Flecainide
Prescription ·Exploratory record · not publication-reviewed ·Updated July 13, 2026
Flecainide is a class IC antiarrhythmic agent used for prevention of paroxysmal supraventricular tachycardias (PSVT), paroxysmal atrial fibrillation, and life-threatening ventricular arrhythmias. The CAST trial demonstrated increased mortality in post-MI patients, so use is restricted to patients without structural heart disease.
Exploratory record, not a reviewed medical publication.
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What the research says.
A quick, data-only summary. The full evidence, dosing, and sources are below.
Flecainide is a class IC antiarrhythmic agent used for prevention of paroxysmal supraventricular tachycardias (PSVT), paroxysmal atrial fibrillation, and life-threatening ventricular arrhythmias. NutriStack rates the supporting evidence as moderate. Common adult dosing is PSVT/PAF: 50–150 mg twice daily; Sustained VT: 100–200 mg twice daily (as prescribed by your physician), though a prescriber sets the actual dose. This profile indexes 10 sources.
- Dizziness and visual disturbances (blurred vision)
- Pro-arrhythmia (ventricular tachycardia, including 1:1 atrial flutter)
- Heart failure exacerbation
- Structural heart disease (prior MI, heart failure, significant LVH)
- Second- or third-degree AV block without pacemaker
The bottom line
Evidence rating moderate. Most-documented uses: effective for maintaining sinus rhythm in atrial fibrillation (without structural heart disease), useful for psvt prevention, effective for wpw-related arrhythmias. 10 sources indexed (1995–2024), with 0 interaction records on file.
How it works, mechanistically.
Core mechanism
Potent sodium channel blocker (class IC) that markedly slows conduction velocity throughout the heart. Prolongs His-Purkinje and ventricular conduction (widens QRS). Has minimal effect on action potential duration and repolarization. Slows conduction in accessory pathways, making it useful for WPW-related arrhythmias. Also has minor potassium channel blocking effects.
Dosing & protocol.
Can be taken with or without food; well absorbed orally with ~95% bioavailability
Full safety detail.
Side effects
- Dizziness and visual disturbances (blurred vision)
- Pro-arrhythmia (ventricular tachycardia, including 1:1 atrial flutter)
- Heart failure exacerbation
- Headache
- Nausea
- Tremor
- QRS widening
Contraindications
- Structural heart disease (prior MI, heart failure, significant LVH)
- Second- or third-degree AV block without pacemaker
- Right bundle branch block with left hemiblock (bifascicular block) without pacemaker
- Cardiogenic shock
- Concurrent use must include AV nodal blocking agent to prevent 1:1 atrial flutter conduction
Sources, by evidence tier.
Numbered references. Citations throughout the page link here.
Meta-analyses & systematic reviews
3- 1Flecainide Toxicity: A Case Report and Systematic Review of its Electrocardiographic Patterns and ManagementPMIDValentino MA, Panakos A, Ragupathi L et al. · Cardiovascular toxicology · 2017
Valentino MA, Panakos A, Ragupathi L et al.. Flecainide Toxicity: A Case Report and Systematic Review of its Electrocardiographic Patterns and Management. Cardiovascular toxicology. 2017
- 2Meta-analysis of flecainide safety in patients with supraventricular arrhythmiasPMIDWehling M · Arzneimittel-Forschung · 2002
Wehling M. Meta-analysis of flecainide safety in patients with supraventricular arrhythmias. Arzneimittel-Forschung. 2002
- 3Treatment of resistant atrial fibrillation. A meta-analysis comparing amiodarone and flecainidePMIDZarembski DG, Nolan PE Jr, Slack MK et al. · Archives of internal medicine · 1995
Zarembski DG, Nolan PE Jr, Slack MK et al.. Treatment of resistant atrial fibrillation. A meta-analysis comparing amiodarone and flecainide. Archives of internal medicine. 1995
Randomized controlled trials
1- 4Flecainide to Prevent Atrial Arrhythmia After Patent Foramen Ovale Closure: AFLOAT Study, A Randomized Clinical TrialPMIDHauguel-Moreau M, Guedeney P, Dauphin C et al. · Circulation · 2024
Hauguel-Moreau M, Guedeney P, Dauphin C et al.. Flecainide to Prevent Atrial Arrhythmia After Patent Foramen Ovale Closure: AFLOAT Study, A Randomized Clinical Trial. Circulation. 2024
Reviews & position papers
1- 5A Case Report of Flecainide Toxicity With Review of LiteraturePMIDKhatiwada P, Clark L, Khunger A et al. · Cureus · 2022
Khatiwada P, Clark L, Khunger A et al.. A Case Report of Flecainide Toxicity With Review of Literature. Cureus. 2022
Reference material
5- 6Echt DS et al. Mortality and morbidity in patients receiving encainide, flecainide, or placebo (CAST). N Engl J Med. 1991.Source linkedPMID
- 7Alboni P et al. Outpatient treatment of recent-onset atrial fibrillation with the 'pill-in-the-pocket' approach. N Engl J Med. 2004.Source linkedPMID
- 8Spillane J et al. Drug treatment for myotonia. Cochrane Database Syst Rev. 2025.Source linkedPMID
- 9Cardiac Arrhythmia Suppression Trial (CAST) Investigators. Preliminary report: effect of encainide and flecainide on mortality in a randomized trial of arrhythmia suppression after myocardial infarction. The New England journal of medicine. 1989Source linkedPMID
- 10Tamargo J, Capucci A, Mabo P. Safety of flecainide. Drug safety. 2012Source linkedPMID
Common questions.
Quick answers about Flecainide, drawn from the data on this page.
What is Flecainide?
Flecainide is a class IC antiarrhythmic agent used for prevention of paroxysmal supraventricular tachycardias (PSVT), paroxysmal atrial fibrillation, and life-threatening ventricular arrhythmias. The CAST trial demonstrated increased mortality in post-MI patients, so use is restricted to patients without structural heart disease.
What is Flecainide used for?
Commonly cited benefits of Flecainide include: Effective for maintaining sinus rhythm in atrial fibrillation (without structural heart disease); Useful for PSVT prevention; Effective for WPW-related arrhythmias; Pill-in-the-pocket strategy for intermittent AF. NutriStack rates the overall evidence as moderate.
What is a typical dose of Flecainide?
A typical adult dose of Flecainide is PSVT/PAF: 50–150 mg twice daily; Sustained VT: 100–200 mg twice daily (as prescribed by your physician). The commonly recommended form is Oral tablet. These are general ranges, not personalized advice; confirm the right dose with a clinician.
What are the side effects of Flecainide?
Reported side effects include dizziness and visual disturbances (blurred vision), pro-arrhythmia (ventricular tachycardia, including 1:1 atrial flutter), heart failure exacerbation, headache, nausea, tremor. This is educational information; check with a healthcare professional before use.
How strong is the evidence for Flecainide?
NutriStack rates this as Moderate, meaning several aligned RCTs or one large RCT plus supporting reviews. Full tier criteria are at https://nutristackapp.com/methodology/evidence-tiers.
Use this with your stack
Flecainide in NutriStack.
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