Background and purpose: Myocardial infarction and stroke are both predominantly manifestations of atherosclerosis, yet stroke is commonly ignored in prognostic studies and therapeutic trials of ischemic heart disease. Our objective was to assess, in a community setting, the relative importance of stroke among patients at high risk for myocardial infarction.
Methods: We analyzed 1985 survey data from the National Academy of Science Twin Registry of white male veterans. To minimize confounding by genetic and environmental factors, we restricted our analysis to the rates of stroke and myocardial infarction among monozygotic twins counted as individuals or as twin pairs.
Results: Among 2764 monozygotic twins aged 58 to 68 years, the overall rate of myocardial infarction was 10% and stroke 3.1%. Among 2632 individual monozygotic twins (95%) with complete responses, the rate of stroke among men with a history of myocardial infarction was 7.5% (17/228) compared with 2.4% (58/2404) among those without myocardial infarction (odds ratio = 3.3, chi square 2 = 19.1, P<.001). A strong association between stroke and myocardial infarction was also found when the data were analyzed for twin pairs (chi square 2 = 135, P<.0005).
Conclusions: Our results suggest that stroke, in addition to myocardial infarction, should be considered as an outcome in clinical investigations of ischemic heart disease.