Utility of incomplete right bundle branch block as an isolated
ECG finding in children undergoing initial cardiac evaluation
Omar Meziab MD
Dominic J. Abrams MD
Mark E. Alexander MD
Laura Bevilacqua MD
Vassilios Bezzerides MD
Doug Y. Mah MD
Edward P. Walsh MD
John K. Triedman MD
Boston Children’s Hospital, Boston,
Omar Meziab, MD, 36 Park Street Apt 4,
Brookline, MA 02446, USA.
Objective: This study evaluates the ability of experienced pediatric electrophysiologists (EPs) to
reliably classify incomplete right bundle branch block (IRBBB) and assesses its clinical utility as an
isolated ECG finding in a group of healthy outpatient children without prior cardiac evaluation.
Design: We performed a retrospective analysis of all electrocardiographic and echocardiographic
records at Boston Children’s Hospital between January 1, 2005, and December 31, 2014. Echocardio-
graphic diagnoses were identified if registered between the date of the index electrocardiogram and
the ensuing year. A selected subset of 473 ECGs was subsequently reanalyzed in a blinded manner
by six pediatric EPs to determine the consistency with which the finding of IRBBB could be assigned.
Results: Of the 331 278 ECGs registered in the BCH database, 32 127 (9.7%) met inclusion crite-
ria and were analyzed for the prevalence of isolated right bundle conduction disturbance findings.
The mean age was 12.1 6 4.0 years, and the population was 49% male. Of the 32 127 ECGs,
72.5% were coded normal, 3.0% were coded IRBBB, and 0.5% were coded complete right bundle
branch block (CRBBB). A total of 7.3% of patients coded as normal had an ensuing echocardio-
gram, compared to 12.5% coded IRBBB. Echo findings were recorded in 0.1% of normal and 0.2%
of IRBBB. Patients with ASD-secundum type were no more likely to have isolated IRBBB on previ-
ous ECG than the general population (2.5% vs 3.0%). Analysis of inter-reader variability in ECG
findings and conduction disturbance identification was high (range of IRBBB prevalence 1-20%
among readers). Reinterpretation of ECGs using explicit diagnostic criteria did not demonstrate
consistent discrimination of IRBBB and Normal ECGs.
Conclusions: IRBBB is not uncommon in a healthy school age population and is observed to have
high inter-reader variability. It was associated with increased use of echocardiographic exam but
was not associated with increased rate of echocardiographic findings when compared with rates
for normal ECGs.
clinical significance, electrocardiogram, incomplete right bundle branch block, pediatric, RSR
Screening by electrocardiogram (ECG) is increasingly used to evalu-
ate children without known heart disease prior to initiation of vari-
ous classes of medication, participation in competitive sports, and
surgical procedures. Although several sets of major criteria for
increased risk of significant heart disease have been proposed,
minor electrocardiographic findings are considerably more common
and of uncertain significance and sometimes cause considerable
Congenital Heart Disease. 2018;13:419–427. wileyonlinelibrary.com/journal/chd
2018 Wiley Periodicals, Inc.
Received: 18 December 2017
Accepted: 19 January 2018