The Effect of Preoperative Circadian Blood Pressure Pattern on Early Postoperative Outcomes in Patients with Coronary Artery Bypass Graft Surgery

Abstract

Objective: The aim of this prospective study was to evaluate the relationship between preoperative circadian blood pressure pattern and early postoperative course in patients undergoing coronary artery bypass graft (CABG) surgery. Methods: One hundred and thirty patients planning to undergo isolated CABG operation were included to the study (80 men; 50 women). All patients were studied with ambulatory blood pressure monitoring performed 24 hours before surgery and were divided into 2 groups according with presence (79 patients) or absence (51 patients) of dipper phenomenon. Non-dippers were defined as those with a nocturnal reduction of systolic and diastolic blood pressures of less than 10% of daytime pressures. Both groups were compared with each other from the aspect of postoperative need for intraaortic balloon counterpulsation (IABP), inotropic drug support, extubation time, length of intensive care unit and hospitalization stays, renal failure, stroke, malignant ventricular arrhythmia, atrial fibrillation, postoperative myocardial infarction and cardiac mortality. Statistical analyses were performed using Chi-square, unpaired t and Mann-Whitney U tests. Logistic regression analysis was performed to establish associations of non-dipper phenomenon with the risk of postoperative complications. Results: When compared with the dipper patients, need for inotropic medications (37.5% vs. 62.5%), low cardiac output syndrome (30.4% vs. 69.6%), postoperative myocardial infarction (28.6% vs. 71.4%) and malignant ventricular arrhythmias (27.8% vs. 72.2%) were higher in the non-dipper patients (p<0.05 for all). Logistic regression analysis demonstrated that non-dipper phenomenon after CABG was associated with longer cardiopulmonary bypass time (OR=1.038, 95%CI 1.016-1,060, p=0.001), more need for postoperative inotropic agent (OR=4.014, 95%CI 1.235-13,047, p=0.021) and postoperative IABP (OR=6.625, 95%CI 1.564-28.069, p=0.01) support, higher risk of low cardiac output syndrome (OR=4.159, 95%CI 0.921-18.775, p=0.064), malignant ventricular arrhythmia (OR=4.653, 95%CI 0.964-22,456, p=0.056) and postoperative myocardial infarction (OR=7.629 95%CI 1.448-40.177, p=0.017). Conclusion: Dipper and non-dipper phenomenon can be used as a simple analysis tool for assessing early postoperative mortality and morbidity.