Right-to-left frequency gradient during atrial fibrillation initiated by right atrial ectopies and its augmentation by adenosine triphosphate: Implications of right atrial fibrillation

BACKGROUND A left-to-right dominant frequency (DF) gradient commonly exists in paroxysmal atrial fibrillation (AF). AF initiated by right atrial (RA) ectopy (AF-RAE) is rare. OBJECTIVE This study aimed to investigate characteristics of AF-RAE using pharmacological maneuvers and spectral analysis. METHODS Seventy-nine consecutive patients referred for catheter ablation of paroxysmal AF were enrolled. Infusions of isoproterenol and adenosine triphosphate (ATP) were used to induce AF. Patients with AF-RAE and patients with AF initiated only by pulmonary vein (PV) ectopies were classified into the RA-ectopy group (n = 7[9%]) and PV-ectopy group (n = 32[41%]), respectively. ATP was also injected during ongoing AF to unmask the driver of AF. High RA, coronary sinus, and PV-left atrial junction electrograms and electrocardiogram lead V-1 underwent spectral analyses. RESULTS Patients in the RA-ectopy group were younger (51 +/- 13 years vs 63 +/- 7 years; P = .01) and more commonly had a family history of AF (71% vs 9%; P < .001) than patients in the PV-ectopy group. There was a baseline right-to-left DF gradient in the RA-ectopy group (PV-left atrial junction: 6.0 +/- 0.4 Hz; coronary sinus: 5.7 +/- 0.6 Hz; RA: 7.3 +/- 0.8 Hz; P < .05) in contrast to a left-to-right DF gradient in the PV-ectopy group (5.9 +/- 0.8, 5.3 +/- 0.7, 5.2 +/- 0.8 Hz; P < .01). ATP injection predominantly increased the DF of the high RA in the RA-ectopy group and augmented a right-to-left DF gradient (7.9 +/- 1.8, 7.6 +/- 1.0, 10.7 +/- 0.7 Hz; P < .001), whereas it augmented a left-to-right DF gradient in the PV-ectopy group (7.9 +/- 1.0, 6.4 +/- 0.5, 6.6 +/- 1.2 Hz; P < .05). CONCLUSION A rare type of paroxysmal AF initiated by RA ectopy may be maintained by a reentrant driver localized in the RA (so-called RA fibrillation).