When an atrial fibrillation episode strikes, the most important thing you can do is stop what you’re doing, sit or lie down, and focus on slowing your breathing. Most episodes are not emergencies, but some are. Knowing the difference, and having a few practical tools ready, can help you stay calm and get through it safely.
Sit Down and Start Slow Breathing
The moment you feel your heart fluttering, racing, or beating irregularly, stop any physical activity and sit down somewhere comfortable. Standing or continuing to exert yourself forces your heart to work harder, which can make symptoms worse and last longer.
Once you’re seated, try slow diaphragmatic breathing. Place one hand on your belly, breathe in slowly through your nose until you feel your stomach expand, then breathe out through your mouth for longer than you inhaled. Close your eyes if it helps. This activates your vagus nerve, which acts as a natural brake on your heart rate. Deep breathing alone won’t convert your heart back to a normal rhythm, but it can bring your rate down and ease the panicky feeling that often accompanies an episode.
When to Call Emergency Services
Not every afib episode requires a trip to the emergency room, but certain symptoms alongside a fast or irregular heartbeat mean you need help immediately. Call emergency services if you experience any of the following during an episode:
- Chest pain or pressure
- Significant shortness of breath
- Fainting, dizziness, or a fall
- Weakness or numbness on one side of your face or body
- Blurred vision or loss of sight
- Confusion or difficulty speaking
- A severe headache
- Sweating, nausea, or vomiting
The last four items on that list are signs of a possible stroke, which is the most dangerous complication of afib. A heart rate above 150 beats per minute with severe symptoms also warrants urgent medical attention. If your rate sits above 120 to 130 bpm and you feel unwell, err on the side of getting help.
Check Your Pulse and Track the Episode
If you have a smartwatch, pulse oximeter, or blood pressure cuff, check your heart rate. Even pressing two fingers to the inside of your wrist for 30 seconds and doubling the count gives you useful information. Knowing your heart rate helps you decide whether the episode is manageable at home or needs medical attention, and it gives your doctor valuable data later.
Note the time the episode started. Write down or remember what you were doing beforehand: drinking alcohol or caffeine, exercising, feeling stressed, eating a large meal, or sleeping poorly. These details help your cardiologist identify triggers and adjust your treatment plan. If the episode resolves on its own, record how long it lasted.
Vagal Maneuvers That May Help
Vagal maneuvers are physical techniques that stimulate the vagus nerve and can sometimes slow a racing heart. They’re more reliably effective for other types of fast heart rhythms (like SVT), but some people with afib find they help reduce heart rate or ease symptoms. If your doctor has discussed these with you, an episode is a reasonable time to try them.
The Valsalva maneuver is the most common. Lie on your back, take a deep breath, then bear down as if you’re straining to have a bowel movement, keeping your nose and mouth closed, for 10 to 30 seconds. It should feel like trying to push air through a blocked straw. A modified version involves doing this while sitting up and then quickly lying flat with your knees pulled toward your chest.
The diving reflex is another option. While seated, take several deep breaths, hold your breath, then submerge your entire face in a bowl of ice water for as long as you comfortably can. If that’s not practical, pressing a bag of ice or an ice-cold wet towel firmly against your face can trigger the same reflex. The sudden cold causes your nervous system to slow the heart.
One important caution: don’t attempt vagal maneuvers if you have low blood pressure, feel faint, or are otherwise unstable. These techniques are for people who feel uncomfortable but are not in danger.
Take Prescribed Medications
If your cardiologist has given you a rate-control medication or a “pill-in-the-pocket” prescription, an active episode is exactly when to use it. Rate-control medications slow your heart rate during the episode, while pill-in-the-pocket drugs are designed to convert your heart back to normal rhythm.
The pill-in-the-pocket approach uses a single dose of an antiarrhythmic medication taken at the start of an episode. Your doctor will have you try this for the first time in a monitored clinical setting to make sure you tolerate it safely, because rare but serious reactions can occur. Once you’ve been cleared, you carry the medication with you and take it when symptoms begin. People with lower body weight are typically given a reduced dose. If your doctor hasn’t specifically prescribed this strategy, don’t take extra heart medications on your own during an episode.
Stay Hydrated and Avoid Triggers
Dehydration and electrolyte imbalances can both trigger and prolong afib episodes. Drink water steadily during an episode, but avoid alcohol, caffeine, and energy drinks, all of which can make things worse. If you’ve been sweating, vomiting, or haven’t eaten well, a drink with electrolytes (like a sports drink or coconut water) is a reasonable choice.
Low potassium levels in particular appear to play a role. Hospital data shows that patients with potassium levels below normal had nearly double the odds of converting back to normal rhythm when given potassium and magnesium intravenously, compared to those who received nothing. You can’t replicate an IV at home, but staying on top of your hydration and eating potassium-rich foods (bananas, potatoes, leafy greens) as part of your regular diet helps keep levels stable and may reduce your episode frequency over time.
What Happens if the Episode Doesn’t Stop
Many afib episodes end on their own within minutes to hours. Some last longer. The general concern with prolonged episodes is blood clot formation: when the upper chambers of your heart quiver instead of contracting fully, blood can pool and clot. That clot can then travel to the brain and cause a stroke.
Your personal stroke risk depends on factors like age, history of high blood pressure, diabetes, prior stroke, and heart failure. People with multiple risk factors face meaningful stroke risk even from short episodes lasting just minutes. For those with fewer risk factors, the concern grows primarily when episodes stretch beyond 24 hours. This is one reason cardiologists often want to restore normal rhythm within 48 hours and may recommend blood thinners for people with recurrent episodes.
If your episode has been going for several hours with no sign of stopping and you haven’t been able to reach your doctor, it’s reasonable to go to an urgent care or emergency department. They can use medications or, if needed, a brief electrical procedure called cardioversion to restore your rhythm. If you’re already on a blood thinner, mention this to the medical team, as it affects their approach.
Building a Long-Term Plan
Surviving individual episodes matters, but so does reducing how often they happen. The 2024 European Society of Cardiology guidelines emphasize that rhythm control, meaning actively working to keep your heart in normal rhythm rather than just managing your heart rate during episodes, should be considered for most people with afib. This can involve daily medications, catheter ablation (a procedure that targets the electrical misfires in the heart), or both.
Catheter ablation is now recommended as a first-line option for people with paroxysmal afib, the type that comes and goes. If medications haven’t kept your episodes under control, it’s worth discussing ablation with your cardiologist. For many people, it significantly reduces episode frequency and can eliminate them entirely.
Between episodes, the most effective things you can do are manage your blood pressure, maintain a healthy weight, limit alcohol, treat sleep apnea if you have it, and exercise regularly. Each of these directly affects how often your heart slips out of rhythm. Keeping a log of your episodes, including when they happen, how long they last, and what you were doing before they started, gives your doctor the clearest possible picture of your condition and the best shot at tailoring your treatment.