Moderate vs. Mild Therapeutic Hypothermia in Comatose Survivors of Out-of-Hospital Cardiac Arrest - CAPITAL CHILL

May 17, 2021
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Author/Summarized by Author:
Dharam J. Kumbhani, MD, SM, FACC
Summary Reviewer:
Deepak L. Bhatt, MD, MPH, MBA, FACC
Trial Sponsor:
University of Ottawa Heart Institute Cardiac Arrest Program
Date Presented:
05/17/2021
Date Updated:
05/17/2021
Original Posted Date:
05/17/2021
References

Contribution To Literature:

The CAPITAL-CHILL trial showed that moderate hypothermia (target temperature 31°C) is not superior to mild hypothermia (target temp 34°C) in improving mortality or neurological outcomes at 6 months among comatose patients with OOHCA.

Description:

The goal of the trial was to compare the safety and efficacy of moderate (target temperature of 31°C) compared with mild (target temperature 34°C) among comatose survivors of out-of-hospital cardiac arrest (OOHCA).

Study Design

Patients were randomized in a 1:1 fashion to either moderate hypothermia (n = 193) or mild hypothermia (n = 196). Stratification was based on initial rhythm (ventricular tachycardia/ventricular fibrillation [VT/VF] vs. non-VT/VF).

In the moderate hypothermia arm, target temperature was maintained for 24 hours, followed by rewarming over 24 hours and normothermia for 24 hours. In the mild hypothermia arm, target temperature was maintained for 24 hours, followed by rewarming over 12 hours and normothermia for 24 hours. Cooling was achieved by means of an endovascular cooling device.

  • Total number of enrollees: 389
  • Duration of follow-up: 180 days
  • Mean patient age: 62 years
  • Percentage female: 18%

Inclusion criteria:

  • OOHCA
  • ≥18 years
  • Unconscious (Glasgow Coma Score of £8)
  • Irrespective of initial rhythm at the time of the cardiac arrest
  • Presumed cardiac cause for the arrest

Exclusion criteria:

  • Known inability to perform activities of daily living
  • Known intracranial bleed
  • Severe coagulopathy with clinical evidence of major bleeding
  • Coma not attributable to the cardiac arrest
  • Life expectancy of <1 year
  • Endovascular cooling device not available

Other salient features/characteristics:

  • Bystander CPR: 76%
  • Initial shockable rhythm: 86%
  • ST-segment elevation myocardial infarction: 38%
  • Arrest to return of spontaneous circulation: 22 minutess
  • Coronary angiography: 97%, percutaneous coronary intervention performed: 58%

Principal Findings:

The primary outcome, death or poor neurological outcome at 180 days, for moderate vs. mild hypothermia, was: 48.4% vs. 45.4% (p = 0.56).

  • Death: 43.5% vs. 41.0% (p = 0.63)
  • Poor neurological outcome: 4.9% vs. 4.4% (p = 0.81)

Secondary outcomes for moderate vs. mild hypothermia:

  • Modified rankin scale score 4-6 at 180 days: 46% vs. 44% (p = 0.71)
  • Pneumonia: 67.4% vs. 63.4% (p = 0.42)
  • Need for renal replacement therapy: 9.2% vs. 9.3% (p = 0.99)
  • Seizure: 12.5% vs. 7.1% (p = 0.08)
  • Thrombolysis in MI (TIMI) major bleed: 23.4% vs. 19.7% (p = 0.39)
  • Length of stay in cardiac intensive care unit (ICU): 10 vs. 7 days (p = 0.004)

Interpretation:

The results of this trial indicate that moderate hypothermia (target temperature 31°C) is not superior to mild hypothermia (target temperature 34°C) in improving mortality or neurological outcomes at 6 months among comatose patients with OOHCA. The vast majority of patients in this trial had an initial shockable rhythm. More intense hypothermia resulted in a longer length of stay in the ICU and numerically higher strokes, bleeding and seizures.

References:

Presented by Dr. Michel R. Le May at the American College of Cardiology Virtual Annual Scientific Session (ACC 2021), May 17, 2021.

Clinical Topics: Arrhythmias and Clinical EP, Invasive Cardiovascular Angiography and Intervention, Noninvasive Imaging, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Interventions and Imaging, Angiography, Nuclear Imaging

Keywords: ACC21, ACC Annual Scientific Session, Arrhythmias, Cardiac, Cardiopulmonary Resuscitation, Coma, Coronary Angiography, Endovascular Procedures, Hypothermia, Intensive Care Units, Length of Stay, Out-of-Hospital Cardiac Arrest, Percutaneous Coronary Intervention, Pneumonia, Renal Replacement Therapy, Rewarming, Seizures, Stroke, Tachycardia, Ventricular, Thrombolytic Therapy, Ventricular Fibrillation


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