INTERMITTENT VENTRICULAR PRE-EXCITATION IN SYMPTOMATIC ADULTS: ALWAYS A MARKER OF LOW RISK?

Background: Intermittent ventricular pre-excitation was considered a low-risk marker for sudden death. However, to date, some studies do not exclude the existence of accessory pathways (APs) with high-risk intermittent antegrade conductive properties. According to current European Guidelines, high-risk features of APs are antegrade pathway conduction ≤250 msec in baseline or during the adrenergic stimulus, inducibility of atrioventricular reciprocating tachycardias (AVRT), inducibility of pre-excited atrial fibrillation (AF), and presence of multiple APs. For all of these transcatheter ablation is recommended. The aim of our study was to evaluate the existence of differences in risk characteristics between patients with intermittent pre-excitation (IPX) and those with persistent pre-excitation (PPX), from a sample of adults with ventricular pre-excitation and symptoms like palpitations. Methods: 293 adults [IPX: 51 (17.4%); PPX: 242 (82.6%)] underwent electrophysiological (EP) study and then catheter ablation of their APs if arrhythmia inducibility (AVRT/AF) was noted, or, conversely, if it was appreciated a fast AP antegrade conduction, in baseline or during intravenous isoproterenol infusion, or if multiple APs were detected. Results: There were no statistically significant differences in demographic characteristics of age [IPX: mean age 37.23±16.89 years vs PPX: mean age 39.03±16.19; p-value = 0.21] and gender [IPX male: 31 (60.8%) vs PPX male: 152 (62.8%); p-value = 0.28]. Also EP features like AVRT/AF inducibility [IPX: 27 (52.9%) vs PPX: 100 (41.3%); p-value = 0.13], antegrade conductive properties [IPX: mean ERP 260±45.8 msec vs PPX: mean ERP 267.7±59.6msec; p-value = 0.5], prevalence of multiple APs (p-value = 0.56), and APs locations (p-value = 0.32) did not demonstrate any significant differences between IPX and PPX patients. Conclusions: In our study, patients with IPX did not show significant differences in clinical and electrophysiological features vs PPX patients.