TY - JOUR
AU1 - Richter, Sergio
AU2 - Ebert, Micaela
AU3 - Bertagnolli, Livio
AU4 - Gebauer, Roman
AU5 - Lucas, Johannes
AU6 - Scheller, Dominik
AU7 - Paetsch, Ingo
AU8 - Hindricks, Gerhard
AU9 - Döring, Michael
AB - Abstract Aims Conventional His bundle pacing (HBP) can be technically challenging and fluoroscopy-intense, particularly in patients with His-Purkinje conduction disease (HPCD). Three-dimensional electroanatomical mapping (EAM) facilitates non-fluoroscopic lead navigation and HB electrogram mapping. We sought to assess the procedural outcome of routine EAM-guided HBP compared with conventional HBP in a real-world population and evaluate the feasibility and safety of EAM-guided HBP in patients with HPCD. Methods and results  We included 58 consecutive patients (72 ± 13 years; 71% male) who underwent an attempt to conventional (EAM− group; n = 29) or EAM-guided (EAM+ group; n = 29) HBP between June 2019 and April 2020. The centre’s learning curve was initially determined (n = 40 cases) to define the conventional control group and minimize outcome bias favouring EAM-guided HBP. His bundle pacing was successful in 26 patients (90%) in the EAM+ and 27 patients (93%) in the EAM− group (P = 0.64). The procedure time was 90 (73–135) and 110 (70–130) min, respectively (P = 0.89). The total fluoroscopy time [0.7 (0.5–1.4) vs. 3.3 (1.4–6.5) min; P < 0.001] and fluoroscopy dose [21.9 (9.1–47.7) vs. 78.6 (27.2–144.9) cGycm2; P = 0.001] were significantly lower in the EAM+ than EAM− group. There were no significant differences between groups in His capture threshold (1.2 ± 0.6 vs. 1.4 ± 1.0 V/1.0 ms; P = 0.33) and paced QRS duration (113 ± 15 vs. 113 ± 17 ms; P = 0.89). In patients with HPCD, paced QRS duration was similar in both groups (121 ± 15 vs. 123 ± 12 ms; P = 0.77). The bundle branch-block recruitment threshold tended to be lower in the EAM+ than EAM− group (1.3 ± 0.7 vs. 1.8 ± 1.2 V/1.0 ms; P = 0.31). No immediate procedure-related complications occurred. One patient (2%) experienced lead dislodgement during 4-week follow-up. Conclusion  Implementation of routine EAM-guided HBP lead implantation is feasible and safe in a real-world cohort of patients with and without HPCD and results in a tremendous reduction in radiation exposure without prolonging procedure time or increasing procedure-related complications. His bundle pacing, Electroanatomical mapping, Radiation exposure, Implantation technique, Cardiac implantable electronic device What’s new? Implementation of electroanatomical mapping (EAM)-guided lead implantation into routine clinical practice for His bundle pacing (HBP) in a real-world patient population. Electroanatomical mapping-guided HBP is feasible and safe in patients with His-Purkinje conduction disease. Our refined approach to EAM-guided lead implantation without routine use of navigation-enabled mapping catheter(s) enables virtual near-zero fluoroscopy HBP without prolonging procedure time or increasing procedure-related complications. Introduction Permanent His bundle pacing (HBP) has been established in clinical practice and is currently recommended as an alternative physiological pacing modality in patients with an indication for ventricular pacing.1 HBP enables synchronous ventricular activation by direct stimulation of the proximal His-Purkinje conduction system and may therefore obviate the potentially deleterious effects of right ventricular pacing (RVP) on cardiac function.2 Clinical and functional benefits of HBP over RVP have consistently been demonstrated in recent studies.3,4 His bundle pacing is also capable of recruiting and normalizing conduction in patients with bundle branch block (BBB) and holds promise as an alternative to cardiac resynchronization therapy (CRT).5,6 However, conventional mapping of the His bundle (HB) region and HBP lead placement can be technically challenging and time consuming and is actually associated with significantly higher fluoroscopy exposure compared to conventional RVP,4,7 particularly in patients with His-Purkinje conduction disease (HPCD) and complex structural abnormalities. Three-dimensional (3D) electroanatomical mapping (EAM) facilitates non-fluoroscopic visualization and navigation of the HBP lead and mapping of the HB region, which translates into a significant reduction in radiation exposure.8 Moreover, the improved spatial resolution allows for precise high-density electrogram (EGM) and pace mapping with non-fluoroscopic visualization and annotation of the His cloud and corresponding pacing responses. The safety and feasibility of different approaches to EAM-guided HBP have recently been demonstrated in small series of pacemaker recipients.8,9 Accordingly, we have implemented EAM-guided lead implantation into our routine clinical practice following a refined protocol in unselected patients with and without HPCD. The aim of the present study was (i) to assess the procedural outcomes of routine EAM-guided HBP compared to conventional fluoroscopy-guided HBP in a real-world population; (ii) to evaluate the feasibility and safety of EAM-guided HBP in patients with HPCD; and (iii) to describe in detail our ‘easy-to-use’ protocol for EAM-guided HBP without routine use of navigation-enabled electrophysiological (EP) catheters. Methods Patient selection This prospective observational single-centre study included consecutive patients with an established indication for antibradycardia pacing or CRT who underwent attempted permanent HBP using the Medtronic Select Secure 3830 pacing lead between March 2018 and April 2020. As of October 2019, EAM-guided lead implantation was performed in all consecutive patients following a refined standardized protocol irrespective of the pacing indication and type of conduction disease. Patients were excluded from analysis if they had undergone investigational HBP using lead delivery tools from other manufacturers, His-optimized CRT procedures, or revision procedures with concomitant transvenous lead extraction. The learning curve and experience of the implanting centre was determined by analysis of the cumulative total fluoroscopy time and exposure per patient in order to define the control group and prevent outcome bias by excluding the run-in-phase procedures performed during the learning curve.7 All patients were >18 years of age and provided written informed consent. The study protocol was approved by the local institutional review board. Implantation procedure De novo or upgrade pacemaker and CRT procedures were performed using standard implantation techniques. Depending on the indication for device therapy, active-fixation right atrial (RA) pacing and/or right ventricular (RV) pacing, or implantable cardioverter-defibrillator leads were implanted in addition to the HBP lead via the cephalic, axillary, or subclavian vein. The RA lead was usually positioned at the RA appendage, the RV lead at the septal RV outflow tract, or mid-septal RV under minimized low-dose fluoroscopic guidance. Implantation of a backup RV lead was considered in the following scenarios: (i) planned atrioventricular nodal ablation (AVNA) for treatment of atrial fibrillation (AF) refractory to rate or rhythm control therapy (pace-and-ablate strategy); (ii) pacing-dependent patients with infranodal conduction block; and (iii) unacceptably low ventricular sensing but perfect pacing response after several lead positioning attempts. The decision to implant a backup RV lead was eventually left to the operator’s discretion. Lead-device configurations relevant for real-world HBP are illustrated in Supplementary material online, Figure S1. A 12-lead electrocardiogram (ECG) was continuously recorded at a sweep speed of 100 mm/s and displayed during the entire procedure