Evaluating strict and conventional left bundle branch block criteria using electrocardiographic simulations.
AIMS
Left bundle branch block (LBBB) is a critical predictor of patient benefit from cardiac resynchronization therapy (CRT), but recent studies suggest that one-third of patients diagnosed with LBBB by conventional electrocardiographic (ECG) criteria may have a false-positive diagnosis. In this study, we tested the hypothesis that recently proposed strict LBBB ECG criteria improve specificity in cases of left ventricular hypertrophy (LVH) /dilatation and incomplete LBBB.


METHODS AND RESULTS
We developed five heart models based on a healthy male with increasing degrees of LV hypertrophy and/or dilation. With each model, we simulated six conduction types: normal conduction, four increments of delayed initiation of LV activation (incomplete LBBB), and complete LBBB. Simulated ECGs were evaluated for the presence of LBBB by conventional (LV conduction delay and QRSd ≥120 ms) and strict ECG criteria (LV conduction delay, QRSd ≥140 ms men or ≥130 ms women, and mid-QRS notching in at least two of the leads I, aVL, V1, V2, V5, and/or V6). Both conventional and strict LBBB criteria had 100% sensitivity. However, conventional criteria falsely diagnosed LBBB in cases with LVH + LV dilated 10 mm, LVH or LV dilated 10 mm combined with LV initiation ≥6 ms after the right ventricle (RV), and with LV dilated 5 mm combined with LV initiation ≥12 ms after RV (48% specificity). Strict LBBB criteria resulted in no false positives (100% specificity).


CONCLUSIONS
New strict LBBB criteria increase the specificity of complete LBBB diagnosis in the presence of LV hypertrophy/dilatation and incomplete LBBB, which is critical for selecting CRT patients.
['Galeotti|Loriano|L|', 'van Dam|Peter M|PM|', 'Loring|Zak|Z|', 'Chan|Dulciana|D|', 'Strauss|David G|DG|']
D000328:Adult D002037:Bundle-Branch Block D058406:Cardiac Resynchronization Therapy D003198:Computer Simulation D004562:Electrocardiography D005260:Female D006329:Heart Conduction System D006333:Heart Failure D006801:Humans D017379:Hypertrophy, Left Ventricular D008279:Magnetic Resonance Imaging D008297:Male D008955:Models, Cardiovascular D018579:Patient Selection D011237:Predictive Value of Tests D011379:Prognosis D016277:Ventricular Function, Left
Left bundle branch block Simulations Cardiac resynchronization therapy Electrocardiography