Abstract
Background
Atrial Fibrillation in Wolff-Parkinson-White syndrome may result in life-threateningly rapid antegrade conduction over a bypass tract, manifested by an irregular broad-complex (pre-excited) tachycardia that can degenerate to ventricular fibrillation. Shortest pre-excited RR interval below 250msec during atrial fibrillation predicts increased risk of sudden cardiac death.
Case summary
We report a case of a 43-year-old man with unremarkable cardiac history who presented due to sudden-onset feeling of palpitations and pre-syncope after strenuous lifting. Electrocardiography depicted fast pre-excited atrial fibrillation. The shortest pre-excited RR interval was estimated at 160msec, indicating an accessory pathway with short antegrade refractory period at risk for mediating sudden cardiac death. Direct current cardioversion restored sinus rhythm unraveling delta-waves. The patient was put on propafenone 450 mg/day having an uneventful clinical course. On day-10 post-admission, electrophysiological study induced rapid atrial fibrillation but the shortest pre-excited RR interval was substantially increased to 264msec. A left anterolateral accessory pathway was ablated. The patient remained symptom-free until his latest follow-up in the third month post-ablation without manifest pre-excitation on surface electrocardiogram.
Discussion
Treatment options of pre-excited atrial fibrillation include anti-arrhythmic agents but mainly electrical cardioversion. Cardioversion can safely restore sinus rhythm, while use of anti-arrhythmics often requires ICU monitoring due to risk of QT prolongation. Catheter ablation is the mainstay of therapy for symptomatic patients. Our rare report highlights the direct impact of propafenone on prolonging the refractoriness of the accessory pathway, effectively and safely, and reappraises propafenone’s worthiness as a protective measure following pre-excited atrial fibrillation episode until ablation.
Mechanisms for the genesis of paroxysmal atrial fibrillation in the Wolff--Parkinson--White syndrome: intrinsic atrial muscle vulnerability vs. electrophysiological properties of the accessory pathway
