Background and purpose: Coronary artery disease is the leading cause of death after TIA. Reliable estimates of the risk of MI after TIA, however, are lacking.
Methods: Our purpose was to determine the incidence of and risk factors for MI after TIA. We cross-referenced preexisting incidence cohorts from the Rochester Epidemiology Project for TIA (1985-1994) and MI (1979-2006) to identify all community residents with incident MI after incident TIA. Incidence of MI after TIA was determined using Kaplan-Meier life-table methods. This was compared to the age-, sex-, and period-specific MI incidences in the general population. Proportional hazards regression analysis was used to examine associations between clinical variables and the occurrence of MI after TIA.
Results: Average annual incidence of MI after TIA was 0.95%. Relative risk for incident MI in the TIA cohort compared to the general population was 2.09 (95% CI, 1.52-2.81). This was highest in patients younger than 60 years old (relative risk, 15.1; 95% CI, 4.11-38.6). Increasing age (hazard ratio, 1.51 per 10 years; 95% CI, 1.14-2.01), male sex (hazard ratio, 2.19; 95% CI, 1.18-4.06), and the use of lipid-lowering therapy at the time of TIA (hazard ratio, 3.10; 95% CI, 1.20-8.00) were independent risk factors for MI after TIA.
Conclusions: Average annual incidence of MI after TIA is ≈1%, approximately double that of the general population. The relative risk increase is especially high in patients younger than 60 years old. These data are useful for identifying subgroups of patients with TIA at highest risk for subsequent MI.