Recurrent myocardial infarction: In-Hospital mortality, cardiovascular complications, and comorbidity profiles.

IMPORTANCE

Recurrent myocardial infarction (RMI) represents a growing clinical challenge due to advances in acute myocardial infarction (AMI) management that prolong survival yet inadvertently increase the prevalence of high-risk patients with prior infarctions. Understanding the unique trajectory and complications associated with RMI is critical for improving care.

OBJECTIVE

To assess the clinical outcomes, complication rates, and comorbidity burden of patients hospitalized with recurrent myocardial infarction (RMI) compared to those with first-time AMI or NSTEMI.

DESIGN, SETTING, AND

PARTICIPANTS

A retrospective cohort study utilizing the Nationwide Readmissions Database (2016-2022), encompassing ∼60 % of U.S. hospitalizations. Adult patients admitted for acute coronary syndrome (ACS) were stratified into RMI and non-RMI (first-time AMI/NSTEMI) cohorts. Multivariable logistic and linear regression models were applied to assess outcomes, adjusting for demographic and clinical covariates.

MAIN OUTCOME AND MEASURES: Primary outcome was in-hospital mortality. Secondary outcomes included acute heart failure (unspecified, HFrEF, HFpEF), ventricular arrhythmias (ventricular fibrillation, ventricular tachycardia), cardiac arrest, cardiogenic shock, mechanical circulatory support (tMCS), use of percutaneous coronary intervention (PCI), length of stay (LOS), hospitalization cost, non-home discharge, and 30-day readmission.

RESULTS

Among 5,511,658 AMI admissions, 17,413 (0.3 %) involved RMI. After adjustment, RMI was associated with increased risk of mortality (AOR 1.59, 95 % CI 1.44-1.76), cardiac arrest (AOR 1.58), cardiogenic shock (AOR 1.96), ventricular fibrillation (AOR 1.91), ventricular tachycardia (AOR 1.44), and tMCS utilization (AOR 2.16). RMI patients experienced longer LOS (+2.46 days) and incurred higher hospitalization costs (+$11,400). Comorbidities such as diabetes, late-stage kidney disease, and chronic lung disease were significantly more prevalent in RMI.

CONCLUSION AND RELEVANCE: RMI is independently associated with significantly worse in-hospital outcomes and greater healthcare utilization compared to first-time AMI/NSTEMI. Enhanced risk stratification, tailored management protocols, and expanded access to advanced therapies are urgently needed to address the complex needs of this vulnerable population.