Hypothermia vs. Normothermia for Cardiogenic Shock Patients on VA-ECMO

Feb 01, 2022
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Authors:
Levy B, Girerd N, Amour J, et al., on behalf of the HYPO-ECMO Trial Group and the International ECMO.
Citation:
Effect of Moderate Hypothermia vs Normothermia on 30-Day Mortality in Patients With Cardiogenic Shock Receiving Venoarterial Extracorporeal Membrane Oxygenation: A Randomized Clinical Trial. JAMA 2022;327:442-453.
Summary By:
Marty Tam, MD, FACC

Quick Takes

  • The results of this study do not support the routine, early use of moderate hypothermia in patients with cardiogenic shock requiring extracorporeal membrane oxygenation compared to maintaining normothermia.
  • Given the non-statistically significant trend to improved mortality with moderate hypothermia, future studies may be warranted to provide further clarity.

Study Questions:

In patients with refractory cardiogenic shock (CS) requiring venoarterial extracorporeal membrane oxygenation (VA-ECMO), does early implementation of moderate hypothermia (33-34 °C) compared with strict normothermia (36-37 °C) improve mortality?

Methods:

This was a randomized, multicenter (20 French centers) trial of intubated, intensive care unit patients with CS on VA-ECMO support for <6 hours between October 2016 and July 2019. Early initiation of moderate hypothermia for a 24-hour period was compared to strict normothermia (36-37 °C). The primary outcome was 30-day mortality. Thirty-one secondary outcomes were assessed, which included mortality and cardiovascular endpoints at various time points, need and duration of pharmacologic and device therapies, need for advanced cardiac therapies, changes in biomarkers, freedom from organ dysfunction, and length of stay. Rates of adverse events were tracked as well.

Results:

There were 374 patients randomized into the study, with 334 patients included in the final analysis (n = 168 for moderate hypothermia, n = 166 for normothermia). No significant baseline differences in groups were seen.

For the primary outcome, there was no statistically significant difference in 30-day mortality when comparing the moderate hypothermia (71 patients, 42%) to the normothermia (84 patients, 51%) group (adjusted odds ratio, 0.71; 95% confidence interval [CI], 0.45-1.13; p = 0.15; risk difference, -8.3%; 95% CI, -16.3% to -0.3%).

Of the 31 secondary outcomes, one outcome was in favor of moderate hypothermia compared to normothermia (the remaining were nonsignificant). This was the composite of death, heart transplant, escalation to left ventricular assist device implantation, or stroke at day 30 (adjusted odds ratio, 0.61; 95% CI, 0.39-0.96; p = 0.03; risk difference, -11.5%; 95% CI, -23.2% to 0.2%).

With respect to adverse events:

  • Incidence of moderate or severe bleeding: 41% with moderate hypothermia, 42% with normothermia
  • Incidence of infections: 52% with moderate hypothermia, 52% with normothermia
  • Incidence of bacteremia: 20% with moderate hypothermia, 30% with normothermia

Conclusions:

In patients with CS requiring VA-ECMO support, the early use of moderate hypothermia for 24 hours did not significantly improve 30-day mortality compared to maintaining strict normothermia.

Perspective:

CS continues to carry a high mortality rate. For patients who are critically ill enough to require temporary mechanical circulatory support like VA-ECMO, there is an ongoing need to target factors that may contribute to the grim prognosis. Current recommendations are for maintenance of normothermia for patients requiring VA-ECMO, although there are a lack of data to guide decision making. Therapeutic hypothermia is a possible intervention that may address the negative immune and hemodynamic changes related to ischemia reperfusion injury. In this study, the authors set out to test this intervention and found that while a trend toward mortality benefit with moderate hypothermia was seen, it was not statistically significant. Given that the study could have been underpowered, the question remains regarding the benefit of moderate hypothermia in this patient population. Current practice will not be altered by the results of this work, but future studies will be needed to provide more clarity.

Clinical Topics: Acute Coronary Syndromes, Cardiac Surgery, Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, Invasive Cardiovascular Angiography and Intervention, Vascular Medicine, ACS and Cardiac Biomarkers, Cardiac Surgery and Heart Failure, Acute Heart Failure, Heart Failure and Cardiac Biomarkers, Heart Transplant, Mechanical Circulatory Support, Interventions and ACS, Interventions and Vascular Medicine

Keywords: Acute Coronary Syndrome, Bacteremia, Biomarkers, Critical Illness, Extracorporeal Membrane Oxygenation, Heart Failure, Heart Transplantation, Heart-Assist Devices, Hemodynamics, Hypothermia, Hypothermia, Induced, Intensive Care Units, Ischemia, Length of Stay, Multiple Organ Failure, Reperfusion Injury, Resuscitation, Shock, Cardiogenic, Stroke


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