This small 122 patient study, conducted by Ken Nagao, Nihon University School of Medicine, Tokyo, adds to evidence from studies conducted in Europe and Australia suggesting that cooling heart attack patients saves lives. A prospective preliminary study of mild hypothermia before return of spontaneous circulations (ROSC) for patients with failed standard cardiopulmonary resuscitation (CPR) was compared with mild hypothermia induced after ROSC.

Prior to ROSC, 20 patients were treated within 30 minutes of arriving in the emergency room with an intravenous infusion of extracellular fluid at 4°C, to achieve a body temperature of 34°C. Patients in this group were then revived using cardiopulmonary bypass, only then was intra-aortic balloon pumping and/or coronary reperfusion therapy performed. Control patients, with ROSC, were treated with cardiopulmonary bypass prior to the extra corporeal cooling process. Mild hypothermia (34°C) was maintained for 3 days. The time interval from emergency room arrival to attainment of 34°C was shorter in the hypothermia before ROSC than the hyperthermia after ROSC group (.5 vs. 4 hours, P<0.001).

The survival rate in the hypothermia prior to ROSC group was 35% (7 out of 22 patients), as compared with 13% (13 out of 102 patients) in the hypothermia after ROSC group (P=0.01). Though the hypothermia prior to ROSC group also had a more favorable neurologic outcome, the results were not statistically significant between the two groups – 15% vs. 11%.

The techniques used in this particular study are quite costly, but relatively inexpensive alternatives (the infusion of chilled saline, ice packs and cooling blankets) can be used to achieve similar results and surveys indicate that one in four US doctors report using mild hypothermia to treat heart attacks.