The Role for Low-Molecular Weight Heparin after a Cath Procedure
Urban legends intrigue me. They are either very prevalent in medicine, or the challenges of documenting simple, common observations are deeper than it would seem likely. An example is the use of low-molecular-weight heparin after a cardiac catheterization procedure. I am not referring to its use in acute coronary syndromes, which was tested in the ACUITY trial. I am referring to the use of these compounds after a diagnostic study or intervention. This is where the “urban legend” comes in. I have heard several reports that low-molecular-weight heparin has been associated with late vascular bleeding complications. This can be particularly dangerous because it allegedly can occur a day or so after the vascular puncture, that is, after the patient has gone home. This is a frightening scenario, as one can envision a very dramatic bleed, potentially life-or-limb threatening, possibly requiring surgery, transfusions, and holding of necessary dual antiplatelet therapy. However, this problem is relatively unreported in the literature, and is not addressed in guidelines for bridging therapies for patients undergoing procedures who are on warfarin.
So my question to the readers is this:
Does this problem actually occur with any frequency, or is it a scary story to frighten the interventional cardiology community – that is, an urban legend?
Secondly, if it does in fact occur enough to be recognized as a problem: Should there be a role for low-molecular-weight heparin as part of a bridging strategy after a cath procedure?
Amongst our group, this question created some debate: some of us thought that low-molecular-weight heparin should be contraindicated after a vascular puncture procedure. However, there were some dissenters. It was pointed out that stating something was “contraindicated” seemed strange, given the lack of reporting of this feared complication, and given that this has not been addressed within guidelines (the package insert for Lovenox states that “if the treatment with enoxaparin sodium is to be continued [after PCI] the next scheduled dose should be given no sooner than 6–8 hours after sheath removal”).
Another pointed out that although perhaps the risk of a major bleeding complication might be a considerable risk after a femoral artery puncture, perhaps it would be negligible if a radial artery puncture were used. (Although this was acknowledged to be a reasonable consideration, one could argue that if a radial artery puncture were to be used, perhaps there would be no need to bridge, since there have been reports on the safety of performing cath procedures via the radial artery on patients without stopping their warfarin). Thus, a policy is being formulated at our institution to address what to do with bridging of patients taking warfarin who are to undergo a cath procedure:
1) Consider simply holding the warfarin prior to the procedure and restarting it afterwards (i.e., no bridging). This is supported by guidelines in certain scenarios, such as atrial fibrillation (no history of stroke), prosthetic aortic valves, and so forth.
2) In slightly higher risk scenarios, preprocedure low-molecular-weight heparin may be considered, to reduce the duration the patient is not anticoagulated, with warfarin to be resumed post-procedure, but without post-procedure heparin.
3) No stopping of warfarin, but using radial artery access. Some disadvantages of this approach might be the possible need to switch to a femoral approach, and the lack of data on periprocedural anticoagulation (e.g., bivalirudin or glycoprotein 2b/3a inhibitors) for patients on warfarin).
4) Bridging with low-molecular-weight heparin before and after the procedure, by using a radial artery access approach. Arguments against this include a paucity of data on the safety of low-molecular-weight heparin for patients at the highest risk: those with mechanical mitral valves, especially with atrial fibrillation and/or depressed left ventricular function. Nonetheless, this strategy is being used for perioperative surgical bridging (notwithstanding a “black box warning for pregnant patients).
5) Not to be forgotten is the traditional method of bridging — using unfractionated heparin, and
6) using low-molecular-weight-heparin as a bridge routinely (when a bridge is needed). The discussion above provides an argument why this approach might not be used, but the likelihood of risk remains unclear. It should be noted that guidelines addressing bridging strategies focus on surgical procedures, without really addressing procedures involving vascular puncture.
The second question I have of readers of this blog is this:
What recommendations might be given to our group as we develop our policy on warfarin bridging? Do other groups have formal policies? If so, how are they structured?
There are several guidelines on this, some of which do comment on the use of low-molecular weight heparin, but combining the different guideline recommendations, and acknowledging the potential problem raised above (low-molecular-weight-heparin post femoral artery puncture) is proving to be somewhat cumbersome.
And finally, is there ever a scenario in which giving low-molecular-weight-heparin after a femoral artery puncture cath procedure seems like a good idea? If so, what is that scenario?
