The potential for prehospital thrombolytic therapy

Several large trials of thrombolytic therapy have shown that treatment initiated in the first 1 or 2 hours following the onset of symptoms of acute myocardial infarction (AMI) is more effective than therapy started later in the course of illness. From our experience in three thrombolytic trials we concluded it would be difficult to reduce the total time from symptom onset to therapy without a major change in patient management. To accomplish this goal we have initiated MITI (Myocardial Infarction Triage and Intervention Project), a program for the prehospital diagnosis of AMI using specially trained paramedics, a checklist to establish eligibility for and contraindications to thrombolytic therapy, and a portable, battery-powered 12-lead electrocardiography (ECG) cellular telephone system that allows an electrocardiographic diagnosis to be made remotely by an emergency department physician. In the feasibility phase of MITI, 2,472 patients with chest pain of presumed cardiac origin were evaluated; 677 (27%) met the rigorous history and physical exam inclusion and exclusion criteria for potential thrombolytic therapy and had an ECG performed in the field. Of these ECGs, 522 were transmitted successfully by cellular telephone to a base station physician. Of the 522 patients, 107 had ST-segment elevation and met our criteria for initiation of thrombolytic therapy. Of the 2,472 patients with chest pain evaluated by the emergency medical technicians, 453 (18%) were diagnosed with AMI during hospitalization. Of these AMI patients, only 105 (23%) met the clinical examination and ECG criteria for pre-hospital thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)