Electrocardiographic evidence of reperfusion occurring before hospital admission

The benefits of thrombolysis are believed to be related to the speed of reperfusion of the infarct-related artery. In this sub-study, evidence for the occurrence of reperfusion before admission to hospital has been sought. In a randomized double-blind controlled trial, 311 patients with suspected acute myocardial infarction were given anistreplase 30 units i.v., either at home at a median 101 min (early group, n = 163), or in hospital at a median 240 min after symptom onset (large group, n = 148). Paired electrocardiograms recorded at home and on admission to hospital were available for study in 143 and 137 patients in early and late groups. Reduction in ST elevation between home and hospital electrocardiograms of > 25% in a single lead was taken as evidence of reperfusion. Patients with significant ST elevation in either electrocardiogram comprised the sub-study groups, and numbered 63/143 (44%) and 68/137 (50%) in early and late groups respectively. A reduction of > 25% in the single lead demonstrating greatest ST elevation on the presenting electrocardiogram was observed in 37/63 (59%) and 23/68 (34%) patients in the early and late sub-study groups (difference 25%, 95% confidence interval 8% to 42%, P = 0.003). It was found that domiciliary thrombolysis was associated with electrocardiographic evidence of an increased rate of reperfusion occurring before admission to hospital. Evidence of reperfusion occurring pre-hospital, whether spontaneous or following thrombolytic therapy, was associated with a better outcome.