Aims: Acute myocardial infarction (AMI) is categorized, according to the presenting electrocardiogram, into non-ST-elevation myocardial infarction (non-STEMI), ST-elevation myocardial infarction (STEMI), or bundle branch block myocardial infarction (BBBMI). Data on the prognostic significance of these categories mainly originate from voluntary based registries or large-scale clinical trials and may be hampered by selection and information bias. The aim of this historical cohort study was to evaluate the prognostic significance of different categories of AMI in an unselected cohort.
Methods and results: From 1 November 1999 to 31 October 2001, patient records were reviewed from all admissions to hospitals serving a study region with 139,000 inhabitants. An Endpoint Committee determined whether patients fulfilled the European Society of Cardiology criteria of AMI. A total of 654 patients with AMI were identified. The proportion having non-STEMI, STEMI, and BBBMI was 54, 39 and 6%, and the associated 1 year mortality was 31, 21, and 55%, respectively (log rank 54, P<0.001). The more favourable outcome observed in patients with STEMI remained significant according to multivariable analysis (P=0.044).
Conclusion: In an unselected cohort of patients admitted with AMI, the mortality was considerably higher than expected from voluntary-based registries and large-scale clinical trials. The most favourable outcome is observed in patients with STEMI.