to facilitate evaluation of selective HBP (S-HBP), non-selective HBP (NS-HBP), and correction of BBB patterns. Implantation procedures were performed in local anaesthesia and either minimal, conscious, or deep sedation. Electrogram- and fluoroscopy-guided His bundle pacing lead implantation Conventional HBP lead implantation was routinely performed using the Select Secure pacing lead (Model 3830, 69 cm; Medtronic, Inc., Minneapolis, MN, USA) delivered through a fixed-curve sheath (C315His; Medtronic, Inc., Minneapolis, MN, USA) as previously described.10 In selected patients with structural heart disease, in whom the HB region could not be reached by the fixed-curve sheath, the HBP lead was delivered through a deflectable sheath (C304, Medtronic, Inc., Minneapolis, MN, USA) or the sheath-in-sheath technique. The Select Secure pacing lead was connected to an alligator clamp threshold cable (St. Jude Medical, Minnetonka, MN, USA) in a unipolar fashion. The alligator clamp cable was pinned to the catheter input module of the EP recording system (Prucka Cardiolab, GE Healthcare, Waukesha, WI, USA) and connected to the pacing system analyzer (PSA) (Merlin PCS 3650, St. Jude Medical, Sylmar, CA, USA) using a custom-made jumper cable for simultaneous recording of EGMs and measured electrical data. After the respective sheath had been introduced over a long guidewire into the RA, the electrically connected HBP lead was advanced to the tip of the guiding sheath with its screw/distal tip exposed minimally to enable unipolar HB electrogram (HBE) mapping and unipolar pacing. Once an appropriate HBE has been identified, unipolar pacing was performed with an initial output of 3.0 V and HB capture threshold assessed at a pulse width of 1.0 ms. The HBP lead was then screwed-in by 4–5 clockwise rotations. When EGM-based mapping could not record an HBE or subsequent pacing at different HB positions failed to result in the requested QRS complex, pace mapping was performed to identify an appropriate pacing site. Withdrawal and slitting of the delivery sheath(s) were performed under minimized low-dose fluoroscopic guidance. Electroanatomical mapping-guided His bundle pacing lead implantation Electroanatomical mapping-guided lead implantation was performed using the EnSite Precision Cardiac Mapping System (St. Jude Medical, St. Paul, MN, USA). In order to assure optimal catheter stability and accuracy during EAM, the tip electrode of an implanted bipolar active-fixation RA or RV lead was used as reference. The reference electrode was connected to a second alligator clamp cable in a bipolar fashion. Similar to the connection of the Select Secure pacing lead, the alligator clamp cable was pinned to the joint catheter input module of the EP recording and 3D mapping systems. The reference electrode was also connected to the PSA via a custom-made jumper cable for simultaneous recording of EGMs and measured electrical data (Supplementary material online, Figure S2). Supplementary material online, Table S2 summarizes the additional technical equipment required for EAM-guided HBP using the EnSite Precision system. Non-fluoroscopic EAM of the HB region was performed in a unipolar fashion with the distal tip of the Select Secure pacing lead positioned slightly beyond the tip of the guiding sheath. A steerable multi-electrode mapping catheter (Inquiry; St. Jude Medical, Irvine, CA, USA; or Advisor HD Grid, Abbott, Plymouth, MN, USA) was only used in preselected patients with complex cardiac anatomy or when the His could not be mapped with the Select Secure pacing lead. In exceptional cases, HBP lead implantation was guided by EAM with integration of the cardiac magnetic resonance (CMR)-derived 3D model of the right heart.11 Once connected to the EAM system, the tip of the pacing lead (or mapping catheter) can directly be visualized and non-fluoroscopically navigated to the HB region with simultaneous acquisition of 3D geometry (Figure 1). Mapping sites which displayed a proximal or distal HBE were recorded and tagged on the map (Figures 1 and2). At appropriate target sites, unipolar pacing was performed via the PSA with an initial output of 3.0 V and HB capture threshold assessed at a pulse width of 1.0 ms. Mapping sites with good/acceptable threshold(s) for S-HBP and/or NS-HBP were tagged and electrical data displayed colour-coded on the map if applicable (Figure 3). After fixation of the HBP lead at an appropriate site and withdrawal of the guiding sheath into the RA, lead position and slack were confirmed by a snapshot fluoroscopic image (Figure 1D). Final slitting of the guiding sheath was also performed under minimized low-dose fluoroscopic guidance to assure and document steady lead position and adequate slack. The HBP lead remained connected to the EAM system throughout these steps to closely monitor lead stability. Figure 1 Open in new tabDownload slide HBP guided by the Ensite-Precision system in a patient with LBBB and second-degree infrahisian conduction block. (A) Electroanatomical maps with tagged proximal (yellow dot), distal (blue and turquoise dots), and the target (red dot) HB locations in right anterior oblique (left panel) and LAO cranial (right panel) projections. The green icon represents the visualized roving lead tip screwed-in at the target HB location. (B) Twelve-lead ECG, bipolar atrial electrogram, and uni-/bipolar HBE recorded from the screwed-in lead tip on the mapping system. (C) Corresponding HBE and NS-HBP with LBBB recruitment at final lead position. Continuous HBE recording revealed second-degree infrahisian conduction block (C, lower panel). (D) Snapshot fluoroscopic image confirming lead position and adequate slack after sheath withdrawal in LAO projection. (E) Twelve-lead ECG at 4-week follow-up demonstrating NS-HBP with LBBB recruitment. ECG, electrocardiogram; HBE, HB electrograms; HBP, His bundle pacing; LAO, left anterior oblique; LBBB, left bundle-branch block; NS-HBP, non-selective HBP. Figure 1 Open in new tabDownload slide HBP guided by the Ensite-Precision system in a patient with LBBB and second-degree infrahisian conduction block. (A) Electroanatomical maps with tagged proximal (yellow dot), distal (blue and turquoise dots), and the target (red dot) HB locations in right anterior oblique (left panel) and LAO cranial (right panel) projections. The green icon represents the visualized roving lead tip screwed-in at the target HB location. (B) Twelve-lead ECG, bipolar atrial electrogram, and uni-/bipolar HBE recorded from the screwed-in lead tip on the mapping system. (C) Corresponding HBE and NS-HBP with LBBB recruitment at final lead position. Continuous HBE recording revealed second-degree infrahisian conduction block (C, lower panel). (D) Snapshot fluoroscopic image confirming lead position and adequate slack after sheath withdrawal in LAO projection. (E) Twelve-lead ECG at 4-week follow-up demonstrating NS-HBP with LBBB recruitment. ECG, electrocardiogram; HBE, HB electrograms; HBP, His bundle pacing; LAO, left anterior oblique; LBBB, left bundle-branch block; NS-HBP, non-selective HBP. Figure 2 Open in new tabDownload slide Targeted HBP guided by the Ensite-Precision system in a patient with RBBB and left atrial macro-reentrant tachycardia with slow ventricular response. (A) Electroanatomical maps with tagged proximal and distal (yellow dots) and the target (red dot) HB locations in right anterior oblique (left panel) and left anterior oblique cranial (right panel) projections. The green icon represents the visualized roving lead tip screwed-in at the target HB location. (B) Twelve-lead ECG and unipolar HBE recorded from the screwed-in lead tip on the mapping system. (C) Corresponding electrograms from the tagged HB locations