Management of asymptomatic Wolff–Parkinson–White syndrome

Wolff–Parkinson–White syndrome (WPW) is a frequently encountered electrocardiographic abnormality and an important diagnostic and therapeutic issue for cardiac specialists. Estimates of WPW prevalence in the general population are contingent on the likelihood of asymptomatic patients having an electrocardiogram (ECG) performed, and range from 0.1–0.2%. WPW consists of pre-excitation of the QRS (the delta wave) caused by eccentric activation of the ventricular myocardium via an accessory atrioventricular (AV) connection (accessory pathway, historically called the bundle of Kent) (fig 1). In addition to ventricular pre-excitation observed in sinus rhythm, the electrophysiological consequences of this connection include the paroxysmal occurrence of atrioventricular reciprocating tachycardia (SVT) and, at considerably lower frequency, the occurrence of rapidly conducted atrial fibrillation, which may result in ventricular fibrillation and death. Figure 1 Wolff–Parkinson–White syndrome with pronounced pre-excitation. Accessory pathways (APs) by definition traverse the AV groove, and are identified in all anatomical quadrants of the tricuspid and mitral annuli. Although WPW is prevalent, pathological demonstration is rare as this myocardial feature is microscopic and rarely systematically sought in postmortem study. Although APs are typically congenital, many well substantiated reports indicate that the clinical aspects of WPW may sometimes be acquired de novo, typically in patients who have undergone cardiac surgical procedures. An increased prevalence of WPW is noted among patients with Ebstein’s anomaly, in whom APs are typically anatomically associated with the abnormal tricuspid valve, and often multiple. Among symptomatic patients, clinical presentation is typically with palpitations or a sustained episode of SVT. A bimodal age distribution is observed: a substantial number of patients present in the first month of life (in some cases, prenatally), and a secondary, more diffuse peak through the school age years. Prenatal and infantile presentation of SVT is often associated with signs of congestive heart failure, perhaps due in part to the relatively prolonged interval …