Myocardial infarction in a large colony of nonhuman primates with coronary artery atherosclerosis

Relatively few cases of myocardial infarction associated with coronary artery atherosclerosis have been described previously in macaques. In this study the authors report the prevalence and characteristics of coronary artery atherosclerosis and myocardial infarction in 10 rhesus (Macaca mulatta) and two cynomolgus (Macaca fascicularis) macaques that were fed atherogenic diets for 16 months or longer. Our findings show clearly that myocardial infarction occurs in macaques with diet-induced atherosclerosis. The frequency seems to be related to the species, composition of the atherogenic diet, and length of time fed the atherogenic diet. The myocardial lesions are remarkably similar to those described in human beings in terms of location and gross and microscopic characteristics. The characteristics of coronary artery atherosclerosis, including the occurrence of thrombosis, severe stenosis, mineralization, atheronecrosis, and sterol clefts, especially in animals fed the atherogenic diets for longer periods of time, also closely resemble those of the arterial lesions found in human beings. The greatest prevalence of myocardial infarcts was found in rhesus monkeys fed a cholesterol-containing diet with 40% of calories supplied by peanut oil and in cynomolgus macaques from Malaya that were fed the same amount of cholesterol with 40% of calories from lard. Electrocardiographic abnormalities as well as the occurrence of unexpected and relatively sudden death in several of these nonhuman primates are also consistent with signs frequently observed in human beings.