DALLAS, Dec. 14 - A blood protein may help predict a person's risk of developing life-threatening complications following angioplasty, a common procedure used to unblock blood vessels to alleviate chest pain, according to a report in today's Circulation: Journal of the American Heart Association.
The blood protein, called creatine kinase or CK-MB, detects heart muscle damage and is used to help diagnose heart attack. Researchers found that the protein predicted which patients faced the highest risk of dying in the year following their angioplasty.
"This marker can offer physicians a powerful new tool for providing targeted therapy to those patients most at risk in the year after angioplasty," says Mun K. Hong, M.D., the study's lead investigator and an interventional cardiologist at the Cardiovascular Research Foundation, Washington Hospital Center, Washington, D.C.
The researchers found that those with the highest elevation of the protein - five times the normal level - were the most likely to die in the year following the procedure.
Researchers examined 1,056 patients who had angioplasty to unblock the saphenous vein that had previously been used as a graft during heart bypass surgery. The saphenous leg vein is often used in bypass surgery to re-route blood flow around a blocked coronary artery. However, the grafted vein often re-blocks. The patients in the study underwent angioplasty - a non-surgical procedure - to clear the grafted vein so they could avoid additional surgery.
About 15 percent of individuals who underwent the angioplasty procedure had CK-MB elevations. After one year, 11.7 percent of the individuals with the highest levels of the protein died, compared to 4.8 percent of those with normal levels.
Hong says that although this study does not prove a cause and effect relationship, prevention of the CK-MB elevation seems warranted. At present, there are two main approaches that could be used to prevent CK-MB elevation during saphenous vein angioplasty, although both are still in the investigational stages.
Hong and his team suspect that bits of plaque and/or blood clots that sometimes break off during a saphenous vein angioplasty may contribute to elevated CK-MB levels. These bits can move "downstream" and block a smaller blood vessel. One approach to prevent this would be to insert a self-expanding metal device during angioplasty that would open inside the vein just past the blockage to trap the debris. The device would act like sort of an umbrella and would be removed after the angioplasty is completed. As yet, there have been no randomized, controlled trials to prove the merits of this approach, but a trial is currently underway.
Another method involves a relatively new class of drugs called glycoprotein IIb/IIa inhibitors, says Hong. In a trial called EPIC, the drug abciximab -- a type of super aspirin -- was shown to help minimize complications in a small group of patients who had undergone the saphenous vein angioplasty. However, the study size was small and further studies are needed to assess the benefits and risks of using this new class of drugs, Hong says.
Co-authors are Roxana Mehran, M.D.; George Dangas, M.D., Ph.D.; Gary S. Mintz, M.D.; Alexandra J. Lansky, M.D.; Augusto D. Pichard, M.D.; Kenneth M. Kent, M.D., Ph.D.; Lowell F. Satler, M.D.; Gregg W. Stone, M.D.; and Martin B. Leon, M.D.
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