Thirty-day Rehospitalizations After Acute Myocardial Infarction: a Cohort Study

Background: Rehospitalization is a quality-of-care indicator, yet little is known about its occurrence and predictors after myocardial infarction (MI) in the community.

Objective: To examine 30-day rehospitalizations after incident MI.

Design: Retrospective cohort study.

Setting: Population-based registry in Olmsted County, Minnesota.

Patients: 3010 patients who were hospitalized in Olmsted County with first-ever MI from 1987 to 2010 and survived to hospital discharge.

Measurements: Diagnoses, therapies, and complications during incident and subsequent hospitalizations were identified. Manual chart review was performed to determine the cause of all rehospitalizations. The hazard ratios and cumulative incidence of 30-day rehospitalizations were determined by using Cox proportional hazards regression models.

Results: Among 3010 patients (mean age, 67 years; 40.5% female) with incident MI (31.2% ST-segment elevation), 643 rehospitalizations occurred within 30 days in 561 (18.6%) patients. Overall, 30.2% of rehospitalizations were unrelated to the incident MI and 42.6% were related; the relationship was unclear in 27.2% of rehospitalizations. Angiography was performed in 153 (23.8%) rehospitalizations. Revascularization was performed in 103 (16.0%) rehospitalizations, of which 46 (44.7%) had no revascularization during the index hospitalization. After adjustment for potential confounders, diabetes, chronic obstructive pulmonary disease, anemia, higher Killip class, longer length of stay during the index hospitalization, and a complication of angiography or reperfusion or revascularization were associated with increased rehospitalization risk. The 30-day incidence of rehospitalization was 35.3% in patients who experienced a complication of angiography during the index MI hospitalization and 31.6% in those who experienced a complication of reperfusion or revascularization during the index MI hospitalization, compared with 16.8% in patients who had reperfusion or revascularization without complications.

Limitation: This study represents the experiences of a single community.

Conclusion: Comorbid conditions, longer length of stay, and complications of angiography and revascularization or reperfusion are associated with increased 30-day rehospitalization risk after MI. Many rehospitalizations seem to be unrelated to the incident MI.

Primary Funding Source: National Institutes of Health.