News | Sudden Cardiac Arrest | May 17, 2021

Lower Temperature Therapeutic Hypothermia Did Not Improve Outcomes After Cardiac Arrest

Cooling patients to a lower temperature showed no benefit over current guidelines

This trial used a therapeutic hypothermia system that used balloon catheters filled with cooled saline, such as the Zoll Thermogard XP temperature management system. #ACC21 #ACC2021 #therapeutichypothermia

This trial used a therapeutic hypothermia system that used balloon catheters filled with cooled saline, such as the Zoll Thermogard XP temperature management system. 

May 17, 2021 — In patients receiving therapeutic hypothermia after suffering out-of-hospital cardiac arrest, those who were cooled below 31 degrees Celsius (about 88 degrees Fahrenheit) for 24 hours showed no difference in terms of death or poor neurological outcomes at six months compared with patients receiving guideline-recommended cooling of 34 C (about 93 F). These findings are part of a study presented at the American College of Cardiology (ACC) 2021 scientific session.

Therapeutic hypothermia is a procedure in which a person’s body is cooled far below normal body temperature. It has been shown to improve survival and reduce brain damage in people who have been resuscitated but remain comatose after suffering cardiac arrest. Current guidelines for therapeutic hypothermia recommend cooling the body to 32-36 C for 24 hours. The new study found no benefit from a deeper cooling to 31 C.

“The results of our trial do not support the use of moderate therapeutic hypothermia of 31 C to improve neurological outcomes in comatose survivors of out-of-hospital cardiac arrest,” said Michel R. Le May, M.D., interventional cardiologist at the University of Ottawa Heart Institute and the study’s lead author. “These findings do not support changing the current guidelines; we need to look for other strategies that can improve outcomes for these patients who currently have a poor prognosis.”

The trial enrolled 367 patients treated for out-of-hospital cardiac arrest at the University of Ottawa Heart Institute between 2013-2020. All patients had been successfully resuscitated, as indicated by a return of blood pressure, but remained comatose. Participants were cooled with an endovascular device that uses temperature-controlled saline-filled balloons inserted near the heart via a vein to alter a patient’s body temperature. For half of the patients, the endovascular device was set to cool the body to 31 C and for the other half the device was set to 34 C. Once the target temperature was achieved, the temperature was maintained for 24 hours before the patient was warmed up to normal body temperature at a rate of 0.25 degrees per hour.

The trial is the first to use a randomized, double-blind approach for testing different target temperatures for therapeutic hypothermia. Physicians overseeing the treatment were prevented from seeing the temperature setting by a shield placed over the temperature display on the endovascular machine. Nurses were aware of the temperatures but maintained separate charts to maintain blinding among the treating physicians.

The study’s primary endpoint, a composite of death or poor neurological outcome at six months, occurred in 48% of those cooled to 31 C and 45% of those cooled to 34 C, a difference that was not statistically significant. There was also no significant difference between groups in terms of the rate of death or the rate of poor neurological outcome when these outcomes were assessed individually. The researchers examined outcomes by sex, age and other variables but found no significant differences in any subgroups analyzed.

Patients cooled to 31 C on average had a longer stay in the cardiac intensive care unit, which Le May said may reflect the fact that both the cool-down and warm-up periods lasted longer for these patients due to the lower target temperature.

Other researchers have assessed whether different temperatures or durations of therapeutic hypothermia can improve outcomes, but these previous studies have similarly demonstrated no improvement over current guidelines. Moving forward, Le May suggested brain monitoring approaches could be used to inform which strategies may be best suited for each patient’s particular situation.

“It may be useful to pool all these studies together and try to figure out if there is a particular temperature that’s more suitable in particular cases,” Le May said. “We also have to find better, noninvasive tools to assess the brain and perhaps turn our attention toward a more personalized way of treating these patients. This would allow us to select the protocol that optimizes the benefit for a particular patient.”

Le May said that many key elements influencing survival after out-of-hospital cardiac arrest come into play before the patient reaches the hospital, including whether bystanders administer basic CPR, how quickly paramedics arrive on the scene and how quickly patients are transferred to specialized cardiac centers. Focusing on these factors could offer opportunities to further improve survival, he said. The study was conducted at a single center, which may limit its generalizability but was helpful in ensuring consistent treatment protocols, Le May said.

The study was funded by the University of Ottawa Heart Institute.

Find links to more ACC 2021 late-breakers

Find more content on therapeutic hypothermia 

 

Related Content

Some of the top technology news from ACC 2021. Top left, the LAAOS III trial showed benefit when surgeons seal off the LAA during other open heart procedures. Bottom left, the ReCor Paradise renal denervation system helped lower blood pressure in patients who did not respond to medication. Top right, for patients with both heart failure and AFib it makes no differences is therapy is focused on controlling the heart rhythm or heart rate. Bottom right, the FLOWER-MI trial found no benefit to FFR-guided PCI.

