From surface to core: does better cooling make a difference after cardiac arrest?

Hypoxic–ischaemic brain injury remains the leading cause of death after out-of-hospital cardiac arrest. Temperature control strategies have evolved substantially following the TTM-2 trial, which showed no survival benefit of hypothermia over active normothermia with fever prevention. In this editorial, Sandroni et al. discuss a post hoc analysis of the TTM-2 trial comparing intravascular cooling (IC) and surface cooling (SFC) in patients receiving therapeutic hypothermia. IC achieved superior temperature control, with faster attainment of target temperature, less time outside the therapeutic range, fewer episodes of post-treatment fever, and reduced overcooling compared with SFC. Although unadjusted analyses suggested improved neurological outcomes with IC, this association disappeared after inverse probability treatment weighting adjustment, indicating no statistically significant improvement in six-month neurological survival. The authors highlight important limitations, including the post hoc design and incomplete data regarding device selection. Experimental studies suggest that earlier and faster cooling may enhance neuroprotection, but clinical implementation remains substantially slower than in animal models. Current evidence therefore continues to support guideline recommendations favoring active normothermia and fever prevention rather than routine hypothermia after cardiac arrest. Ongoing trials such as STEPCARE may clarify optimal temperature management strategies in this population.