Nonpersistent pre-excitation was associated with fewer high-risk accessory pathway (APs), although it did not exclude risk for sudden cardiac arrest (SCA) or rapidly conducted pre-excited atrial fibrillation (RC-AF) in children with Wolff Parkinson White syndrome (WPW), according to a study published in Heart Rhythm.
WPW syndrome is associated with a risk for sudden cardiac death in children due to AF with rapid antegrade conduction via the AP and resultant ventricular fibrillation. It is thought that abrupt loss of ventricular pre-excitation on noninvasive testing, or nonpersistent pre-excitation indicates a long AP refractory period and lower risk for life-threatening events.
In this retrospective, multicenter, international study, the data of patients ≤21 years (n=1589; 13.1±3.9 years; 60% men) with WPW and non-persistent and persistent pre-excitation from 26 Centers were analyzed to compare AP characteristics and occurrences of SCA and RC-AF. Two multicenter databases were consulted to retrieve patient data. The first database was from a retrospective case-control study comparing children with WPW and history of SCA or RC-AF with children with WPW who underwent electrophysiology study (EPS) and did not have SCA or RC-AF. The second database was a multicenter retrospective cohort study of children with WPW who had undergone EPS. Nonpersistent pre-excitation was defined as intermittent absence of ventricular pre-excitation on ECG or Holter, or sudden loss on exercise stress test (EST). RC-AF was defined as clinical pre-excited AF with shortest pre-excited RR interval (SPERRI) ≤250ms, or clinical pre-excited AF associated with hemodynamic compromise, syncope, or seizure, regardless of clinical SPERRI. High-risk AP was defined as antegrade AP effective refractory period (APERP), shortest pre-excited paced cycle length (SPPCL) during atrial pacing or SPERRI during atrial fibrillation (EPS-SPERRI) ≤250ms.
Non-persistent pre-excitation was found in 244 patients (15%) and persistent pre-excitation in 1345 patients (85%). No differences were observed in sex, age or ethnicity between non-persistent and persistent pre-excitation groups.
Patients with persistent vs nonpersistent pre-excitation had longer APERP (344±76 vs 312±61ms, respectively; P <.001) and SPPCL (394±123 vs 317±82ms, respectively; P <.001), and comparable EPS-SPERRI (331±71 vs 316±73ms, respectively; P =.15). High-risk AP was found to be more frequent in patients with persistent vs nonpersistent pre-excitation (23% vs 13%, respectively; P <.001). In addition, of the 213 patients (87%) with nonpersistent pre-excitation patients who underwent risk stratification at EPS, 27 patients (13%) met high-risk criteria. Lastly, 10% of patients with SCA or RC-AF had nonpersistent pre-excitation.
Limitations of the study include differences in the methods used for the noninvasive evaluations of patients, the presence of bias, as asymptomatic patients with nonpersistent pre-excitation were less likely to undergo EPS, and the fact that the determination of the presence of multiple APs and loss of ventricular pre-excitation during noninvasive testing was not independently confirmed which may have led to patient misclassification.
“This study demonstrates that the presence of nonpersistent pre-excitation in children with WPW may not guarantee absence of a high-risk AP nor absence of risk for a SCA or RC-AF,” the authors noted.
Escudero CA, Ceresnak SR, Collins KK, Pass RH, Aziz PF, Blaufox AD. Loss of ventricular pre-excitation during non-invasive testing does not exclude high-risk accessory pathways: A multicenter study of WPW in children. Heart Rhythm. 2020 Jun 1;S1547-5271(20)30533-6.