Bridging Therapy: How to Safely Switch Between Blood Thinners

Switching between blood thinners isn’t something you do on a whim. It’s a high-stakes decision that can mean the difference between a clot forming and a dangerous bleed. If you’re on warfarin and need surgery, a dental procedure, or any kind of invasive treatment, your doctor might talk about bridging therapy. But here’s the thing: for most people, bridging isn’t needed anymore. And if you’re on one of the newer blood thinners, you probably don’t need it at all.

What Is Bridging Therapy, Really?

Bridging therapy means using a short-acting injectable blood thinner-like low molecular weight heparin (LMWH), such as enoxaparin (Lovenox)-to temporarily replace your regular blood thinner when you have to stop it. The goal? Keep your blood from clotting during the time your main medication is turned off.

This used to be standard practice. Back in the 2000s, if you were on warfarin and needed a procedure, doctors would stop your pill a week before and start you on daily injections. The idea was simple: don’t leave you unprotected.

But in 2015, the BRIDGE trial changed everything. Researchers looked at over 1,800 patients with atrial fibrillation who were on warfarin and needed surgery. Half got bridging with LMWH. The other half didn’t. The results? Bridging didn’t lower the risk of stroke or clots. But it doubled the chance of major bleeding-2.3% versus 1%. That’s not a small trade-off. It’s a clear signal: for most people, the risk of bleeding outweighs the benefit of bridging.

When Do You Actually Need Bridging?

Not everyone. In fact, only a small group still needs it.

The current guidelines (from the American Heart Association, 2020) say bridging is only recommended for people with very high risk of clots. That means:

• People with a mechanical heart valve in the mitral position
• People who had a blood clot in their lung or leg within the last 3 months

That’s it. If you have atrial fibrillation, a mechanical valve in the aortic position, or even a history of stroke from AFib-but no recent clot-you likely don’t need bridging. The risk of bleeding from injections and extra anticoagulation is higher than the risk of a clot forming during the short window your warfarin is off.

Warfarin vs. DOACs: Why One Needs Bridging and the Other Doesn’t

This is where things get simple if you understand how the drugs work.

Warfarin takes days to build up in your system and days to leave it. That’s why you have to stop it 5-6 days before surgery. Your INR (a blood test that measures clotting time) has to drop below 1.5 before the procedure. That leaves a gap where you’re unprotected-hence the need for bridging in high-risk cases.

DOACs-like apixaban (Eliquis), rivaroxaban (Xarelto), dabigatran (Pradaxa), and edoxaban (Savaysa)-work differently. They kick in within hours and leave your body in 12-48 hours, depending on your kidney function. That means:

• You stop your DOAC 24-48 hours before surgery (sometimes even less, depending on the procedure)
• You restart it 12-24 hours after, once bleeding risk is low
• You don’t need injections. You don’t need bridging.

A 2018 protocol from the American College of Cardiology says it plainly: Bridging is not necessary in DOAC patients due to the rapid onset and offset. That’s why, as of 2023, 75% of new prescriptions for blood thinners are DOACs-not warfarin. Doctors are moving away from warfarin because it’s harder to manage. And bridging? It’s part of that old, complicated system.

How Bridging Works: The Timing Matters

If you’re one of the few who need bridging, timing is everything. Get it wrong, and you risk clotting or bleeding.

Here’s the standard protocol for warfarin patients needing bridging:

1. Stop warfarin 5-6 days before surgery.
2. Check your INR 1-2 days before stopping-it should be below 2.0 to start bridging safely.
3. Start LMWH (like Lovenox) 24-48 hours after the last warfarin dose.
4. Give LMWH twice daily at therapeutic dose (usually 1 mg/kg).
5. Stop LMWH 24 hours before surgery.
6. Restart warfarin 12-24 hours after surgery, often at 15-20% higher than your previous daily dose.
7. Check INR 3-4 days after restarting.

For patients on fondaparinux (Arixtra), stop it 36-48 hours before surgery. For unfractionated heparin (given by IV), stop it 4-6 hours before.

Important: Never skip the INR check. If your INR is still above 2.0 when you start LMWH, you’re at risk for bleeding. If it’s below 1.5, you’re not protected enough.

The Hidden Costs of Bridging

It’s not just about bleeding risk. Bridging is expensive and inconvenient.

A 7-day course of LMWH costs between $300 and $500 in the U.S. without insurance. You have to inject yourself-usually twice a day. Many patients struggle with this. Studies show 15-20% don’t follow the injection schedule correctly. Some skip doses. Others inject at the wrong time. That increases both clot and bleeding risks.

There’s also the mental toll. Worrying about shots, timing, bleeding, and when to restart your pill adds stress to an already stressful time-preparing for surgery.

And here’s the kicker: if you’re on a DOAC, you avoid all of this. No shots. No INR checks. No bridging. Just stop, wait, restart. Simpler. Safer.

What About After the Procedure?

Restarting your blood thinner after surgery is just as important as stopping it.

For warfarin patients on bridging:

• Restart warfarin 12-24 hours after surgery
• Use a slightly higher dose (15-20% above your usual) to get back to therapeutic levels faster
• Check INR in 3-4 days
• Stop LMWH once your INR is above 2.0

For DOAC patients:

• Restart 12-24 hours after low-risk procedures (like colonoscopy or cataract surgery)
• Wait 48-72 hours after major surgery (like hip replacement or open-heart surgery)
• Restart only when bleeding risk is low-your surgeon will tell you

Don’t guess. Always follow your care team’s instructions. Restarting too soon can cause bleeding. Too late can cause a clot.

Why Doctors Are Changing Their Minds

Ten years ago, bridging was routine. Now, it’s rare.

The BRIDGE trial (2015) and the PERIOP2 trial (2020) showed no benefit-only harm. The American College of Cardiology, the American Heart Association, and the American College of Chest Physicians all updated their guidelines to reflect this. The message is clear: Don’t bridge unless you absolutely have to.

Dr. James Douketis, lead researcher of the BRIDGE trial, said it best: “Perioperative bridging anticoagulation with LMWH in patients with atrial fibrillation... did not significantly reduce the risk of arterial embolism but significantly increased the risk of major bleeding.”

Many doctors still default to bridging out of habit. But the evidence is in. If your doctor suggests bridging and you don’t have a mechanical mitral valve or a recent clot, ask: “Is this really necessary?”

What You Can Do to Stay Safe

If you’re on a blood thinner and have a procedure coming up:

• Know which one you’re taking-warfarin or a DOAC?
• Ask your doctor: “Am I at high risk for clots? Do I need bridging?”
• Make sure your INR is checked before stopping warfarin.
• Ask if you can switch to a DOAC before your procedure-it might eliminate the need for bridging altogether.
• Write down your medication schedule and share it with your surgeon and pharmacist.
• Don’t stop or restart your meds on your own.

Most importantly: Don’t assume bridging is the default. It’s not. It’s the exception.

What’s Next for Blood Thinners?

The future is clear: fewer warfarin users. More DOACs. Less bridging.

DOACs are safer, easier, and more predictable. They don’t need regular blood tests. They don’t interact with food the way warfarin does. And they don’t require injections. As more people switch, bridging therapy will become a relic of the past-used only in rare, high-risk cases.

If you’re still on warfarin and need a procedure, talk to your doctor about switching to a DOAC. It might make your next surgery safer, simpler, and less stressful.

It’s not about doing more. It’s about doing less-only what’s truly necessary.