Flecainide in quinidine-resistant atrial fibrillation

Area of Science:

• Cardiology
• Clinical Pharmacology

Background:

• Paroxysmal atrial fibrillation (PAF) management often requires alternative therapies for patients unresponsive or intolerant to standard treatments like quinidine.
• Quinidine's inefficacy or intolerance affects a significant number of patients with symptomatic PAF.
• Underlying cardiac conditions were minimal in the study population, suggesting flecainide's potential in a broader PAF patient group.

Purpose of the Study:

• To evaluate the efficacy and tolerability of flecainide for long-term prevention of paroxysmal atrial fibrillation (PAF).
• To assess flecainide's effectiveness in patients with symptomatic PAF refractory to quinidine therapy.
• To identify potential adverse events and specific patient subgroups benefiting most from flecainide treatment.

Main Methods:

• A cohort of 52 patients with frequent symptomatic PAF, resistant or intolerant to quinidine, received flecainide (100 mg twice daily).
• Follow-up duration ranged from 1 to 5.8 years.
• Thirty-three patients also received amiodarone concurrently, and 35 had vagally induced PAF documented.

Main Results:

• Complete resolution of PAF was achieved in 73% (38 out of 52) of patients.
• The success rate was marginally higher in patients with vagally induced PAF (p = 0.07).
• Adverse events leading to treatment discontinuation occurred in only 3 patients; however, 7 patients on combined amiodarone and flecainide required pacemakers due to bradycardia. Two patients experienced 1:1 atrioventricular conduction during atrial flutter.

Conclusions:

• Flecainide is an effective and well-tolerated option for the long-term prevention of paroxysmal atrial fibrillation in patients who have not responded to quinidine.
• Careful monitoring is advised, particularly regarding potential bradycardia when combined with amiodarone and the risk of 1:1 AV conduction in atrial flutter.
• Alternative agents like verapamil or beta-blockers may be considered alongside flecainide for patients with a history of atrial flutter and 1:1 AV conduction risk.