June 10, 2010 – There is currently no proven therapy to reduce infarct volume, but a pilot study demonstrated use of mild hypothermia (below 35 C) in ST-elevated myocardial infarction (STEMI) patients prior to performing an angioplasty may help. Results showed a 38 percent preservation of heart tissue as compared to angioplasty alone. The study was presented last week at EuroPCR.
Lund University in Sweden conducted the pilot study using Philips InnerCool endovascular cooling system, which uses both surface and endovascular cooling. The study, headed by Matthias Götberg, M.D., and Göran Olivecrona M.D., is the culmination of more than 15 years of preclinical and clinical work in the area of myocardial preservation with the use of mild hypothermia.
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.
Twenty patients with acute myocardial infarction planned to undergo primary percutaneous coronary intervention (PCI) were enrolled in this prospective randomized study. After two to six days, myocardium at risk (MaR) and infarct size were assessed by cardiac magnetic resonance imaging (MRI) using T2-weighted imaging and late gadolinium enhancement imaging. A core body temperature of less than 35 C was achieved before reperfusion without significant delay in door-to-balloon time (an average of 43 minutes vs. about 40 minutes). Despite similar duration of ischemia, infarct size normalized to MaR was reduced by 38 percent in the hypothermia group compared to the controls. This was supported by a significant decrease in both peak and cumulative release of troponin T in the hypothermia group.
The protocol demonstrates the ability to safely reach a core body temperature of less than 35 C before reperfusion without delaying primary PCI. It also showed that combination hypothermia as an adjunct therapy in STEMI resulted in a reduced infarct size.
Philips InnerCool Emergency Care Solutions is seeking to commence a 80-patient, multicenter, randomized trial in Europe to secure the CE mark indication for cooling of STEMI patients pre-PCI.