Improved survival after myocardial infarction (MI) could result in MI survivors' contributing to the US heart failure epidemic. Conversely, since the severity of MI is declining over time, a decline in post-MI heart failure might also be anticipated. This study tested the hypothesis that the incidence of post-MI heart failure was declining over time in a geographically defined MI incidence cohort. Between 1979 and 1994, 1,537 patients with incident MI and no prior history of heart failure were hospitalized in Olmsted County, Minnesota. Framingham Heart Study criteria were used to ascertain the incidence of inpatient and outpatient heart failure over a mean follow-up period of 7.6 years (standard deviation 5.5). Overall, 36% of patients experienced heart failure. After adjustment for factors related to post-MI heart failure (age, hypertension, smoking, and biomarkers), the incidence of heart failure declined by 2% per year (relative risk = 0.98, 95% confidence interval: 0.96, 0.99; p = 0.01). The relative risk of developing heart failure among persons with MIs occurring in 1994 versus 1979 was 0.72 (95% confidence interval: 0.55, 0.93), indicating a 28% reduction in the incidence of heart failure. Administration of reperfusion therapy within 24 hours after MI was associated with lower risk of post-MI heart failure and accounted for most of the temporal decline in heart failure. This suggests that improved survival after MI is unlikely to be a major contributor to the heart failure epidemic.