and NS-HBP with RBBB recruitment at final lead position. (D) Unipolar HBE recorded from the screwed-in lead tip on the analyzer. (B and D) Note the HB injury current on the unipolar HBE (arrow). ECG, electrocardiogram; HBE, HB electrograms; HBP, His bundle pacing; NS-HBP, non-selective HBP; RBBB, right bundle-branch block. Figure 2 Open in new tabDownload slide Targeted HBP guided by the Ensite-Precision system in a patient with RBBB and left atrial macro-reentrant tachycardia with slow ventricular response. (A) Electroanatomical maps with tagged proximal and distal (yellow dots) and the target (red dot) HB locations in right anterior oblique (left panel) and left anterior oblique cranial (right panel) projections. The green icon represents the visualized roving lead tip screwed-in at the target HB location. (B) Twelve-lead ECG and unipolar HBE recorded from the screwed-in lead tip on the mapping system. (C) Corresponding electrograms from the tagged HB locations and NS-HBP with RBBB recruitment at final lead position. (D) Unipolar HBE recorded from the screwed-in lead tip on the analyzer. (B and D) Note the HB injury current on the unipolar HBE (arrow). ECG, electrocardiogram; HBE, HB electrograms; HBP, His bundle pacing; NS-HBP, non-selective HBP; RBBB, right bundle-branch block. Figure 3 Open in new tabDownload slide LBBAP guided by the Ensite-Precision system in a patient with new-onset LBBB and intermittent atrioventricular block after transcatheter aortic valve replacement and insufficient QRS narrowing with HBP. (A) Electroanatomical maps with tagged HB cloud (yellow dots), proximal and distal RB locations (blue dots), and the target (red dot) LBB location in right anterior oblique (left panel) and LAO cranial (right panel) projections. The green icon represents the visualized roving lead tip screwed-in at the target LBB location. Local activation times during HB and RB activation are displayed colour-coded on the map. (B) Sheath angiography in LAO projection confirming the lead tip deep in the interventricular septum (arrow). (C) Twelve-lead ECG, corresponding proximal and distal HBE with best possible HBP response, and LBBAP response at final lead position. (D) Echocardiographic image in apical four-chamber view confirmed lead position in the interventricular septum (arrow). (E) Twelve-lead ECG at 4-week follow-up demonstrating NS-LBBAP with LBBB recruitment. ECG, electrocardiogram; HBE, HB electrograms; LAO, left anterior oblique; LBBAP, left bundle branch area pacing; HBP, His bundle pacing; LBBB, left bundle-branch block; NS-LBBAP, non-selective left bundle branch area pacing; RB, right bundle; Figure 3 Open in new tabDownload slide LBBAP guided by the Ensite-Precision system in a patient with new-onset LBBB and intermittent atrioventricular block after transcatheter aortic valve replacement and insufficient QRS narrowing with HBP. (A) Electroanatomical maps with tagged HB cloud (yellow dots), proximal and distal RB locations (blue dots), and the target (red dot) LBB location in right anterior oblique (left panel) and LAO cranial (right panel) projections. The green icon represents the visualized roving lead tip screwed-in at the target LBB location. Local activation times during HB and RB activation are displayed colour-coded on the map. (B) Sheath angiography in LAO projection confirming the lead tip deep in the interventricular septum (arrow). (C) Twelve-lead ECG, corresponding proximal and distal HBE with best possible HBP response, and LBBAP response at final lead position. (D) Echocardiographic image in apical four-chamber view confirmed lead position in the interventricular septum (arrow). (E) Twelve-lead ECG at 4-week follow-up demonstrating NS-LBBAP with LBBB recruitment. ECG, electrocardiogram; HBE, HB electrograms; LAO, left anterior oblique; LBBAP, left bundle branch area pacing; HBP, His bundle pacing; LBBB, left bundle-branch block; NS-LBBAP, non-selective left bundle branch area pacing; RB, right bundle; Definitions His bundle pacing was defined successful if the HBP lead could be permanently implanted at the HB with good/acceptable capture threshold(s) (<3.0 V/1.0 ms) for S-HBP and/or NS-HBP, or corrective HBP in patients with BBB. The criteria for S-HBP, NS-HBP, and HBP with and without BBB recruitment were adopted from previously published recommendations.12 Follow-up Follow-up was performed pre-discharge and 4 weeks post-implantation for the purpose of the study. At the outpatient follow-up visit, the clinical status and device function were assessed. His capture threshold testing including assessment of the type of HBP and BBB recruitment was performed during continuous 12-lead ECG recording at a sweep speed of 25 mm/s. Lead-related complications were routinely tracked. Devices were programmed based on the indication, complexity of the system, and patients’ individual needs.13 Patients scheduled for the pace-and-ablate strategy underwent AVNA usually at 4-week follow-up after confirmation of good and stable HBP lead parameters. Statistical analysis Data are expressed as number and percentage for categorical variables and median (interquartile range) or mean ± SD for continuous variables. The changes in QRS duration with HBP are also expressed as mean ± SEM. Descriptive statistics were reported for the overall cohort and subgroup of patients with HPCD stratified by EAM-guided (EAM+) HBP and non-EAM-guided (EAM−) HBP. The χ2 and Fisher’s exact tests were used to compare categorical variables. Continuous variables between groups were analysed by the Student’s t-test or Mann–Whitney test, as appropriate. A probability value <0.05 was considered statistically significant. Statistical analysis was performed using SPSS 26.0 software package (SPSS Inc., Chicago, IL, USA). Results A total of 98 patients fulfilled the selection criteria and were basically considered for analysis. Initial assessment of the learning curve revealed that radiation exposure rapidly decreased with increasing number of cases and experience in HBP until plateauing after about 40 cases (Figure 4). In particular, the cumulative median total fluoroscopy time levelled off at 3 min until EAM-guided HBP lead implantation was implemented and routinely performed (Figure 4A). Comparable plateauing was observed for the cumulative median total fluoroscopy dose (Figure 4B). Accordingly, the initial 40 cases were excluded from analysis in order to minimize outcome bias favouring EAM-guided HBP. Figure 4 Open in new tabDownload slide Cumulative total fluoroscopy time (A) and fluoroscopy dose (B) per patient with attempted HBP. Note the rapid decline in radiation exposure as experience in HBP increased until plateauing after about 40 cases. Determination of the LC provided the rationale to exclude the first 40 patients from analysis and defined the control group (patient #41–69). EAM+ indicates implementation of EAM-guided HBP (patient #70–98). Data represent the cumulative mean and median total FT and FD per 10 consecutive patients. EAM, electroanatomical mapping; FD, fluoroscopy dose; FT, fluoroscopy time; HBP, His bundle pacing; LC, learning curve. Figure 4 Open in new tabDownload slide Cumulative total fluoroscopy time (A) and fluoroscopy dose (B) per patient with attempted HBP. Note the rapid decline in radiation exposure as experience in HBP increased until plateauing after about 40 cases. Determination of the LC provided the rationale to exclude the first 40 patients from analysis and defined the control group (patient #41–69). EAM+ indicates implementation of EAM-guided HBP (patient #70–98). Data represent the cumulative mean and median total FT and FD per 10 consecutive patients. EAM, electroanatomical mapping; FD, fluoroscopy dose; FT, fluoroscopy