Impact of presenting rhythm on short- and long-term neurologic outcome in comatose survivors of cardiac arrest treated with therapeutic hypothermia.

OBJECTIVES: To compare short- and long-term neurologic outcomes in comatose survivors of out-of-hospital cardiac arrest treated with mild therapeutic hypothermia presenting with nonshockable versus shockable initial rhythms.

DESIGN: Retrospective cohort study.

SETTING: Emergency department and ICU of an academic hospital.

PATIENTS: One hundred twenty-three consecutive post-out-of-hospital cardiac arrest adults (57 nonshockable rhythms, 66 shockable rhythms) treated with therapeutic hypothermia between 2006 and 2012.

INTERVENTIONS: None.

MEASUREMENTS AND MAIN RESULTS: Data were collected from electronic health records. Neurologic outcomes were dichotomized by Cerebral Performance Category at discharge and 6- to 12-month follow-up and analyzed via multivariable logistic regressions. Groups were similar, except nonshockable rhythm patients were more likely to have a history of diabetes mellitus (p = 0.01), be dialysis dependent (p = 0.01), and not have bystander cardiopulmonary resuscitation (p = 0.05). At discharge, 3 of 57 patients (5%) with nonshockable rhythm versus 28 of 66 (42%) with shockable rhythm had a favorable outcome (unadjusted odds ratio, 0.08; 95% CI, 0.02-0.3; adjusted odds ratio, 0.1; 95% CI, 0.03-0.4). At follow-up, 4 of 55 patients (7%) versus 29 of 60 (48%) with nonshockable rhythm and shockable rhythm, respectively, had a favorable Cerebral Performance Category (odds ratio, 0.08; 95% CI, 0.03-0.3; adjusted odds ratio, 0.09; 95% CI, 0.09-0.3). Among those surviving hospitalization, favorable neurologic outcome was more likely at long-term follow-up than at hospital discharge for both groups (odds ratio, 2.5; 95% CI, 1.3-4.7; adjusted odds ratio, 2.9; 95% CI, 1.4-6.2). No significant interaction between changes in neurologic status over time and presenting rhythm was seen (p = 0.93).

CONCLUSIONS: These data indicate an association between initial nonshockable rhythm and significantly worse short- and long-term outcomes in patients treated with mild therapeutic hypothermia. Among survivors, neurologic status significantly improved over time for all patients and shockable rhythm patients and tended to improve over time for the small number of nonshockable rhythm patients who survived beyond hospitalization. No significant interaction between changes in neurologic status over time and presenting rhythm was seen.