A meta-analysis of intraoperative factors associated with postoperative cardiac complications

Abstract

Background: Preoperative cardiac risk is commonly determined with the help of risk scores and risk stratification tools. This predetermined cardiac risk may be profoundly changed by intraoperative surgical events. This meta-analysis aimed to identify intraoperative factors that independently predict postoperative cardiac complications in the presence of preoperative cardiac risk factors. Method: A PubMed Central search was conducted from January 1966 to June 2010, to identify independent intraoperative predictors of postoperative cardiac complications in observational perioperative studies and randomised controlled trials which controlled for preoperative cardiac risk factors. Results: Eleven studies were identified for inclusion in this meta-analysis. Intraoperative blood transfusion [odds ratio (OR) 2.6, 95% confidence interval (CI) 1.8-3.4] was the only independent intraoperative risk predictor identified in more than one study. Other identified independent intraoperative factors included a > 20 mmHg fall in mean arterial blood pressure for > 60 minutes (OR 3.0, 95% CI 1.8-4.9), > 30% increase in baseline systolic pressure (OR 8.0, 95% CI 1.3-50), tachycardia in the recovery room (> 30 beats per minute from baseline for > 5 minutes) (OR 7, 95% 1.9-26), new onset atrial fibrillation (OR 6.6, 95% CI 2.5-20), hypothermia (OR 2.2, 95% CI 1.1-5) and remote ischaemic preconditioning (OR 0.22, 95% CI 0.070.67). None of these studies controlled for blood transfusion. Conclusion: Both surgical and haemodynamic intraoperative events significantly increased the risk of postoperative cardiac complications. Intraoperative blood transfusion has the strongest evidence that supports this finding. It is possible that modification of these intraoperative risk factors by anaesthetists and surgeons might reduce postoperative cardiac events.