Therapeutic Hypothermia for Post-Arrest Patients With Nonshockable Rhythms
Does therapeutic hypothermia (TH) improve neurologic outcome and survival in post-arrest patients with nonshockable rhythms (pulseless electrical activity or asystole)?
A total of 519 patients were identified who had after in- and out-of-hospital cardiac arrest with nonshockable initial rhythms, were comatose, and had return of spontaneous circulation within the Penn Alliance for Therapeutic Hypothermia (PATH) registry between 2000 and 2013. Patients either underwent TH with standard goal temperatures of 32°-34°C or received standard post-arrest care. Propensity score matching was used. Patient and arrest characteristics used to estimate the propensity to receive TH were age, sex, location of arrest, witnessed arrest, and duration of arrest. The primary outcome was neurologic outcome at hospital discharge as dichotomized into “good” outcome (CPC 1-2) or “poor” outcome (CPC 3-5), and a secondary outcome was survival to hospital discharge.
About 50.5% of the entire cohort of comatose patients underwent TH. Of 201 propensity score matched pairs, mean age was 63 ± 17 years; 51% were male; and 60% had an initial rhythm of pulseless electrical activity. Patients undergoing TH were more often outpatients, younger, and had a longer duration of arrest and a higher incidence of asystole. Survival to hospital discharge was greater in patients who received TH (17.6% vs. 28.9%; p < 0.01), as was discharge CPC of 1-2 (13.7% vs. 21.4%; p = 0.04). In adjusted analyses, patients who received TH were more likely to survive (odds ratio [OR], 2.8; 95% confidence interval [CI], 1.6-4.7) and to have better neurologic outcome (OR, 3.5; 95% CI, 1.8-6.6) than those who did not receive TH.
Based on propensity score matching, patients with nonshockable initial rhythms treated with TH had better survival and neurologic outcome at hospital discharge than those who did not receive TH.
The results have been inconclusive in the multiple retrospective cohort studies examining the association between TH and neurologic outcomes in patients who arrest with nonshockable rhythms. Thus the Class IIb recommendation in the guidelines. The findings provide further support for the use of TH in patients with initial nonshockable rhythms, and should encourage its use while awaiting data from randomized trials.
Keywords: Acute Coronary Syndrome, Arrhythmias, Cardiac, Heart Arrest, Hypothermia, Induced, Out-of-Hospital Cardiac Arrest, Patient Discharge, Resuscitation, Survival
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