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
—William Check, PhD