Autonomic modulation and atrial fibrillation in the Wolff- Parkinson-Whitesyndrome

Twenty-four-hour frequency-domain heart period variability was measured in 22 patients with Wolff-Parkinson-White (WPW) syndrome; 8 patients had parox ysmal atrial fibrillation in whom a relative predominance of sympathetic ac tivity was found. Orthodromic tachycardia cycle length correlated directly with high-frequency spectral power and inversely with the low-frequency/hig h-frequency ratio; these findings indicate that vagal withdrawal and sympat hetic predominance in patients with WPW syndrome is associated with rapid o rthodromic tachycardia and atrial fibrillation.