Differential Release Kinetics of Cardiac Biomarkers in Patients Undergoing Valve Replacement Surgery

BACKGROUND: Differential release kinetics of cardiac biomarkers including brain natriuretic peptide (BNP), Troponin-I, and CK-MB following valve replacement (VR) are not well characterized. METHODS AND RESULTS: We serially measured these biomarkers 24 hours prior, six hours, 24 hours, 48 hours, and one month following mitral/aortic VR in 100 patients. Baseline BNP, Tn-I, and CK-MB levels were 304.01 pg/mL, 0.03 ng/mL, and 0.99 ng/mL, respectively. While BNP levels decreased at six hours, and then peaked at 24 hours, Tn-I and CK-MB levels increased within six hours and then showed declining trends by 24 hours. While Tn-I and CK-MB levels normalized at one month, 33% patients still had BNP >200 pg/mL. Those with baseline BNP >200 pg/mL more commonly had AF, higher RV systolic pressure, longer inotrope and ventilator duration, and longer mean ICU/hospital stay as compared to those with lower BNP, although echocardiographic left ventricular ejection fraction and Tn-I/CK-MB levels were similar. Inotrope duration >42 hours, ventilation time >29 hours, and ICU stay >4 days was seen in 42% versus 19%, 30% versus 9%, and 33% versus 14%, respectively, in those with BNP >/<200 pg/mL. Baseline BNP had a significant positive correlation with mean inotrope duration, ICU, and hospital stay. Baseline BNP was also a significant predictor of inotrope duration (odds ratio [OR]=5.9, 95% confidence interval [CI]=1.20-29.68, p=0.01) and ventilation time (OR=4.7, 95% CI=1.76-17.21, p=0.02). CONCLUSION: Release kinetics of cardiac biomarkers is significantly different following VR; BNP levels increase following an initial transient decline. Only BNP was a predictor of postoperative variables.