Feasibility and Timing of Prehospital Administration of Reteplase in Patients with Acute Myocardial Infarction

Background: In myocardial infarction patients undergoing thrombolysis, treatment delays negatively impact outcomes. This pilot study was conducted to determine the feasibility and timing of field administration of intravenous double bolus reteplase in patients with ST-elevation myocardial infarction. Methods: Sixty three patients with symptoms and EKG changes consistent with acute myocardial infarction of less than six hours duration received the first bolus of reteplase before arriving at the emergency department. A second bolus of reteplase was given in the emergency department. Subsequent resolution of ST-segment elevation was measured. Mean time from symptom onset to paramedic dispatch, and paramedic arrivals to first bolus of reteplase were measured. The mean time from the first bolus of reteplase to heparin bolus in an emergency department was also measured. All patients with evidence of ST-elevation and suspected acute myocardial infarction gave consent for the thrombolytic therapy. There were no refusals of therapy among those candidates eligible for thrombolysis. Results: The mean times from the first bolus of reteplase to heparin bolus in the emergency department was substantially longer than the in-field times. Resolution of ST-segment elevation was recorded in 52 of the 63 patients and the times of resolution ranged from five minutes after the first bolus dose to 190 minutes after the second bolus of reteplase. Resolution of ST-segment elevation and relief of pain occurred almost simultaneously. Conclusions: These results demonstrated that in-field administration of thrombolytic therapy is a viable option to reduce the delay from symptom onset to initiation of thrombolysis. They demonstrated that satisfactory resolution of ST-segment elevation can be recorded in the field. The reduction in mortality observed in this study is comparable to previously published studies on inpatients.Abbreviated Abstract. This open-label pilot study was conducted to determine the feasibility and timing of field administration of intravenous double-bolus reteplase and to measure subsequent resolution of ST elevation in 63 patients with symptoms and ECG changes consistent with acute myocardial infarction for less than 6 hours. These results demonstrated that in-field administration of thrombolytic therapy is a viable option to reduce the delay from symptom onset to initiation of thrombolytic therapy.