Flecainide Contraindications in Structural Heart Disease
Flecainide is contraindicated in patients with coronary artery disease (particularly post-myocardial infarction), significant ventricular dysfunction, and severe heart failure, based on increased mortality risk demonstrated in landmark trials and consistently reinforced across major cardiology guidelines. 1, 2
Absolute Contraindications
Ischemic Heart Disease
- Patients with prior myocardial infarction should never receive flecainide, as the CAST trial demonstrated a 5.1% mortality rate versus 2.3% with placebo in post-MI patients with ventricular arrhythmias 2
- Coronary artery disease of any severity is a contraindication according to ESC guidelines, which explicitly state that "patients who have coronary artery disease should not receive flecainide or propafenone" 1
- The FDA label warns that flecainide use is "generally unacceptable in patients without life-threatening ventricular arrhythmias" given the lack of survival benefit and documented mortality risk 2
Heart Failure and Ventricular Dysfunction
- Significant ventricular dysfunction is an absolute contraindication, particularly in patients with reduced left ventricular ejection fraction who have structural disease 1, 2
- NYHA Class III-IV heart failure excludes flecainide use entirely 1
- In adult congenital heart disease (ACHD) patients, flecainide "should not be administered for treatment of SVT in ACHD patients with significant ventricular dysfunction," as 7 of 8 cardiac arrests in one series occurred in patients with mild-to-moderate dysfunction or complex anatomy 1
Chronic Atrial Fibrillation
- Flecainide is NOT recommended for chronic atrial fibrillation, with the FDA label explicitly stating this in capital letters due to 10.5% incidence of ventricular tachycardia/fibrillation in this population 2
- The proarrhythmic risk includes 1:1 atrioventricular conduction with paradoxical ventricular rate acceleration 2
Relative Contraindications Requiring Caution
Left Ventricular Hypertrophy
- Marked LVH (wall thickness >1.4 cm) raises proarrhythmic concerns, though flecainide may be used cautiously in less severe cases 1
- ESC guidelines note "some concern about proarrhythmic risk, especially in patients with marked hypertrophy" when combined with coronary disease 1
Complex Congenital Heart Disease
- Systemic right ventricle or single-ventricle anatomy increases risk in ACHD populations, with these anatomies accounting for the majority of adverse events in observational data 1
Safe Use Populations
No Structural Heart Disease
- Flecainide is first-line therapy in patients without structural heart disease for both acute cardioversion and rhythm maintenance in atrial fibrillation 1
- This includes the "pill-in-the-pocket" approach for self-administration after in-hospital safety testing 1
Stable Nonobstructive CAD (Emerging Evidence)
- Recent research suggests flecainide may be safe in carefully selected patients with stable nonobstructive coronary disease (no prior MI, preserved function), though this contradicts guideline recommendations and should be approached with extreme caution 3
- This applies only to low-risk stable disease, not acute coronary syndromes or obstructive lesions 3
Critical Monitoring Requirements
When flecainide is used in borderline cases:
- Obtain baseline ECG and monitor QRS duration, with >25% increase from baseline indicating dangerous proarrhythmic risk requiring immediate discontinuation 4
- Avoid in renal dysfunction without dose adjustment, as flecainide is renally cleared 5
- Ensure concomitant AV nodal blocking agents (beta-blockers or digoxin) to prevent rapid ventricular response in atrial flutter 2
Common Pitfall to Avoid
The most dangerous error is assuming "stable" coronary disease or "mild" structural abnormalities permit flecainide use—any documented coronary disease or significant structural abnormality should default to amiodarone or dronedarone as safer alternatives per ESC and ACC/AHA guidelines 1.