Some of the top technology news from ACC 2021. Top left, the LAAOS III trial showed benefit when surgeons seal off the LAA during other open heart procedures. Bottom left, the ReCor Paradise renal denervation system helped lower blood pressure in patients who did not respond to medication. Top right, for patients with both heart failure and AFib it makes no difference if therapy is focused on controlling the heart rhythm or heart rate. Bottom right, the FLOWER-MI trial found no benefit to FFR-guided PCI in STEMI with multi-vessel disease.

Feature | ACC | June 08, 2021 | By Dave Fornell, Editor
Here are the top 10 takeaways from the late-breaking studies on cardiovascular technologies presented at the 2021 ...
AMERICAN COLLEGE OF CARDIOLOGY (ACC) Late-breaking clinical trial study presentations at ACC.21. @ACC21 @ACC2021
Feature | ACC | May 18, 2021 | Dave Fornell, Editor
The latest cardiology practice-changing scientific breakthrough, late-breaking study presentations have been announce
To help monitor the health of ACC 2021 in-person attendees for signs of COVID infection, the meeting will use BioIntelliSense's wearable BioButton continuous wireless temperature and vital signs monitoring. The wearable monitor is the size of a coin and is disposable.

To help monitor the health of ACC 2021 in-person attendees for signs of COVID infection, the meeting will use BioIntelliSense's wearable BioButton continuous wireless temperature and vital signs monitoring. The wearable monitor is the size of a coin and is disposable.

News | ACC | February 09, 2021 | By Dave Fornell, Editor
UPDATE Feb 22, 2021 — ...
The American College of Cardiology (ACC) released a list of the latest practice-changing presentations at the ACC.20 annual meeting March 28-30, 2020, in Chicago. This includes five late-breaking clinical trial (LBCT) sessions and three featured clinical research sessions. There also are two LBCT deep-dive sessions where the experts will break down the hottest trials and attendees can find out what the impact might be on the practice of cardiology and patients.
Feature | ACC | April 09, 2020 | Dave Fornell, Editor
Here is the list of American College of Cardiology (ACC) practice-
ACC Cancels 2020 Conference Amid Coronavirus Concerns. #COVID19 #coronavirus #2019nCoV
Feature | ACC | March 09, 2020 | Dave Fornell, Editor
March 9, 2020 — Less than week after the American College of Cardiolog...
American College of Cardiology Names Douglas Drachman Next Annual Scientific Session Vice Chair

Image courtesy of Massachusetts General Hospital

News | ACC | October 08, 2019
Douglas Drachman, M.D., FACC, has been selected as the next vice chair of the American College of Cardiology’s (ACC)...
SyncVision iFR Co-registration from Philips Healthcare maps pressure readings onto angiogram. Results from an international study presented at ACC 2019 indicates pressure readings obtained using iFR (instantaneous wave-free ratio, also referred to as instant wave-free ratio or instant flow reserve) in coronary arteries may localize stenoses that remain after interventions. FFR in the cath lab.

SyncVision iFR Co-registration from Philips Healthcare maps pressure readings onto angiogram. Results from an international study presented at ACC 2019 indicates pressure readings obtained using iFR (instantaneous wave-free ratio, also referred to as instant wave-free ratio or instant flow reserve) in coronary arteries may localize stenoses that remain after interventions.

Feature | ACC | March 27, 2019 | Greg Freiherr, Contributing Editor
The fingerprints of value-added medicine were all over products and works-in-progress on the exhibit floor of the a

The opening late-breaking trial at ACC 2019 is the Apple Heart Study, a large-scale, app-based study to identify atrial fibrillation using a smartwatch. Earlier, smaller trials showed this approach might be used in a population health application to proactively identify AFib patients earlier.

Feature | ACC | March 19, 2019
The American College of Cardiology (ACC) released a list of the late
A patient who received HeartMate III LVAD system at ACC.18. The HeartMate 3 was the topic of of the the key late-breaking trials at #ACC18

A patient who received the HeartMate III LVAD system showing off his external battery pack. He served as a patient ambassador in the Abbott booth at ACC.18. The HeartMate III, with its magnetic levitated pump, showed a big reduction in clotting over previous LVADs in a key late-breaking trial at this year's conference.

Feature | ACC | March 27, 2018 | Dave Fornell
There were several notable presentations of new data on cardiovascular technologies at the recent 2018 American Colle