Meta-analysis depicting the outcomes of hypothermia versus normothermia post cardiac arrest

Abstract

Abstract Background The current American Heart Association (AHA) 2020 guidelines recommend targeted temperature monitoring (TTM) for cardiac arrest patients. However, more recently published trials intrigued us to review the therapeutic benefit of TTM. Objective To assess the usefulness of recommended TTM temperature (< 36° C), we performed this updated meta-analysis of randomized controlled trials (RCTs), including the latest Targeted Hypothermia Versus Targeted Normothermia After Out-of-hospital Cardiac Arrest-2 (TTM2) trial and trial conducted by Wolfrum S., comparing neurological and mortality outcomes in targeted hypothermia (TH) (< 36° C) with normothermia group (> 36° C). Methods We searched Cochrane, MEDLINE, and EMBASE from inception to December 2022. Only trials with patients randomized for TTM and reported neurological and mortality outcomes were included. Non-randomized design, retrospective cohorts, and non-English abstracts were excluded. The data was extracted using full text for all RCTs except two where abstract and previous meta-analysis was used. Statistical analysis was performed using Cochrane Review Manager using the random effects model and calculated pooled risk ratios of outcomes using the Mantel-Haenszel method. Results A total of 12 RCTs and 4,262 patients were included in the review (Table 1). Almost 80% weight was carried by four trials (Lascarrou JB, Dankiewicz J, Nielsen N, and Wolfrum S). The neurological outcomes were mainly measured using the cerebral performance category (CPC) scoring in the RCTs. Patients had significantly improved neurological outcomes [Risk Ratio (RR) 0.90, 95% Confidence Interval (CI): 0.83, 0.98, p = 0.02, I² = 61%] in the TH group (Figure 1). However, no significant difference in mortality was observed [RR 0.97, 95% CI: 0.90, 1.06, p = 0.55, I² = 38%]. In patients with an initial shockable rhythm, no significant difference in the neurological [RR 0.82 (95% CI: 0.67, 1.00), p = 0.05, I² = 82] and mortality outcomes [RR 0.82, 95% CI: 0.57,1.18, p=0.29, I²=94%] was seen between the two groups. Conclusion Our meta-analysis indicates a therapeutic benefit in neurological outcomes of patients undergoing TH post-cardiac arrest. Our findings align with the current AHA guidelines and demonstrate the utility of TH irrespective of the initial rhythm.Table 1Figure 1