Improved long-term prognosis for patients with unstable coronary syndromes 1988-1995

Abstract

Aims: A more aggressive approach to unstable coronary syndromes has developed over the last decade. We set out to examine the long-term outcome among patients with acute coronary syndromes with respect to period of admission since 1988.

Methods: 3918 patients with unstable angina or a non-Q wave myocardial infarction who were admitted to the coronary care unit at Ostra Hospital in the period 1988-1997 were included. Standardized criteria were used to define a non-Q wave myocardial infarction and included fulfilment of the following: (1) typical enzyme changes (serial serum aspartate aminotransferase above 0.7 microkat x l(-1), serial creatine kinase above 3.3 microkat x l(-1) or serial creatine kinaseMB subunit mass concentration above 15 microg x l(-1)), and at least one of the following: (2) chest pain, shock, syncope or pulmonary oedema suggestive of a myocardial infarction, (3) development of electrocardiographic changes with serial ST-T changes without Q waves. The standardized criteria for unstable angina pectoris were fulfilment of at least one of the following: (1) a clear worsening of a previous stable pattern of angina pectoris, (2) chest pain at rest or minimal effort with transient ST-segment elevation or depression on electrocardiogram or elevation of cardiac enzymes not reaching the criteria for myocardial infarction. Information on vital status and cause of death after discharge was collected from the national cause-specific mortality register.

Results: Two-year mortality decreased from 30% in 1988 to 19% in 1995 (relative risk per year 0.94 (0.90-0.97), 95% confidence interval). The improvement was consistent regardless of differences in age, prior myocardial infarction, diabetes mellitus, hypertension, development of non-Q wave myocardial infarction, treatment with heparin or thrombolytics or performance of acute coronary angiograms. The cumulative survival at 10 years was 53% in the unstable angina group and 36% in the non-Q wave myocardial infarction group (P<0.0001).

Conclusion: Against a background of a more aggressive approach to acute coronary syndromes a decrease in long-term mortality is seen between 1988 and 1995.