AUGMENTED SYMPATHOADRENAL ACTIVITY DURING TREADMILL EXERCISE IN PATIENTS WITH WOLFF-PARKINSON-WHITE SYNDROME AND ATRIAL-FIBRILLATION

It is believed that reciprocating tachycardia and accessory pathways p lay important roles in atrial fibrillation (AF) in patients with Wolff -Parkinson-White (WPW) syndrome. However, the mechanism by which AF oc curs is not yet fully understood. This study was performed to evaluate the contribution of sympathoadrenal activity to the onset of AF in pa tients with WPW syndrome. Symptom-limited treadmill exercise testing w as performed and plasma norepinephrine and epinephrine concentrations were measured simultaneously in 27 patients with WPW syndrome and 20 c ontrol subjects. In 13 patients with WPW syndrome and AF, plasma norep inephrine and epinephrine concentrations increased to 3.69+/-2.44 and 0.76+/-0.69 ng/ml at maximum exercise, respectively. These values were significantly higher (p<0.001) than those in control subjects and in patients without AF. Pretreatment with 0.2 mg/kg of propranolol signif icantly reduced the incidence of exercise-induced atrial premature com plexes (chi(2)=7.33, p<0.05). With oral beta-blockade for an average o f 22.8 months, the incidence of AF decreased significantly from 1.77+/ -0.53/patient per year to 0.33+/-0.57/patient per year (p<0.001). Augm ented sympathoadrenal activity in patients with WPW syndrome may contr ibute to AF.