Unplanned Readmissions Due to Post-acute Myocardial Infarction Complications: Insights From the Nationwide Readmission Database (2016-2020).

Introduction Acute myocardial infarction (MI) readmissions within 30 days (30-dr) are affecting patient outcomes and healthcare costs. This study analyzed trends in 30-dr for patients discharged after an acute MI. Methods We analyzed the 2016-2020 Nationwide Readmission Database for patients aged 18 years or older with an initial admission for acute MI who were readmitted within 30 days. Variables were identified using ICD-10 codes. The primary outcome was trends in 30-dr; secondary outcomes included trends in complications, mortality, length of stay (LOS), and healthcare costs. Multivariate and descriptive bivariate analyses were conducted, with p-values <0.05 considered statistically significant. Results Among 2,572,790 acute MI index admissions, 221,910 (8.6%) were readmitted within 30 days, with a significant decline in readmission risk over the study period (p < 0.001). Mean age was 66.9 ± 13.5 years. In-hospital mortality decreased over time (OR 0.92, 95% CI 0.88-0.96; p trend < 0.01). During index admissions, vasopressor use and acute kidney injury increased, while periprocedural bleeding declined (OR 0.38, 95% CI 0.33-0.43). In multivariable Cox regression, 30-day readmission risk declined from 2017 to 2019 (HR 0.93 to 0.87) with a slight increase in 2020 (HR 0.94). Higher age (HR 1.01) and comorbidity burden (HR 1.07) were associated with increased risk, while male sex was protective (HR 0.92 [0.90-0.94]). Periprocedural circulatory complications (OR 0.30, 95% CI 0.17-0.51) and bleeding (OR as low as 0.07, 95% CI 0.03-0.17) declined, while post-procedural anemia (OR 1.16, 95% CI 1.06-1.26) and non-inflammatory pericardial effusion (OR 1.62, 95% CI 1.34-1.97) increased. Conclusion 30-dr after acute MI declined over time, but remains driven by increasing comorbidity burden and evolving procedural complication profiles, underscoring the need for targeted risk stratification and post-discharge care. This study highlights relevant data to inform targeted interventions to reduce readmissions and complications.