Key result
Post-TAVR LBBB shifts frontal QRS axis leftward by ~70° across baseline electrical heart positions.
Why the study?
LBBB after TAVR alters ventricular activation and challenges ECG interpretation, motivating the establishment of novel ECG criteria to define the electrical position of the heart before and after post-TAVR LBBB.
Does new-onset LBBB after TAVR alter the electrocardiographic criteria used to define the electrical position of the heart in TAVR patients?
Observational (n=74)
No
Does new-onset LBBB after TAVR alter the electrocardiographic criteria used to define the electrical position of the heart in TAVR patients?
Novel ECG criteria allow reliable classification of cardiac electrical position before and after post-TAVR LBBB, demonstrating that leftward axis deviation with LBBB often reflects intrinsic heart position rather than new pathology.
Post-TAVR LBBB axis shifts may reflect intrinsic position; hypothesis-generating for refined ECG criteria pending validation.
Background Left bundle branch block (LBBB) is a frequent complication after transcatheter aortic valve replacement (TAVR), altering ventricular activation and challenging ECG interpretation. This study sought to establish novel electrocardiographic criteria to define the electrical position of the heart (EPH) before and after LBBB post-TAVR. Methods In this single-center, retrospective study, 439 TAVR patients (2018–2023) were screened; 74 developed new LBBB. Patients with pre- and post-TAVR ECGs, without pacemaker, infiltrative disease, or baseline conduction disorders, were included. ECGs were analyzed for QRS duration, electrical axes (AQRS, AT), and patterns of concordance/discordance in leads II/III and aVL/aVF. EPH was categorized as intermediate (IEP), horizontal (HEP), or vertical (VEP) by AQRS. Morphology in leads I, aVL, V5, and V6 was also assessed. Results Among 74 patients with LBBB, 36 (48.6%) had IEP, 32 (43.2%) HEP, and 6 (8.1%) VEP. In patients without LBBB, AQRS averaged 50°±15° in IEP and –10°±20° in HEP (p<0.0001). With LBBB, AQRS shifted to –20°±25° in IEP and –60°±30° in HEP (p<0.0001). Positive concordance in II/III and aVL/aVF identified IEP, whereas positive discordance indicated HEP. In LBBB, negative concordance in II/III with positive discordance in aVL/aVF defined HEP, while positive discordance in II/III with positive concordance in aVL/aVF characterized IEP. Conclusion Novel ECG criteria enable reliable classification of cardiac electrical position in both baseline and post-TAVR LBBB. Leftward axis deviation with LBBB often reflects intrinsic EPH rather than new pathology, enhancing interpretation and clinical decision-making.Figure 1Figure 2
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Guillot et al. (2026) conducted an observational in New left bundle branch block (LBBB) after transcatheter aortic valve replacement (TAVR) (n=74). New post-TAVR left bundle branch block (LBBB) / ECG criteria for electrical position of the heart vs. Baseline pre-TAVR without LBBB / across electrical position categories (IEP vs HEP) was evaluated on QRS electrical axis (AQRS) and classification of electrical position of the heart (EPH: intermediate [IEP], horizontal [HEP], or vertical [VEP]) (p=<0.0001). Post-TAVR LBBB shifted mean AQRS from 50° to –20° in intermediate and from –10° to –60° in horizontal electrical heart positions (p<0.0001), enabling reliable ECG classification.
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