Demographic and Clinical Predictors of Postoperative Outcomes in Patients Undergoing Coronary Artery Bypass Grafting: A Cross-sectional Study from a Tertiary Center in Iran

Abstract

Background: Coronary artery bypass grafting (CABG) is a critical surgical intervention for patients with coronary artery disease (CAD). Objectives: This study aimed to evaluate the demographic and clinical characteristics, as well as postoperative outcomes, of patients undergoing CABG in a tertiary referral center in Iran. Methods: A descriptive cross-sectional study was conducted on 379 elective CABG patients at Dr. Heshmat Hospital during 2024. Data on demographic factors, comorbidities, risk factors, and postoperative complications (mortality, renal, respiratory, hepatic failure, arrhythmias, sternal infections, and reoperation) were collected and analyzed using SPSS version 21. Postoperative complications were defined using standard clinical criteria: renal failure according to kidney disease: Improving global outcomes (KDIGO) criteria, respiratory failure requiring > 48 hours of mechanical ventilation, life-threatening arrhythmias (including new-onset atrial fibrillation, ventricular tachycardia, or heart block requiring intervention), hepatic failure as a bilirubin level > 2 mg/dL with international normalized ratio (INR) > 1.5, and sternal wound infection based on Centers for Disease Control and Prevention (CDC) criteria. A convenience sampling method was employed, and the sample size was calculated based on an estimated complication rate of 30% from previous local studies, with a 5% margin of error and 95% confidence level, resulting in a minimum required sample of 323. We enrolled 379 patients to account for potential missing data. Statistical significance was assessed via chi-square tests (P < 0.05). For continuous variables, normality was assessed using the Shapiro-Wilk test. Independent samples t-test was used for normally distributed data and Mann-Whitney U test for non-normal distributions. Multivariable logistic regression was also performed to identify independent predictors of the composite complication endpoint. Results: The majority of patients were male (68.9%), with a mean age of 60.37 ± 7.37 years. Hypertension (69.7%), hyperlipidemia (67.3%), and diabetes (55.1%) were prevalent comorbidities. Postoperative complications occurred in 35.1% of patients (133/379). Arrhythmias (21.4%) were the most common complication. In univariate analysis, a significant association was found between a history of previous myocardial infarction (MI) and the incidence of any postoperative complication (P < 0.001). However, in the multivariable logistic regression model controlling for age, gender, diabetes, hypertension, and smoking, a history of previous MI remained an independent predictor of postoperative complications [adjusted odds ratio (AOR) = 2.95, 95% confidence interval (CI): 1.68 - 5.18, P < 0.001]. No other risk factors, including diabetes, hypertension, and smoking, showed a significant association with complications. The 30-day mortality was 1.6%. No statistically significant associations were found between the studied preoperative risk factors and post-CABG mortality. Conclusions: The CABG outcomes in this cohort were comparable to global standards, with low mortality but notable complications. The primary finding was the strong, independent association between a history of previous MI and postoperative complications. This underscores the critical importance of thorough preoperative cardiac assessment and optimization for patients with a prior MI. Enhanced preoperative optimization, including consideration of specialized preoperative clinics for high-risk patients and robust management of comorbidities, and adherence to guidelines may further improve outcomes.