Differential release kinetics of cardiac biomarkers in patients undergoing off pump coronary artery bypass surgery

Results Baseline BNP, TnI and CKMB levels were 105.8 pg/ml, 0.9 ng/ml and 2.34 ng/ml. Although all biomarkers increased significantly within 6 hours of surgery, release kinetics were different. While peak BNP levels occurred in 96% patients by 24-48 hours, for TnI and CKMB, this was observed in only two-thirds. A trend towards fall in all biomarkers was seen by 48 hours; while TnI and CKMB levels normalized in all at 1 month, 42% patients still had BNP > 100 pg/ml. Those with baseline BNP > 100 pg/ml had lower LVEF (43.6vs55.6%,p<0.01), longer inotrope duration (43.8vs31.4 hrs, p=0.03) and ventilator support time (33.9vs25.6 hrs, p=0.04); mean ICU and hospital stay were similar to those with lower BNP. Despite baseline BNP differences, levels of TnI and CKMB at all times were similar in these two groups. BNP levels had positive correlation with patient age and angiographic Syntax score (p=0.02) and negative correlation with LVEF. Of all biomarkers, only baseline BNP predicted inotrope duration (OR4.9, 95%CI:1.3-17.7, p=.01) and ventilation time (OR4.5, 95%CI:1.2-16.6, p=.02). Post-operative levels of BNP at 6,24 and 48 hours and delta BNP were significant predictors of mean ventilation time only.