Therapeutic hypothermia yielded positive neurological outcomes among certain cardiac arrest patients

Mooney MR. Circulation. 2011;doi:10.1161/circulationaha.110.986257.

More than 90% of patients who had received therapeutic cooling as treatment for an out-of-hospital cardiac arrest survived with positive neurological outcomes, according to trial results.

There were 140 out-of-hospital cardiac arrest patients who participated in the trial between February 2006 and August 2009. Eligible patients had remained unresponsive after a return of spontaneous circulation. These patients were cooled and re-warmed with an automated, non-invasive cooling device.

Three-quarters of the patients (n=107) — including those with non-ventricular fibrillation arrest or cardiogenic shock — were transferred to a therapeutic hypothermia-capable hospital via referral from other hospitals within the participating network. Sixty-eight patients with concurrent STEMI received cardiac intervention and cooling simultaneously.

The overall survival to discharge rate was 56%. Ninety-two percent of survivors had a positive neurological outcome at discharge.

No differences in survival rates were observed between transferred and non-transferred patients. Non-ventricular fibrillation arrest and presence of cardiogenic shock were strongly linked to death. However, survivors with non-ventricular fibrillation arrest had a 100% positive neurological recovery rate, and survivors with cardiogenic shock present had an 89% positive neurological recovery rate.

For each hour of delay in initiating cooling, mortality risk increased 20% (95% CI, 4-39).

The endpoint of positive neurological outcome was defined as cerebral performance category 1 or 2 at discharge.

The researchers said therapeutic hypothermia is an underused treatment strategy despite showing signs that it improves survival and confers neuroprotection on patients who have a cardiac arrest outside of the hospital, and regional systems of care for these patients are necessary. A comprehensive protocol may result in further dispersion of this “essential therapy for [out-of-hospital cardiac arrest].”

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