Hi Jeff.
Per your request, please see the publication linked below. BTW, in getting my INR down below 1.5, I did not have to completely hold warfarin for even one day. I ended up going about 90% of my normal dose 2 days before surgery, 60% of my normal dose 1 day before surgery and about 23% of normal dose the day of surgery. I tested often to make sure I did not drop much below 1.5. This method also enabled me to bounce back quickly. The day after surgery I resumed my dosing with about 120% of my normal dose, taken in the evening.
The instructions the surgeon gave me were to be at under 1.5 INR the day of the procedure and to be under 2.0 for next day. After that my normal range of 2.0- 3.0 was fine. I ended up at 1.4 the day of procedure, 1.9 the next day and 2.3 two days after my procedure. I tested several times that week and as the procedure approached I would dose in the morning and then decide if I needed to dose again in the evening.
Pellicle has an entry in his blog in which he documents in more detail how I achieved this. I think in managing most people, they err on the side of going lower than I did. But, because I self manage and keep account of all my data, I know how quickly my INR drops when I hold or reduce my dosage. I burned through about $75 worth of test strips the week of my procedure, but I wanted to get below the INR level needed and not much lower, and the feedback enabled me to do this. $75 to lower my risk of a stroke or a bleed is peanuts. I would also note that I believe that I clear warfarin faster than most. I see a change in my INR the next day, either up or down, from even a small tweak to my dosage.
Also, it should be noted, both my cardiologist and the surgeon were on board with the plan. If I wanted to I could have bridged, but I had confidence that this would be lower risk than bridging. Bridging brings with it both thrombotic and bleeding risks. The risk is low, but real. From my perspective, the idea is to bring the risk from low to very low. For myself, I would rather spend one day at INR of 1.4 and know where I'm at vs the unknowns that bridging brings. The issue with bridging is that while the bridging agent is running the show, you don't know where you're at.
By the time of your procedure, your warfarin has been cleared from your system, and they hold the bridging agent. It has a very short half life and so at the time of the operation, you could be at the equivalent of 1.0 INR. That brings more risk of stroke than needed. If your team believes that 1.4 or 1.5 INR is sufficient, why risk going lower than that? Then on the other side of surgery, the bridging agent is resumed, at the same time warfarin is resumed. This brings with it some risk of having a bleed, as you are in a zone for a time where both agents are working to inhibit anticoagulation.
Warfarin Therapy - Management During Invasive Procedures and Surgery
www2.gov.bc.ca
Here is the link to Pellicle's blog in which he documents what I did in more detail:
A post on the management of Anti Coagulation Therapy (ACT) by Vitamin K Antagonist (VKA) - Warfarin I've decided to call this the rapid Du...
cjeastwd.blogspot.com