Aortic valve implantation-induced conduction block as a framework towards a uniform electrocardiographic definition of left bundle branch block.

INTRODUCTION: New-onset left bundle branch block (LBBB) following transcatheter or surgical aortic valve replacement (LBBBAVI) implies a proximal pathogenesis of LBBB. This study compares electrocardiographic characteristics and concordance with LBBB definitions between LBBBAVI and non-procedure-induced LBBB controls (LBBBcontrol). METHODS: All LBBBAVI patients at Ghent University Hospital between 2013 and 2019 were enrolled in the study. LBBBAVI patients were matched for age, sex, ischaemic heart disease and ejection fraction to LBBBcontrol patients in a 1:2 ratio. For inclusion, a non-strict LBBB definition was used (QRS duration ≥ 120 ms, QS or rS in V1, absence of Q waves in V5-6). Electrocardiograms were digitally analysed and classified according to three LBBB definitions: European Society of Cardiology (ESC), Strauss and American Heart Association (AHA). RESULTS: A total of 177 patients (59 LBBBAVI and 118 LBBBcontrol) were enrolled in the study. LBBBAVI patients had more lateral QRS notching/slurring (100% vs 85%, p = 0.001), included a higher percentage with a QRS duration ≥ 130 ms (98% vs 86%, p = 0.007) and had a less leftward oriented QRS axis (-15° vs -30°, p = 0.013) compared to the LBBBcontrol group. ESC and Strauss criteria were fulfilled in 100% and 95% of LBBBAVI patients, respectively, but only 18% met the AHA criteria. In LBBBcontrol patients, concordance with LBBB definitions was lower than in the LBBBAVI group: ESC 85% (p = 0.001), Strauss 68% (p < 0.001) and AHA 7% (p = 0.035). No differences in electrocardiographic characterisation or concordance with LBBB definitions were observed between LBBBAVI and LBBBcontrol patients with lateral QRS notching/slurring. CONCLUSION: Non-uniformity exists among current LBBB definitions concerning the detection of proximal LBBB. LBBBAVI may provide a framework for more consensus on defining proximal LBBB.