First cold-activated anti-clotting drug beneficial for medically-induced hypothermia

According to scientists, the new antiplatelet drug appears to be activated at low temperatures, making it potentially the first to protect against clotting during therapeutic hypothermia without provoking bleeding at rewarming.

The agent showed strong binding to activated platelets at the temperature usually used for hypothermia but none at normal body temperature, during preclinical experiments conducted by Karlheinz Peter, MD, PhD, of Baker IDI Heart & Diabetes Institute in Melbourne, Australia.

According to the report shared at the American Heart Associations's Arteriosclerosis, Thrombosis and Vascular Biology meeting in San Francisco, the agent also kept fibrinogen from binding to activated platelets at 22C but not at 37C.

Peter said this profile has the potential to substantially improve the safety of medically-induced hypothermia.

Although much further investigation of the safety and efficacy of the agent is required, the proof-of-concept results do look promising, said Robert A. Hegele, MD of the University of Western Ontario in London.

Bringing the temperature down during cardiovascular surgery and intensive care for cardiac arrest reduces the metabolic requirements of the brain and other tissues, allowing them to survive with less ischemic injury.

The AHA recommends using cooling blankets, ice packs and other methods to reduce body temperature for 12 to 24 hours which has been shown to improve overall survival rates and reduce long-term disability, but this therapy triggers clots.

Peter explained that lower temperatures partially activate platelets, and as blood flow slows due to the chill, the platelets come closer together and may stagnate.

He also said, adding to this problem, patients are immobile and cardiac surgery often introduces clotting risk from the heart-lung machine.

For these reasons, anticlotting drugs are given to patients for standard care during therapeutic hypothermia.

However, these drugs have a long half-life, and they continue working when they are no longer needed, increasing the risk of bleeding complications when patients are brought back to normal body temperature, said Peter.

The new antiplatelet drug that would make the technique safer, could definitely increase its use, suggested Peter.

Researchers cautioned that much study is required in animal models before the agent could enter human trials.