BACKGROUND: Abrupt loss of ventricular preexcitation on noninvasive evaluation, or nonpersistent preexcitation, in Wolff-Parkinson-White syndrome (WPW) is thought to indicate a low risk of life-threatening events. OBJECTIVE: The purpose of this study was to compare accessory pathway (AP) characteristics and occurrences of sudden cardiac arrest (SCA) and rapidly conducted preexcited atrial fibrillation (RC-AF) in patients with nonpersistent and persistent preexcitation. METHODS: Patients 21 years or younger with WPW and invasive electrophysiology study (EPS) data, SCA, or RC-AF were identified from multicenter databases. Nonpersistent preexcitation was defined as absence/sudden loss of preexcitation on electrocardiogram, Holter monitoring, or exercise stress test. RC-AF was defined as clinical preexcited atrial fibrillation with shortest preexcited R-R interval (SPERRI) ≤ 250 ms. AP effective refractory period (APERP), SPERRI at EPS , and shortest preexcited paced cycle length (SPPCL) were collected. High-risk APs were defined as APERP, SPERRI, or SPPCL ≤ 250 ms. RESULTS: Of 1589 patients, 244 (15%) had nonpersistent preexcitation and 1345 (85%) had persistent preexcitation. There were no differences in sex (58% vs 60% male; P=.49) or age (13.3±3.6 years vs 13.1±3.9 years; P=.43) between groups. Although APERP (344±76 ms vs 312±61 ms; P<.001) and SPPCL (394±123 ms vs 317±82 ms; P<.001) were longer in nonpersistent vs persistent preexcitation, there was no difference in SPERRI at EPS (331±71 ms vs 316±73 ms; P=.15). Nonpersistent preexcitation was associated with fewer high-risk APs (13% vs 23%; P<.001) than persistent preexcitation. Of 61 patients with SCA or RC-AF, 6 (10%) had nonpersistent preexcitation (3 SCA, 3 RC-AF). CONCLUSION: Nonpersistent preexcitation was associated with fewer high-risk APs, though it did not exclude the risk of SCA or RC-AF in children with WPW.

Children's Heart Centre 2nd Faculty of Medicine Charles University Prague and Motol University Hospital Prague Czech Republic

Department of Arrhythmia and Cardiac Pacing Cardiocentro Pediatrico William Soler Havana Cuba

Department of Paediatric Cardiology University Hospital of Wales Cardiff Wales United Kingdom

Department of Pediatric Cardiology Cleveland Clinic Children's Cleveland Clinic Lerner College of Medicine Cleveland Ohio

Department of Pediatrics Division of Cardiology Seattle Children's Hospital Seattle Washington

Department of Pediatrics Division of Cardiology Texas Children's Hospital Houston Texas

Department of Pediatrics Division of Cardiology UCSF Benioff Children's Hospital San Francisco California

Department of Pediatrics Division of Cardiology University of Colorado Aurora Colorado

Department of Pediatrics Division of Pediatric Cardiology Cohen Children's Medical Center of New York New Hyde Park New York

Department of Pediatrics Division of Pediatric Cardiology UCLA Medical Center Los Angeles California

Department of Pediatrics Division of Pediatric Cardiology University of Alberta Stollery Children's Hospital Edmonton Alberta Canada

Department of Pediatrics Division of Pediatric Cardiology University of Iowa Stead Family Children's Hospital Iowa City Iowa

Department of Pediatrics Division of Pediatric Cardiology University of Utah and Primary Children's Hospital Salt Lake City Utah

Department of Pediatrics University of British Columbia Children's Heart Centre Vancouver British Columbia Canada

Department of Pediatrics University of Michigan Ann Arbor Michigan

Department of Pediatrics University of Tokyo Hospital Tokyo Japan

Division of Cardiology Miami Children's Hospital Miami Florida

Division of Cardiology Nationwide Children's Columbus Ohio

Division of Pediatric Cardiology Advocate Children's Heart Institute at Advocate Children's Hospital Oak Lawn Illinois

Division of Pediatric Cardiology Department of Cardiology Lucile Packard Children's Hospital Stanford University Palo Alto California

Division of Pediatric Cardiology Inova Children's Hospital Fairfax Virginia

Division of Pediatric Cardiology Maine Medical Center Portland Maine

Division of Pediatric Cardiology Mayo Clinic Rochester Minnesota

Division of Pediatric Cardiology The Children's Hospital at Montefiore Medical Center Bronx New York

Division of Pediatric Cardiology University California San Diego Rady Children's Hospital San Diego California

Division of Pediatric Cardiology UNMC CUMC Children's Hospital and Medical Center Omaha Nebraska

Labatt Family Heart Centre The Hospital for Sick Children Department of Paediatrics Toronto Ontario Canada

Starship Children's Hospital Auckland New Zealand

Heart Rhythm. 2020 Oct;17(10):1738-1739. doi: 10.1016/j.hrthm.2020.07.002 PubMed