Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an angiopathy caused by mutations in the NOTCH3 gene. Typical microvascular changes are found throughout the arterial tree, but the documented disease expression is confined to the central nervous system. In an ongoing CADASIL study, we noted a number of patients with early acute myocardial infarction (before the age of 50 years), as well as patients with electrocardiogram (ECG) abnormalities. We analyzed these data to determine whether myocardial ischemia is associated with NOTCH3 mutations. ECGs were recorded in mutated (n = 41) and nonmutated (n = 22) individuals from 15 genetically confirmed CADASIL families, and blindly classified according to the Minnesota code. Cardiologic history was assessed and cardiovascular disease risk factors were determined. Evidence for myocardial infarction was defined as a positive history for acute myocardial infarction and/or a Minnesota Code 1 (Q-waves) on ECG. We examined CADASIL myocardial tissue ultrastructurally and immunohistochemically for evidence of microangiopathy. We found that almost 25% (10/41) of mutation carriers had evidence of myocardial infarction, versus none of the 22 nonmutation carriers (p = 0.011). Five had a medical history of acute myocardial infarction, and 5 had current pathologic Q-waves on ECG. Acute myocardial infarction occurred at a mean age of 39.6 +/- 5.22 years, and predated major neurologic symptoms of CADASIL in all cases. Pathologic examination of myocardial tissue revealed typical CADASIL arteriopathic changes of the coronary microvasculature. To our knowledge, this is the first study showing that NOTCH3 mutation carriers may be at increased risk of early acute myocardial infarction, expanding CADASIL disease expression beyond the central nervous system to include the heart.