CHILL-MI: Therapeutic Hypothermia Most Effective in Early Anterior STEMI

San Francisco, CA—Rapid endovascular catheter core cooling combined with cold saline was safe and effective in patients with anterior or large inferior STEMI, according to results from the CHILL-MI trial presented at TCT 2013. However, the trial did not meet its primary endpoint of reduced infarct size in relation to myocardium at risk (IS/MaR) at 4 ± 2 days; secondary endpoints included IS/MaR in patients with anterior and inferior infarctions, IS/MaR assessed by cardiac MRI at 6 months and death and heart failure (HF) within 45 days.

Data were presented by David Erlinge, MD, PhD, of Lund University in Sweden.

The prospective, randomized, multicenter trial included 120 patients with anterior and inferior STEMI with infarct duration <6 hours. All patients underwent PCI and were randomly assigned to standard of care (n=59) or hypothermia induced by cold saline (infusion of up to 2,000 mL) and endovascular cooling (n=61). One-hour cooling was initiated prior to reperfusion in the hypothermia group at a target temperature of <35ºC, followed by spontaneous re-warming. Cooling to ≤35˚C prior to reperfusion occurred in 77% of patients, with 92% achieving a temperature of ≤35.4˚C. There was a 9-minute delay in time from randomization to balloon in the hypothermia group.

MRI was performed at day 4 ± 2 in 81% of patients, at which point there was a 13% relative reduction in IS/MaR among all patients (P=.15). Among those with inferior STEMI, there was a 9% relative reduction (RR) (P=.76) and in those with anterior STEMI the RR was 27% (P=.22).

In an exploratory analysis of patients with early MI (<4 hours) hypothermia resulted in a 21% RR (P=.049) in all patients, a 13% RR (P=NS) in those with inferior STEMI and a 33% RR (P=.046) in those with anterior STEMI. 

There were no cases of mortality in the control or hypothermia groups at 45 days. HF, however, occurred at a lower rate in the hypothermia group vs. the control group 14% vs. 3%; (P<.05); HF occurred only in patients with anterior STEMI.

There was no difference between groups in terms of other clinical events, including atrial fibrillation, pneumonia, pulmonary edema or major bleeding.  

Erlinge reported a trend toward slightly improved ST resolution in the hypothermia group vs. controls (83% vs. 75.7%; P=.13), with significantly lower 90-minute ST elevation (2 mm vs. 3.5 mm; P=.04), but there was no difference in patients with ST resolution of more than 50% (84% vs. 86%; P=1).

CHILL-MI was designed to confirm the findings of the RAPID MI-ICE pilot study, which demonstrated a 38% reduction in infarct size as a result of cold saline and endovascular cooling. Findings from the current study warrant a randomized, controlled trial in early anterior STEMI patients, Erlinge said.

Disclosures: 

Erlinge reports receiving speaker’s honoraria from Philips and ZOLL.