OBJECTIVES: For patients that suffered from an acute myocardial infarct (AMI), the 2001 guidelines of the American Heart Association (AHA) recommend indefinite treatment with 1) statins; 2) beta-blockers; 3) ace inhibitors or, if not tolerated, angiotensin-receptor blockers; and 4) aspirin. This study investigates how the recommendations are followed by patients and physicians as observed in pharmacy claims. METHODS: Retrospective, claims database study performed using data from a large health insurer in the Mid-Atlantic region. Patients were selected if they had an initial AMI episode (ICD-9 Code: 410.x1) between January 1, 2002 and August 31, 2004. These patients were then matched to their pharmacy claims between January 1, 2001 and December 31, 2004. For each patient, adherence is defined as the proportion of days covered. RESULTS: A total of 1958 patients were identified. The mean age was 60 years and 58% were male. Overall post-AMI adherence rates with recommended therapy were as follows: 1) statins: 43%; 2) beta-blockers: 45%; 3) ace-inhibitors or ARB's: 36%. Requiring at least 6 months (1 year, 2 years) of follow-up data post discharge, adherence rates drop to 1) statins: 42% (40%, 35%); and 2) beta-blockers: 43% (41%, 35%), ace-inhibitors or ARB's: 35% (33%, 29%). A total of 13% of patients can be defined as adherent to the AHA recommendations, filling more than 80% of all recommended prescriptions, whereas 19% of patients have filled zero of the recommended prescriptions. Notably, 12%-15% of patients were receiving at least one of the drugs even before their first AMI. In this subgroup adherence rates decrease after the AMI by 1) statins: 20%; and 2) beta-blockers: 22%, ace-inhibitors or ARB's: 30%. CONCLUSION: The AHA post-AMI treatment recommendations are followed only by a minority of patients. In addition, mean adherence rates drop after the AMI if the patient was receiving prophylactic therapy.