Response to Letter Regarding Article, “Wolff-Parkinson-White Syndrome in the Era of Catheter Ablation: Insights From a Registry Study of 2169 Patients”

We thank Fenici et al for their interest in our experience on the natural history of the Wolff-Parkinson-White (WPW) syndrome. he authors, on the basis of their experience, suggest the routine use of ambulatory transesophageal atrial pacing (TEAP) as an intermediate approach to minimize "invasiveness" for risk assessment in the asymptomatic WPW population. It is well known that, unlike invasive electrophysiological testing (EPT), TEAP provides less accurate information about "the real electrophysiological profile of the risk" in WPW patients. Potential limitations are an approximate value of the anterograde refractory period of accessory pathways (APs), no identification of multiple APs, no reproducibility or inducibility of atrial fibrillation, no information on AP retrograde conduction, and no AP localization, all of which in a modern electrophysiology laboratory are indeed unacceptable when evaluating the risk of sudden death. 2] Unfortunately, 3 years later, this "good asymptomatic boy" underwent both EPT and RFA of AP immediately after experiencing a resuscitated cardiac arrest caused by ventricular fibrillation as demonstrated by EPT. Because asymptomatic ventricular preexcitation has been supposed for many decades to be at no or minimal risk of sudden death, it is comprehensible that in the pre-RFA era this ambulatory strategy began to be used to stratify a "benign" disease. Besides these important methodological and physiopathological considerations, TEAP is a semi-invasive technique and is not entirely risk free. High-output pacing may frequently be required to activate the atrium from the esophagus, which can be painful, requiring the use of heavy sedation, all of which can modify the electrophysiological properties of AP. Albeit rarely, TEAP may also induce ventricular tachyarrhythmias, including ventricular fibrillation. Our experience with >11 000 WPW patients indicates that in a modern electrophysiology laboratory EPT and RFA performed in the same session are both safe and effective to definitively eliminate the risk of sudden death in patients with ventricular pre-excitation regardless of symptoms. We believe that TEAP remains a pioneering approach in the pre-RFA era that nowadays has become anachronistic, being abandoned by most modern electrophysiology laboratories worldwide, as shown by the fact that in the last 30 years the use of TEAP in patients with WPW syndrome has not been reported in the literature. Our large experience indicates that the risk of sudden death in patients with ventricular pre-excitation essentially depends on intrinsic electrophysiological AP properties rather than on symptoms. Thus, EPT indeed represents the gold standard to more accurately characterize in the single patient the electrophysiological properties of potentially dangerous AP to correctly identify subjects at risk of sudden death for prophylactic ablation.