Release of Brain Natriuretic-Related Peptides (BNP, NT-proBNP) and Cardiac Troponins (cTnT, cTnI) in On-pump and Off-pump Coronary Artery Bypass Surgery

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

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.

The Role of BNP and CRP in Predicting the Development of Atrial Fibrillation in Patients Undergoing Isolated Coronary Artery Bypass Surgery

Objective. To evaluate the association of BNP and CRP with the development of postoperative atrial fibrillation following coronary artery bypass grafting surgery. Methods. The series consists of 125 patients (aged 65 ± 9 years), who underwent isolated CABG-surgery. BNP and CRP levels were measured pre- and 24 hours postoperatively and their correlation to the development of postoperative AF was analyzed. Results. Forty-four patients (35%) developed AF postoperatively. They were significantly older (68 ± 8 versus 63 ± 9, P = 0.01) and predominantly nonsmokers (18% versus 46%, P = 0.004), compared to the non-AF cases. In addition they showed significant higher preoperative mean BNP levels of 629 versus 373 pg/mL (P = 0.019). Postoperative BNP levels were significantly higher in both groups (AF-group: 1032 pg/mL versus non-AF group: 705 pg/mL; P < 0.001), while there was a trend of more increased postoperative levels in AF-cases (P = 0.065). AF-episodes appeared significantly more frequent in the two highest quartiles of BNP levels with 44% (P = 0.035). On the contrary pre- and postoperative CRP levels were not associated with AF. Multivariable analysis revealed only increased preoperative BNP levels as independent predictor for postoperative AF (P = 0.036). Conclusion. Elevated preoperative BNP serum levels are associated with the development of post-CABG AF, while CRP does not seem to be influential.

Comparison of inflammatory response during on-pump and off-pump coronary artery bypass surgery

PURPOSE

On-pump coronary artery bypass graft (CABG) surgery has been traditionally associated with a higher magnitude of inflammatory response than off-pump CABG. However with the development of polymer-coated biocompatible extracorporeal circuits, we wanted to see if cardiopulmonary bypass still played an important role in triggering this inflammatory response.

METHODS

In this prospective observational study, 33 patients undergoing CABG surgeries (25 on-pump and 8 off-pump patients) were studied. Serial plasma cytokine (TNF IL-6, IL-10) and procalcitonin concentrations were measured at different time-points during and after the surgery. Demographic and baseline clinical data, intra-operative management details and post-operative complications were also collected from the patients' charts.

RESULTS

Plasma levels of all 4 mediators increased during surgery and returned towards normal postoperatively. There were no differences between groups for any mediator at any time-point.

CONCLUSIONS

We conclude that with the use of recent polymer-coated biocompatible extracorporeal circuits, the inflammatory response triggered by on-pump CABG becomes very similar in magnitude and pattern to that triggered by off-pump CABG. Thus, the surgical procedure contributes to most of the inflammatory response, with the extra-corporeal circuit having minimal to no effect on this response.