Flecainide Use in the ICU: Critical Contraindications and High-Risk Scenarios

Patient Selection and Contraindications

• The American College of Cardiology recommends that flecainide is absolutely contraindicated in patients with ischemia, prior myocardial infarction, and should be avoided in patients with other structural heart diseases 1
• The American Heart Association suggests that flecainide should only be used in patients without structural heart disease or ischemic heart disease 2
• The American College of Cardiology advises that sodium channel blockers, such as flecainide, increase pacing thresholds and defibrillation energy requirements, potentially causing loss of capture in paced patients 1

Conduction System Abnormalities and Drug Interactions

• The American Heart Association recommends that flecainide should be held in patients with AV block or infranodal conduction disease 3
• The American College of Cardiology suggests that flecainide should be avoided in patients with Brugada syndrome 3, 4
• The American Heart Association advises that flecainide is metabolized by CYP2D6; inhibitors (quinidine, fluoxetine, tricyclics) increase plasma concentrations 3
• The American College of Cardiology recommends that flecainide should not be combined with other Class IA, IC, or III antiarrhythmics, which may exacerbate cardiac toxicity 5

Proarrhythmic Risk and Toxicity Management

• The American College of Cardiology suggests that flecainide can convert atrial fibrillation to atrial flutter with 1:1 AV conduction, creating wide QRS complexes that mimic ventricular tachycardia 1
• The American Heart Association advises that flecainide can accelerate ventricular rate during AF 4
• The American College of Cardiology recommends that intravenous sodium bicarbonate (1-2 mEq/kg boluses) is the treatment of choice for flecainide toxicity 5

Common Pitfalls to Avoid

• The American College of Cardiology advises that one should not mistake flecainide-induced atrial flutter with 1:1 conduction for ventricular tachycardia, as this can lead to inappropriate treatment 1
• The American Heart Association recommends that one should not continue flecainide in patients requiring pacemakers or ICDs without checking device function, as increased pacing thresholds may cause loss of capture 1