Background

Coronary artery disease (CAD) with myocardial infarction (MI) as its acute manifestation is the leading cause of death worldwide. Approximately, 3.8 million men and 3.4 million women die of CAD each year. In Europe, CAD accounts for almost 1.8 million deaths (1/5 of all deaths) per year with large variations between countries. In patients with acute MI, early and successful myocardial reperfusion is the most effective strategy to reduce the size of MI and to improve the clinical outcome substantially.

Patients with cardiac arrest due to ST-elevation MI (STEMI) are at very high risk for death. Therapeutic hypothermia (between 32 and 36°C) was accompanied by survival benefits in patients with cardiac arrest in several studies and is recommended for patients who remain unconscious after resuscitation driven by cardiac arrest (of presumed cardiac cause). However, other studies failed to show beneficial effects regarding infarct size and for survival.

Methods

Patients with STEMI and cardio-pulmonary resuscitation were identified by screening the German nationwide inpatient sample (2005-2019). Patients were stratified for therapeutic hypothermia. Impact of hypothermia on mortality and adverse in-hospital outcomes was analysed (source: RDC of the Federal Statistical Office and the Statistical Offices of the federal states, DRG Statistics 2005-2019, and own calculations).

Results

Overall, 133,070 hospitalizations of patients with STEMI with cardio-pulmonary resuscitation (53.3% aged ≥70 years; 34.0% females), were recorded in Germany 2005-2019, of whom 12.3% (16,386 patients) underwent hypothermia.

Female sex was less frequent in patients with hypothermia than in those without (23.8% vs. 35.4%, P<0.001). Patients, who were not treated with hypothermia, were more often aged ≥70 years (55.9% vs. 34.9%, P<0.001).

Remarkable, in-hospital death rate was lower in STEMI with cardio-pulmonary resuscitation, who underwent hypothermia, in comparison to those without hypothermia (53.5% vs. 66.7%, P<0.001), whereas stroke (4.3% vs. 3.2%, P<0.001), pneumonia (29.2% vs. 16.1%, P<0.001) and acute kidney injury (32.3% vs. 16.1%, P<0.001) were more prevalent in patients with hypothermia.

Hypothermia was independently associated with reduced in-hospital mortality rate (OR 0.74 [95%CI 0.71-0.76], P<0.001), but also associated with an increased risk for stroke (OR 1.23 [95%CI 1.13-1.34], P<0.001), pneumonia (OR 1.84 [95%CI 1.77-1.92], P<0.001) and acute kidney injury (OR 2.29 [95%CI 2.15-2.43], P<0.001).

Conclusions

Hypothermia was associated with a survival benefit in STEMI patients, who had to underwent cardio-pulmonary resuscitation.