Abstract
Cardiac resynchronization therapy (CRT) is a well-established treatment for symptomatic heart failure with electrical dyssynchrony. The LV lead position in patients with left bundle branch block is usually recommended at the LV posterolateral to the lateral site, which is the latest electrical activation site. In contrast, the preferable LV lead position in patients who plan to upgrade from conventional RV apical pacing to CRT remains unclear.
This study aimed to identify the preferable LV lead position for upgrading to CRT from conventional RV apical pacing.
An electrophysiological study was performed on patients who underwent ablation for atrial fibrillation. The electrode catheters were positioned at the RV apex, LV anterolateral, and LV posterolateral sites via the coronary sinus branches. During RV apical pacing, the activation time from the RV apex to the LV anterolateral and posterolateral sites was measured, and the activation time ratio to QRS duration was calculated. Biventricular pacing from both the RV apex and LV anterolateral or LV posterolateral sites was performed, and the difference in QRS duration and LV dP/dt compared to only the RV apical pacing state was measured.
We enrolled 37 patients who exhibited anterolateral and posterolateral LV coronary sinus branches. During RV apical pacing, the average activation time ratio to QRS duration was higher at the LV anterolateral site than at the LV posterolateral site (0.89±0.07 vs. 0.71±0.11, P <0.001). The shortening ratio of QRS duration during biventricular pacing compared to baseline RV apical pacing was greater at LV anterolateral site than at the LV posterolateral site (45.7±18.0% vs. 32.0±17.6%, P <0.001). The improvement ratio of LV dP/dt during biventricular pacing was also better from the LV anterolateral site than from the LV posterolateral site (12.7±8.9% vs. 3.7±8.2%, P <0.001).
Author notes
Funding Acknowledgements: None.