time; HBP, His bundle pacing; LC, learning curve. Baseline characteristics The study cohort consisted of 58 consecutive patients (mean age 72 ± 13 years; 71% male) who underwent attempted HBP. The first 29 of these patients (patient #41–69 in Figure 4) underwent conventional fluoroscopy-guided HBP (EAM− group), the subsequent 29 patients (patient #70–98 in Figure 4) underwent EAM-guided HBP (EAM+ group). The baseline LVEF of the study cohort was 54 ± 13%, the baseline QRS duration (QRSd) 131 ± 37 ms. Twenty-nine patients (50%) had an intrinsic QRSd >120 ms, 8 patients (14%) presented with LBBB and 21 patients (36%) with RBBB. The leading indication for HBP was intermittent or persistent AV block in 50%, followed by CRT in 24% of the cases. Importantly, there were no significant differences between groups in baseline characteristics, indication for pacing, or type of implanted device (Table 1). Baseline characteristics did also not differ between EAM+ and EAM− groups in patients with HPCD, including intrinsic QRSd (163 ± 15 vs. 167 ± 13 ms, respectively; P = 0.48) and incidence of infrahisian block (54% vs. 41%, respectively; P = 0.49). Table 1 Baseline characteristics . All patients (n = 58) . EAM+ (n = 29) . EAM− (n = 29) . P value . Age (years) 72 ± 13 73 ± 13 71 ± 13 0.67 Male, n (%) 41 (71) 20 (69) 21 (72) 0.77 Cardiac comorbidities  AF, n (%) 27 (47) 13 (45) 14 (48) 0.79  HTN, n (%) 48 (83) 23 (79) 25 (86) 0.49  CAD, n (%) 15 (26) 7 (24) 8 (28) 0.76  Ischaemic CMP, n (%) 4 (7) 2 (7) 2 (7) 1.00  Non-ischaemic CMP, n (%) 13 (22) 7 (24) 6 (21) 0.75  AVR, n (%) 5 (9) 2 (7) 3 (10) 1.00  MVR, n (%) 2 (3) 0 (0) 2 (7) 0.49 Baseline ECG characteristics  Sinus rhythm, n (%) 44 (76) 23 (79) 21 (72) 0.54  PR interval (ms) 234 ± 65 231 ± 54 237 ± 75 0.76  QRS duration (ms) 131 ± 37 127 ± 34 136 ± 39 0.35   >120 ms, n (%) 29 (50) 12 (41) 17 (59) 0.23  LBBB, n (%) 8 (14) 4 (14) 4 (14) 1.00  RBBB, n (%) 21 (36) 8 (28) 13 (45) 0.17 Baseline ECHO characteristics  LVEF (%) 54 ± 13 53 ± 13 54 ± 13 0.68   36–50%, n (%) 9 (16) 5 (17) 4 (14) 1.00   ≤35%, n (%) 8 (14) 4 (14) 4 (14) 1.00  IVS, mm 12 ± 2 12 ± 2 12 ± 2 0.86  Mild TR (I°), n (%) 37 (64) 21 (72) 16 (55) 0.17  Moderate TR (II°), n (%) 2 (3) 0 (0) 2 (7) 0.24  RA enlargement, n (%) 9/52 (17) 3/27 (11) 6/25 (24) 0.28 Indications for pacing  AVB, n (%) 29 (50) 15 (52) 14 (48) 0.79  SND, n (%) 8 (14) 4 (14) 4 (14) 1.00  CRT, n (%) 14 (24) 6 (21) 8 (28) 0.54   Upgrade to CRT, n (%) 5 (9) 1 (3) 4 (14) 0.35  Pace-and-ablate, n (%) 7 (12) 4 (14) 3 (10) 1.00 Implanted devices  Single-chamber PM, n (%) 0 (0) 0 (0) 0 (0) –  Dual-chamber PM, n (%) 26 (45) 11 (38) 15 (52) 0.29  Biventricular PM, n (%) 26 (45)a 14 (48) 12 (41) 0.60  Biventricular ICD, n (%) 6 (10) 4 (14)b 2 (7) 0.67 . All patients (n = 58) . EAM+ (n = 29) . EAM− (n = 29) . P value . Age (years) 72 ± 13 73 ± 13 71 ± 13 0.67 Male, n (%) 41 (71) 20 (69) 21 (72) 0.77 Cardiac comorbidities  AF, n (%) 27 (47) 13 (45) 14 (48) 0.79  HTN, n (%) 48 (83) 23 (79) 25 (86) 0.49  CAD, n (%) 15 (26) 7 (24) 8 (28) 0.76  Ischaemic CMP, n (%) 4 (7) 2 (7) 2 (7) 1.00  Non-ischaemic CMP, n (%) 13 (22) 7 (24) 6 (21) 0.75  AVR, n (%) 5 (9) 2 (7) 3 (10) 1.00  MVR, n (%) 2 (3) 0 (0) 2 (7) 0.49 Baseline ECG characteristics  Sinus rhythm, n (%) 44 (76) 23 (79) 21 (72) 0.54  PR interval (ms) 234 ± 65 231 ± 54 237 ± 75 0.76  QRS duration (ms) 131 ± 37 127 ± 34 136 ± 39 0.35   >120 ms, n (%) 29 (50) 12 (41) 17 (59) 0.23  LBBB, n (%) 8 (14) 4 (14) 4 (14) 1.00  RBBB, n (%) 21 (36) 8 (28) 13 (45) 0.17 Baseline ECHO characteristics  LVEF (%) 54 ± 13 53 ± 13 54 ± 13 0.68   36–50%, n (%) 9 (16) 5 (17) 4 (14) 1.00   ≤35%, n (%) 8 (14) 4 (14) 4 (14) 1.00  IVS, mm 12 ± 2 12 ± 2 12 ± 2 0.86  Mild TR (I°), n (%) 37 (64) 21 (72) 16 (55) 0.17  Moderate TR (II°), n (%) 2 (3) 0 (0) 2 (7) 0.24  RA enlargement, n (%) 9/52 (17) 3/27 (11) 6/25 (24) 0.28 Indications for pacing  AVB, n (%) 29 (50) 15 (52) 14 (48) 0.79  SND, n (%) 8 (14) 4 (14) 4 (14) 1.00  CRT, n (%) 14 (24) 6 (21) 8 (28) 0.54   Upgrade to CRT, n (%) 5 (9) 1 (3) 4 (14) 0.35  Pace-and-ablate, n (%) 7 (12) 4 (14) 3 (10) 1.00 Implanted devices  Single-chamber PM, n (%) 0 (0) 0 (0) 0 (0) –  Dual-chamber PM, n (%) 26 (45) 11 (38) 15 (52) 0.29  Biventricular PM, n (%) 26 (45)a 14 (48) 12 (41) 0.60  Biventricular ICD, n (%) 6 (10) 4 (14)b 2 (7) 0.67 Data are presented as mean ± SD or n (%). AF, atrial fibrillation; AVB, atrioventricular block; AVR, (transcatheter or surgical) aortic valve replacement; CAD, coronary artery disease; CMP, cardiomyopathy; CRT, cardiac resynchronization therapy; EAM, electroanatomical mapping; ECG, electrocardiogram; HTN, hypertension; ICD, implantable cardioverter-defibrillator; IVS, interventricular septum; LBBB, left bundle branch block; LVEF, left ventricular ejection fraction; MVR, mitral valve replacement or repair; PM, pacemaker; RA, right atrial; RBBB, right bundle branch block; SND, sinus node dysfunction; TR, tricuspid regurgitation. a Patients either underwent an upgrade from dual-chamber pacing to HBP or received a backup RV lead (HB lead in LV port). b Including one patient with LBBB and failed HBP who underwent conventional LV lead placement. Open in new tab Table 1 Baseline characteristics . All patients (n = 58) . EAM+ (n = 29) . EAM− (n = 29) . P value . Age (years) 72 ± 13 73 ± 13 71 ± 13 0.67 Male, n (%) 41 (71) 20 (69) 21 (72) 0.77 Cardiac comorbidities  AF, n (%) 27 (47) 13 (45) 14 (48) 0.79  HTN, n (%) 48 (83) 23 (79) 25 (86) 0.49  CAD, n (%) 15 (26) 7 (24) 8 (28) 0.76  Ischaemic CMP, n (%) 4 (7) 2 (7) 2 (7) 1.00  Non-ischaemic CMP, n (%) 13 (22) 7 (24) 6 (21) 0.75  AVR, n (%) 5 (9) 2 (7) 3 (10) 1.00  MVR, n (%) 2 (3) 0 (0) 2 (7) 0.49 Baseline ECG characteristics  Sinus rhythm, n (%) 44 (76) 23 (79) 21 (72) 0.54  PR interval (ms) 234 ± 65 231 ± 54 237 ± 75 0.76  QRS duration (ms) 131 ± 37 127 ± 34 136 ± 39 0.35   >120 ms, n (%) 29 (50) 12 (41) 17 (59) 0.23  LBBB, n (%) 8 (14) 4 (14) 4 (14) 1.00  RBBB, n (%) 21 (36) 8 (28) 13 (45) 0.17 Baseline ECHO characteristics  LVEF (%) 54 ± 13 53 ± 13 54 ± 13 0.68   36–50%, n (%) 9 (16) 5 (17) 4 (14) 1.00   ≤35%, n (%) 8 (14) 4 (14) 4 (14) 1.00  IVS, mm 12 ± 2 12 ± 2 12 ± 2 0.86  Mild TR (I°), n (%) 37 (64) 21 (72) 16 (55) 0.17  Moderate TR (II°), n (%) 2 (3) 0 (0) 2 (7) 0.24  RA enlargement, n (%) 9/52 (17) 3/27 (11) 6/25 (24) 0.28 Indications for pacing  AVB, n (%) 29 (50) 15 (52) 14 (48) 0.79  SND, n (%) 8 (14) 4 (14) 4 (14) 1.00  CRT, n (%) 14 (24) 6 (21) 8 (28) 0.54   Upgrade to CRT, n (%) 5 (9) 1 (3) 4 (14) 0.35  Pace-and-ablate, n (%) 7 (12) 4 (14) 3 (10) 1.00 Implanted devices  Single-chamber PM, n (%) 0 (0) 0 (0) 0 (0) –  Dual-chamber PM, n (%) 26 (45) 11 (38) 15 (52) 0.29  Biventricular PM, n (%) 26 (45)a 14 (48) 12 (41) 0.60  Biventricular ICD, n (%) 6 (10) 4 (14)b 2 (7) 0.67 . All patients (n = 58) . EAM+ (n = 29) . EAM− (n = 29) . P value . Age (years) 72 ± 13 73 ± 13 71 ± 13 0.67 Male, n (%) 41 (71) 20 (69) 21 (72) 0.77 Cardiac comorbidities  AF, n (%) 27 (47) 13 (45) 14 (48) 0.79  HTN, n (%) 48 (83) 23 (79) 25 (86) 0.49  CAD, n (%) 15 (26) 7 (24) 8 (28) 0.76  Ischaemic CMP, n (%) 4 (7) 2 (7) 2 (7) 1.00  Non-ischaemic CMP, n (%) 13 (22) 7 (24) 6 (21) 0.75  AVR, n (%) 5 (9) 2 (7) 3 (10) 1.00  MVR, n (%) 2 (3) 0 (0) 2 (7) 0.49 Baseline ECG characteristics  Sinus rhythm, n (%) 44 (76) 23 (79) 21 (72) 0.54  PR interval (ms) 234 ± 65 231 ± 54 237 ± 75 0.76  QRS duration (ms) 131 ± 37 127 ± 34 136 ± 39 0.35   >120 ms, n (%) 29 (50) 12 (41) 17 (59) 0.23  LBBB, n (%) 8 (14) 4 (14) 4 (14) 1.00  RBBB, n (%) 21 (36) 8 (28) 13 (45) 0.17 Baseline ECHO characteristics  LVEF (%) 54 ± 13 53 ± 13 54 ± 13 0.68   36–50%, n (%) 9 (16) 5 (17) 4 (14) 1.00   ≤35%, n (%) 8 (14) 4 (14) 4 (14) 1.00  IVS, mm 12 ± 2 12 ± 2 12 ± 2 0.86  Mild TR (I°), n (%) 37 (64) 21 (72) 16 (55) 0.17  Moderate TR (II°), n (%) 2 (3) 0 (0) 2 (7) 0.24  RA enlargement, n (%) 9/52 (17) 3/27 (11) 6/25 (24) 0.28 Indications for pacing  AVB, n (%) 29 (50) 15 (52) 14 (48) 0.79  SND, n (%) 8 (14) 4 (14) 4 (14) 1.00  CRT, n (%) 14 (24) 6 (21) 8 (28) 0.54   Upgrade to CRT, n (%) 5 (9) 1 (3) 4 (14) 0.35  Pace-and-ablate, n (%) 7 (12) 4 (14) 3 (10) 1.00 Implanted devices  Single-chamber PM, n (%) 0 (0) 0 (0) 0 (0) –  Dual-chamber PM, n (%) 26 (45) 11 (38) 15 (52) 0.29  Biventricular PM, n (%) 26 (45)a 14 (48) 12 (41) 0.60  Biventricular ICD, n (%) 6 (10) 4 (14)b 2 (7) 0.67 Data are presented as mean ± SD or n (%). AF, atrial fibrillation; AVB, atrioventricular block; AVR, (transcatheter or surgical) aortic valve replacement; CAD, coronary artery disease; CMP, cardiomyopathy; CRT, cardiac resynchronization therapy; EAM, electroanatomical mapping; ECG, electrocardiogram; HTN, hypertension; ICD, implantable cardioverter-defibrillator; IVS, interventricular septum; LBBB, left bundle branch block; LVEF, left ventricular ejection fraction; MVR, mitral valve replacement or repair; PM, pacemaker; RA, right atrial; RBBB, right bundle branch block; SND, sinus node dysfunction; TR, tricuspid regurgitation. a Patients either underwent an upgrade from dual-chamber pacing to HBP or received a backup RV lead (HB lead in LV port). b Including one patient with LBBB and failed HBP who underwent conventional LV lead placement. Open in new tab Procedural outcome The overall success of attempted HBP lead implantation was 91% with no difference between groups. Permanent HBP was successful in 26 patients (90%) in the EAM+ group and 27 patients (93%) in the EAM− group (P = 0.64). All five patients with unsuccessful HBP either had LBBB (n = 2) or RBBB plus LAFB (n = 3) with broad QRS complex (QRSd 170 ± 17 ms). The reason for failure was inability to recruit the distal His-Purkinje conduction system and/or significantly narrow the QRS complex at reasonable pacing output. Two patients were successfully switched to LBB area pacing (LBBAP) (Figure 3) and one patient to conventional biventricular pacing. The remaining two patients with RBBB and LAFB were managed by HBP with AV/VV delay optimization. The procedure time was 93 (70–131) min and did not differ between the EAM+ and EAM− groups [90 (73–135) vs. 110 (70–130) min; P = 0.89]. Likewise, there was no difference in procedure time among patients with HPCD [120 (73–135) vs. 120 (70–130) min; P = 0.67]. An EP mapping catheter was additionally used in four patients (14%) in the EAM+ group and two patients (7%) in the EAM− group (P = 0.67). Three patients with complex cardiac abnormalities underwent EAM-guided HBP with integration of the CMR-derived 3D model of the right heart. Procedural characteristics and HBP lead parameters are summarized in Table 2. Table 2 Procedural outcome . All patients (n = 58) . EAM+ group (n = 29) . EAM− group (n = 29) . P value . Successful HBP, n (%) 53 (91) 26 (90) 27 (93) 0.64 Successful HBP + LBBAP, n (%) 55 (95) 27 (93) 28 (97) 0.55 Procedural characteristics  Procedural time (min) 93 (70–131) 90 (73–135) 110 (70–130) 0.89  Total fluoroscopy time (min) 1.4 (0.7–4.1) 0.7 (0.5–1.4) 3.3 (1.4–6.5) <0.001  Total fluoroscopy dose (cGycm2) 36.1 (18.3–94.8) 21.9 (9.1–47.7) 78.6 (27.2–144.9) 0.001  HBP lead fluoroscopy time (min) – 0.4 (0.3–0.6) NAa –  HBP lead fluoroscopy dose (cGycm2) – 13.2 (5.4–22.5) NAa –  Use of an EP mapping catheter, n (%) 6 (10) 4 (14) 2 (7) 0.67  CMR image integration 3 (5) 2 (7) 1 (3)b 1.00  Change to steerable sheath (C304), n (%) 6 (10) 5 (17) 1 (3) 0.19 Electrogram and HBP lead parameters  Paced QRS duration (ms) 113 ± 16 113 ± 15 113 ± 17 0.89  His capture threshold (V/1.0 ms) 1.3 ± 0.8 1.2 ± 0.6 1.4 ± 1.0 0.33  Ventricular sensing (mV) 3.7 ± 2.0 4.2 ± 2.2 3.2 ± 1.7 0.07  Pacing impedance (Ohm) 488 ± 102 516 ± 89 460 ± 107 0.04  S-HBP, n (%) 25/54 (46) 13/26 (50) 12/28 (43) 0.60  HBE recording, n (%) 58 (100) 29 (100) 29 (100) –  HV interval (ms) 59 ± 20 57 ± 18 60 ± 22 0.54   HV >70 ms, n (%) 12/50 (24) 5/26 (19) 7/24 (29) 0.41   HV block, n (%) 15/58 (26) 7/29 (24) 8/29 (28) 0.76  HB injury current, n (%) 29/54 (54) 16/26 (62) 13/28 (46) 0.27 . All patients (n = 58) . EAM+ group (n = 29) . EAM− group (n = 29) . P value . Successful HBP, n (%) 53 (91) 26 (90) 27 (93) 0.64 Successful HBP + LBBAP, n (%) 55 (95) 27 (93) 28 (97) 0.55 Procedural characteristics  Procedural time (min) 93 (70–131) 90 (73–135) 110 (70–130) 0.89  Total fluoroscopy time (min) 1.4 (0.7–4.1) 0.7 (0.5–1.4) 3.3 (1.4–6.5) <0.001  Total fluoroscopy dose (cGycm2) 36.1 (18.3–94.8) 21.9 (9.1–47.7) 78.6 (27.2–144.9) 0.001  HBP lead fluoroscopy time (min) – 0.4 (0.3–0.6) NAa –  HBP lead fluoroscopy dose (cGycm2) – 13.2 (5.4–22.5) NAa –  Use of an EP mapping catheter, n (%) 6 (10) 4 (14) 2 (7) 0.67  CMR image integration 3 (5) 2 (7) 1 (3)b 1.00  Change to steerable sheath (C304), n (%) 6 (10) 5 (17) 1 (3) 0.19 Electrogram and HBP lead parameters  Paced QRS duration (ms) 113 ± 16 113 ± 15 113 ± 17 0.89  His capture threshold (V/1.0 ms) 1.3 ± 0.8 1.2 ± 0.6 1.4 ± 1.0 0.33  Ventricular sensing (mV) 3.7 ± 2.0 4.2 ± 2.2 3.2 ± 1.7 0.07  Pacing impedance (Ohm) 488 ± 102 516 ± 89 460 ± 107 0.04  S-HBP, n (%) 25/54 (46) 13/26 (50) 12/28 (43) 0.60  HBE recording, n (%) 58 (100) 29 (100) 29 (100) –  HV interval (ms) 59 ± 20 57 ± 18 60 ± 22 0.54   HV >70 ms, n (%) 12/50 (24) 5/26 (19) 7/24 (29) 0.41   HV block, n (%) 15/58 (26) 7/29 (24) 8/29 (28) 0.76  HB injury current, n (%) 29/54 (54) 16/26 (62) 13/28 (46) 0.27 Data are presented as median (IQR), mean ± SD, or n (%). CMR, cardiac magnetic resonance; EAM, electroanatomical mapping; EP, electrophysiological; HB, His bundle; HBE, His bundle electrogram; HBP, His bundle pacing; HV, His-ventricular; LBBAP, left bundle-branch area pacing; NA, not applicable; S-HBP, selective HBP. a HBP lead fluoroscopy time and dose have not been consistently recorded prior to implementation of the refined EAM protocol. b In a patient with acquired dextroposition of the heart.11 Open in new tab Table 2 Procedural outcome . All patients (n = 58) . EAM+ group (n = 29) . EAM− group (n = 29) . P value . Successful HBP, n (%) 53 (91) 26 (90) 27 (93) 0.64 Successful HBP + LBBAP, n (%) 55 (95) 27 (93) 28 (97) 0.55 Procedural characteristics  Procedural time (min) 93 (70–131) 90 (73–135) 110 (70–130) 0.89  Total fluoroscopy time (min) 1.4 (0.7–4.1) 0.7 (0.5–1.4) 3.3 (1.4–6.5) <0.001  Total fluoroscopy dose (cGycm2) 36.1 (18.3–94.8) 21.9 (9.1–47.7) 78.6 (27.2–144.9) 0.001  HBP lead fluoroscopy time (min) – 0.4 (0.3–0.6) NAa –  HBP lead fluoroscopy dose (cGycm2) – 13.2 (5.4–22.5) NAa –  Use of an EP mapping catheter, n (%) 6 (10) 4 (14) 2 (7) 0.67  CMR image integration 3 (5) 2 (7) 1 (3)b 1.00  Change to steerable sheath (C304), n (%) 6 (10) 5 (17) 1 (3) 0.19 Electrogram and HBP lead parameters  Paced QRS duration (ms) 113 ± 16 113 ± 15 113 ± 17 0.89  His capture threshold (V/1.0 ms) 1.3 ± 0.8 1.2 ± 0.6 1.4 ± 1.0 0.33  Ventricular sensing (mV) 3.7 ± 2.0 4.2 ± 2.2 3.2 ± 1.7 0.07  Pacing impedance (Ohm) 488 ± 102 516 ± 89 460 ± 107 0.04  S-HBP, n (%) 25/54 (46) 13/26 (50) 12/28 (43) 0.60  HBE recording, n (%) 58 (100) 29 (100) 29 (100) –  HV interval (ms) 59 ± 20 57 ± 18 60 ± 22 0.54   HV >70 ms, n (%) 12/50 (24) 5/26 (19) 7/24 (29) 0.41   HV block, n (%) 15/58 (26) 7/29 (24) 8/29 (28) 0.76  HB injury current, n (%) 29/54 (54) 16/26 (62) 13/28 (46) 0.27 . All patients (n = 58) . EAM+ group (n = 29) . EAM− group (n = 29) . P value . Successful HBP, n (%) 53 (91) 26 (90) 27 (93) 0.64 Successful HBP + LBBAP, n (%) 55 (95) 27 (93) 28 (97) 0.55 Procedural characteristics  Procedural time (min) 93 (70–131) 90 (73–135) 110 (70–130) 0.89  Total fluoroscopy time (min) 1.4 (0.7–4.1) 0.7 (0.5–1.4) 