Elsevier

The American Journal of Cardiology

Volume 133, 15 October 2020, Pages 48-53
The American Journal of Cardiology

Meta-Analysis of the Usefulness of Therapeutic Hypothermia After Cardiac Arrest

https://doi.org/10.1016/j.amjcard.2020.07.038Get rights and content

Despite current guidelines recommending therapeutic hypothermia (TH) for post cardiac arrest comatose patient, its use remains limited. Randomized controlled trials (RCTs) have also reported conflicting results on the efficacy of TH. Therefore, we conducted an updated meta-analysis to evaluate the effect of TH in post cardiac arrest patients. We searched electronic databases for RCTs comparing TH (32°C to 34°C) with controls (normothermia or temperature ≥36°C) in comatose patients who sustained cardiac arrest. Mortality and neurological outcomes were the outcomes of interest. We used random effect meta-analysis to estimate risk ratio (RR) with 95% confidence interval (CI). Eight RCTs with a total of 2,026 patients (TH n = 1,025 and control n = 1,001) were included. Irrespective of initial rhythm, TH was associated with significant reduction in poor neurological outcomes (RR 0.87, 95% CI 0.77 to 0.98; p = 0.02) without any difference in mortality (RR 0.94, 95% CI 0.85 to 1.03; p = 0.17). In patients with initial shockable rhythm compared with control, TH reduced mortality (RR 0.85, 95% CI 0.73 to 0.99; p = 0.04) and poor neurological outcomes (RR 0.81, 95% CI 0.67 to 0.99; p = 0.04). Whereas, in patients with initial nonshockable rhythm, TH was associated with decreased poor neurological outcomes after excluding one trial (RR 0.95 95% CI 0.91 to 1.00; p = 0.05). In conclusion, TH is associated with improved neurological outcomes in all patients sustaining cardiac arrest and with decreased mortality in patients with initial shockable rhythm.

Section snippets

Methods

We searched MEDLINE, EMBASE, and Cochrane databases for RCTs published since inception through January 31st, 2020. We used search terms like “TTM,” “cardiac arrest,” “comatose,” “TH,” “normothermia,” “out of hospital cardiac arrest (OHCA),” “in-hospital cardiac arrest (IHCA),” “shockable rhythm,” and “nonshockable rhythm” in different combinations.

Studies were included if they met the following criteria: RCTs of adult human subjects reporting clinical outcomes in patients with OHCA or IHCA who

Results

The initial study search yielded 6,903 studies out of which 8 RCTs were identified.5,6,8,12,15, 16, 17, 18 Supplementary Figure 1 shows the search strategy. A total of 2,026 patients with 1,025 in the TH arm and 1,001 patients in the control arm were included in the final analysis (Table 1). Data for one of the trials was accessed using an abstract and previous meta-analysis.18, 19, 20, 21 The duration of follow-up was from 14 days to 180 days or until hospital discharge. Baseline patient

Discussion

This updated meta-analysis of 2,026 comatose post cardiac arrest patients demonstrated that TH improved neurological outcomes irrespective of initial rhythm. In the subgroup of patients with initial shockable rhythm, significant improvement in mortality was also observed, whereas such a benefit was not noticed in patients with initial nonshockable rhythm.

Current guidelines recommend using TH between 32°C and 36°C in all postcardiac arrest patients.9,10 Despite this, recent study suggests TH

Authors’ Contributions

Amit Rout: Conceptualization, Methodology, Software, Writing;

Sahib Singh: Data curation, Writing- Original draft preparation;

Sauradeep Sarkar: Data curation, Writing;

Immad Munawar: Data curation;

Aakash Garg: Methodology, Writing;

Christopher R. D'Adamo: Methodology, Software;

Udaya S. Tantry: Writing- Reviewing and Editing;

Ashwin Dharmadhikari: Reviewing and Editing;

Paul A. Gurbel: Reviewing and Editing.

Disclosures

The authors declare that they have no known competing financial interests or personal relations that could have appeared to influence the work reported in this study.

References (29)

  • https://mycares.net/sitepages/data. 2018Annual Report. Accessed on February 20,...

  • Mild therapeutic hypothermia to improve the neurologic outcome after cardiac arrest

    N Engl J Med

    (2002)
  • SA Bernard et al.

    Treatment of comatose survivors of out-of-hospital cardiac arrest with induced hypothermia

    N Engl J Med

    (2002)
  • MA Peberdy et al.

    American Heart Association. Part 9: post-cardiac arrest care: 2010 American Heart Association Guidelines for cardiopulmonary resuscitation and emergency cardiovascular care

    Circulation

    (2010)

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    Funding: The authors received no financial support for the research, authorship, and/or publication of this article.

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