TTM2 (post-hoc analysis)
Trial question
What is the effect of intravascular cooling in out-of-hospital cardiac arrest patients who received therapeutic hypothermia?
Study design
Multi-center
Single blinded
RCT
Population
Characteristics of study participants
20.0% female
80.0% male
N = 876
876 patients (171 female, 705 male).
Inclusion criteria: out-of-hospital cardiac arrest patients who received therapeutic hypothermia.
Key exclusion criteria: no record of device type; who underwent both intravascular cooling and surface cooling; rewarming or death during the intervention period; unknown outcome at 6 months.
Interventions
N=239 intravascular cooling (target temperature of 33 deegres C using intravascular cooling).
N=637 surface device cooling (target temperature of 33 deegres C using surface device cooling).
Primary outcome
Proportion of patients successfully reaching target temperature within 4 hours
69.6%
49.2%
69.6 %
52.2 %
34.8 %
17.4 %
0.0 %
Intravascular
cooling
Surface device
cooling
Significant
increase ▲
NNT = 4
Significant increase in the proportion of patients successfully reaching target temperature within 4 hours (69.6% vs. 49.2%; AD 20.4%, 95% CI 8.3 to 32.5).
Secondary outcomes
Significant decrease in the proportion of temperature variability during cooling period (17.2% vs. 39.6%; ARD -22.4, 95% CI -35.69 to -9.11).
Significant decrease in post-targeted temperature management fever (0% vs. 6.3%; ARD -6.3, 95% CI -10.04 to -2.56).
No significant difference in survival rates at 6 months (55.2% vs. 50.2%; OR 1.22, 95% CI 0.89 to 1.68).
Safety outcomes
No significant difference in serious adverse events.
Significant differences in any shivering at day 1 (30% vs. 23%), severe shivering at day 3 (7.3% vs. 3.6%).
Conclusion
In out-of-hospital cardiac arrest patients who received therapeutic hypothermia, intravascular cooling was superior to surface device cooling with respect to proportion of patients successfully reaching target temperature within 4 hours.
Reference
Akil Awad, Martin Jonsson, Johan Holgersson et al. Intravascular vs. surface cooling in out-of-hospital cardiac arrest patients receiving hypothermia after hospital arrival: a post hoc analysis of the TTM2 trial. Intensive Care Med. 2025 Apr;51(4):721-730.
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