Differential release kinetics of cardiac biomarkers in off-pump coronary bypass

Abstract

Background

Differential release kinetics of the cardiac biomarkers (B-type natriuretic peptide, troponin I, and creatine kinase-MB) following off-pump coronary artery bypass are not well characterized.

Methods

Biomarker levels were assessed at 6, 24, 48 h, and 1 month preoperatively, in 80 patients who underwent off-pump coronary artery bypass.

Results

All biomarkers increased within 6 h of surgery. Peak B-type natriuretic peptide levels occurred at 24–48 h in 96% of patients, but only two-thirds had peak troponin I and creatine kinase-MB levels at this time, reflecting different release patterns. Levels of all biomarkers declined within 48 h, but 42% of patients still had B-type natriuretic peptide >100 pg·mL⁻¹ at 1 month. Those with baseline B-type natriuretic peptide > 100 pg·mL⁻¹ had a lower left ventricular ejection fraction (43.6% vs. 55.6%, p < 0.01) and longer inotropic (43.8 vs. 31.4 h, p = 0.03) and ventilator support (34 vs. 25.5 h, p = 0.04) than those with lower levels. B-type natriuretic peptide levels correlated positively with angiographic Syntax score (p = 0.02) and negatively with left ventricular ejection fraction (p < 0.001). Only baseline B-type natriuretic peptide predicted the durations of inotropic support (p = 0.01) and ventilation (p = 0.02). Postoperative B-type natriuretic peptide at 6, 24, and 48 h and delta B-type natriuretic peptide were significant predictors of mean ventilation time.

Conclusion

Even in patients undergoing off-pump surgery, there is significant natriuretic peptide and myocardial enzyme release. Only B-type natriuretic peptide levels had an association with postoperative variables.