['Comatose patients resuscitated after out-of-hospital cardiac arrest receive therapeutic hypothermia. Bradycardia is frequent during therapeutic hypothermia, but its impact on outcome remains unclear. We explore a possible association between bradycardia during therapeutic hypothermia and neurologic outcome in comatose survivors of out-of-hospital cardiac arrest.', 'Retrospective cohort study, from January 2009 to January 2011.', 'University hospital medical and cardiac ICUs.', 'One hundred eleven consecutive comatose out-of-hospital cardiac arrest patients treated with therapeutic hypothermia.', 'Patients treated with standardized treatment protocol after cardiac arrest.', "All out-of-hospital cardiac arrest patients' records were reviewed. Hemodynamic data were obtained every fourth hour during the first days. The patients were in temperature target range (32-34°C) 8 hours after out-of-hospital cardiac arrest and dichotomized into bradycardia and nonbradycardia groups depending on their actual heart rate less than or equal to 60 beats/min or more than 60 beats/min at that time. Primary endpoint was Cerebral Performance Category score at hospital discharge. More nonbradycardia group patients received epinephrine during resuscitation and epinephrine and norepinephrine in the early in-hospital period. They also had lower base excess at admission. Survival rate with favorable outcome was significantly higher in the bradycardia than the nonbradycardia group (60% vs 37%, respectively, p = 0.03). For further heart rate quantification, patients were divided into quartiles: less than or equal to 49 beats/min, 50-63 beats/min, 64-77 beats/min, and more than or equal to 78 beats/min, with respective proportions of patients with good outcome at discharge of 18 of 27 (67%), 14 of 25 (56%), 12 of 28 (43%), and 7 of 27 (26%) (p = 0.002). Patients in the lowest quartile had significantly better outcome than the higher groups (p = 0.027), whereas patients in the highest quartile had significantly worse outcome than the lower three groups (p = 0.013)."] Is bradycardia during therapeutic hypothermia associated with good neurologic outcome in comatose survivors of out-of-hospital cardiac arrest?