Target temperature management of 33°C and 36°C in patients with out-of-hospital cardiac arrest with initial non-shockable rhythm - a TTM sub-study

Purpose: Despite a lack of randomized trials in comatose survivors of out-of-hospital cardiac arrest (OHCA) with an initial non-shockable rhythm (NSR), guidelines recommend induced hypothermia to be considered in these patients. We assessed the effect on outcome of two levels of induced hypothermia in comatose patient resuscitated from NSR.

Methods: Hundred and seventy-eight patients out of 950 in the TTM trial with an initial NSR were randomly assigned to targeted temperature management at either 33°C (TTM33, n=96) or 36°C (TTM36, n=82). We assessed mortality, neurologic function (Cerebral Performance Score (CPC) and modified Rankin Scale (mRS)), and organ dysfunction (Sequential Organ Failure Assessment (SOFA) score).

Results: Patients with NSR were older, had longer time to ROSC, less frequently had bystander CPR and had higher lactate levels at admission compared to patients with shockable rhythm, p<0.001 for all. Mortality in patients with NSR was 84% in both temperature groups (unadjusted HR 0.92, adjusted HR 0.75; 95% CI 0.53-1.08, p=0.12). In the TTM33 group 3% survived with poor neurological outcome (CPC 3-4, mRS 4-5), compared to 2% in the TTM36 group (adjusted OR 0.67; 95% CI 0.08-4.73, p=0.69 for both). Thirteen percent in the TTM33 group and 15% in the TTM36 group had good neurologic outcome (CPC 1-2, mRS 0-3, OR 1.5, CI 0.21-12.5, p=0.69). The SOFA-score did not differ between temperature groups.

Conclusion: Comatose patients after OHCA with initial NSR continue to have a poor prognosis. We found no effect of targeted temperature management at 33°C compared to 36°C in these patients.