Deep Negative Deflection in Unipolar His-Bundle Electrogram as a Predictor of Excellent His-Bundle Pacing Threshold Postimplant

Abstract

Background: His-bundle pacing (HBP) is a physiological form of pacing. Although high capture thresholds are common, few predictors of low HBP threshold have been determined. We aimed to identify electrophysiological predictors. Methods: Fifty-one patients (53% with atrioventricular block) underwent HBP for bradycardia with an intrinsic QRS duration of <120 ms. Attempts to anchor the HBP lead were guided by unipolar His-bundle electrograms (HB EGMs) recorded with an electrophysiology recording system. Patients were followed-up for >6 months. Results: In total, 153 attempts at anchoring the HBP lead were made, of which, 45 achieved acceptable HBP thresholds (≤2.5 V at 1 ms). The amplitude of negative deflection in HB EGM and the selective HBP form at fixation were independently associated with achieving an acceptable threshold. A negative amplitude of ≥0.060 mV in HB EGM was determined as the optimal value for identifying the acceptable threshold. This deep negative HB EGM was recorded with an HBP threshold of 1.4±1.3 V (in 34 attempts), significantly lower than that of positive HB EGM without deep negative deflection (2.8±1.3 V, in 31 trials; or >5 V, in 38 trials). The permanent HBP lead remained with deep negative (≥0.060 mV) or positive HB EGMs in 28 and 14 patients, respectively, and with positive or negative HB injury current in 19 and 23 patients, respectively. During follow-up, increased HBP threshold of >1 V was significantly more prevalent in the positive HB EGM group. The HBP thresholds of deep negative HB EGM and HB injury current, but not of the selective HBP group, were significantly lower than the other subgroups during follow-up. Conclusions: Deep negative HB EGM at fixation was associated with an excellent short-term HBP threshold, similar to HB injury current. Analysis of unipolar HB EGM postfixation may enable prediction of permanent HBP threshold.

Electrophysiological characteristics and clinical values of left bundle branch current of injury in left bundle branch pacing

“…LBB COI reflects the anatomic location of the 3830 lead tip in the LBB region, presumably because of focally damaged cell membranes consequent to the trauma of electrode pressure against main conduction branch. LBB COI was observed in 77 out of 115 (67.0%) patients with an LBB potential, a rate higher than reported at the His bundle COI (37%‐45%) 3,4 . Compared with anatomical characteristics of His bundle which is in a small and often insulated region of the atrioventricular junction, and often buried deep within the endocardium, the proximal left bundle branches fan out through the LV septum and forms a wider target 12 .…”

“…Fixation of leads into myocardial tissue during cardiac device implantation results in acute tissue injury also known as current of injury (COI) and is recognized by an elevation of the ST‐segment compared with baseline and an increase in the duration of the intracardiac electrogram (EGM) 1 . Several studies have demonstrated that the presence of a COI is associated with better acute performance and long‐term stability with active fixation leads 1–6 . Vijayaraman et al 3 reported the presence of His bundle COI with leads implanted at the His bundle.…”

“…performance and long-term stability with active fixation leads. [1][2][3][4][5][6] Vijayaraman et al 3 reported the presence of His bundle COI with leads implanted at the His bundle. His bundle COI was noted in 37% of cases undergoing His bundle pacing (HBP) and was associated with a low pacing threshold.…”

“…LBB COI was observed in 77 out of 115 (67.0%) patients with an LBB potential, a rate higher than reported at the His bundle COI (37%-45%). 3,4 Compared with anatomical characteristics of His bundle which is in a small and often insulated region of the atrioventricular junction, and often buried deep within the endocardium, the proximal left bundle branches fan out through the LV septum and forms a wider target. 12 Thus, it is easier to reach the LBB region, directly cause injury of local bundle around the tip of the lead at successful site with an associated LBB COI.…”

Study design and protocol for evaluating the long‐term prognosis of patients receiving his bundle pacing: A multicenter observational study

“…In Japan, HBP was introduced in 2017, and the number of HBP implantations performed for conduction diseases has been gradually increasing. There were several reports of unique observations in patients who received HBP, and studies with small sample sizes in single centers in Japan . However, the long‐term performance, efficacy, and safety of HBP in Japanese patients are unknown.…”