The QRS frontal plane axis changes during left bundle branch block after transcatheter aortic valve replacement
Oren Yagel1,2, Bernard Belhassen1,3, David Planer1,2
1Heart Institute, Hadassah Medical Center, Jerusalem, Israel.
Insights
New left bundle branch block (LBBB) after transcatheter aortic valve replacement (TAVR) can shift the QRS axis. A rightward or no QRS axis shift post-TAVR is linked to a higher risk of high-degree atrioventricular block (AVB).
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.
Background And Aims:
Left bundle branch block (LBBB) is common after transcatheter aortic valve replacement (TAVR) and associated with a left or normal QRS axis. We aim to assess the QRS frontal plane axis shift changes during LBBB after TAVR and determine if the risk of procedure-related high degree atrioventricular block (AVB) is affected by QRS axis shift changes.
Methods And Results:
In a retrospective single-center study of 720 consecutive patients who underwent TAVR, 141 (19.6%) with normal baseline QRS duration developed a new LBBB after TAVR and constituted the study group. Most patients (59.6%) were females and the mean age of the cohort was 81.2 ± 6 years.
Results:
As compared with the baseline QRS axis before TAVR, the occurrence of LBBB was associated with a leftward QRS axis shift (by 40 ± 28.3°) in 73% of the study patients and a rightward (by 18.6 ± 19.4°) or no change in QRS axis in 25.6% and 1.4% of the study patients, respectively. A left QRS axis (-30°) was observed in 14.9% and 38.3% of the study patients before and after TAVR, respectively. The group of patients exhibiting a rightward or no QRS axis shift had a greater incidence of high degree AVB than the group of patients exhibiting a leftward QRS axis shift (18.4% vs. 6.8%, p = .056).
Conclusion:
Although post TAVR-LBBB is associated with a leftward QRS axis shift in most patients, a non-negligible proportion of patients (27%) exhibited a rightward or no QRS axis shift. The latter group tend to have a higher risk of developing high degree AVB.
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