Mild Hypothermia in Cardiogenic Shock Complicating Myocardial Infarction: Randomized SHOCK-COOL Trial

Background: Experimental trials suggest improved outcome by mild therapeutic hypothermia for cardiogenic shock after acute myocardial infarction. The objective of this study was to investigate the hemodynamic effects of mild therapeutic hypothermia in patients with cardiogenic shock complicating acute myocardial infarction. Methods: Patients (n=40) with cardiogenic shock undergoing primary percutaneous coronary intervention without classic indications for mild therapeutic hypothermia underwent randomization in a 1:1 fashion to mild therapeutic hypothermia for 24 hours or control. The primary end point was cardiac power index at 24 hours; secondary end points included other hemodynamic parameters and serial measurements of arterial lactate. Results: No relevant differences were observed for the primary end point of cardiac power index at 24 hours (mild therapeutic hypothermia versus control: 0.41 [interquartile range, 0.31-0.52] versus 0.36 [interquartile range, 0.31-0.48] W/m(2); P=0.50; median difference, -0.025 W/m(2); 95% CI, -0.12 to 0.06). Similarly, all other hemodynamic measurements were not statistically different. Arterial lactate levels at 6, 8, and 10 hours were significantly higher in patients in the mild therapeutic hypothermia group with a slower decline (P for interaction=0.03). There were no differences in 30-day mortality (60% versus 50%; hazard ratio, 1.27; 95% CI, 0.55-2.94; P=0.55). Conclusions: In this randomized trial, mild therapeutic hypothermia failed to show a substantial beneficial effect on cardiac power index at 24 hours in patients with cardiogenic shock after acute myocardial infarction. Clinical Trial Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01890317.