Accessory Pathway Antegrade Electrophysiologic Features Among Wolff-Parkinson-White Patients: The Risk in Relation to the Location.

BACKGROUND: Wolff-Parkinson-White (WPW) syndrome is a disorder characterized by presence of an accessory pathway (AP) which predisposes patients to tachyarrhythmia and sudden death. The aim of this study was to evaluate the prevalence of high-risk electrophysiologic AP features among WPW patients referred for electrophysiological study (EPS) and to explore whether the AP location can predict the high-risk nature of the AP.

METHODS: This descriptive observational study was carried out on 70 patients with WPW subjected to invasive EPS. All patients were subjected to determination of AP anterograde conduction properties [AP effective refractory period (APERP) and shortest pre-excited RR interval (SPERRI)], mapping for localization, and ablation attempts of the AP.

RESULTS: Twenty-five patients (35.7%) had an AP antegrade refractory period (APERP) ≤ 240 ms. The shortest RR interval during pre-excited AF (SPERRI) was ≤ 250 ms in 17 patients. Thirty-two APs (45.7%) were classified as high-risk AP (having APERP ≤ 240 ms and/or SPERRI ≤ 250 ms). Radiofrequency ablation was successful in 59/63 patients (93.7%). The mean APERP was significantly lower in postero-septal than anteroseptal and mid-septal APs (p < 0.003), and in left sided than right sided APs (p value = 0.001). Left non-septal APs (specially the left lateral APs) were significantly associated with the presence of high-risk than low-risk parameters. Septal APs (anterior, mid, and posterior) were significantly associated with the presence of low-risk than high-risk parameters.

CONCLUSIONS: High-risk AP features as determined by the antegrade conduction properties are common among WPW patients. AP location may hold significance in predicting the presence of those high-risk electrophysiologic features.