Background: Sudden cardiac death can be the first clinical presentation of asymptomatic ventricular preexcitation.
Methods and results: From 1995 to 2005, we prospectively collected clinical and electrophysiological data among 293 adults with asymptomatic ventricular preexcitation (61.4% males; median age, 36 years; interquartile range [IQR], 28 to 47.5). After electrophysiological testing, patients were prospectively followed, taking no drugs. The primary end point of the study was the occurrence of a first arrhythmic event. Predictors of arrhythmic events were analyzed by univariate and multivariate Cox models. Over a median follow-up of 67 months (minimum to maximum, 8 to 90), after electrophysiological testing, 262 patients (median age, 37 years; IQR, 30 to 48) did not experience arrhythmic events, remaining totally asymptomatic, whereas 31 patients (median age, 25 years; IQR, 22 to 29; median follow-up, 27 months; minimum to maximum, 8 to 55) had a first arrhythmic event, which was potentially life-threatening in 17 of them (median age, 24 years; IQR, 20 to 28.5; median follow-up, 25 months; minimum to maximum, 9 to 55). Potentially life-threatening tachyarrhythmias resulted in resuscitated cardiac arrest (1 patient), presyncope (7 patients) syncope (4 patients), or dizziness (5 patients). In multivariate analysis age (P=0.004), inducibility (P=0.001) and anterograde effective refractory period of the accessory pathway < or = 250 ms (P=0.001) predicted potentially life-threatening arrhythmias.
Conclusions: These results indicate that prognosis of adults who present with asymptomatic ventricular preexcitation is good, and the risk of a significant event is small. Short anterograde effective refractory period of the accessory pathway and inducibility at baseline are independent predictors of potentially life-threatening arrhythmic events, and the risk decreases with increasing age.