Cool It With the Therapeutic Hypothermia for In-Hospital Cardiac Arrest, Study Suggests
Therapeutic hypothermia seems to do more harm than good among patients with in-hospital cardiac arrest, according to new observational data.
The practice of deliberately cooling patients with various cardiac conditions has been contentiously disputed in recent years with studies showing that it reduces heart failure but not infarct size after STEMI, leads to a high rate of adverse events after STEMI, potentially causes stent thrombosis in patients with out-of-hospital cardiac arrest, and shows hints of neuroprotective benefits among acute stroke patients after thrombolysis.
But so far, there have been no randomized trials analyzing the procedure in the in-hospital setting, and the observational studies in the literature were small and did not show a survival benefit, according to lead author Paul S. Chan, MD (Saint Luke’s Mid America Heart Institute, Kansas City, MO), and colleagues.
They looked at data from the Get With the Guidelines-Resuscitation registry on 26,183 patients with in-hospital cardiac arrest at 355 US hospitals between 2002 and 2014; among them, 6.0% were treated with therapeutic hypothermia. Their results—published in the October 4, 2016, issue of the Journal of the American Medical Association—show that cooling was associated with lower in-hospital survival in an adjusted propensity score matched analysis of 1,524 patients treated with hypothermia and 3,714 treated without (27.4% vs 29.2%; RR 0.88; 95% CI 0.80-0.97). This finding was similar for nonshockable and shockable cardiac arrest rhythms (P for interaction = 0.74).
Additionally, the hypothermia arm reported less favorable neurological survival compared with the no hypothermia arm overall (17.0% vs 20.5%; RR 0.79; 95% CI 0.69-0.90) and for both rhythm types (P for interaction = 0.88).
“Collectively, these findings do not support current use of therapeutic hypothermia for patients with in-hospital cardiac arrest,” Chan and colleagues write.
They cite several potential limitations of the study, including residual confounding, differing hypothermia protocols, poor hypothermia implementation, and variability in neurological survival evaluations. But while “the finding that therapeutic hypothermia was not associated with better survival outcomes may raise questions about plausibility,” the authors say, “clinical trials have found that [it] leads to worse survival outcomes for other conditions, such as traumatic brain injury and bacterial meningitis.”
Further, findings from randomized studies looking at cooling for patients with out-of-hospital cardiac arrest cannot be generalized to those with in-hospital cardiac arrest as the latter “is a different condition with faster response times, . . . potentially limiting the theorized benefit of therapeutic hypothermia to reduce free radical-mediated reperfusion injury from anoxic brain injury,” they write.
Because of these issues, Chan and colleagues say that a randomized clinical trial is “warranted” to test the efficacy of therapeutic cooling for this patient group.
Chan PS, Berg RA, Tang Y, et al. Association between therapeutic hypothermia and survival after in-hospital cardiac arrest. JAMA. 2016;316:1375-1382.
- Chan reports receiving support from the National Heart, Lung, and Blood Institute.