Thrombolytic eligibility in acute myocardial infarction patients admitted to Norwegian hospitals

We characterised the population of acute myocardial infarction patients admitted to Norwegian hospitals and quantified the actual use and potential maximal use of thrombolytic therapy. Data were collected by medical record review of all acute myocardial infarction patients discharged from hospital in April and May 1993 in Health region 1. The clinical population differed significantly from the patients recruited to the thrombolytic clinical trials. Patients were more likely to have ST depression on admission (23% vs. 7%) and to be over 74 years (42% vs. 10%) than in the trials. A fifth of patients presented more than 12 h after symptom onset (or time indeterminate). Thrombolysis was given to 32% of patients, mainly utilising streptokinase. Late presentation or diagnostic difficulty appeared to be the main reasons for non- thrombolysis. Approximately 50% of the clinical population were eligible for thrombolysis. Eligibility for thrombolytic therapy was therefore severely restricted by the presenting characteristics of the clinical population. Substantial numbers of patients belonged to subgroups where the reported benefit from thrombolysis is equivocal. Uncertainty remains on the extrapolation of the trials evidence to those subgroups who were under-represented in the clinical trials.