# Therapeutic hypothermia in patients with acute myocardial infarction complicated by out-of-hospital cardiac arrest

## TL;DR

Therapeutic hypothermia reduces in-hospital deaths in heart attack patients who had a cardiac arrest outside the hospital, but it doesn't improve brain recovery at discharge.

## Contribution

This study is the first large-scale analysis showing hypothermia reduces mortality in AMI-OHCA patients and highlights the importance of early treatment.

## Key findings

- Therapeutic hypothermia significantly lowers in-hospital mortality in AMI-OHCA patients.
- Early hypothermia initiation is linked to better survival and neurological outcomes.
- Neurological outcomes at discharge were not significantly improved by hypothermia.

## Abstract

There is a lack of data regarding outcomes of therapeutic hypothermia in patients with acute myocardial infarction (AMI) complicated by out-of-hospital cardiac arrest (OHCA). This study aimed to evaluate the effect of therapeutic hypothermia on clinical outcomes in comatose patients after percutaneous coronary intervention (PCI) for AMI following OHCA.

Using a prospective nationwide registry from 2016 to 2021, we selected 2925 patients with AMI who underwent emergency PCI among 182,508 OHCA cases. These patients were divided into groups receiving hypothermia treatment (n = 624) and those not receiving hypothermia treatment (n = 2301). The primary endpoint was in-hospital mortality, and secondary endpoints were mortality rate at 24 h and neurological outcomes at discharge.

The hypothermia group showed a significantly lower rate of in-hospital mortality than the non-hypothermia group (odds ratio [OR] 0.71; 95% confidence interval [CI], 0.59–0.85; P < 0.001). However, there was no significant difference in neurological outcomes at discharge between the two groups. Furthermore, quartile analysis of door-to-cooling (DtC) time, defined as the time from hospital arrival to initiation of hypothermia, demonstrated that a shorter DtC time was associated with a decreased risk of mortality and poor neurological outcomes (mortality: adjusted OR, 0.40; 95% CI, 0.30–0.54; P < 0.001; poor neurological outcome: adjusted OR, 0.59; 95% CI, 0.45–0.77; P < 0.001 for quartile 1 versus quartile 4).

Therapeutic hypothermia reduced the rate of in-hospital mortality in patients with AMI complicated by OHCA. Moreover, early initiation of hypothermia demonstrated a reduction in mortality and poor neurological outcomes.

URL: http://clinicaltrials.gov. Unique identifier: NCT05724914.

In this large, government-controlled, nationwide, prospective real-world registry with AMI and complicated by OHCA, we demonstrated therapeutic hypothermia reduced the rate of in-hospital mortality, but it did not improve neurological outcomes at discharge. Our findings also showed that early initiation of hypothermia was significantly associated with reduced in-hospital mortality and poor neurological outcomes.

The findings of this study suggest that therapeutic hypothermia reduces in-hospital mortality in patients with AMI complicated by OHCA. Early application of hypothermia should be considered as a potential means of improving neurological outcomes in patients with AMI-OHCA undergoing emergency PCI.

The online version contains supplementary material available at 10.1186/s12916-025-03997-0.