Bivalirudin Ill-Suited for Speedy Stenting?

Short procedures may disadvantage bivalirudin (Angiomax) use during primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI), according to a secondary analysis of HORIZONS-AMI pointing to early stent thrombosis risk.

When bivalirudin was used, rates of definite acute stent thrombosis within 24 hours were higher if PCI took less than 45 minutes from arrival at the catheterization laboratory to the final angiogram than if it the procedure was longer (2.1% versus 0.7%, RR 2.87, 95% CI 1.01-8.17). However, no difference by procedure duration was seen with heparin plus glycoprotein IIb/IIIa receptor inhibitor (GPI) use.

"Short-acting medications, such as bivalirudin, may not allow for adequate antithrombotic effect of oral antiplatelets in fast procedures," suggested Duane S. Pinto, MD, MPH, of Beth Israel Deaconess Medical Center in Boston, and colleagues in their reported appearing online in JAMA Cardiology. "The pharmacokinetics of bivalirudin and clopidogrel offer insight."

"When the primary PCI procedure is completed rapidly, adequate antiplatelet effect may not have been achieved with oral agents, particularly if gastrointestinal tract absorption has been slowed in STEMI. In this setting, the short half-life of bivalirudin (25 minutes) leaves the newly implanted stent relatively unprotected against acute stent thrombosis for short procedures," Pinto's group explained.

"Conversely, the duration of antithrombin effect is longer and rapid antiplatelet effect is achieved with heparin plus GPI."

The authors suggested that alternate strategies, such as a high-dose prolonged infusion, are warranted in order to preserve the survival and reduced bleeding benefits of bivalirudin while chipping away at the stent thrombosis problem.

Their present analysis of the HORIZONS-AMI randomized clinical trial included 3,602 STEMI patients who presented within 12 hours of symptom onset. Participants were randomized to bivalirudin or heparin plus GPI.

Shorter procedures were less complicated and tended to be performed in younger patients that were less likely to smoke or have high blood pressure.

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