EFFECT OF TIME FROM ONSET TO COMING UNDER CARE ON FATALITY OF PATIENTS WITH ACUTE MYOCARDIAL-INFARCTION - EFFECT OF RESUSCITATION AND THROMBOLYTIC TREATMENT

Objective-To examine the relation between time from onset of symptoms and coming under ambulance and hospital care on fatality in patients w ith evolving acute myocardial infarction, and on the proportions who s urvive because of resuscitation and thrombolytic treatment. Design-Pro spective community and hospital study over two years. Delay was measur ed from the onset of symptoms to arrival at hospital, and from the ons et to coming under care from ambulance personnel. Setting-Four general hospitals serving three United Kingdom health districts. Patients-221 3 patients under 75 years of age, 111 of whom had been successfully re suscitated from out of hospital cardiac arrest. Interventions-Resuscit ation from cardiac arrest; thrombolytic treatment. Main outcome measur es-30 day fatality and lives saved by the two forms of treatment. Resu lts-Times from symptom onset to coming under hospital care and to star ting thrombolytic treatment (given to 53% of patients) were less than or equal to 1 hour in 15% and 2% of patients respectively, less than o r equal to 2 hours in 54% and 25%, and less than or equal to 4 hours i n 67% and 55%. Overall, 30 day fatality was 138/1000 patients treated; 64/1000 (95% confidence interval 54 to 74) survived because of treatm ent, and 80% of this salvage was attributable to resuscitation. Delay was an important factor: 107/1000 (60 to 144) lives were saved for tho se coming under care within 1 hour compared with 21/1000 (5 to 37) for those who delayed for more than 12 hours. Further analysis including the 111 patients with out of hospital arrest showed that 34% of those coming to hospital by ambulance came under ambulance care within 1 hou r; for this subset, 30 day fatality was 173/1000, and 136 (109 to 163) lives were saved by treatment. Conclusions-Results of treatment are s trongly related to delay in coming under care. Reduction in delay can reduce mortality from acute myocardial infarction.