Epidemiology, clinical features, and prognosis of acute myocardial infarction in the elderly.

The incidence and prevalence of acute myocardial infarction (MI) increase progressively with age. In the United States, over 60% of acute MIs occur in patients 65 years of age or older, and approximately one third occur in persons over age 75. In addition, mortality rates following acute MI increase exponentially with age, such that approximately 60% of all MI deaths in the United States occur in the 6% of the population 75 years of age or older. The clinical features of acute MI vary by age. In particular, very elderly patients are less likely than younger patients to report chest pain. Conversely, confusion or altered mental status may be the presenting manifestation of acute MI in up to 20% of patients over 85 years of age. Older patients are also more likely to have "silent" or unrecognized MIs, as well as MIs without ST-segment elevation, compared with younger patients. Elderly patients with acute MI are more likely than younger patients to experience heart failure, atrial fibrillation, cardiac rupture, and shock, all of which are associated with increased mortality. Other factors contributing to the poor prognosis following acute MI in elderly individuals include a marked decline in cardiovascular reserve in the elderly, increased prevalence of comorbid conditions, underutilization of evidence-based therapies, and increased risk of iatrogenic complications.