Magnetic resonance imaging in comatose adults resuscitated after out-of-hospital cardiac arrest: A posthoc study of the Targeted Therapeutic Mild Hypercapnia after Resuscitated Cardiac Arrest trial.

Background: Neuroimaging with magnetic resonance imaging (MRI) may assist clinicians in evaluating brain injury and optimising care in comatose adults resuscitated after out-of-hospital cardiac arrest (OHCA). However, contemporary international data on its use are lacking.

Aim: The primary aim was to compare the patient characteristics, early postresuscitation care, and neurological outcomes of patients according to MRI use.

Methods: We performed a posthoc analysis of the Targeted Therapeutic Mild Hypercapnia after Resuscitated Cardiac Arrest (TAME) trial, a multinational randomised trial comparing targeted mild hypercapnia or normocapnia in comatose adults after OHCA.

Results: After exclusions, 1639 patients enrolled in the TAME trial were analysed. Of these, 149 (9%) had an MRI. Compared to non-MRI patients, MRI patients were younger (58.9 versus 61.7 years, p: 0.02), had a longer median time from OHCA to return of spontaneous circulation (30 versus 25 min, p < 0.0001), and had a higher average arterial lactate level (8.78 versus 6.74 mmol/L, p < 0.0001) on admission to hospital. MRI patients were more likely to receive additional advanced diagnostic assessments during intensive care unit admission (p < 0.0001). At 6 months, 23 of 140 patients (16.4%) in the MRI group had a favourable neurological outcome, compared with 659 of 1399 patients (47.1%) in the no-MRI group (p < 0.001). On multivariable modelling, country of enrolment was the dominating predictor in the likelihood of an MRI being performed.

Conclusions: In the TAME trial, 9% of patients had an MRI during their intensive care unit admission. Among these patients, only 16% had a favourable neurological outcome at 6 months.