Wolff-Parkinson-White Syndrome Observed by Portable Monitoring

Twenty-seven patients with Wolff-Parkinson-White syndrome (preexcitation) were monitored for 24 hours with a portable electrocardiographic recorder. During monitoring, no episodes of paroxysmal supraventricular tachycardia were detected. Despite this, eight patients experienced episodes of palpitation. These episodes reflected sinus tachycardia, premature beating, or no electrocardiographic abnormality. Of the 27 patients, 18 had intermittent preexcitation: 9 had gradual normalization as heart rate increased, 3 had sudden normalization above a critical atrial rate, and 6 had episodic unpredictable normalization of conduction. Thirteen patients had marked sinus arrhythmia, with or without sinus bradycardia, A-V junctional escapes, A-V dissociation, or sinus arrest. We conclude that [1] in a random 24-hour period the average patient with preexcitation does not experience paroxysmal supraventricular tachycardia; [2] symptoms suggesting such tachycardia are misleading; [3] intermittent preexcitation is common, reflecting changing autonomic tone, anomalous pathway refractoriness, or unknown causes; and [4] sinus node dysfunction is frequent in patients with preexcitation.