No free lunch: Transradial access in patients on coumadin.
The Ying and Yang of percutaneous coronary intervention (PCI) continues to focus on balancing the risks of ischemic complications with bleeding. Once considered a “necessary evil” of PCI, efforts to decrease bleeding has taken center stage as mounting evidence links bleeding events to increased short- and long-term mortality. Added to the mix of different pharmocotherapies, dosing, timing, and drug–drug interactions that sway the balance between decreased ischemia and increased bleeding is the adoption of a transradial rather than transfemoral approach to coronary angiography and PCI. There is strong evidence that a transradial approach may permit a greater reduction in bleeding risk than pharmacologic strategies alone and its use must be considered when discussing bleeding avoidance strategies in coronary angiography and PCI.
How then shall we manage patients on Warfarin therapy, referred for coronary angiography? Current standard practice recommends a cessation of Warfarin therapy before cardiac catheterization to decrease the risk of access-site complications and depending on the risk of a thromboembolic event, bridging therapy with heparin or low-molecular-weight-heparin (LMWH). However, bridging therapy has been associated with an increased risk of thromboembolism associated with subtherapeutic anticoagulation and an increased risk of bleeding during LMWH bridging after cardiac catheterization. In this issue of Catheterization and Cardiovascular Interventions (CCI), Ziakas et al. examined the safety and efficacy of the transradial versus transfemoral route for cardiac catheterization and PCI during uninterrupted Warfarin therapy. Access site complications occurred only in patients who underwent PCI: three (37.5%) in the femoral versus zero (0%) in the radial group (P = 0.034). One patient (3.7%) randomized to radial access was switched to femoral access after severe spasm after radial sheath insertion.
In the literature, there has been a consistent decrease in access related bleeding complications associated with the transradial versus transfemoral approach. This has been seen independent of the intensity of anticoagulation. A more relevant clinical comparator group in practice would be a default transradial approach in both groups and then comparing patients on therapeutic Warfarin versus the conventional protocol of stopping Warfarin with or without bridging. These trials would be complex and necessitate a stratified randomization based on the risk of thromboembolic events off Warfarin. This type of trial would be impractical to consider given the low relative number of patients on Warfarin and a sample size of at least 2,000 patients per arm to have 80% power to detect an increase in bleeding complications from 1 to 2%. It is unlikely that this RCT will ever be conducted, so in the mean time, does a 0% access site bleeding complications in 21 patients establish safety?
Finally and more importantly, what is the optimal antithrombotic regimen in patients fully anticoagulated with Warfarin? Although we have a paucity of data on the risk of bleeding or ischemic complications on a bridging protocol, we have over 100,000 RCT patients informing our decisions on optimal antithrombotic therapy in patients with normal INRs undergoing PCI. An INR of 2.5 does not equate to an ACT of 250. Therefore the lack of data regarding the safety and efficacy of different antithrombotic regimens during PCI including traditional measures of MACCE above and beyond access complications should give the clinician pause when considering this strategy in patients on chronic Warfarin therapy in an elective setting. As a radial first, femoral second operator, we reserve transradial catheterization in fully anticoagulated patients to urgent and emergent cases where the risk of waiting for the INR to fall or reversing with FFP has their own inherent risks.
Catheterization and Cardiovascular Interventions, Volume 76, Issue 4, pages 500–501.