3.3 (1.4–6.5) <0.001  Total fluoroscopy dose (cGycm2) 36.1 (18.3–94.8) 21.9 (9.1–47.7) 78.6 (27.2–144.9) 0.001  HBP lead fluoroscopy time (min) – 0.4 (0.3–0.6) NAa –  HBP lead fluoroscopy dose (cGycm2) – 13.2 (5.4–22.5) NAa –  Use of an EP mapping catheter, n (%) 6 (10) 4 (14) 2 (7) 0.67  CMR image integration 3 (5) 2 (7) 1 (3)b 1.00  Change to steerable sheath (C304), n (%) 6 (10) 5 (17) 1 (3) 0.19 Electrogram and HBP lead parameters  Paced QRS duration (ms) 113 ± 16 113 ± 15 113 ± 17 0.89  His capture threshold (V/1.0 ms) 1.3 ± 0.8 1.2 ± 0.6 1.4 ± 1.0 0.33  Ventricular sensing (mV) 3.7 ± 2.0 4.2 ± 2.2 3.2 ± 1.7 0.07  Pacing impedance (Ohm) 488 ± 102 516 ± 89 460 ± 107 0.04  S-HBP, n (%) 25/54 (46) 13/26 (50) 12/28 (43) 0.60  HBE recording, n (%) 58 (100) 29 (100) 29 (100) –  HV interval (ms) 59 ± 20 57 ± 18 60 ± 22 0.54   HV >70 ms, n (%) 12/50 (24) 5/26 (19) 7/24 (29) 0.41   HV block, n (%) 15/58 (26) 7/29 (24) 8/29 (28) 0.76  HB injury current, n (%) 29/54 (54) 16/26 (62) 13/28 (46) 0.27 Data are presented as median (IQR), mean ± SD, or n (%). CMR, cardiac magnetic resonance; EAM, electroanatomical mapping; EP, electrophysiological; HB, His bundle; HBE, His bundle electrogram; HBP, His bundle pacing; HV, His-ventricular; LBBAP, left bundle-branch area pacing; NA, not applicable; S-HBP, selective HBP. a HBP lead fluoroscopy time and dose have not been consistently recorded prior to implementation of the refined EAM protocol. b In a patient with acquired dextroposition of the heart.11 Open in new tab Fluoroscopy exposure The overall total fluoroscopy time and dose were 1.4 (0.7–4.1) min and 36.1 (18.3–94.8) cGycm2, respectively. There was a highly significant difference in the total fluoroscopy time between the EAM+ and EAM− groups [0.7 (0.5–1.4) vs. 3.3 (1.4–6.5) min, respectively; P < 0.001]. Importantly, the total fluoroscopy dose was also significantly lower in the EAM+ group compared to the EAM− group [21.9 (9.1–47.7) vs. 78.6 (27.2–144.9) cGycm2, respectively; P = 0.001]. Similar results were observed for the subgroup of patients with HPCD (Figure 5). The outliners observed in the EAM+ group represent two patients with complex cardiac abnormalities (ccTGA with dextrocardia; cardiac amyloidosis with septal involvement) and one patient with dilated cardiomyopathy and failed LBBB recruitment in whom a conventional LV lead was finally placed (Figure 5A). The HBP lead fluoroscopy time and dose in the EAM+ group were 0.4 (0.3–0.6) min and 13.2 (5.4–22.5) cGycm2, respectively. Figure 5 Open in new tabDownload slide Comparison of the median total fluoroscopy time (A) and dose (B) between EAM+ and EAM− groups for all patients and patients with HPCD. The outliners in the EAM+ group represent two patients with complex cardiac abnormalities (ccTGA with dextrocardia; cardiac amyloidosis) and one patient with dilated cardiomyopathy and failed left bundle-branch block recruitment in whom a conventional left ventricular lead was finally placed. ccTGA, congenitally corrected transposition of the great arteries; EAM, electroanatomical mapping; HPCD, His-Purkinje conduction disease. Figure 5 Open in new tabDownload slide Comparison of the median total fluoroscopy time (A) and dose (B) between EAM+ and EAM− groups for all patients and patients with HPCD. The outliners in the EAM+ group represent two patients with complex cardiac abnormalities (ccTGA with dextrocardia; cardiac amyloidosis) and one patient with dilated cardiomyopathy and failed left bundle-branch block recruitment in whom a conventional left ventricular lead was finally placed. ccTGA, congenitally corrected transposition of the great arteries; EAM, electroanatomical mapping; HPCD, His-Purkinje conduction disease. His bundle electrogram mapping and His bundle pacing lead parameters A HB potential could be identified by conventional fluoroscopy-guided and EAM-guided HBE mapping in all patients. The HV interval in patients without complete infrahisian block (n = 50) was 59 ± 20 ms. Twelve patients (24%) had an HV interval >70 ms, 15 patients (26%) had any type of second-degree (n = 7) or third-degree (n = 8) infrahisian block. There were no significant differences in HV conduction time or incidence of infrahisian block between groups. Selective HBP was achieved in 50% of patients in the EAM+ group and 43% of patients in the EAM− group (P = 0.60). The His capture threshold was 1.2 ± 0.6 V at 1.0 ms in the EAM+ group and 1.4 ± 1.0 V at 1.0 ms in the EAM− group (P = 0.33). There was no significant difference in paced QRSd between the EAM+ and EAM− groups (113 ± 15 vs. 113 ± 17 ms, respectively; P = 0.89). Similar findings were observed for patients with HPCD (Supplementary material online, Table S1). In these patients, the baseline QRSd significantly narrowed with HBP among both EAM+ (163 ± 15 to 121 ± 15 ms; P < 0.001) and EAM− (167 ± 13 to 123 ± 12 ms; P < 0.001) groups. The BBB recruitment threshold tended to be lower in the EAM+ group compared to the EAM− group without reaching statistical significance (1.3 ± 0.7 vs. 1.8 ± 1.2 V at 1.0 ms; P = 0.31). Figure 6 summarizes the changes in QRSd with HBP for the study cohort stratified according to EAM group and presence of HPCD. Figure 6 Open in new tabDownload slide Changes in QRS duration with HBP for the study cohort stratified according to patient group (EAM+ vs. EAM−) and intrinsic QRS duration (QRS ≤120 vs. >120 ms). Data are expressed as mean ± SEM. EAM, electroanatomical mapping; HBP, His bundle pacing. Figure 6 Open in new tabDownload slide Changes in QRS duration with HBP for the study cohort stratified according to patient group (EAM+ vs. EAM−) and intrinsic QRS duration (QRS ≤120 vs. >120 ms). Data are expressed as mean ± SEM. EAM, electroanatomical mapping; HBP, His bundle pacing. Complications and follow-up No immediate procedure-related complications occurred in either group. One patient in the EAM− group (2% of the study cohort) experienced HBP lead dislodgement within 4 weeks after implantation. Overall, the paced QRSd and His capture threshold remained basically stable at 1-month follow-up (114 ± 15 ms and 1.3 ± 1.0 V at 1.0 ms, respectively) without differences between the EAM+ and EAM− groups (113 ± 16 vs. 115 ± 15 ms, P = 0.67; and 1.1 ± 0.9 vs. 1.5 ± 1.0 V at 1.0 ms, P = 0.17, respectively). An increase in His capture threshold >1.0 V was noted in one patient (2%) who was in the EAM+ group. Three patients (one in the EAM+ and two in the EAM− group) had His capture thresholds >2.5 V (median 3.5 V) at 1.0 ms. In patients with HPCD, the BBB recruitment threshold increased slightly during follow-up to 2.0 ± 1.2 V at 1.0 ms. The increase in BBB recruitment threshold was similar between the EAM+ (1.3 ± 0.7 to 1.6 ± 1.0 V) and EAM− (1.8 ± 1.2 to 2.3 ± 1.3 V) group. Two patients in the EAM− group and none in the EAM+ group had an increase >1.0 V in BBB recruitment threshold. No patient with HPCD had loss of BBB recruitment during follow-up. Six of 7 patients with an indication for the pace-and-ablate strategy underwent uneventful AVNA at a median of 1.2 months after successful implantation, the other patient was managed by pharmacological rate-control therapy. Discussion The present study evaluated the impact of EAM-guided lead implantation on procedural outcome of HBP in an unselected real-world population. The results of our study show that routine EAM-guided HBP is associated with a tremendous reduction in radiation exposure without prolonging procedure time or increasing procedure-related complications. Moreover, our study is the first to systematically describe the safety and feasibility of EAM-guided HBP in patients with HPCD. Conventional fluoroscopy-guided HBE mapping and lead implantation can be technically challenging, time