Pacing and ECG characteristics during LBBAP
Pacing and ECG characteristics are summarized in Table 2. Implant pacing thresholds were low and comparable between the SDL and LLL group (unipolar pacing threshold 0.5±0.15 versus 0.4±0.17V at 1.0ms pulse width, p=0.251). Sensing values and lead impedances were comparable between both groups.
Paced QRS duration was 127±20.3ms in the SDL group compared to 131±23.6ms in the LLL group, p=0.570). Stimulus to LVAT measured 73±15.2ms in the SDL group compared to 71±11.2ms in the LLL group (p=0.703). In patients with narrow QRS, paced QRS duration increased significantly from 98±15.9ms to 121±17.7ms (p=0.005) with LBBAP, whereas in patients with left bundle branch block (LBBB) QRS duration decreased significantly from 170±16.7ms to 126±26.3ms (p= 0.011) with LBBAP. Changes in QRS duration for both narrow QRS and LBBB patients were comparable for SDL and LLL. LBBp were observed in 38% of the SDL patients compared to 13% of the LLL patients (p=0.198).