Differences in therapy and outcome among hospitals have been reported, but these studies have seldom used adjustment for differences in patient characteristics. The objective was to investigate the differences in treatment of acute myocardial infarction (AMI) among different hospitals within 1 country and the possible causes and outcomes of these differences.

Prospective cohort study using data from the Register of Information and Knowledge about Swedish Heart Intensive care Admissions (RIKS-HIA) on 32954 consecutive primary admissions of patients with AMI admitted to the intensive coronary care units of 67 Swedish hospitals in 1999-2000. An activity index was calculated for each hospital based on the hospital's ranking regarding proportion of performed examination or given therapy among the AMI patients.

After adjustment for 24 background characteristics, there were few significant deviations among hospitals in the proportion treated with acute reperfusion, antiplatelets, β-blockers, or angiotensin-converting enzyme (ACE) inhibitors. However, 3- to 10-fold differences existed among hospitals in the proportion of patients treated with intravenous β-blockers, intravenous nitroglycerin, intravenous or subcutaneous anticoagulants, and lipid-lowering medication, and even larger discrepancies in echocardiography and revascularization within 14 days. There was a strong (r = 0.69, P < .001) correlation between hospital activity index between the years and a correlation between the hospital's activity index and 1-year mortality (r = −0.30, P = .014). There was no correlation between hospital size and activity index.

Even after adjustment for differences in patient characteristics, there are differences between the hospital treatment cultures for patients with AMI that persists over time. Concerning everywhere-available treatment options, the treatment activity is independent of the size of the center. A more active treatment tradition is associated with a lower short- and long-term mortality in AMI patients.