consuming, and fluoroscopy-intense. The latter may in particular be the case during the operator’s early implant experience (learning curve) and in patients with HPCD or complex structural abnormalities. Actually, significant fluoroscopy need has consistently been reported for conventional HBP even in patients with normal heart and standard indication for anti-bradycardia pacing.4,7 In the landmark study on outcome of conventional HBP in 304 successfully implanted patients with an indication for single- or dual-chamber pacing, the mean fluoroscopy time was 10.3 ± 6.5 min.4 Similarly, in a recent multicentre observational study, the mean fluoroscopy time was 11.7 ± 12.0 min among 422 successfully implanted patients with available data on fluoroscopy times.7 Remarkably, fluoroscopy times in patients with an unsuccessful attempt to permanent HBP were not considered in either study, which would have resulted in higher scores.14 In contrast, the mean fluoroscopy time across all procedures including unsuccessful attempts was 3.9 ± 4.9 (median 2.0) min in our study. We observed a rapid decline in fluoroscopy time and exposure with increased experience in HBP until plateauing after about 40 patients. This is well in line with the finding by Keene et al.7 that the decline in fluoroscopy time reliably indicated the centres’ learning curve with a levelling off after 30–50 cases. The notedly low fluoroscopy time (median 3.3 min) and dose (median 78.6 cGycm2) observed after the learning curve in the conventional EAM− group (Figure 5) were mainly the result of a rather strict attempt to an EGM-based mapping approach under minimized low-dose fluoroscopic guidance.15 The implementation of EAM-guided lead implantation into our routine implant practice for HBP further resulted in a significant (∼5-fold) reduction in fluoroscopy time without prolonging procedure time or increasing procedure-related complications. Importantly, the decline in fluoroscopy time was associated with a significant (∼4-fold) decrease in fluoroscopy exposure down to a median dose area product (DAP) of 22 cGycm2 despite triple-lead implantation in >60% of the EAM+ patients (Figure 5). Moreover, the procedure time actually tended to be shorter in the EAM+ group compared with the EAM− group (90 vs. 110 min, respectively). This is in contrast to the prolonged procedure time (134 ± 23 min) observed in the initial feasibility study by Sharma et al.,8 in which 10 patients with an indication for dual-chamber pacing underwent EAM-guided HBP using either the Carto or EnSite NavX system. Compared to our study, they reported a similar total fluoroscopy time (0.8 ± 0.3 min) along with a total DAP of 96 ± 83 cGycm2. The observed differences may likely be explained by the use of distinct EAM systems and protocols for HBE mapping. We have refined and implemented a standardized protocol which enables precise non-fluoroscopic visualization and navigation of the HBP lead tip and unipolar EGM mapping with no need for initial acquisition of 3D right heart geometry. Targeted EAM of the HB region (Figure 2) can thus be performed without the additional use of a navigation-enabled EP catheter or need for femoral access. Besides, catheter stability and mapping accuracy have substantially been improved by setting up an active-fixation lead as reference. Similar to the conventional approach, non-fluoroscopic EAM-guided unipolar mapping can immediately be started as soon as the electrically connected HBP lead has been advanced to the tip of the guiding sheath. Therefore, no additional procedure time is required for mapping. Conversely, the ability to annotate mapping points with HB potentials and corresponding pacing responses allows to easily get back to any location without fluoroscopy in case high-density mapping of the His cloud or lead repositioning becomes necessary. This may potentially reduce not only fluoroscopy exposure but also procedure time especially in challenging cases with HPCD or complex structural abnormalities. However, we did not observe significant differences in procedure time between the EAM+ and EAM− groups in patients with HPCD. A properly powered multi-centre study may be needed in this respect. Nevertheless, the present study is the first to demonstrate that EAM-guided HBP is feasible and safe in patients with HPCD and results in similar electrical outcomes compared to the conventional approach. The thresholds for His capture and BBB recruitment tended to be lower in the EAM+ vs. EAM− group, which may be attributed to the improved spatial resolution and facility of high-density EGM and pace mapping when using an EAM system. In addition, we observed that the willingness to search for a better-than-acceptable HBP lead position seems to be higher in EAM-guided procedures since it is much easier to get back to any annotated point without fluoroscopy. On the other side of the coin, implementation of EAM-guided HBP is associated with additional costs and depends on the availability of an EP laboratory equipped with EP recording and 3D mapping systems. Equally important are well-trained medical and allied health care professionals who need to be familiar with invasive electrophysiology and cardiac mapping. In our experience, the additional costs are relatively low and account mainly for the electrode patches and alligator clamp threshold cables. In contrast to previously reported protocols,9,16 no navigation-enabled EP catheter is needed for our Ensite Precision-guided approach. In particular, HBP guided by the Carto system requires initial ablation catheter-based creation of a critical matrix for visualization and tracking of the lead tip.8 This cost-intensive approach may exceptionally be reasonable for a pace-and-ablate strategy, in which EAM-guided HBP is combined with AVNA in the same session. Three-dimensional EAM is pivotal for catheter mapping and ablation of complex cardiac arrhythmias. Over the last decade, we have consistently performed near-zero fluoroscopy catheter ablation using EAM in conjunction with non-fluoroscopic catheter visualization.17 Moreover, we implemented the same sensor-based electromagnetic tracking technology for low-fluoroscopy LV lead implantation in CRT.18 Since HBP is the pacing technique that leads to the most physiological approach to ventricular activation, EAM enables high-density mapping of the His cloud with high accuracy and very low radiation exposure. However, it is important to notice that not necessarily the fluoroscopy time but rather the dose (area product) is key for reduction of overall radiation exposure and cancer risk of patients and catheterization laboratory staff.19 Although the strict EGM-only guided approach to HBP described by Zanon et al.15 resulted in a short total fluoroscopy time (1.5 ± 1.3 min), the reported median total DAP of 2175 cGycm2 was almost 100-fold higher than that observed for the EAM+ group in our study. An approach with such high radiation exposure seems far away from near-zero fluoroscopy HBP irrespective of the fluoroscopy time. Besides the use of an EAM system, best efforts should be made and measures taken to reduce radiation exposure during transvenous lead implantation including reduction of the frame rate and use of maximal collimation and decreased geometric magnification.20 Study limitations This is a prospective observational single-centre study. Hence, the major limitations are imposed by the non-randomized nature and narrow sample size of the present study. Nonetheless, determination of the centre’s learning curve with plateauing of radiation exposure with gained experience allowed to define the best possible control group, which actually matched perfectly with the EAM+ group regarding baseline