A community-based study of stroke incidence after myocardial infarction

Background: The rate of stroke after myocardial infarction (MI) remains unclear. Objectives: To examine the rate of stroke after incident MI; compare it with that observed in the population of Rochester, Minnesota; determine how the rate of stroke after MI has changed over time; and examine the impact of stroke on survival after incident MI. Design: Community-based cohort. Setting: Olmsted County, Minnesota. Participants: Persons with incident (first-ever) MI between 1979 and 1998. Measurements: Ischemic or hemorrhagic stroke in hospitalized and nonhospitalized patients that was identified by screening of the medical record for stroke diagnostic codes and subsequent stroke confirmation by physician review of the recorded event. Medical record review was used to ascertain baseline characteristics and death. Results: A total of 2160 persons with incident MI were hospitalized between 1979 and 1998 and followed for a median of 5.6 years (range, 0 to 22.2 years). The rate of stroke was 22.6 per 1000 person-months (95% CI, 16.3 to 30.6 per 1000 person-months) during the first 30 days after Mi, corresponding to a 44-fold increase (standardized morbidity ratio, 44 [95% CI, 32 to 59]) risk for stroke in the population of Rochester, Minnesota. The risk for stroke remained 2 to 3 times higher than expected during the first 3 years after Mi. Older age, previous stroke, and diabetes increased the risk for stroke, which did not decline over the study period. Strokes were associated with a large Increase in the risk for death after MI (hazard ratio, 2.89 [CI, 2.44 -to 3.43]). Limitations: Findings may not be generalizable to different populations. The authors measured outcomes by reviewing medical records. Conclusions: in the community, the risk for stroke is markedly increased after MI, particularly early after MI, compared with the expected risk in population without Mi. Stroke is associated with a large increase in the risk for death after Nil.