To test the efficacy of transcutaneous pacing in prehospitaI bradyasystolic arrest, we applied an external transcutaneous pacing device to patients with asystole, pulseless idioventricular rhythms (PIVR), and pulseless bradycardias. Pacemaker units were carried by emergency medical services (EMS) physicians and specially trained EMS personnel. Patients were followed to determine hospital course and outcome. Of the 112 patients evaluated, information to adequately document the presence or absence of electrical capture was available in 105 cases. Fifty-five (52%) of these cases demonstrated electrical capture; 9 of 112 patients (8%) recovered pulses. Of those in asystole, 26 of 50 (52%) showed electrical capture, while the rate was 60% for those with PIVR (24 of 40 patients) and complete heart block (CHB) (3 of 5 patients), and 25% for other pulseless bradycardias (2 of 8 patients). Pulses developed following capture in five of 55 patients (9%) in asystole and in four of 44 patients (9%) with PIVR. No patient with CHB or other bradycardias developed a pulse. No patients survived to be discharged from the hospital. The average time to application of the pacing device was 29 minutes after loss of pulse. Our data strongly suggest that delayed use of the transcutaneous pacing device does not improve the dismal survival rates of patients who suffer bradyasystolic cardiac arrest. Further studies should be directed toward investigating survival rates in patients paced immediately after the onset of cardiac arrest. ]