Electrophysiologic Characteristics of the Atrium in Sinus Node Dysfunction:

71 subjects, comprising 46 patients with sinus node dysfunction (SND) (mean age 70 +/- 8 years; 16 with documented paroxysmal AF, 30 with SND alone) and 25 control subjects (mean age 63 +/- 14 years) referred for unexplained syncope or AV conduction disturbances.

Electrophysiologic (EP) study evaluating atrial substrate (measuring effective and functional refractory periods, latencies, atriogram widths, latent vulnerability index, and intra-atrial conduction times).

Control group of subjects referred for unexplained syncope or AV conduction disturbances.

Electrophysiologic parameters including atriogram durations (A1 and A2), latent vulnerability index (ERP/A2), refractory periods, and intra-atrial conduction times.surrogate