Flecainide Must Be Discontinued Immediately in This Patient
Flecainide is absolutely contraindicated in this patient due to her history of myocardial infarction and should be stopped immediately. 1, 2, 3
Why Flecainide is Contraindicated
Absolute Contraindication: Prior Myocardial Infarction
The American Heart Association and American College of Cardiology explicitly state that flecainide is absolutely contraindicated in patients with coronary artery disease or previous myocardial infarction due to increased risk of mortality and proarrhythmia. 1, 2
The FDA label clearly warns that flecainide should not be used in patients with a history of myocardial infarction, and the landmark CAST trial demonstrated a 2.5-fold increase in total mortality (7.7% vs 3.0%) and 3.6-fold increase in arrhythmic death (4.5% vs 1.2%) in post-MI patients treated with flecainide compared to placebo. 3, 4, 5
The 2024 ESC guidelines for atrial fibrillation management explicitly recommend that flecainide or propafenone should only be used in patients excluding those with coronary artery disease. 6
Additional Concerning Features in This Patient
The presence of valvular heart disease (aortic and mitral regurgitation) represents structural heart disease, which is another relative contraindication for flecainide use. 2, 3
While the patient has preserved ejection fraction, the FDA label warns that flecainide can cause or worsen heart failure, particularly in patients with any structural heart disease, and her exertional dyspnea may represent early decompensation. 3
The patient's pacemaker is particularly problematic because flecainide increases pacing thresholds and may suppress ventricular escape rhythms, requiring careful monitoring that becomes even more critical in someone with contraindications. 3
Clinical Action Plan
Immediate Steps
Discontinue flecainide immediately given the absolute contraindication of prior MI. 1, 2
Evaluate the original indication for flecainide (likely atrial fibrillation given the clinical context) and consider alternative rhythm control strategies. 6
Alternative Antiarrhythmic Options
Amiodarone is the recommended antiarrhythmic drug for patients with coronary artery disease requiring rhythm control, as the 2024 ESC guidelines specifically recommend amiodarone when cardioversion or rhythm control is desired in patients with coronary artery disease. 6
Dronedarone is also recommended for patients with ischemic heart disease or valvular disease requiring long-term rhythm control to prevent AF recurrence and progression. 6
Catheter ablation should be considered as a first-line or second-line option for rhythm control, particularly given the contraindications to Class IC agents in this patient. 6
Important Caveats About Recent Observational Data
While recent 2025 observational studies suggest flecainide may be safer in stable, non-obstructive coronary disease than previously thought 7, 8, 9, these findings do not apply to patients with documented prior myocardial infarction.
The CAST trial specifically studied post-MI patients, and this remains the highest-quality randomized controlled trial evidence available, showing definitive harm in this exact population. 4, 5
Current FDA labeling and all major cardiology society guidelines maintain the absolute contraindication for post-MI patients, and deviating from this standard of care would be inappropriate without compelling individualized reasons and specialist consultation. 1, 2, 3
Evaluation of Dyspnea
The patient's exertional dyspnea requires thorough evaluation, as it may represent: worsening valvular disease, flecainide-induced heart failure (occurs in 6.3% of patients with ventricular arrhythmias), uncontrolled atrial fibrillation, or ischemia. 3
Consider stress testing to evaluate for inducible ischemia once flecainide is discontinued, as ongoing coronary disease would further support the decision to avoid Class IC agents permanently. 1