Role of coronary interventional procedures in improved postinfarction survival in the 1990s

The contribution of increased use of same-admission percutaneous coronary interventional procedures to recent improvements in hospital survival of patients with acute myocardial infarction (AMI) remains unclear. Patients with International Classification of Diseases codes for AMI (code 410), who were admitted to the emergency coronary care unit and underwent an initial episode of treatment, were studied over the 9-year period 1990 to 1998 (n = 2,628). Three triennia between 1990 and 1998 were compared. Trends in risk, the use of procedures, and hospital outcomes were analyzed. Hospital mortality was 33% lower (p <0.02) in the third triennium (5.8%) than in the earlier 2 triennia (8.7%), equivalent to an absolute reduction of 29 hospital deaths/1,000 patients treated. The lower hospital mortality was not due to: (1) shorter hospital stays (reduction in mortality was primarily in the first 3 hospital days), (2) treatment of lower risk subjects (a risk score based on age, gender, and presence of diabetes increased between the first and third triennia), or (3) use of in-hospital interventional procedures (although the use of percutaneous coronary intervention more than doubled in the third triennium, most procedures were performed in patients with a 1% risk of hospital death). We conclude from this study that there has been a substantial improvement over a 9-year period in early case fatality after AMI, but that this cannot be attributed to the increased use of in-hospital coronary interventions, which were largely performed on low-risk patients.