I believe the authors are on the right track by exploring more optimal anticoagulation and antiplatelet strategies in treating patients with peripheral arterial disease (PAD), and especially critical limb ischemia (CLI). The limitations and bleeding complications with unfractionated heparin (UFH) have been well documented during percutaneous coronary intervention (PCI), and likewise over the last several years during percutaneous peripheral intervention (PPI).1,2 The PAD patients, and especially the CLI patients, are at significantly higher risks for all hemorrhagic and thrombotic complications than PCI cohorts, therefore nonheparin PPI alternatives such as direct thrombin inhibition (DTI) with bivalirudin (Angiomax, The Medicines Company, Parsippany, New Jersey) are attractive. The safety and feasibility of DTI in CLI have been reported both without and in combination with GP IIb/IIIa inhibition.3 There are little published data with enoxaparin in PPI.
The authors report more procedural bleeding in the UFH group (23.6%) and less in the DTI group (15.4%) despite 30% of the DTI group receiving GP IIb/IIIa inhibitors and 11.5% receiving fibrinolytic therapy. These results are consistent with previous reports further documenting the increased bleeding risks associated with UFH versus DTI and the overall higher bleeding risks of the PPI versus PCI patient population. The multiple limitations of UFH and benefits of the short half-life (T = 1/2 of 25 minutes) of bivalirudin are likely responsible for the improved bleeding outcomes reported in similar PPI series using DTI as the anticoagulation foundation. It is of interest and note that preprocedural rate of clopidogrel (Plavix, Sanofi, New York, New York) use in the three groups were between 62.5–73.4%, which may have contributed to thrombotic complications and lessened the bleeding complications. In general, all CLI patients today should have pre-procedural and post-procedural clopidogrel.
At first glance, this series seems extremely small, and it is too small to derive any definitive conclusions, but a review of the literature will unfortunately produce only a few larger similar reports dedicated to anticoagulation and antiplatelet strategies in CLI. I might also add the same for UFH in PPI, as there exists no scientific evidence that UFH should be the “gold standard” anticoagulant in treating PAD. This report further adds to the mounting evidence that clinicians and industry need to design larger scale multicenter randomized trials to scientifically investigate the optimal anticoagulation and antiplatelet strategy in treating patients with PPI and especially CLI. Novel “endopharmacotherapies” are “tools” likely as important as novel device technologies if we are to improve outcomes in the CLI patient population.
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1. Shammas NW, Lemke JH, Dippel EJ, et al. In-hospital complications of peripheral vascular interventions using unfractionated heparin as the primary anticoagulant. J Invasive Cardiol 2003;15:242–246.
2. Shammas NW. Complications in peripheral vascular interventions: Emerging role of direct thrombin inhibitors. J Vasc Interv Radiol 2005;16:165–171.
3. Allie DE, Hebert CJ, Walker CM, et al. A safety and feasibility report of combined direct thrombin and GP IIb/IIIa inhibition with bivalirudin and tirofiban in peripheral vascular disease interventions: Treating critical limb ischemia like acute coronary syndrome. J Invasive Cardiol 2005;17:427–432.
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