Therapeutic hypothermia in acute myocardial infarction: a systematic review

Therapeutic hypothermia preserves neurologic function in post-cardiac arrest patients. Several studies suggest that hypothermia may preserve myocardial function in patients with acute myocardial infarction (AMI). We carried out a systematic review to evaluate the efficacy of therapeutic hypothermia at reducing infarct size and decreasing major adverse cardiac events (MACEs) and all-cause mortality in AMI patients. We searched ClinicalTrials.gov, the Cochrane Clinical Trials Register, EMBASE, and MEDLINE through July 2010 for studies investigating therapeutic hypothermia in AMI patients. Data were extracted by 2 reviewers. We identified 5 studies (693 patients), 2 of which were feasibility trials and 3 of which were randomized controlled trials (RCTs). Feasibility trials showed that therapeutic hypothermia is a safe and feasible intervention. RCTs showed that cardiac outcomes were similar at 30 days' follow-up for the hypothermia and control groups. Mean infarct size ranged from 2.0% to 14.1% of the left ventricle in the hypothermia group and from 8.0% to 13.8% of the left ventricle in the control group. MACEs ranged from 0.0% to 6.2% in the hypothermia group and 3.9% to 10.0% in the control group. All-cause mortality ranged from 0.0% to 3.4% and 2.2% to 10.0% in the hypothermia and control groups, respectively. Subgroup analyses suggested that hypothermia may reduce infarct size in patients with anterior wall infarction. Our review suggests that therapeutic hypothermia is safe and feasible. However, more evidence is needed to determine whether therapeutic hypothermia is associated with improved infarct size, MACEs, or all-cause mortality in RCTs of AMI patients.