Atrial Fibrillation (AF) & Surgery

Why AF matters for your operation

Atrial fibrillation means the top chambers of your heart quiver instead of beating cleanly. Two things flow from that, and both affect surgery.

• Your heart rate — in AF the pulse can run fast, especially under the stress of an operation. The anaesthetist wants it well controlled so the heart copes smoothly.
• Clot and stroke risk — pooled blood in a fibrillating atrium can form clots, which is why most people with AF take a blood thinner. That same thinner is the main thing we have to manage around surgery.

Knowing you have AF lets the team plan ahead rather than discover it on the day. Always tell your pre-assessment nurse, even if your AF is well settled.

Your rate and rhythm medicines usually continue

The drugs that control your heartbeat are generally taken as normal, including the morning of surgery, with a small sip of water. Stopping them suddenly can let your heart race or your blood pressure swing.

• Beta blockers (bisoprolol, atenolol, metoprolol) — almost always continued. See our blood pressure medicines before surgery guide for how these are handled.
• Digoxin — usually continued; the team may check your level and your kidney function.
• Calcium channel blockers (diltiazem, verapamil) and amiodarone — normally continued too.

Don't change or skip these on your own. If a dose is to be altered, your pre-assessment team will tell you exactly when.

The blood thinner is the big decision

This is where most of the planning goes. Your blood thinner has to be paused so you don't bleed excessively, then restarted so you're not unprotected from stroke for any longer than necessary.

• DOACs — apixaban, rivaroxaban and dabigatran are usually stopped a fixed number of days before, based on the drug, the bleeding risk of the operation and your kidney function. For some low-bleeding-risk procedures this can be as little as a day; for higher-risk surgery it is longer. See apixaban, rivaroxaban and dabigatran before surgery.
• Warfarin — typically stopped about 5 days before so your INR can drift down to a safe level. See warfarin before surgery.

For minor procedures (some skin or dental work), the thinner may simply be continued. Follow the specific plan you are given — timing is everything here.

Bridging with heparin — when and why

Most people with AF do not need bridging — including many on warfarin. Large studies have shown that for ordinary AF, routinely filling the gap with heparin causes more bleeding without preventing more strokes. Bridging is reserved for people at genuinely high clotting risk — for example a mechanical heart valve, or a very recent stroke or TIA (usually within the last few months) — where the short unprotected window matters more.

When bridging is used, the gap left by stopping warfarin is filled with heparin injections — usually into the tummy — for a few days. Heparin wears off fast, so the last dose is timed close to surgery and stopped at the right moment. People on a DOAC for AF almost never need bridging, because DOACs clear quickly on their own. Your cardiology or anticoagulation team decides this — never start or stop heparin yourself.

On the day and your recovery

You'll usually have a fresh ECG and blood tests (kidney function, salts, and clotting or INR) before your operation. The team monitors your heart rhythm throughout.

AF can flare or first appear after surgery — it is one of the most common post-operative heart rhythm problems, triggered by stress, fluid shifts and inflammation. If it happens you may feel palpitations or a fast, irregular pulse; the team will treat it, often just by controlling the rate and correcting any low potassium or magnesium.

Your blood thinner is restarted once the surgeon is happy the bleeding risk has passed — sometimes the same evening, sometimes a day or two later. You'll be told exactly when and what to take.