NT-proBNP changes, oxidative stress, and energy status of hypertrophic myocardium following ischemia/reperfusion injury

Abstract

N-terminal pro-B-type natriuretic peptide (NT-proBNP) is a sensitive functional marker in heart disease, including left ventricular hypertrophy (LVH) secondary to valvular aortic stenosis (AS). We evaluated the association between NT-proBNP changes, oxidative stress, energy status and severity of LVH in patients with AS. Ten patients undergoing aortic valve replacement for AS were studied. Plasma NT-proBNP concentrations were performed by electroluminescence immunoassay 15 min after the induction of anesthesia (t0), before aortic cross-clamping (t1), before clamp removal (t2), 15 min after myocardial reperfusion (t3), and 24 h after surgery (t4). Heart biopsies were obtained and high energy phosphates (ATP, ADP, AMP) were analyzed by capillary electrophoresis (CE). In plasma samples from the coronary sinus, nitrate plus nitrite (NOx) concentrations were also analyzed by CE. Echocardiographic measurements were acquired and correlations between biochemical markers and severity of AS were assessed. NT-proBNP peaked significantly at t4 ( p < 0.001). A linear correlation between NT-proBNP values measured at t0 and t4 was found ( R 2 = 0.89; p < 0.001). A negative correlation between NT-proBNP production and phosphorylation potential (ATP/ADP ratio) was observed ( R 2 = 0.62; p < 0.01). NOx values positively correlated with NT-proBNP levels ( p < 0.01). NT-proBNP inversely correlated with aortic valvular area ( r = 81, p < 0.01), positively correlated with mean ( r = 0.82, p < 0.01) and maximum left ventricle-to-aortic gradients ( r = 0.80, p < 0.01), and with left ventricular mass ( r = 0.69, p < 0.01). NT-proBNP is a useful marker of LVH and severity of AS. It may complement echocardiographic evaluation of patients with AS in identifying the optimum time for surgery.