Targeted Hypothermia Versus Targeted Normothermia After Out-of-hospital Cardiac Arrest (TTM2) - A Randomised Clinical Trial

The TTM2 trial is a continuation of the collaboration that resulted in the previous Targeted Temperature Management after out-of-hospital cardiac arrest trial (hereafter: TTM1). With its planned size with it will supersede the TTM1 trial as the largest trial on temperature management as a post-cardiac arrest treatment.

The TTM1 trial (NCT01020916) was a multicenter, multinational, outcome assessor-blinded, parallel group, randomised clinical trial comparing two strict target temperature regimens of 33°C and 36°C in adult patients, who have sustained return of spontaneous circulation and are unconscious after out-of-hospital cardiac arrest, when admitted to hospital. The trial did not demonstrate any difference in survival until end of trial (Hazard Ratio with a point estimate in favour of 36°C of 1.06 (95% confidence interval 0.89-1.28; P=0.51) or neurologic function at six months after the arrest, measured with CPC and mRS.

The planned study is a international, multicenter, parallel group, non-commerical, randomized, superiority trial in which a target temperature om 33°C after cardiac arrest will be compared to normothermia and early treatment of fever.

Patients eligible for inclusion will be unconscious adult patients with OHCA of a presumed cardiac cause with stable return of spontaneous circulation. Randomization will be performed by a physician in the emergency department, in the angiography suite or in the intensive care unit via web-based application using permuted blocks with varying sizes, stratified by site. Due to the nature of the intervention, health care staff will not be blinded to the intervention. However, the physicians who will assess outcomes will be blinded to temperature allocation, as will those who perform prognostication.

The intervention period will commence at the time of randomization. Cooling in the hypothermia group will achieved by means of cold fluids and state-of-the-art cooling devices (intravascular or body-surface applied closed loop systems). The initial aim will be to achieve a body temperature of 33.0°C. When this has been achieved, the target temperature will be 33°C until 28 hours after randomisation. When 28 hours have passed, gradual rewarming at a rate of 1/3°C per hour will commence, this will allow 12 hours for rewarming.