Incidence, Predictors, and Outcomes of Early Acute Myocardial Infarction Following Coronary Artery Bypass Grafting

Abstract

Large-scale data on early postdischarge acute myocardial infarction (AMI) after coronary artery bypass grafting (CABG) are lacking. We queried the National Readmission Database (2015 to 2016) to identify patients who underwent CABG between January 1 and June 31 (i.e., had 6 months of follow-up). The study's end points were the incidence, predictors, and outcomes of early post-CABG AMI. Of the 203,760 included patients, 3,829 (1.8%) were readmitted for AMI. Compared with patients without readmissions for AMI, those with AMI were younger (65 ± 11 vs 66 ± 10 years), had more females (35.5% vs 25.1%), and higher prevalence of hypertension, diabetes, obstructive lung disease, anemia, vascular disease, renal insufficiency, and liver cirrhosis, but less atrial fibrillation (p <0.001). They also had a distinctive profile of their index CABG surgery. The strongest predictors of post-CABG AMI readmission were female gender (odds ratio [OR] 1.46, 95% confidence interval [CI] = 1.36 to 1.57), heart failure (OR 1.37, 95% CI = 1.27 to 1.50), dialysis (OR 1.5%, 95% CI = 1.25 to 1.78), cirrhosis (OR 1.61, 95% CI = 1.14 to 2.27), nonelective CABG (OR 1.70, 95% CI = 1.57 to 1.84), perioperative mechanical circulatory support (OR 1.37, 95% CI = 1.23 to 1.51), low-volume centers (OR 1.36, 95% CI = 1.18 to 1.56), and nonhome discharge after CABG (OR 1.47, 95% CI = 1.35 to 1.59). In the patients who were readmitted for AMI, 86.3% had non-ST-elevation AMI and 13.7% had ST-elevation AMI. Coronary angiography was performed in 2,096 patients (54.7%). Of those, 63.5% received percutaneous coronary intervention, and 1.7% had redo-CABG. Readmissions for AMI were associated with significant in-hospital mortality (5.7%), acute kidney injury (22.1%), and new dialysis (2.1%). Median length-of-stay was 3 days (25th/75th percentile 2,6), and the mean hospital cost was $22,207 ± 29,071.