Predictors of gastrointestinal complications after conventional and beating heart coronary surgery

Gastrointestinal complications after cardiac surgery remain a significant problem despite improvements in pre-operative, operative and post-operative care. The pathophysiology is uncertain, and their prevention remains suboptimal. This prospective, randomised study was designed to define the role of cardiopulmonary bypass (CPB) and cardioplegic arrest in the pathogenesis of gastrointestinal complications following coronary artery surgery.

Three hundred patients were prospectively randomised to (1) on-pump conventional coronary artery surgery [150 patients, 114 men, mean age 64 (45-75 years)] with mild hypothermic (32c) CPB and cardioplegic arrest of the heart or (2) off-pump surgery [150 patients, 113 men, mean age 64 (38-66) years] on the beating heart. The association of perioperative factors with gastrointestinal complications was investigated by univariate analysis. Significant variables were then included into a stepwise logistic regression model to ascertain their independent influence on the occurrence of gastrointestinal complications. There were no significant baseline differences between the groups. Eleven patients in the on-pump group and one patient in the off-pump group had post-operative gastrointestinal complications. Univariate analysis showed that CPB inclusive of cardioplegic arrest, left ventricular ejection fraction <50%, emergency surgery, prolonged aortic cross clamp and CPB time, post-operative low cardiac output syndrome, post-operative inotropic requirement, new onset atrial fibrillation (AF), excessive post-operative blood loss and redo thoracotomy <24 hours were predictors of gastrointestinal complications after coronary artery surgery (all p<0.05). However, stepwise multivariate regression analysis identified CPB inclusive of cardioplegic arrest as the only predictor of post-operative gastrointestinal complications (OR7.4; CI 3.4-17.9).

Cardiopulmonary bypass, inclusive of cardioplegic arrest, is the main independent predictor of post-operative gastrointestinal complications in patients undergoing coronary revascularisation.