Bridging Therapy: How to Safely Switch Between Blood Thinners

Switching between blood thinners isn’t just a matter of stopping one pill and starting another. For patients on long-term anticoagulation, a poorly timed change can lead to a stroke, a dangerous clot, or uncontrolled bleeding. This is where bridging therapy comes in-but it’s not always the right answer. In fact, for most people today, it’s not needed at all.

What Is Bridging Therapy, Really?

Bridging therapy means using a fast-acting injectable blood thinner-like low molecular weight heparin (LMWH) or unfractionated heparin-to temporarily cover the gap when you stop your regular blood thinner, usually warfarin, before surgery or a procedure. The idea is simple: keep your blood from clotting while your main medication wears off. But the reality is messy. For years, doctors did this routinely. Now, we know better.

The BRIDGE trial in 2015 changed everything. Researchers gave over 2,000 patients with atrial fibrillation either bridging therapy or a placebo during their warfarin break. The results? Bridging didn’t prevent a single stroke. But it doubled the risk of major bleeding-2.3% versus 1%. That’s not a trade-off worth making for most people.

When Bridging Therapy Is Still Necessary

Not everyone can skip bridging. There are only two real situations where it’s still recommended:

• You have a mechanical heart valve in your mitral position
• You had a blood clot in your leg or lung within the last 3 months

That’s it. These are the only two groups where the risk of a clot outweighs the risk of bleeding during a procedure. For everyone else-especially those with atrial fibrillation, even with a high CHA₂DS₂-VASc score-bridging is more harmful than helpful. The American Heart Association updated its guidelines in 2020 to reflect this. What used to apply to half of all anticoagulated patients now applies to just 10-15%.

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

The reason bridging even exists comes down to how long drugs stay in your body. Warfarin has a half-life of 36 to 42 hours. That means it takes days to clear. You have to stop it 5 to 6 days before surgery, and your INR needs to drop below 1.5 before you’re safe to operate. That’s a long window where you’re unprotected.

Direct oral anticoagulants (DOACs)-like apixaban (Eliquis), rivaroxaban (Xarelto), and dabigatran (Pradaxa)-are different. They clear from your system in hours, not days. Apixaban is gone in about 12 hours. Dabigatran in 17. That’s why you don’t need bridging with them. You simply skip the next dose before your procedure and restart it as soon as it’s safe afterward. No injections. No extra risk.

And here’s the kicker: DOACs now make up 75% of all new anticoagulant prescriptions in the U.S. as of 2023. More people are switching to them not just for convenience, but because they eliminate the whole bridging dilemma.

How Bridging Therapy Works (If You Need It)

If you’re one of the few who still need bridging, here’s how it’s done-step by step:

1. Stop warfarin 5 to 6 days before your procedure. Your doctor will check your INR to make sure it’s below 1.5.
2. Start therapeutic-dose LMWH (like enoxaparin) 3 days before the procedure. This is usually two shots a day.
3. Stop the LMWH 24 hours before surgery. If you’re on a lower, prophylactic dose, stop it 12 to 24 hours before.
4. After the procedure, restart LMWH 24 to 48 hours later, depending on bleeding risk.
5. Restart warfarin at 15-20% higher than your previous daily dose, and check your INR in 3 to 4 days.

Timing matters. Miss a dose, and your clot risk spikes. Give too much too soon after surgery, and you could bleed internally. That’s why this only works with careful coordination between your cardiologist, surgeon, and pharmacist.

Why Bridging Is Risky and Expensive

Even when it’s technically needed, bridging isn’t easy. Here’s what you’re signing up for:

• Bleeding risk: 2.3% chance of major bleeding, even in low-risk patients.
• Injections: You’ll need to give yourself shots twice a day for up to a week. Many people struggle with this-studies show 15-20% skip or mess up doses.
• Cost: A 7-day course of LMWH can cost $300 to $500 out of pocket in the U.S. without insurance.
• Logistics: You need blood tests (INR), coordination with multiple providers, and precise timing. One misstep can land you in the ER.

Compare that to DOACs: no shots, no INR checks, no bridging. Just skip the pill before surgery, take it again after. Simpler. Safer. Cheaper.

What to Do If You’re on Warfarin and Need Surgery

Don’t wait until the day before your procedure to ask about blood thinners. Start this conversation at least 3 weeks ahead. Ask your doctor these questions:

• Am I in one of the two high-risk groups that still need bridging?
• Would switching to a DOAC before surgery be an option?
• Can we avoid bridging entirely by timing the procedure around my last dose?
• What’s my bleeding risk using the HAS-BLED score?

If you’ve been on warfarin for years, you might feel stuck. But you’re not. Many patients can safely switch to a DOAC weeks before surgery. It’s not always possible-especially if you have kidney problems or a mechanical valve-but it’s worth exploring.

The Bottom Line: Less Bridging, More Smart Choices

The old rule-“always bridge when you stop warfarin”-is outdated. It’s based on fear, not evidence. Today’s guidelines are clear: bridging should be the exception, not the rule.

If you’re on warfarin and need a procedure, ask if you can switch to a DOAC first. If you can’t, make sure your team follows the 2020 AHA guidelines and only bridges if you have a mechanical mitral valve or a recent clot. Don’t let tradition override data. Your body will thank you.

And if you’re just starting anticoagulation? Consider a DOAC from the start. No bridging. No injections. No weekly blood tests. Just a daily pill that works-and lets you live your life without the constant shadow of a dangerous transition.