Long-term cognitive outcomes following out-of-hospital cardiac arrest: A population-based study

Objective: To report the neurologic outcomes in long-term survivors of out-of-hospital cardiac arrest with ventricular fibrillation as the presenting rhythm (OHCA VF) at a population level. Methods: All adults who experienced OHCA VF in Olmsted County, MN, from 1990 to 2008, survived more than 6 months postarrest, and were alive at the time of study recruitment were invited to participate in structured neuropsychological testing and a neurologic examination. Cognitive test results were compared to the normal population using the Mayo's Older Adults Normative Studies. Linear regression models were fit to evaluate each neuropsychological test result in relation to call-to-shock time, sex, age at cardiac arrest, time elapsed since event, witnessed vs unwitnessed arrest, and administration of bystander cardiopulmonary resuscitation. Results: Of 332 OHCA VF arrests, 140 people (42.2%,95%confidence interval 36.9%-47.5%) survived to discharge. No patient entered a minimally conscious or permanent vegetative state. Long-term survivors (n= 47, median survival 7.8 years postarrest) had lower scores on measures of long-term memory and learning efficiency (p= 0.001) but higher than average scores on verbal IQ (p= 0.001). Nearly all survivors were functionally independent and scored high on the Mini- Mental State Examination (MMSE) (median Barthel Index 100/100, median MMSE 29/30). Conclusions: Long-term survivors of OHCA VF have long-term memory deficits compared to the normal population at the same age and education level. These findings provide a baseline for cognitive outcomes studies of OHCA VF as new techniques are developed to improve survival.