Trends in the in-hospital treatment of acute myocardial infarction between 1984 and 1993 - The Halifax County MONICA Project.

ABSTRACT

BACKGROUND: The Halifax County MONItoring of trends and determinants in CArdiovascular disease (MONICA) Project found that between 1984 and 1988, the proportion of myocardial infarctions (MIs) that were fatal within 28 days remained constant, but declined between 1989 and 1993. The objective was to investigate association among case fatality, treatment and case severity of MI in hospitalized patients. PATIENTS AND METHODS: The MONICA MI register contains data on demographics, health history, in-hospital investigations, interventions and treatment, and vital status at 28 days after onset of symptoms for all MIs occurring in residents of Halifax County, aged 25 to 74 years. Logistic regression analysis was used to estimate trends in the use of cardioactive drugs and revascularization procedures. A case severity score was developed from patient characteristics at time of admission. Case fatality was calculated as the proportion of MIs that were fatal within 28 days. RESULTS: Between 1984 and 1988, a large increase (OR 1.3) occurred in the use of angiotensin-converting enzyme (ACE) inhibitors, acetylsalicylic acid (ASA), thrombolysis and percutaneous transluminal coronary angioplasty (PTCA); a minor increase occurred in use of calcium channel blockers (OR=1.29, 99% CI 1.19 to 1.40); beta-blocker use decreased; case fatality remained constant and case severity score increased. From 1989 to 1993, ACE inhibitor use increased (OR=1.4, 99% CI 1.27 to 1.55); minor increases occurred in use of ASA and beta-blockers, and in PTCA and coronary artery bypass grafting; case severity did not change and case fatality decreased. CONCLUSIONS: While use of beneficial treatment increased between 1984 and 1988, MI case fatality did not decrease, probably because case severity increased. Between 1989 and 1993, case severity remained constant, and the further increase in the use of beneficial therapy was associated with a decline in case fatality.