CHILL-MI trial starts patient enrolment to study endovascular cooling treatment of STEMI patients


Philips has started enrolment of the first patients in its CHILL-MI clinical study. CHILL-MI is a prospective, randomised, multicentre study designed to further evaluate the safety and effectiveness of the company’s InnerCool RTx endovascular cooling system in patients suffering from ST-elevation myocardial infarction (STEMI).

The study will enrol 120 patients at multiple sites in Europe with a primary endpoint of reducing infarct size as a percentage of myocardium at risk, as assessed by cardiac magnetic resonance imaging. The study will also reinforce the safety and efficacy data demonstrated in the RAPID MI-ICE trial in a larger patient group. The RAPID MI-ICE trial showed a 38% reduction in infarct size in STEMI patients who were cooled to a temperature of <35°C prior to performing angioplasty.


According to researchers at Lund University in Sweden, one of the CHILL-MI study centres, the key to reducing infarct size is to cool patients with therapeutic hypothermia to <35°C prior to reperfusion or opening of the blocked artery.


“The success of the RAPID MI-ICE study was a breakthrough in the treatment of STEMI patients. With the initiation of CHILL-MI, we aim to confirm the results in a larger multicentre trial. We hope this study will help to demonstrate the positive impact that therapeutic hypothermia can have on the outcomes of patients suffering acute myocardial infarction and bring us a step closer to making it a standard of care,” said David Erlinge, head department of cardiology at Lund University in Sweden and principle investigator for the CHILL-MI study.


Use of the Philips RTx endovascular cooling system for the treatment of myocardial infarction is investigational and is not approved for this indication in the USA.


The CHILL-MI study


The Phase II/III CHILL-MI study will enrol 120 patients from multiple centres in Europe. Patients in the treatment group will receive endovascular cooling therapy in combination with 1-2 L of cold saline. The control group will receive the current standard of care. The primary endpoint will be the myocardial infarct size as a percentage of at-risk myocardium at 4 days (± 2 days), as measured by cardiac magnetic resonance imaging. Secondary safety and efficacy endpoints will also be evaluated.


The RAPID MI-ICE study


The RAPID MI-ICE study enrolled 20 STEMI patients who were randomised to receive immediate percutaneous coronary intervention with or without adjunct rapid endovascular cooling. The study demonstrated that the induction of mild hypothermia (<35°C) in STEMI patients prior to performing an angioplasty can save up to 38% more heart tissue than the current standard of care. Data showed that, in the control group, more patients experienced heart failure (n=3) and ventricular tachycardia/ventricular fibrillation (VT/VF; n=2) than in the endovascular cooling group, which had no instance of either complication (P=0.21). Three patients in the endovascular cooling group experienced infections, while no patients in the control group had infections (P=0.21). The conclusion that the rapid induction of hypothermia with endovascular catheter is safe and feasible in patients with acute myocardial infarction prompted the initiation of the CHILL-MI study to investigate this technology in a larger multicentre trial.