Cognitive Function in Survivors of Out-of-Hospital Cardiac Arrest After Target Temperature Management at 33°C Versus 36°C

Abstract

Background— Target temperature management is recommended as a neuroprotective strategy after out-of-hospital cardiac arrest. Potential effects of different target temperatures on cognitive impairment commonly described in survivors have not been investigated sufficiently. The primary aim of this study was to evaluate whether a target temperature of 33°C compared with 36°C was favorable for cognitive function; the secondary aim was to describe cognitive impairment in cardiac arrest survivors in general. Methods and Results— Study sites included 652 cardiac arrest survivors originally randomized and stratified for site to temperature control at 33°C or 36°C within the Target Temperature Management trial. Survival until 180 days after the arrest was 52% (33°C, n=178/328; 36°C, n=164/324). Survivors were invited to a face-to-face follow-up, and 287 cardiac arrest survivors (33°C, n=148/36°C, n=139) were assessed with tests for memory (Rivermead Behavioural Memory Test), executive functions (Frontal Assessment Battery), and attention/mental speed (Symbol Digit Modalities Test). A control group of 119 matched patients hospitalized for acute ST-segment–elevation myocardial infarction without cardiac arrest performed the same assessments. Half of the cardiac arrest survivors had cognitive impairment, which was mostly mild. Cognitive outcome did not differ ( P >0.30) between the 2 temperature groups (33°C/36°C). Compared with control subjects with ST-segment–elevation myocardial infarction, attention/mental speed was more affected among cardiac arrest patients, but results for memory and executive functioning were similar. Conclusions— Cognitive function was comparable in survivors of out-of-hospital cardiac arrest when a temperature of 33°C and 36°C was targeted. Cognitive impairment detected in cardiac arrest survivors was also common in matched control subjects with ST-segment–elevation myocardial infarction not having had a cardiac arrest. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01946932.

Adaptation of global hemostasis to therapeutic hypothermia in patients with out-of-hospital cardiac arrest: Thromboelastography study

“…The present approach to analyze blood samples collected from patients during MTH at 32°C and 37°C allowed a more accurate assessment of cooling-induced coagulation impairment. The finding that TEG results may be affected by the in vitro temperatures have already been confirmed in some studies [15,28,31,43], while in other studies it was considered insignificant [19,44]. However, in the largest randomized clinical trial conducted to date by Nielsen et al [45], it was shown that there were no differences in risk of death and neurological outcome between group with 33°C (MTH) vs. 36°C of targeted temperature management (TTM) This takes into consideration new ILCOR guidelines which recommend both therapies -MTH or targeted temperature management are nowadays the standard procedures in OHCA patients.…”

Cognitive decline after cardiac arrest – It is more to the picture than hypoxic brain injury

“…3 Recently we reported that similar levels of cognitive impairment were found in cardiac arrest survivors treated with target temperature management as in a matched control group of myocardial infarction patients who shared the same cardiovascular risk factors. 4 Extensive literature supports the role of cardiovascular burden as the major determinant of age-related cognitive decline 11 and such burden is likely to have affected the participants of the present study as well. Since cardiac arrest often is the dramatic effect of an underlying cardiovascular disease it is likely that the cardiac arrest population will be at increased risk for a cognitive decline both before and after the arrest.…”

“…Adding to the complexity, studies using neuropsychological tests report cognitive problems in as much as half of the survivors when assessed during the first year after the arrest. 3,4 The degree of cognitive impairment appears relatively stable over time but a few small studies have reported improvement as well as decline during the first year 5,6 leading to the frequent call for studies with longer observation times.…”

Should age be a factor for initiating post-cardiac arrest care or for temperature management strategies?

“…In this issue of Resuscitation, Winther-Jensen et al, reports an additional analysis from the TTM trial by Nielsen et al 1,2 The current study is one in a series of recently published secondary and subgroup analyses from the TTM trial [3][4][5][6][7][8] and Winther-Jensen et al explores two relevant questions within the TTM dataset namely: (1) whether age is associated with outcomes after cardiac arrest and (2) whether the effect of targeted temperature management at 33 • C vs. 36 • C differs by age.…”