Of 352 prehospital cardiac arrest patients studied during a three year period, the initial mechanism recorded by rescue personnel was ventricular fibrillation in 220 (62 per cent), ventricular tachycardia in 24 (7 per cent) and bradyarrhythmias or asystole in 108 (31 per cent). Early survival was best in the group with ventricular tachycardia (16 of 24 patients resuscitated and survived hospitalization-67 per cent); the prognosis was worst in the group with bradyarrhythmias asystole (nine of 108 admitted to the hospital alive-none survived hospitalization); and 51 of 220 patients with ventricular fibrillation (23 per cent) were resuscitated and survived subsequent hospitalization, a significantly better outcome than previously reported for ventricular fibrillation. Central nervous system damage accounted directly or indirectly for 28 of 48 in-hospital deaths (59 per cent), and hemodynamic abnormalities for 31 per cent. Only five in-hospital deaths (10 per cent) were primary arrhythmic. The majority of survivors had evidence of left ventricular hemodynamic abnormalities (mean left ventricular end-diastolic pressure = 17.80 ± 8.99 mm Hg; mean cardiac index = 2.62 ± 0.72 liters/min/m2; mean ejection fraction = 38.58 ± 17.55 per cent), but approximately one third of the surviving patients had normal left ventricular function. Early in-hospital electrophysiologic data demonstrated persistent, drug-resistant complex ventricular arrhythmias during the first 72 hours; but intracardiac electrophysiologic studies elicited specific patterns only in patients with ventricular tachycardia, whose arrhythmias were reproducible in five of six patients studied. The risk of recurrent ventricular fibrillation in the first 72 hours was predicted better by coexistent conducting system abnormalities, than by the persistent ventricular arrhythmia alone. We conclude that the electrical mechanism of prehospital cardiac arrest provides early prognostic information, that early survival rates are improving and that one third of the discharged survivors have normal indices of left ventricular function. The presence of conducting system abnormalities identifies a subgroup at high risk for in-hospital recurrent ventricular fibrillation.
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