3.4 Performance of conventional interrupted vs. continuous implantation technique
Excellent pacing performance was demonstrated in all patients (see table 1).
In the validation-group, conventional interrupted implantation leaded to successful LBBAP at first attempt in 7 patients (70%). Failure of success at first attempt was caused by difficulties in further progression of the lead, after initial penetration of the helix into the RV septum. By interruption after the initial rotations, loss of torque and momentum occurred, preventing further penetration and progression of the lead through the septum.
At final position, 6/10 patients (60%) had non-selective capture of the LBB, in the other 40% selective capture could be reached.
In the feasibility-group, continuous uninterrupted lead deployment leaded to successful LBBAP at first attempt in 18 patients (90%), at second (1 patients, 5%) or third attempt (1 patient, 5%). Failure of success at first attempt was exclusively due to suboptimal orientation of the sheath, impeding a good initial penetration of the helix into the RV septum. Small corrections in the position of the sheath enabled easy implantation of the lead in patients with a first failed attempt. At final position, 6/20 patients (30%) had non-selective capture of the LBB (p=0.77 vs validation-group), in the other 70%, selective capture could be reached (p=0.584 vs validation-group). No significant differences between the validation and feasibility-groups were observed for the paced QRS duration (median QRSd 116ms [IQR109-134ms] vs median QRSd 120ms [IQR 113-144ms] respectively, p=0.4018). However, the pLVAT tended to be longer in the validation compared to the feasibility-group without reaching significance (median pLVAT 87ms [IQR 72-100] vs median pLVAT 73ms [IQR 69-80], respectively, p=0.0577). Bipolar pacing thresholds at final position were significantly lower in the feasibility-group compared to the validation-group (mean threshold 0.81 ± 0.4 V vs 1.17 ± 0.4 V, respectively, p=0.0253) with comparable median bipolar sensing 6.5mV [IQR 4.6-9.5] in the feasibility group vs 9.9mmV [IQR 6.5-14] in the validation-group, p=0.0615) and mean impedance values (624 ± 101 Ohm in the feasibility-group vs 645 ± 74Ohm in the validation-group, p=0.4339). Total (skin to skin) fluoroscopic dose for device implantation was similar between groups with mean DAP 3110 ± 1587 mGycm2 in the validation-group, compared to 2793 ± 4079 mGycm2 in the feasibility-group (p=0.1405).