Children with Wolff-Parkinson-White Syndrome (WPW) are at risk for sudden death. The gold standard for risk stratification in this population is the shortest pre-excited RR interval during atrial fibrillation (SPERRI).Our aim was to determine how closely measurements made in the electrophysiology lab in patients with WPW compared to the SPERRI obtained during an episode of clinical pre-excited atrial fibrillation (Clinical-SPERRI).This is a subgroup analysis of a multicenter study of children with WPW. Subjects in our study (n=49) were included if they had a Clinical-SPERRI measured in addition to one or more of three surrogate measurements: SPERRI obtained in the EP lab (EP-SPERRI), accessory pathway effective refractory period (APERP), or shortest pre-excited paced cycle length with 1:1 conduction (SPPCL).Seventy percent of EP measurements were made under general anesthesia. Clinical-SPERRI moderately correlated with EP-SPERRI (r=0.495, p=0.012). However, 24% of our patients with Clinical-SPERRI ≤250ms would have been misclassified as having a low risk pathway based on an EP-SPERRI of >250ms. Clinical-SPERRI did not correlate with APERP or SPPCL (r<0.3, p>0.1). Mean EP-SPERRI, APERP and SPPCL were all greater than Clinical-SPERRI.EP lab measurements of pathway characteristics made under general anesthesia do not correlate well with Clinical-SPERRI. Of APERP, SPPCL, and EP-SPERRI, only EP-SPERRI has a moderate correlation with Clinical-SPERRI. In addition, this study questions the predictive ability of invasive risk stratification under general anesthesia, given that 24% of patients with a high risk Clinical-SPERRI (≤250ms) had an EP-SPERRI that may be considered low risk (>250ms).