Unplanned 30-Day Readmission after Coronary Artery Bypass in Patients with Acute Myocardial Infarction

Background/purpose: The Centers for Medicare and Medicaid services penalizes hospitals with higher than expected readmissions for coronary artery bypass graft surgery (CABG). Little information exists regarding outcomes in patients who sustain an acute myocardial infarction (MI) and undergo CABG as the primary revascularization strategy. Our goal was to determine the unplanned 30-day readmission rate in this high-risk population and predictors of readmission.

Materials/methods: An institutional database was queried to identify patients from 2011 to 2017 who were admitted with an acute MI and underwent CABG within 30 days. Chart review was performed to collect demographics, medical comorbidities and clinical information related to hospital course and readmission status.

Results: A total of 150 patients were included. The 30-day unplanned readmission rate was 23%, and the majority (80%) were non-cardiac related. Predictors of unplanned readmission included female sex (OR 2.61, 95% CI 1.042-6.549, p = 0.041), CABG performed <7 days following MI (OR 2.82, 95% CI 1.21-6.59, p = 0.017), and post-operative atrial fibrillation (OR 3.25, 95% CI 1.07-9.87, p = 0.038). Complications were identified in 32% of clinic visits in patients who did not require readmission.

Conclusions: Patients who undergo CABG following MI are a high-risk population with nearly one-quarter readmitted within 30 days. Female sex, <7 days between the index MI and CABG, and post-operative atrial fibrillation are strong predictors for readmission. Early outpatient follow-up may be an effective intervention to reduce hospital readmissions by reassuring patients that non-cardiac symptoms are in line with anticipated post-operative pain and healing.