Bridging Therapy: How to Safely Switch Between Blood Thinners

Switching between blood thinners isn’t as simple as stopping one pill and starting another. For patients on long-term anticoagulation-especially those taking warfarin-surgery, dental work, or other procedures often require a temporary pause. But stopping blood thinners without a plan can lead to deadly clots. On the other hand, continuing them can cause dangerous bleeding. That’s where bridging therapy comes in. But here’s the catch: for most people, it’s no longer needed.

What Is Bridging Therapy, Really?

Warfarin takes days to clear from your system. That’s why you stop it 5-6 days before surgery. But during those days, your body has no protection against clots. That’s where LMWH steps in. You start injections 2-3 days before the procedure and stop them 24 hours before. After surgery, you restart warfarin and keep the injections going until your INR (a blood test that measures clotting time) gets back into range.

But here’s what most people don’t realize: this approach was developed decades ago, before we had better options. Today, we know that for the vast majority of patients, bridging doesn’t prevent strokes-it just increases bleeding.

When Bridging Therapy Is Actually Necessary

According to the latest American Heart Association guidelines (2020), bridging is only recommended for patients with very high risk of clots. That means:

• People with mechanical heart valves in the mitral position (not aortic)
• Those who’ve had a blood clot in the last 3 months (like a deep vein thrombosis or pulmonary embolism)
• Patients with atrial fibrillation and a CHA₂DS₂-VASc score of 7 or higher (a scoring system that estimates stroke risk)

That’s it. That’s the entire list. For everyone else-about 85-90% of people on warfarin-bridging does more harm than good.

The BRIDGE trial (2015), a major study published in the New England Journal of Medicine, found that patients who were bridged had a 2.3% risk of major bleeding. Those who weren’t bridged? Just 1.0%. And guess what? The rate of strokes and clots was the same in both groups.

Dr. James Douketis, who led that trial, put it plainly: “Bridging doesn’t protect against clots. It just makes you bleed more.”

Why DOACs Changed Everything

Unlike warfarin, DOACs leave your body fast. Their half-lives range from 5 to 17 hours, depending on kidney function. That means:

• You stop taking them 24-48 hours before surgery (sometimes even less)
• You restart them 12-24 hours after, once bleeding risk drops
• No injections. No blood tests. No bridging.

In 2023, 75% of new anticoagulant prescriptions in the U.S. were for DOACs. Why? Because they’re easier, safer, and more predictable. No more weekly INR checks. No more dietary restrictions. And no more messy bridging regimens.

Transitioning from warfarin to a DOAC? That’s straightforward: stop warfarin, wait until your INR is below 2.0, then start the DOAC. No heparin needed. Transitioning from a DOAC to warfarin? Start warfarin and overlap it with the DOAC for a few days until the INR hits the target range. Again-no bridging.

The Hidden Dangers of Bridging

Bridging isn’t just about bleeding. It’s about complexity. Here’s what you’re signing up for:

• Injecting yourself daily-often twice a day-for up to a week. Many patients skip doses because it’s painful or inconvenient. Studies show 15-20% non-adherence.
• Cost-a 7-day course of LMWH can cost $300-$500 out of pocket in the U.S., even with insurance.
• Timing errors-if you stop the injection too late, you risk bleeding during surgery. Too early, and clots form.
• Confusion after surgery-when do you restart warfarin? How much? When do you check your INR? Many patients get conflicting advice from their surgeon and their cardiologist.

And here’s the kicker: the 2021 PERIOP2 trial showed that even patients with mechanical valves didn’t benefit from bridging. That’s huge. It means the old standard of care for the highest-risk group might be outdated too.

What Should You Do Instead?

Here’s what to do based on your medication:

If you’re on warfarin:

1. Ask your doctor: “Am I in the high-risk group that actually needs bridging?”
2. If yes, get your INR checked 5-6 days before surgery. Stop warfarin when INR drops below 2.0.
3. Start LMWH 3 days before surgery. Stop it 24 hours before.
4. After surgery, restart warfarin at 15-20% higher than your previous dose. Check INR in 3-4 days.

If you’re on a DOAC:

1. Stop the DOAC 24-48 hours before surgery (longer if you have kidney problems).
2. Restart it 12-24 hours after surgery, once bleeding risk is low.
3. No injections. No bridging. No fuss.

For minor procedures like dental work or skin biopsies, you might not even need to stop your blood thinner at all. Always ask.

Who Decides? It Takes a Team

Ask for a pre-op anticoagulation review. Many hospitals now have anticoagulation clinics that specialize in this. They’ll review your risk scores, your meds, your procedure, and your kidney function-and give you a clear, written plan.

Don’t let your surgeon say, “We always bridge.” That’s outdated. Push for evidence-based care.

The Bottom Line

If you’re on warfarin and need surgery, ask: “Do I really need this?” If you’re on a DOAC, you almost certainly don’t. The goal isn’t to keep you on blood thinners forever-it’s to keep you alive without bleeding out or clotting up.

More people are switching to DOACs every year. And that’s a good thing. Less bridging. Less injections. Less stress. Better outcomes.

Know your risk. Ask the right questions. And don’t accept a plan just because it’s what’s always been done.