Benefits of therapeutic hypothermia shown in STEMI patients.

There is currently no proven therapy to reduce infarct volume, but a pilot study from Lund University demonstrates that the induction of mild hypothermia (<35C) in STEMI patients prior to performing an angioplasty can save 38% of heart tissue compared with the procedure alone. The study was presented at EuroPCR in Paris recently.

The investigators used Philips InnerCool endovascular cooling system—the only system commercially available that is capable of both surface and endovascular cooling. This study is the culmination of over 15 years of pre-clinical and clinical work in the area of myocardial preservation with the use of mild hypothermia. It takes about 5 minutes to cool the patient.

Background:

Experimental studies have shown that induction of hypothermia before reperfusion of acute coronary occlusion reduces infarct size. Previous clinical studies, however, have not been able to show this effect, which is believed to be mainly because therapeutic temperature was not reached before reperfusion in the majority of the patients. This study aimed to evaluate the safety and feasibility of rapidly induced hypothermia by infusion of cold saline and endovascular cooling catheter before reperfusion in patients with acute myocardial infarction.

Methods and results:

Twenty patients with acute myocardial infarction planned to undergo primary PCI were enrolled in this prospective randomized study. After 4±2 days, myocardium at risk (MaR) and infarct size (IS) were assessed by cardiac magnetic resonance using T2-weighted imaging and late gadolinium enhancement imaging, respectively. A core body temperature of < 35°C (34.7±0.3°C) was achieved before reperfusion without significant delay in door-to-balloon time (43±7min vs. 40±6min, hypothermia vs. controls, p=0.12). Despite similar duration of ischemia (174±51min vs. 174±62min, hypothermia vs. controls, p=1.00), IS normalized to MaR was reduced by 38% in the hypothermia group compared to the controls (29.8±12.6% vs. 48.0±21.6%, p=0.04). This was supported by a significant decrease in both peak and cumulative release of Troponin T in the hypothermia group (p=0.01 and p=0.03, respectively).

According to the principal investigator, Dr Göran K Olivecrona, Department of Cardiology, Lund University Hospital, the study demonstrates the ability to safely reach a core body temperature of < 35°C before reperfusion without delaying primary PCI, and that combination hypothermia as an adjunct therapy in AMI resulted in a 38% reduction in infarct size.

Philips InnerCool Emergency Care Solutions is seeking to commence a 80 patient multi-center, randomized trial in Europe to secure the CE mark indication for cooling of STEMI patients pre PCI.