Background: Multiple chronic conditions (MCCs) are common in patients hospitalized with acute myocardial infarction (AMI). We examined the association of 12 MCCs with the risk of a 30-day hospital readmission and/or dying within one year among those discharged from the hospital after an AMI. We also examined the five most prevalent pairs of chronic conditions in this population and their association with the principal study endpoints.

Methods: The study population consisted of 3,294 adults hospitalized with a confirmed AMI at the three major medical centers in central Massachusetts on an approximate biennial basis between 2005 and 2015. Patients were categorized as ≤1, 2-3, and ≥4 chronic conditions.

Results: The median age of the study population was 67.9 years, 41.6% were women, and 15% had ≤1, 32% had 2-3, and 53% had ≥4 chronic conditions. Patients with ≥4 conditions tended to be older, had a longer hospital stay, and received fewer cardiac interventional procedures. There was an increased risk for being rehospitalized during the subsequent 30 days according to the presence of MCCs, with the highest risk for those with ≥4 conditions. There was an increased, but attenuated, risk for dying during the next year according to the presence of MCCs. Individuals with diabetes/hypertension and those with heart failure/chronic kidney disease were at particularly high risk for developing the principal study outcomes.

Conclusion: Development of guidelines that include complex patients, particularly those with MCCs and those at high risk for adverse short/medium term outcomes, remain needed to inform best treatment practices.