Flecainide is Contraindicated in Hemodynamically-Significant Valvular Heart Disease
Do not use flecainide in patients with hemodynamically-significant valvular disease. 1
Guideline-Based Contraindications
The European Heart Rhythm Association explicitly states that flecainide and propafenone should not be used in patients with severe structural heart diseases, specifically including hemodynamically-significant valvular disease. 1 This represents a clear absolute contraindication based on the risk of proarrhythmic events and potential hemodynamic compromise in patients whose cardiac function is already compromised by valvular pathology.
The 2024 ESC Guidelines for Atrial Fibrillation management reinforce this position, recommending flecainide only for patients without severe left ventricular hypertrophy, heart failure with reduced ejection fraction, or coronary artery disease. 1 While the guidelines focus primarily on these conditions, the exclusion of structural heart disease encompasses significant valvular pathology.
What Constitutes "Hemodynamically-Significant" Valvular Disease
Hemodynamically-significant valvular disease includes:
- Severe aortic stenosis - explicitly contraindicated for vernakalant (a similar class agent), suggesting similar concerns for flecainide 1
- Moderate-to-severe mitral regurgitation or stenosis causing left atrial enlargement or elevated filling pressures 1
- Any valvular lesion causing heart failure symptoms (NYHA Class II-IV) 2
- Valvular disease resulting in left ventricular dysfunction (LVEF <50%) 2
Safe Alternative Antiarrhythmic Options
When rhythm control is needed in patients with valvular disease:
- Amiodarone is the recommended first-line agent for patients with structural heart disease, including valvular pathology, accepting that cardioversion may be delayed. 1
- Dronedarone is recommended in patients with valvular disease (excluding severe aortic stenosis) for long-term rhythm control. 1
- Both agents have safer profiles in the setting of structural abnormalities compared to class IC agents. 1
Critical Monitoring If Flecainide Was Inadvertently Started
If flecainide has already been initiated before valvular disease was recognized:
- Discontinue immediately if new structural heart disease or reduction in LVEF develops. 3
- Obtain urgent echocardiography to quantify valvular severity and assess ventricular function. 3
- Monitor for QRS widening ≥25% from baseline, which signals dangerous proarrhythmic risk. 3, 2
- Watch for development of new bundle branch block or sustained ventricular tachycardia. 3
Common Clinical Pitfall
The most dangerous error is assuming that "mild" or "moderate" valvular disease is safe for flecainide use. The threshold is hemodynamic significance, not just anatomic severity. 1 A patient with moderate mitral regurgitation who has developed left atrial enlargement, elevated filling pressures, or any degree of ventricular dysfunction should be considered to have hemodynamically-significant disease and flecainide should be avoided. 1, 2
When Flecainide IS Safe
Flecainide remains first-line therapy for rhythm control in patients without structural heart disease, including those with:
- Trace or mild valvular regurgitation without chamber enlargement 1
- Normal ventricular function (LVEF >50%) 4
- No left ventricular hypertrophy (wall thickness <1.4 cm) 2
- No coronary artery disease 2, 4
The FDA label explicitly restricts flecainide to patients "without structural heart disease" for supraventricular arrhythmias, reinforcing this conservative approach. 4