PONTE VEDRA BEACH, FLA. — Administration of an antiplatelet IIb/IIIa drug to patients undergoing percutaneous coronary intervention for bypass-graft stenosis significantly boosted the incidence of myocardial infarctions in a registry with more than 34,000 patients.
The study used data from the American College of Cardiology National Cardiovascular Data Registry, which included more than 448,000 percutaneous coronary interventions (PCIs) done during 2001–2003, reported Satish K. Surabhi, M.D., at the annual meeting of the Society for Cardiovascular Angiography and Interventions.
The registry included 34,720 patients who had PCI of a coronary artery bypass graft; 24,279 (70%) were treated with a glycoprotein IIb/IIIa inhibitor and 10,441 (30%) were not.
Following PCI, the in-hospital mortality rate was almost identical in the two subgroups: a 1.4% death rate in patients who received a IIb/IIIa inhibitor and a 1.3% rate in those who didn't get the drug.
In the first weeks following PCI, the incidence of MIs was significantly higher in patients treated with a IIb/IIIa inhibitor, 2.4% than in those who did not, 1.4%. The MIs included all new ST-segment elevations, Q-wave events, left bundle branch blocks, and elevations in serum levels of creatine kinase that exceeded three times the upper limit of normal.
In a multivariate analysis that controlled for various baseline differences in demographic and clinical variables, use of a IIb/IIIa inhibitor was linked with a significant 63% increased rate in MIs following PCI, said Dr. Surabhi, a cardiologist in private practice in Greer, S.C.
Most patients in this registry were not treated with a distal protection device, which may have been the most important element of their management, he said. “Only 5% of these patients were treated with a distal protection device. The major factor [causing bad outcomes] seems to be distal embolization, not formation of a thrombus.”
If a distal protection device or distal balloon occlusion is not used during a PCI of an aortocoronary bypass graft, then the patient should not receive a IIb/IIIa inhibitor, on the basis of the new findings, said Dr. Surabhi.
The study did not address whether it's useful to use a IIb/IIIa inhibitor to treat a patient who's undergoing a bypass graft PCI with distal protection, but Dr. Surabhi suggested that adding the drug may not help.