise (from 27±18 to 35±24pg/ml, p<0.001) and peak exercise BNP was correlated to exercise LV ejection fraction (EF) (r=-0.36, p=0.007) and to exercise Sa velocity (r=-0.41, p<0.001), TP-Sa (r=0.32, p=0.02) and TP-Ea (r=0.39, p=0.004). The best correlation with peak BNP was found with peak GLS (r=-0.58, p<0.0001). In addition, there were significant associations between the changes in BNP and the changes in LVEF (r=-0.35, p=0.009), Sa velocity (r=-0.37, p=0.005), TP-Ea (r=0.35, p=0.01), and GLS (r=-0.44, p=0.0001). On multivariate analysis, after adjustment for age, sex and LVEF, only peak GLS and TP-Ea were independently associated with peak BNP (r 2 =0.34, p<0.0001 and r 2 =0.11, p=0.003, respectively). Furthermore, only changes in Sa velocity (r 2 =0.23, p=0.0004) and in GLS (r 2 =0.17, p=0.03) were independently associated, after adjustment, with the changes in BNP. Exercise and exercise-induced changes in LV longitudinal function are the major determinants of both exercise and changes in BNP during exercise, in patients with OMR. These results suggest that LV longitudinal function should be systematically quantified during stress echocardiography to detect latent subclinical LV dysfunction.