Rate, causes, and predictors of 90-day readmissions and the association with index hospitalization coronary revascularization following non-ST elevation myocardial infarction in the United States

Objectives: To assess the causes and predictors of readmission after NSTEMI. Background: Studies on readmissions following non-ST elevation myocardial infarction (NSTEMI) are limited. We investigated the rate and causes for readmission and the impact of coronary revascularization on 90-day readmissions following a hospitalization for NSTEMI in a large, nationally representative United States database. Methods: We queried the National Readmission Database for the year 2016 using appropriate ICD-10-CM/PCS codes to identify all adult admissions for NSTEMI. We determined the 90-day readmissions for major adverse cardiac events (MACE). All-cause readmission was a secondary endpoint. The association between coronary revascularization and the likelihood of readmission was analyzed using multivariate Cox regression analysis. Results: A total of 296,965 adult discharges following an admission for NSTEMI were included in this study. The rate of readmissions for MACE was 5.2% (n = 15,637) and for any cause was 18.0% (n = 53,316). 38% of MACE readmissions and 40% of all-cause readmissions occurred between 30- and 90-days following the index hospitalization. During index hospitalization, 51.0% underwent coronary revascularization (40.8% with PCI and 10.2% with CABG). This was independently predictive of a lower risk of 90-day readmission for MACE (adjusted HR 0.59, 95% confidence interval (CI) 0.56–0.63, p <.001) and for any cause (adjusted HR 0.65, 95% CI 0.63–0.67, p <.001). In-hospital mortality for MACE readmissions was significantly higher compared to that of index hospitalization (3.8% vs. 2.6%, p <.001). Conclusion: Readmissions following NSTEMI carry higher mortality than the index hospitalization. Coronary revascularization for NSTEMI is associated with a lower readmission rate at 90 days.