Impact of changing diagnostic criteria on incidence, management, and outcome of acute myocardial infarction: retrospective cohort study

Abstract

Acute myocardial infarction used to be defined by criteria based on symptoms, changes in electrocardiograms and the concentrations of cardiac enzymes, as recommended by the World Health Organization.1 Specific markers of myocardial damage, including troponin T, are more sensitive indicators than total creatine kinase concentration for ischaemic myocardial necrosis and prognosis.2 In 2000, the European Society of Cardiology and the American College of Cardiology recommended changing the diagnostic criteria for acute myocardial infarction to include raised troponin T concentrations in addition to changes in electrocardiograms or coronary intervention.3 Some patients with acute coronary syndrome who had been diagnosed as having unstable angina are now classified as having myocardial infarction. We investigated the impact of using the new criteria on the incidence, management, and outcome of myocardial infarction. Since 1997, all patients admitted with chest pain to Monklands Hospital, Airdrie, had their troponin T concentrations measured. We identified patients …