Objectives: To evaluate the outcomes of cardiac arrest survivors with myoclonus receiving modern postresuscitation care.
Design: Retrospective review of registry data.
Setting: Cardiac arrest receiving centers in Europe and the United States from 2002 to 2012.
Patients: Two thousand five hundred thirty-two cardiac arrest survivors 18 years or older enrolled in the International Cardiac Arrest Registry.
Interventions: None.
Measurements and main results: Eighty-eight percent of patients underwent therapeutic hypothermia and 471 (18%) exhibited myoclonus. Patients with myoclonus had longer time to professional cardiopulmonary resuscitation (8.6 vs 7.0 min; p < 0.001) and total ischemic time (25.6 vs 22.3 min; p < 0.001) and less often presented with ventricular tachycardia/ventricular fibrillation, a witnessed arrest, or had bystander cardiopulmonary resuscitation. Electroencephalography demonstrated myoclonus with epileptiform activity in 209 of 374 (55%), including status epilepticus in 102 of 374 (27%). Good outcome (Cerebral Performance Category 1-2) at hospital discharge was noted in 9% of patients with myoclonus, less frequently in myoclonus with epileptiform activity (2% vs 15%; p < 0.001). Patients with myoclonus with good outcome were younger (53.7 vs 62.7 yr; p < 0.001), had more ventricular tachycardia/ventricular fibrillation (81% vs 46%; p < 0.001), shorter ischemic time (18.9 vs 26.4 min; p = 0.003), more witnessed arrests (91% vs 77%; p = 0.02), and fewer "do-not-resuscitate" orders (7% vs 78%; p < 0.001). Life support was withdrawn in 330 of 427 patients (78%) with myoclonus and poor outcome, due to neurological futility in 293 of 330 (89%), at 5 days (3-8 d) after resuscitation. With myoclonus and good outcome, median ICU length of stay was 8 days (5-11 d) and hospital length of stay was 14.5 days (9-22 d).
Conclusions: Nine percent of cardiac arrest survivors with myoclonus after cardiac arrest had good functional outcomes, usually in patients without associated epileptiform activity and after prolonged hospitalization. Deaths occurred early and primarily after withdrawal of life support. It is uncertain whether prolonged care would yield a higher percentage of good outcomes, but myoclonus of itself should not be considered a sign of futility.