Reliability and reproducibility of QRS duration in the selection of candidates for cardiac resynchronization therapy.
BACKGROUND
A QRS >120 ms remains the recommended criterion for the selection of cardiac resynchronization therapy (CRT) candidates. However, the reproducibility of this measurement has not been studied thoroughly.


METHODS
QRS duration was measured by 3 experienced cardiologists and by automatic measurement on 228 electrocardiograms (ECGs) randomly collected from 188 subjects, including neonates, healthy adults, patients with complete and incomplete bundle branch block, and CRT candidates. All ECGs were recorded at a 25 mm/s sweep speed. Forty recordings were duplicated and 50 ECGs were recorded at both 25 and 50 mm/s.


RESULTS
Significant interobserver differences (P < 0.001) were found between each combination of paired observers, with an up to 50-ms absolute variability between cardiologists and low concordance with computerized measurements. Intraobserver absolute variability was also significant (P < 0.01) for the 3 observers. These significant differences persisted (P < 0.01) when focusing our interest on the ECGs in the 100-140 ms range (defined as at least one out of the 4 measures in this range). Considering the 120 ms limit, 22 (27.5%) ECGs were differently classified by at least one of the cardiologists. We observed similar interobserver differences between each combination of paired observers with a 50 mm/s sweep speed.


CONCLUSIONS
Manual QRS duration measurements were associated with significant inter- and intraobserver variability and low concordance with computerized measurements. The measurement of QRS is, therefore, operator-dependent and a reevaluation of the measurement methods may be essential to develop clinical and investigative standards.
University Victor Segalen, 33000 Bordeaux France, Hospital Haut Leveque, Pessac, France.
Maxime
M
De Guillebon
Jean-Benoit
JB
Thambo
Sylvain
S
Ploux
Antoine
A
Deplagne
Frederic
F
Sacher
Pierre
P
Jais
Michel
M
Haissaguerre
Philippe
P
Ritter
Jacques
J
Clementy
Pierre
P
Bordachar
D000328:Adult; D057205:Automation, Laboratory; D002037:Bundle-Branch Block / Q000175:diagnosis / Q000503:physiopathology / Q000628:therapy*; D058406:Cardiac Resynchronization Therapy; D002648:Child; D004562:Electrocardiography; D005602:France; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D007231:Infant, Newborn; D015588:Observer Variation; D018579:Patient Selection; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013997:Time Factors