In an era of rapid STEMI reperfusion with Primary Percutaneous Coronary Intervention is there a role for adjunct therapeutic hypothermia? A structured literature review

Mild hypothermia has been shown to improve neurological outcome and reduce mortality following out of hospital cardiac arrest. In animal models the application of hypothermia with induced coronary occlusion has demonstrated a reduction in infarct size. Consequently, hypothermia has been proposed as a treatment, in addition to Primary Percutaneous Coronary Intervention (PPCI) for ST segment elevation myocardial infarction (STEMI). However, there is incomplete understanding of the mechanism and magnitude of the protective effect of hypothermia on the myocardium, and limited outcome data. We undertook a structured literature review of therapeutic hypothermia as adjuvant to PPCI for acute STEMI. We examined the feasibility, safety, impact on infarct size and the resultant effect on major adverse cardiac events and mortality. There were 13 studies between 1946 and 2016. With the exception of one study, therapeutic hypothermia for STEMI was reported to be feasible and safe, and its only demonstrable benefit was a modest reduction in post-infarct heart failure events. Evidence to date, however, is from small clinical trials and in an era of low early mortality following PPCI for STEMI, demonstrating a mortality benefit will be challenging. Post-myocardial infarction left ventricular dysfunction is a more frequent, alternative clinical outcome and therefore any intervention that mitigates this warrants further investigation.