Cardiac memory in patients with Wolff-Parkinson-White syndrome: Noninvasive imaging of activation and repolarization before and after catheter ablation

Background - Cardiac memory refers to a change in ventricular repolarization induced by and persisting for minutes to months after cessation of a period of altered ventricular activation (eg, resulting from pacing or preexcitation in patients with Wolff-Parkinson-White syndrome). ECG imaging (ECGI) is a novel imaging modality for noninvasive electroanatomic mapping of epicardial activation and repolarization. Methods and Results - Fourteen pediatric patients with Wolff-Parkinson-White syndrome and no other congenital disease, were imaged with ECGI a day before and 45 minutes, 1 week, and 1 month after successful catheter ablation. ECGI determined that preexcitation sites were consistent with sites of successful ablation in all cases to within a 1-hour arc of each atrioventricular annulus. In the preexcited rhythm, activation-recovery interval (ARI) was the longest (349±6 ms) in the area of preexcitation leading to high average base-to-apex ARI dispersion of 95±9 ms (normal is ≈40 ms). The ARI dispersion remained the same 45 minutes after ablation, although the activation sequence was restored to normal. ARI dispersion was still high (79±9 ms) 1 week later and returned to normal (45±6 ms) 1 month after ablation. Conclusions - The study demonstrates that ECGI can noninvasively localize ventricular insertion sites of accessory pathways to guide ablation and evaluate its outcome in pediatric patients with Wolff-Parkinson-White syndrome. Wolff-Parkinson-White is associated with high ARI dispersion in the preexcited rhythm that persists after ablation and gradually returns to normal over a period of 1 month, demonstrating the presence of cardiac memory. The 1-month time course is consistent with transcriptional reprogramming and remodeling of ion channels.