Key result
Post-TAVR LBBB is linked to significant leftward QRS axis shift reflecting baseline electrical position.
Why the study?
LBBB frequently complicates TAVR, altering ventricular activation and challenging ECG interpretation.
Do novel ECG criteria reliably determine the electrical position of the heart in baseline rhythm and post-TAVR LBBB?
Observational (n=74)
No
Do novel ECG criteria reliably determine the electrical position of the heart in baseline rhythm and post-TAVR LBBB?
Novel ECG criteria using limb lead concordance and discordance can reliably classify cardiac electrical position in baseline and post-TAVR LBBB, demonstrating that leftward axis deviation often reflects intrinsic position rather than new pathology.
Novel ECG criteria for EPH post-TAVR LBBB may aid interpretation; leaves open prospective validation before clinical use.
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.
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Robledo-Nolasco et al. (2026) conducted an observational in Left bundle branch block post-TAVR (n=74). Post-TAVR left bundle branch block vs. Baseline rhythm (without LBBB) was evaluated on AQRS shift in intermediate and horizontal electrical positions (p=<0.0001). Post-TAVR left bundle branch block significantly shifts the QRS axis leftward (p<0.0001), reflecting intrinsic electrical position of the heart rather than new pathology.
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