Therapeutic hypothermia: is it effective for non-VF/VT cardiac arrest?

Since 2003, therapeutic hypothermia (TH) is recommended for all comatose survivors after cardiac arrest (CA) due to VF/VT. However, only 25–30 % of CA patients have VF/VT as the initial recorded cardiac rhythm, and this percentage has further decreased in recent years. The benefit of TH for non-VF/VT CA are controversial. Methods: Meta-analysis. All studies evaluating the benefit of TH in adult comatose survivors from CA were included. No limitations of study design, publication date and publication status were imposed. Resuts: Two randomised trials and 15 observational studies were identified. Neither of the randomised trials was specifically designed to assess the benefit of TH in this patient population.TH-treated patients had a higher 6-mo survival rate than controls (5/22 vs. 2/22; risk ratio [RR] for mortality 0.85 [0.65–1.11] p = 0.24). Results of the 15 observational studies (12 reporting survival to discharge on 1,581 patients, and 13 reporting neurological outcome on 1,998 patients) showed that TH was associated to a significant reduction in the RR for both hospital mortality (0.88 [0.82–0.95]) and poor neurological outcome (0.95 [0.90–0.99]). However, several studies suggested no effect or possible harm from TH. Conclusions: in patients resuscitated from non-VF/VT CA, use of TH is associated with a significant decrease in both hospital mortality and neurological outcome. Observed heterogeneity in study results may be explained by differences in case mix or cooling protocols and the presence of uncontrolled confounders, being most of the studies observational.