According to an analysis of Swedish registry data, use of aspirin, beta-blockers, angiotensin-converting enzyme [ACE] inhibitors, or statins before hospital admission in patients with a first acute myocardial infarction (MI) was found to be associated with substantially less risk of presenting with ST-segment elevation MI (STEMI), a more damaging and severe type of MI. The risk was found to decrease with the increasing number of these medications used before acute MI, emphasising the importance of preventive medication in high-risk patients.

The study investigators used data from the Swedish Register of Information and Knowledge About Swedish Heart Intensive Care Admissions (RIKS-HIA) which includes all patients admitted to hospitals with coronary care units from 1995 to 2006. They extracted data on 103 459 consecutive patients admitted between January 1, 1996, and December 31, 2006, with a first acute MI. The criteria for a diagnosis of acute MI were standardised and identical for all participating hospitals using the World Health Organization, Joint European Society of Cardiology, and American College of Cardiology Committee criteria.

The following observations were noted:

• Of the 43.5% of patients who presented with STEMI (43.5% of the total), patients were younger, had less prior cardiovascular disease, and used fewer medications before hospitalisation.
• Patients with STEMI used aspirin (20.4% vs 33.5%), β-blockers (22.5% vs 33.2%), ACE inhibitors (10.3% vs 15.8%), and statins (8.1% vs 15.0%) less often than did non-STEMI patients before acute MI (P < .001 for all).
• Of the STEMI patients, 61.4% had used no medication vs 45.9% of the patients with non-STEMI.
• After multiple adjustments (age, sex, hypertension, diabetes, heart failure, angina, prior revascularisation, smoking, year of admission and previous use of aspirin, β-blockers, ACE inhibitors, and statins), previous use of aspirin (multiply adjusted OR, 0.72; 99% CI, 0.69-0.76), β-blockers (0.82; 0.78-0.86), ACE inhibitors (0.84; 0.79-0.89), and statins (0.79; 0.74-0.84) were all independently associated with substantially lower risk of presenting with STEMI
• Furthermore, the risk decreased with the number of previous medications, and the use of 3 or more medications was associated with a multiple adjusted odds ratio of presenting with STEMI of 0.48 (99% confidence interval, 0.44-0.52) compared with no medications at admission.