Long-Term Warfarin and Percutaneous Intervention

Despite improvements in interventional procedural techniques and equipment, vascular and bleeding complications remain a too frequent complication of percutaneous coronary intervention (PCI). In the National Cardiovascular Network database of over 100,000 patients undergoing cardiac catheterization the transfusion rate was 4% and the vascular complication rate was 3.5%.1 Contemporary PCI trials report rates of major bleeding of 1 to 2% and minor bleeding rates of 3–6%.2,3 The optimal peri-procedural strategy for patients requiring ongoing anticoagulation with warfarin is unclear. In the current issue of the Journal of Invasive Cardiology, MacDonald et al. describe the use of peri-procedural enoxaparin as a bridge to resumption of long-term oral anticoagulation. They report a 4.2% incidence of severe vascular or bleeding complications in 119 patients with this approach. See MacDonald et al. on pages 60–62 A high level of anticoagulation at the time of catheterization is associated with an increased risk of vascular complications.4 To avoid the potential of transient over-anticoagulation during conversion from low molecular weight heparin to warfarin Macdonald et al suggest reducing the dosage of enoxaparin during the overlap period. However, low level anticoagulation may not achieve the desired therapeutic effect; an issue of particular concern in patients with mechanical heart valves. There is literature to suggest that, at least in the setting of pregnancy, low-dose enoxaparin may not provide reliable prophylaxis against prosthetic valve thrombosis.5 Low molecular weight heparin is increasingly finding a role in the cardiac catheterization lab. Several studies have documented the safety of catheterization in enoxaparin treated patients if anticoagulation is held for a brief period prior to vascular access and hemostasis.6,7 The NICE 1 and NICE 4 studies suggest that the use of enoxaparin during PCI is safe and effective.3 A recent report suggests that immediate sheath removal following intervention with enoxaparin is safe.8 The ongoing SYNERGY trial is currently evaluating algorithms for the use of enoxaparin before, during and following PCI in acute coronary syndrome patients. Information with respect to the safety of long-term low molecular weight heparin therapy post intervention can be obtained from several contemporary trials of acute coronary syndrome. In the FRISC,9 REDUCE,10 EMPAR,11 ESSENCE and TIMI 11b12 trials the risks of major bleeding was acceptable or similar to unfractionated heparin. Largely due to improved vascular access management, bleeding rates fell from 8% in the EPIC trial to 2.9% in the EPILOG trial, and 1.7% in the EPISTENT trial in the absence of glycoprotein IIb/IIIa inhibition.13 Ensuring femoral arterial puncture at the mid femoral head level, minimizing catheter size, avoiding posterior wall puncture, avoiding unnecessary venous sheaths, prompt sheath removal following heparin reversal and experienced sheath management can help minimize these complications. Hemostasis in fully anticoagulated patients undergoing intervention via the femoral route is problematic. However several studies have demonstrated that the radial approach facilitates immediate sheath removal and reliable hemostasis in fully heparinized patients.14,15 Vascular closure devices are relevant to this discussion. One recent study documented a low 1.5% rate of complications in a large number of fully heparinized PCI patients following vascular closure.16 Others have reported similar favorable experience. However data on the safety and efficacy of this approach in patients on oral anticoagulation are currently lacking. The implications of device failure differ in heparinized patients in whom coagulation is expected to normalize within hours and those in whom normalization may take days. Some evidence suggests that angiography17 and PCI18 can be performed relatively safely in the setting of uninterrupted anticoagulation. However, prudence would seem to dictate that long-acting anticoagulation is a significant concern in the immediate peri-procedural period. Bridging with short acting anticoagulants, closure devices, radial access and meticulous access site management are all valid approaches. There is still room for more work on this subject.

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