Cognitive outcomes of patients undergoing therapeutic hypothermia after cardiac arrest

Objective: We aimed to study the long-term cognitive abilities of patients surviving out-of-hospital cardiac arrest who were treated with therapeutic hypothermia (TH).

Methods: We prospectively identified and examined consecutive survivors of out-of-hospital cardiac arrest who underwent TH at our institution from June 2006 to May 2011. The results of brain imaging, serum neuron-specific enolase (NSE) measurements, and EEGs were recorded. We assessed cognitive domains using the modified Telephone Interview for Cognitive Status. An education-adjusted score of ≥32 was considered normal.

Results: Of 133 total patients, 77 (58%) were alive at a median follow-up of 20 months (interquartile range 14–24 months). We interviewed 56 patients (73% of those alive). Median age was 67 years (range 24–88 years). Fifty-one patients (91%) were living independently. Modified Telephone Interview for Cognitive Status scores ranged from 16 to 41. Thirty-three (60%) were considered cognitively normal and 22 (40%) were cognitively impaired. The time to assessment did not differ among the cognitive outcomes (p = 0.557). The median duration of coma was 2 days, possibly indicating that patients with severe anoxic injury were not included. Eighteen patients were not working at the time of their cardiac arrest (17 were retired and 1 was unemployed). Of the 38 patients who were working up to the time of the cardiac arrest, 30 (79%) returned to work. Cognitive outcome was not associated with age, time to return of spontaneous circulation, brain atrophy, or leukoaraiosis.

Conclusions: The majority of surviving patients who underwent TH after cardiac arrest in this series had preserved cognitive function and were able to return to work.