BACKGROUND: There are limited data informing the optimal treatment strategy for acute myocardial infarction in the oldest old (aged > /= 85 years). The study aim was to examine whether decade-long increases in guideline-based cardiac medication use mediate declines in post-discharge mortality among oldest old patients hospitalized with acute myocardial infarction.

METHODS: The study sample included 1137 patients aged > /= 85 years hospitalized in 6 biennial periods between 1997 and 2007 for acute myocardial infarction at all 11 greater Worcester, Massachusetts, medical centers. We examined trends in 90-day survival after hospital discharge and guideline-based medication use (aspirin, angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, beta-blockers, lipid-lowering agents) for acute myocardial infarction during hospitalization and at discharge. Sequential multivariable Cox regression models examined the relationship among guideline-based medication use, study year, and 90-day post-discharge survival rates.

RESULTS: Patients hospitalized between 2003 and 2007 experienced higher 90-day survival rates than those hospitalized between 1997 and 2001 (69.1% vs 59.8%, P < .05). Between 1997 and 2007, the average number of guideline-based medications prescribed at discharge increased significantly (1.8 to 2.9, P < .001). The unadjusted hazard ratio for 90-day post-discharge mortality in 2003-2007 compared with 1997-2001 was 0.73 (95% confidence interval, 0.60-0.89); after adjustment for patient characteristics and guideline-based cardiac medication use, this relationship was no longer significant (hazard ratio, 1.26; 95% confidence interval, 1.00-1.58).

CONCLUSIONS: Between 1997 and 2007, 90-day survival improved among a population-based sample of patients aged > /= 85 years hospitalized for acute myocardial infarction. This encouraging trend was explained by increased use of guideline-based medications.