Therapeutic Hypothermia in STEMI

Study Questions:

What is the efficacy and safety of therapeutic hypothermia (TH) in patients with acute ST elevation myocardial infarction (STEMI)?

Methods:

Electronic databases were used to identify randomized controlled trials (RCTs) of TH in the patient population with STEMI. The primary efficacy endpoint was major adverse cardiovascular event (MACE). Secondary efficacy endpoints included all-cause mortality, infarct size, new myocardial infarction, and heart failure/pulmonary edema (HF/PE). All-bleeding, ventricular arrhythmias, and bradycardias were recorded as the safety endpoints. Data were summarized across treatment arms using the one-step (Peto) OR for dichotomous data and standardized difference in mean (SDM) for continuous data with fixed-effects models.

Results:

Six RCTs were included in this meta-analysis, enrolling a total of 819 patients. There was no significant benefit from TH in preventing MACE (odds ratio [OR], 01.04; 95% confidence interval [CI], 0.37-2.89), all-cause mortality (OR, 1.48; 95% CI, 0.68-3.19), new MI (OR, 0.99; 95% CI, 0.20-4.94), HF/PE (OR, 0.52; 95% CI, 0.15-1.77), or infarct size (SDM, −0.1; 95% CI, −0.23 to 0.04). However, a significant reduction of infarct size was observed with TH utilization in anterior wall MI (SDM, −0.23; 95% CI, −0.45 to −0.02). There was no significant difference seen for the safety endpoints all-bleeding (OR, 1.32; 95% CI, 0.77-2.24), ventricular arrhythmias (OR, 0.85; 95% CI, 0.54-1.36), or bradycardias (OR, 1.16; 95% CI, 0.74-1.83).

Conclusions:

The authors concluded that a meta-analysis of published RCTs indicates that benefit of TH is limited to reduction of infarct size in patients with anterior wall involvement with no demonstrable effect on all-cause mortality, recurrent MI, or HF/PE.

Perspective:

This pooled analysis of RCTs did not show a reduction in MACE, all-cause mortality, HF/PE, new MIs, and infarct size with TH when compared with controls. However, the use of TH did show some benefit when used to treat anterior wall STEMI. In addition, it appears that TH is a safe intervention, as there was no significant difference between both groups with regard to adverse effect outcomes. These findings indicate the need for further investigation into the optimal use of TH to improve outcome after a STEMI. An adequately powered RCT limited to patients with anterior wall STEMI may help confirm or refute the preliminary subgroup findings of benefit in this cohort.

Clinical Topics: Acute Coronary Syndromes, Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Chronic Heart Failure

Keywords: Acute Coronary Syndrome, Anterior Wall Myocardial Infarction, Arrhythmias, Cardiac, Bradycardia, Edema, Cardiac, Heart Failure, Hypothermia, Induced, Mortality, Myocardial Infarction, Pulmonary Edema, Secondary Prevention


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