ROLE OF ATRIAL ELECTROPHYSIOLOGY AND AUTONOMIC NERVOUS-SYSTEM IN PATIENTS WITH SUPRAVENTRICULAR TACHYCARDIA AND PAROXYSMAL ATRIAL-FIBRILLATION

Objectives. The purposes of this study were to evaluate the atrial ele ctrophysiology and autonomic nervous system in patients who had paroxy smal supraventricular tachycardia (PSVT) associated with paroxysmal at rial fibrillation (PAF).Background. PAF frequently appeared in patient s with PSVT. However, the critical determinants for the occurrence of PAF were not clear. Methods. This study population consisted of 50 pat ients who had PSVT with (n = 23) and without (n = 27) PAF. Atrial pres sure, atrial size, atrial effective refractory periods (AERPs), and AE RP dispersion were evaluated during baseline and PSVT, respectively. T wenty-four hour heart rate variability and baroreflex sensitivity (BRS ) were also examined. Results. There was greater baseline AERP dispers ion in patients with PAF than in those without PAF. The atrial pressur e, atrial size, AERPs in the right posterolateral atrium and distal co ronary sinus, and AERP dispersion were increased during PSVT as compar ed with those during baseline. Patients with PAF had greater AERP disp ersion than those without PAF during PSVT. The differences of atrial s ize, right posterolateral AERP, and AERP dispersion between baseline a nd PSVT were greater in patients with PAF than in those without PAF. B RS, but not heart rate variability, was higher in patients with PAF th an in those without PAF. Univariate analysis showed that higher BRS (> 4.5 ms/mm Hg, p = 0.0002, odds ratio = 16.1), AERP dispersion during P SVT (>40 ms, p = 0.0008, odds ratio = 9.7), and increase of right atri al area during PSVT (>2 cm(2), p = 0.016, odds ratio = 10.7) were sign ificantly correlated with the occurrence of PAF in patients with PSVT. Conclusions. Disturbed atrial electrophysiology and higher vagal refl ex could play important roles in the genesis of PAF in patients with P SVT. (J Am Coll Cardiol 1998;32:732-8) (C)1998 by the American College of Cardiology.