Blood thinners and your procedure

Blood thinners are medicines that stop blood clots from forming or growing. Clots can cause strokes, heart attacks, blocked arteries and clots in the legs or lungs. The medicines do not actually make blood thinner; they slow down clotting.

People take them for atrial fibrillation (an irregular heartbeat), a past blood clot, heart or artery stents, artificial heart valves, or after a stroke or heart attack. Some supplements, such as fish oil, vitamin E, turmeric and ginkgo, and pain relievers such as ibuprofen and naproxen, also affect bleeding. Tell us about them too.

Deciding whether to pause a blood thinner means weighing two risks: the risk of bleeding from the procedure, and the risk of a clot while you are off the medicine. We look at three things.

For some low-risk procedures, you can keep taking your blood thinner. For others, we will ask you to pause it, and sometimes we will ask your cardiologist, hematologist or primary care doctor to weigh in first. Blood tests such as the INR (for warfarin) and a platelet count may be checked before the procedure.

Based on published interventional radiology society guidance. Your plan may differ, especially if you have a recent heart stent, a mechanical valve, a recent clot or kidney disease. Never stop clopidogrel, prasugrel or ticagrelor after a recent heart stent without your cardiologist's approval.

Most patients restart their blood thinner the day after the procedure, and some the same evening. After a higher-risk procedure, such as a kidney biopsy, we may ask you to wait 2 to 3 days. Your discharge instructions will give you the exact day and time.

Warfarin takes about 4 to 5 days after restarting to fully work again. If you need protection sooner, you may need bridging.

Bridging means using a short-acting injectable blood thinner, usually enoxaparin (Lovenox), to cover the days when warfarin is not working. It is like a temporary bridge over a gap. Enoxaparin wears off in about a day, so it can be stopped just before the procedure and restarted soon after.

Bridging is only needed for some people on warfarin, mainly those with a mechanical heart valve (especially in the mitral position), a clot in the last 3 months, or atrial fibrillation with a recent stroke. Most people with atrial fibrillation do not need bridging, because studies show it adds bleeding without preventing strokes for most patients. People on apixaban, rivaroxaban, edoxaban or dabigatran almost never need bridging, because these medicines wear off and restart quickly.

1. About 5 days before
   Last dose of warfarin.
2. About 3 days before
   Start enoxaparin injections, as instructed.
3. Day before
   Last enoxaparin dose, usually in the morning, about 24 hours before the procedure.
4. Procedure day
   No blood thinners. INR is checked.
5. Day after
   Restart warfarin at your usual dose, plus enoxaparin when we say it is safe.
6. About 4 to 5 days later
   Stop enoxaparin once your INR is back in range. Your prescribing doctor checks it.

This is an example schedule. Your dates, doses and timing will come from your prescribing doctor and our team.

When I plan a procedure for someone on a blood thinner, the first thing I ask is why they take it. Pausing Eliquis for two days in a healthy person with atrial fibrillation is very different from pausing Plavix a month after a heart stent. When the answer is not clear, I call the cardiologist or hematologist myself, and I make sure you leave with a written plan that says exactly when to stop and when to restart.

Fabio Komlos, MD, interventional radiologist · About Dr. Fabio Komlos