Potential impact of interventions to reduce times to thrombolysis.

OBJECTIVES To estimate the lifesaving potential of interventions to accelerate the administration of intravenous thrombolysis for myocardial infarction. METHODS Data were analysed from a prospective, observational study of all patients transported to hospital by ambulance, who subsequently received intravenous thrombolysis at 20 hospitals and two ambulance services in Victoria, Australia (n = 1147). Regression models estimated the association between predictor variables age, sex, route of referral, symptom onset to call time, ambulance pre-notification of the receiving hospital, emergency department thrombolysis, and the outcome, time to thrombolysis. Further modelling estimated the number needed to treat to save one life by several recommended interventions to reduce time delays. RESULTS Presentation via a rural hospital or general practitioner was associated with an approximate doubling of the onset to call time (2.08 and 2.30 respectively). Ambulance-hospital pre-notification and emergency department thrombolysis reduced door to needle times by 21% and 27% respectively. Modelling showed that each of the following interventions would be expected to save one life: 1069 hospital pre-notifications, 714 cases of emergency department thrombolysis, 184 cases of prehospital thrombolysis, 340 cases to bypass their rural hospital, or 50 cases to bypass their general practitioner. CONCLUSIONS Hospital pre-notification and emergency department thrombolysis reduce time delays, although the mortality impact seems to be modest. Prehospital thrombolysis has the potential to save lives, although validation in real practice is required. Advising patients to call directly for an ambulance, rather than the general practitioner, has the greatest potential to save lives.