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 collected in the American College of Cardiology National Cardiovascular Data Registry, which included more than 448,000 percutaneous coronary interventions (PCIs) done in the United States during 2001–2003, reported Satish K. Surabhi, M.D., at the annual meeting of the Society for Cardiovascular Angiography and Interventions.
Included in the registry were 34,720 patients who had PCI of a bypass graft. In this group, 24,279 patients (70%) were treated with a IIb/IIIa inhibitor, and 10,441 patients (30%) were not.
Following PCI, the in-hospital mortality rate was almost identical in the two subgroups of patients: a 1.4% death rate in patients who received a IIb/IIIa inhibitor and a 1.3% rate in those who did not get the drug.
In the first weeks following PCI, the incidence of myocardial infarctions was significantly higher among patients treated with a IIb/IIIA inhibitor, 2.4%, than in patients who didn't get this class of drug, 1.4%. 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 associated with a statistically significant 63% increased rate of MIs following PCI, said Dr. Surabhi, a private practice cardiologist 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, he said.
The study did not address whether it's useful to use a IIB/IIIa inhibitor to treat a patient who is undergoing a bypass graft PCI with distal protection, but Dr. Surabhi suggested that adding the drug may not help. “I personally think that in stable patients, a IIb/IIIa inhibitor is not useful.” Treatment with heparin alone should provide adequate anticoagulant coverage, he added.