Mechanism of spontaneous transition from typical atrial flutter to atrial fibrillation: Role of ectopic atrial fibrillation foci

Paroxysmal AF has been known to be initiated by ectopic beats, especially i n the pulmonary veins (PVs), and radiofrequency catheter ablation could cur e it. We considered that the spontaneous transition from typical atrial flu tter to AF also could be initiated by ectopic beats. Twenty patients (18 me n, mean age 66 +/- 14 years) with episodes of spontaneous transition from t ypical atrial flutter to AF were included in this study. They underwent det ailed mapping of both atria. All the patients had spontaneous AF initiated by ectopic bears, and all of them had typical atrial flutter and spontaneou s transition from typical atrial flutter (12 patients with counterclockwise atrial flutter and 8 patients with clockwise atrial flutter) to AF. The tr ansition was initiated by ectopic beats from the PVs (17 foci, 85%), crista terminalis (2 foci, 10%), and superior vena cava (2 focus, 5%). After succ essful ablation of AF foci, typical atrial flutter was induced again, but n o spontaneous transition was found after at least 10 minutes of observation . We concluded that paroxysmal AF and spontaneous transition from typical a trial flutter to AF were initiated by ectopic beats, and successful cathete r ablation of the ectopic foci can eliminate paroxysmal AF and spontaneous transition from typical atrial flutter to AF.