CHILL-MI: Therapeutic hypothermia benefited patients with early anterior STEMI

SAN FRANCISCO — Results from the CHILL-MI trial indicate that induced hypothermia before PCI significantly reduced infarct size in patients with early anterior STEMI but not across the entire study population.

David Erlinge, MD, who presented the data at TCT 2013, and colleagues randomly assigned 120 patients in nine centers with anterior and inferior STEMI with infarct duration less than 6 hours to primary PCI with standard care or PCI preceded by hypothermia. Hypothermia was induced via rapid infusion of 1 L to 2 L cold saline and endovascular cooling and maintained for 1 hour after reperfusion with a target temperature of 33°C. The primary endpoint was infarct size in relation to area at risk, as indicated by cardiac MRI. Secondary endpoints included infarct size among patients with anterior or inferior infarctions, infarct size as indicated by cardiac MRI at 6 months and incidence of HF or death within 45 days of treatment.

David Erlinge

Forty-nine patients in the hypothermia group and 48 controls were included in the analysis. Those in the hypothermia group experienced a nonsignificant 13% reduction in infarct size relative to the area at risk (P=.15).

Exploratory analysis of patients with infarct duration 4 hours or less (hypothermia, n=42; control, n=40) revealed a significant 21% reduction in infarct size in the hypothermia group (P=.049). Further analysis of the hypothermia group showed a significant 31% reduction in infarct size among patients with anterior STEMI but a nonsignificant 13% reduction among those with inferior STEMI.

No deaths occurred during the course of the study. Eight controls and two patients in the hypothermia group experienced HF (P=.047 for difference). All HF events occurred among patients with anterior STEMI. Door-to-balloon time increased by a mean of 9 minutes in the hypothermia group as a result of cooling.

“We did not achieve the primary endpoint … in the total study population,” Erlinge, who is professor in the cardiology department at Lund University and Skane University Hospital in Sweden, said during a press conference. “Exploratory analysis indicates reduced [infarct size] in early, anterior hypothermia patients. … The protocol was safe, easy to administer and well tolerated by patients, and also by doctors and nurses. The current findings, in conjunction with the strategy of recently published studies, support a future [randomized clinical trial] focus on early anterior STEMI patients.”

For more information:

Erlinge D. Session IX: First report investigations I. Presented at: TCT 2013; Oct. 27-Nov. 1, San Francisco.

Disclosure: Philips sponsored the trial, and Erlinge reported receiving a speaker’s honoraria from Philips.