OBJECTIVES: To compare the long-term clinical and economic outcomes of elderly (75 years) versus younger acute coronary syndrome patients. METHODS: We used the Duke Cardiovascular Databank to identify patients with a recent (<6 weeks) myocardial infarction or unstable angina, index cardiac cath between 1986 and 1997, significant coronary artery disease (CAD), and no previous cardiac procedures. Follow-up extended through 1998. We modeled clinical events (death, MI, coronary artery bypass graft surgery (CABG), percutaneous coronary intervention (PCI), and other rehospitalizations) to 12 years for pts with censored follow-up. We modeled inpatient and outpatient medical costs for all patients using inpatient costs from the GUSTO IIb clinical trial and other secondary data sources. RESULTS: Elderly (n = 1401) vs. younger (n = 8475) patients were more likely female (58% vs. 32%) and non-smokers (41% vs. 69%), had greater history of congestive heart failure (25% vs. 14%) and cerebral vascular disease (17% vs. 9%), less single vessel disease (30% vs. 46%) and more three vessel disease (43% vs. 26%), and greater 30-day mortality (9.8% vs. 3.2%). While median 12-year medical costs were greater for younger ($57,475) than for elderly ($53,431) patients, mean survival was less for elderly patients (6.4 vs. 9.3 years) yielding greater costs per year of survival ($8075 vs. $6037) for the elderly. CONCLUSIONS: CAD patients undergoing an initial cardiac cath after age 75 represent a high-risk group undetected by current CAD screening algorithms. These findings point to the need for improved screening tools and disease management strategies in high-risk, pre-CAD populations.