Validation of the novel criteria, delta-V6 and global R-Wave peak time for the confirmation of left bundle branch capture in patients with narrow QRS

We are continuously searching for straightforward criteria to confirm left bundle branch (LBB) capture during LBB area pacing (LBBAP), and delta-V6 R-Wave peak time (RWPT) and global RWPT were recently proposed as the most accurate criteria.

To validate and compare the performance of delta-V6RWPT and global RWPT as criteria for LBB capture in an external population of patients with a narrow QRS complex.

This was a single-center, retrospective study involving patients with narrow baseline QRS complex receiving LBB area pacing with bradycardia indication. LBB capture type was defined based on the presence of LBB-potential and QRS-morphology transition criteria during decremental pacing. In our study, delta-V6RWPT was measured from the beginning of the pacing artifact. Global RWPT was measured as V6RWPT + lead I RWPT. ROC analysis was performed, and the optimal cut-off values for discriminating LBBP from LVSP for both methods were calculated based on the Youden index.

Our analysis included 107 patients: 75 ECGs with non-selective LBB pacing (LBBP) and 92 ECGs with left ventricular septal pacing (LVSP). Delta-V6RWPT and global RWPT were significantly longer during LVSP than LBBP (51 ± 8 ms vs. 33 ± 7 ms; p<0.001 for delta-V6RWPT and 177 ± 15 ms vs. 145 ± 22 ms; p<0.01 for global RWPT). Both criteria performed well in discriminating LBBP from LVSP: for delta-V6RWPT, the cut-off value of 41 ms had an AUC of 0.96, a sensitivity of 91%, and a specificity of 93%, and for global RWPT, the cut-off value of 161.5 ms had an AUC of 0.93, a sensitivity of 91%, and a specificity of 88%. No statistical difference was found between AUC values for the above criteria (p=0.14).

Nevertheless, the combination of global RWPT and delta-RWPT optimal cut-off values demonstrated better diagnostic performance than the isolated measurements (AUC of 0.98, a sensitivity of 92% and a specificity of 96%, p=0.01 compared to global RWPT and p=0.09 compared to delta-V6RWPT).

Both delta-V6RWPT and global RWPT are highly specific and sensitive criteria that could be used to confirm LBB capture in patients with narrow QRS. Their combination might result in better diagnostic performance than the isolated measurements.

ROC curves for each criteria