Flecainide-induced Increase in QRS Duration and Proarrhythmia during Exercise

Area of Science:

• Cardiology
• Clinical Electrophysiology
• Pharmacology

Background:

• Flecainide is used for atrial and ventricular arrhythmias.
• Exercise-induced arrhythmias are potentially linked to flecainide's effects on QRS duration.

Purpose of the Study:

• To identify predictors of flecainide-induced QRS widening and proarrhythmia (PA) during exercise.
• To analyze risk factors associated with flecainide's impact on cardiac electrophysiology.

Main Methods:

• Retrospective analysis of 119 patients treated with flecainide.
• Maximal treadmill testing was performed to assess QRS widening and PA.
• Echocardiography and cardiac catheterization evaluated cardiac structure and function.

Main Results:

• Previous myocardial infarction predicted QRS widening at rest and during exercise.
• Structural heart disease and impaired left ventricular ejection fraction (LVEF) predicted PA.
• A QRS widening ≥ 25% at rest was a threshold for high PA risk in patients with impaired LVEF.

Conclusions:

• Predictors for QRS widening and PA during flecainide treatment differ.
• Identifying patients at risk for flecainide-induced PA is crucial, especially those with underlying heart conditions.
• Prospective trials are needed to confirm these retrospective findings.