Monitoring antiplatelet agents

November 2005

Feature Story

In addition to monitoring anticoagulant drugs, an emerging area is monitoring for antiplatelet agents, says Mark T. Cunningham, MD, director of the hematology laboratory at the University of Kansas Medical Center, Kansas City. For coronary bypass surgery and angioplasty, a new issue is monitoring of aspirin and Plavix [clopidogrel], Dr. Cunningham says.

“There are some data that patients with greater than 60 percent platelet inhibition by Plavix have a very high rate of operative bleeding when they go to CABG,” he says (Chen L, et al. J Thorac Cardiovasc Surg. 2004;128:425–431). “There are now tests for platelet inhibition, and clinicians at our institution are very interested in having this test done in patients on Plavix whom they want to send for CABG.”

Currently physicians take such patients off the drug and wait five days for the drug effect to wear off before sending them for surgery or angioplasty. With a test, they could take this same course with patients who have a high level of platelet inhibition, but send patients with an acceptable level of inhibition to surgery immediately. “This is an area where we will start to see more testing,” Dr. Cunningham predicts.

He is evaluating a commercial test, Accumetrics’ Verify Now P2Y12, which measures an ADP receptor response on platelets that is inhibited by Plavix and aspirin.

—William Check, PhD