Trends in the in-hospital treatment of acute myocardial infarction between1984 and 1993 - The Halifax County MONICA Project

BACKGROUND: The Halifax County MONItoring of trends and determinants in CAr diovascular disease (MONICA) Project found that between 1984 and 1988, the proportion of myocardial infarctions (MIs) that were fatal within 28 days r emained constant, but declined between 1989 and 1993. The objective was to investigate association among case fatality, treatment, and case severity o f MI in hospitalized patients. PATIENTS AND METHODS: The MONICA MI register contains data on demographics, health history, in-hospital investigations, interventions and treatment, a nd 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 anal ysis was used to estimate trends in the use of cardioactive drugs and revas cularization procedures. A case severity score was developed from patient c haracteristics at time of admission. Case fatality was calculated as the pr oportion of MIs that were fatal within 28 days. RESULTS: Between 1984 and 1988, a large increase (OR greater than or equal to 1.3) occurred in the use of angiotensin-converting enzyme (ACE) inhibito rs, acetylsalicylic acid (ASA), thrombolysis and percutaneous transluminal coronary angioplasty (PTCA); a minor increase occurred in use of calcium ch annel 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 198 9 re, 1993, ACE inhibitor use increased (OR=1.4, 99% CI 1.27 to 1.55); mino r increases occurred in use of ASA and beta-blockers, and in PTCA and coron ary artery bypass grafting; case severity did not change and case fatality decreased. CONCLUSIONS: While use of beneficial treatment increased between 1984 and 1 988, MI case fatality did not decrease, probably because case severity incr eased. Between 1989 and 1993, case severity remained constant, and the furt her increase in the use of beneficial therapy was associated with a decline in case fatality.