Benefit of Hypothermia in Out-of-hospital Cardiac Arrest Complicating Acute Myocardial Infarction

Out-of-hospital cardiac arrest (OHCA) is a leading cause of mortality worldwide. Due to significant improvement in the management of patients with OHCA, an increasing number of initially resuscitated patients are being admitted to hospitals. Nevertheless, OHCA remains associated with a poor prognosis, with a survival rate of approximately 8.8% to hospital discharge. Moreover, international registry data have indicated that favorable neurological outcome at hospital discharge or 30 days after OHCA is only 2.8-18.2% across all registries.

The majority of adult cardiac arrest cases are associated with obstructive coronary artery disease. Thus, current guideline recommended that immediate angiography and primary revascularization in all patients with resuscitated cardiac arrest and ST-segment elevation on electrocardiography, and also in patients with resuscitated cardiac arrest without ST-segment elevation, but with high probability of acute coronary occlusion. However, even after prompt restoration of blood flow, a substantial proportion of patients with myocardial infarction (MI) experience extensive necrosis. The application of hypothermia in patients with acute MI focuses on the reducing energy consumption at cardiac level, a factor consistently linked to diminished infarction size in animal study. However, in a recent meta-analysis of randomized trials comparing different strategies for therapeutic hypothermia adjunctive to percutaneous coronary intervention (PCI) versus standard of care in patients with acute MI, faille to demonstrate clear benefit. It is important to note, however, these randomized trials were underpowered and as a results, they were unable to draw firm conclusions regarding the impact of therapeutic hypothermia.

Therefore, this study aimed to investigate the impact of therapeutic hypothermia on clinical outcomes in patients who underwent primary PCI for acute MI after OHCA.