Chemical Cardioversion: Medicines, Procedure and Risks
Updated: 2 days ago
Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: November 2026 · How we review
Quick Answer
Chemical cardioversion, or pharmacologic cardioversion, uses medicines to change an abnormal heart rhythm back to normal. It treats fast or irregular rhythms such as atrial fibrillation, atrial flutter and supraventricular tachycardia. You're watched in the hospital with heart monitoring. It's an alternative to electrical cardioversion, but long-term success may be only about 50%.
What the research says
An IV drug restored rhythm in about half of ER patients: in the RAFF2 trial of 396 people with sudden-onset Afib in the ER, IV procainamide alone restored normal rhythm in 52%; drug-then-shock worked in 96% versus 92% for shock only, with no serious side effects (Stiell IG et al., Lancet, 2020) [2]
A single pill often reset recent Afib: a review of 22 trials with 2,320 people found that about 8 hours after one oral dose, normal rhythm returned in 73% with flecainide and 70% with propafenone, versus 32% with placebo or rate control and 28% with amiodarone (Ibrahim OA et al., Europace, 2021) [3]
Key takeaways
Chemical cardioversion uses medicine to restore a normal rhythm.
It treats Afib, atrial flutter and other fast rhythms.
It's done in the hospital with heart monitoring.
Blood thinners lower stroke risk before and after.
Long-term success may be about 50%.
What is chemical cardioversion?
It's one type of cardioversion; the other uses an electric shock. Success depends on the rhythm's cause, how long it has lasted and the medicine used. Atrial fibrillation is the most common abnormal rhythm. Sources: [1]
Rhythms it treats
Causes include heart attack, heart failure, infections, lung disease and some medicines.
Atrial fibrillation.
Atrial tachycardia.
Ventricular tachycardia (ventricular fibrillation needs an emergency shock, not medicine). Sources: [1]
Medicines used
The choice depends on your rhythm.
Medicine | Notes |
Flecainide, propafenone | Often used for recent-onset Afib |
Amiodarone, dronedarone | Used for many rhythms |
Procainamide, ibutilide, sotalol, quinidine | Antiarrhythmics given by mouth or IV |
Adenosine | Often used for SVT |
Diltiazem, metoprolol, digoxin | Slow the heart rate |
Sources: [1, 2, 3]
How to prepare
Fast for eight hours before.
Tell your provider about all medicines, including over-the-counter ones.
A transesophageal echocardiogram may check for clots.
If Afib has lasted more than two days, take blood thinners for three weeks before. Sources: [1]
Low blood pressure may call for electrical cardioversion instead. Sources: [1]
What happens during the procedure
It may be same-day or overnight.
You're monitored in the ICU or another hospital room.
Your blood pressure and EKG are tracked, and a defibrillator is ready.
The medicine is given by mouth or IV.
More than one dose may be needed.
You're watched for 24 to 48 hours. Sources: [1]
Risks
A new or worse abnormal rhythm.
A blood clot causing stroke.
Nausea and tiredness.
Some medicines take months to work.
Medicines may be only 50% effective long term. Sources: [1]
If medicines fail, electrical cardioversion or catheter ablation may be needed. Sources: [1, 2]
Chemical vs. electrical cardioversion
Electrical cardioversion works faster and more often. Sources: [1, 2]
Recovery
You're monitored for 24 to 48 hours.
Keep taking blood thinners for at least four weeks to lower stroke risk.
You may need regular visits to check your blood thinner dose. Sources: [1]
When to get help
Call 911 for palpitations, dizziness, lightheadedness, weakness, sweating, an allergic reaction, chest pain or trouble breathing. Keep taking your prescribed medicines. Sources: [1]
Conclusion
Chemical cardioversion can reset a fast or irregular heart rhythm without a shock. Blood thinners and follow-up care help keep you safe afterward.
Keep learning: read about cardioversion and atrial fibrillation.
Frequently asked questions
What is chemical cardioversion?
Using medicine to restore a normal heart rhythm.
What rhythms does it treat?
Afib, atrial flutter, SVT and ventricular tachycardia.
What medicines are used?
Flecainide, propafenone, amiodarone, procainamide and others.
Is it done in the hospital?
Yes, with heart monitoring.
Do I need blood thinners?
Yes, if Afib has lasted more than two days.
How long will I be monitored?
About 24 to 48 hours.
Does it always work?
No. Long-term success may be about 50%.
Is it better than electrical cardioversion?
Electrical cardioversion usually works faster and more often.
What are the risks?
New rhythm problems, stroke, nausea and tiredness.
What if it doesn't work?
Electrical cardioversion or ablation may be next.
Related Reading
Cardioversion: Procedure, Types, Risks and Recovery electrical and chemical cardioversion.
Atrial Fibrillation (AFib): Symptoms, Causes & Treatment Guide the most common rhythm it treats.
Atrial Flutter: Symptoms, Causes, Diagnosis & Treatment — Complete Guide another rhythm it treats.
Catheter Ablation: How It Works, Success Rates, Risks and Recovery an option if medicines fail.
Digoxin: Uses, Normal Levels and Toxicity a heart rate medicine.
References
Cleveland Clinic. How Chemical Cardioversion Works. Cleveland Clinic. Last updated May 23, 2022. https://my.clevelandclinic.org/health/treatments/23133-chemical-cardioversion
Stiell IG, Sivilotti MLA, Taljaard M, et al. Electrical versus pharmacological cardioversion for emergency department patients with acute atrial fibrillation (RAFF2): a partial factorial randomised trial. Lancet. 2020;395(10221):339-349. PMID 32007169. https://doi.org/10.1016/S0140-6736(19)32994-0
Ibrahim OA, Belley-Côté EP, Um KJ, et al. Single-dose oral anti-arrhythmic drugs for cardioversion of recent-onset atrial fibrillation: a systematic review and network meta-analysis of randomized controlled trials. Europace. 2021;23(8):1200-1210. PMID 33723602. https://doi.org/10.1093/europace/euab014
Medical disclaimer
This article is for general education only and does not replace advice from a qualified healthcare professional. Talk to your doctor about your own diagnosis and treatment, and seek emergency care right away for severe or sudden symptoms.
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