The QRS frontal plane axis changes during left bundle branch block after transcatheter aortic valve replacement

Area of Science:

• Cardiology
• Electrophysiology
• Cardiac Surgery

Background:

• Left bundle branch block (LBBB) is a frequent complication following transcatheter aortic valve replacement (TAVR).
• LBBB after TAVR is typically associated with a left or normal QRS axis.

Purpose of the Study:

• To evaluate changes in the QRS frontal plane axis during LBBB after TAVR.
• To determine if QRS axis shift changes influence the risk of high-degree atrioventricular block (AVB) related to the procedure.

Main Methods:

• Retrospective analysis of 720 patients undergoing TAVR.
• Identified 141 patients who developed new LBBB post-TAVR with normal baseline QRS duration.
• Analyzed QRS axis shifts from baseline to post-TAVR.

Main Results:

• New LBBB after TAVR was associated with a leftward QRS axis shift in 73% of patients.
• A rightward or no QRS axis shift occurred in 27% of patients.
• Patients with rightward/no QRS axis shift had a higher incidence of high-degree AVB (18.4%) compared to those with leftward shift (6.8%).

Conclusions:

• While most post-TAVR LBBB cases show a leftward QRS axis shift, a significant minority (27%) exhibit a rightward or no shift.
• This subgroup with non-leftward QRS axis shift faces an elevated risk of developing high-degree AVB.