characteristics. It is tempting to speculate that the exceptionally low fluoroscopy exposure achieved in both groups would not have further decreased by including more consecutive patients. However, larger sample sizes are certainly needed to potentially detect significant differences in procedure time and pacing parameters in favour of the EAM-guided approach. Moreover, the procedures were performed by an electrophysiologist with significant experience in cardiac pacing and invasive electrophysiology at a high-volume centre with expertise in near-zero fluoroscopy approaches to catheter ablation and lead implantation. Radiation exposure may not be reduced to such extents in centres without EP background and limited experience in conventional HBP. Conclusions Implementation of EAM-guided lead implantation into our routine implant practice for HBP was feasible and safe in a real-world cohort of consecutive patients with and without HPCD and resulted in a tremendous reduction in radiation exposure without prolonging procedure time or increasing procedure-related complications. Our refined EAM-guided approach to HBP facilitates virtual near-zero fluoroscopy lead implantation and should be recommended for standard use, at least in challenging cases. Supplementary material Supplementary material is available at Europace online. Acknowledgements The authors are greatly indebted to Christian Mehnert, Sylvia Merzky, Susann Kohlbach, and Kerstin Nowotnick for professional assistance in device interrogation, 12-lead ECG recording, and data collection during outpatient follow-up. Conflict of interest: S.R. is a member of the HBP advisory board of Biotronik and has received speaker honoraria and proctor fees from Biotronik and Abbott to his institution without personal financial benefits. D.S. is an employee of Abbott. G.H. has received research grants from Abbott and Boston Scientific to his institution without personal financial benefits. The remaining authors have declared no conflicts of interest. Data availability The data underlying this article will be shared on reasonable request to the corresponding author. References 1 Kusumoto FM , Schoenfeld MH , Barrett C , Edgerton JR , Ellenbogen KA , Gold MR et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay: executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines, and the Heart Rhythm Society . Circulation 2019 ; 140 : e333 – 81 . Google Scholar PubMed OpenURL Placeholder Text WorldCat 2 Tops LF , Schalij MJ , Bax JJ. The effects of right ventricular apical pacing on ventricular function and dyssynchrony: implications for therapy . J Am Coll Cardiol 2009 ; 54 : 764 – 76 . Google Scholar Crossref Search ADS PubMed WorldCat 3 Sharma PS , Dandamudi G , Naperkowski A , Oren JW , Storm RH , Ellenbogen KA et al. Permanent his-bundle pacing is feasible, safe, and superior to right ventricular pacing in routine clinical practice . Heart Rhythm 2015 ; 12 : 305 – 12 . Google Scholar Crossref Search ADS PubMed WorldCat 4 Abdelrahman M , Subzposh FA , Beer D , Durr B , Naperkowski A , Sun H et al. Clinical outcomes of his bundle pacing compared to right ventricular pacing . J Am Coll Cardiol 2018 ; 71 : 2319 – 30 . Google Scholar Crossref Search ADS PubMed WorldCat 5 Sharma PS , Dandamudi G , Herweg B , Wilson D , Singh R , Naperkowski A et al. Permanent his-bundle pacing as an alternative to biventricular pacing for cardiac resynchronization therapy: a multicenter experience . Heart Rhythm 2018 ; 15 : 413 – 20 . Google Scholar Crossref Search ADS PubMed WorldCat 6 Arnold AD , Shun-Shin MJ , Keene D , Howard JP , Sohaib SMA , Wright IJ et al. His resynchronization versus biventricular pacing in patients with heart failure and left bundle branch block . J Am Coll Cardiol 2018 ; 72 : 3112 – 22 . Google Scholar Crossref Search ADS PubMed WorldCat 7 Keene D , Arnold AD , Jastrzębski M , Burri H , Zweibel S , Crespo E et al. His bundle pacing, learning curve, procedure characteristics, safety, and feasibility: insights from a large international observational study . J Cardiovasc Electrophysiol 2019 ; 30 : 1984 – 93 . Google Scholar Crossref Search ADS PubMed WorldCat 8 Sharma PS , Huang HD , Trohman RG , Naperkowski A , Ellenbogen KA , Vijayaraman P. Low fluoroscopy permanent his bundle pacing using electroanatomic mapping: a feasibility study . Circ Arrhythm Electrophysiol 2019 ; 12 : e006967 . Google Scholar Crossref Search ADS PubMed WorldCat 9 Hu Y , Ding L , Hua W , Gu M , Cai M , Chen X et al. Comparison between His-bundle pacing guided by Ensite NavX system and conventional fluoroscopy . J Interv Card Electrophysiol 2020 ; 57 : 107 – 14 . Google Scholar Crossref Search ADS PubMed WorldCat 10 Dandamudi G , Vijayaraman P. How to perform permanent His bundle pacing in routine clinical practice . Heart Rhythm 2016 ; 13 : 1362 – 6 . Google Scholar Crossref Search ADS PubMed WorldCat 11 Richter S , Bertagnolli L , Doering M , Paetsch I. Electroanatomical mapping-guided His bundle pacing in acquired dextroposition of the heart . Eur Heart J 2020 ; 41 : 1142 . Google Scholar Crossref Search ADS PubMed WorldCat 12 Vijayaraman P , Dandamudi G , Zanon F , Sharma PS , Tung R , Huang W et al. Permanent His bundle pacing: recommendations from a multicenter his bundle pacing collaborative working group for standardization of definitions, implant measurements, and follow-up . Heart Rhythm 2018 ; 15 : 460 – 8 . Google Scholar Crossref Search ADS PubMed WorldCat 13 Burri H , Keene D , Whinnett Z , Zanon F , Vijayaraman P. Device programming for His bundle pacing . Circ Arrhythm Electrophysiol 2019 ; 12 : e006816 . Google Scholar Crossref Search ADS PubMed WorldCat 14 Bhatt AG , Musat DL , Milstein N , Pimienta J , Flynn L , Sichrovsky T et al. The efficacy of His bundle pacing: lessons learned from implementation for the first time at an experienced electrophysiology center . JACC Clin Electrophysiol 2018 ; 4 : 1397 – 406 . Google Scholar Crossref Search ADS PubMed WorldCat 15 Zanon F , Marcantoni L , Zuin M , Pastore G , Baracca E , Tiribello A et al. Electrogram-only guided approach to his bundle pacing with minimal fluoroscopy: a single-center experience . J Cardiovasc Electrophysiol 2020 ; 31 : 805 – 12 . Google Scholar Crossref Search ADS PubMed WorldCat 16 Orlov MV , Koulouridis I , Monin AJ , Casavant D , Maslov M , Erez A et al. Direct visualization of the His bundle pacing lead placement by 3-dimensional electroanatomic mapping: technique, anatomy, and practical considerations . Circ Arrhythm Electrophysiol 2019 ; 12 : e006801 . Google Scholar Crossref Search ADS PubMed WorldCat 17 Sommer P , Bertagnolli L , Kircher S , Arya A , Bollmann A , Richter S et al. Safety profile of near-zero fluoroscopy atrial fibrillation ablation with non-fluoroscopic catheter visualization: experience from 1000 consecutive procedures . Europace 2018 ; 20 : 1952 – 8 . Google Scholar Crossref Search ADS PubMed WorldCat 18 Doring M , Sommer P , Rolf S , Lucas J , Breithardt OA , Hindricks G et al. Sensor-based electromagnetic navigation to facilitate implantation of left ventricular leads in cardiac resynchronization therapy . J Cardiovasc Electrophysiol 2015 ; 26 : 167 – 75 . Google Scholar Crossref Search ADS PubMed WorldCat 19 Venneri L , Rossi F , Botto N , Andreassi MG , Salcone N , Emad A et al. Cancer risk from professional exposure in staff working in cardiac catheterization laboratory: insights from the national research council's biological effects of ionizing radiation vii report . Am Heart J 2009 ; 157 : 118 – 24 . Google Scholar Crossref Search ADS PubMed WorldCat 20 Agarwal S , Parashar A , Ellis SG , Heupler FA Jr , Lau E , Tuzcu EM et al. Measures to reduce radiation in a modern cardiac catheterization laboratory . Circ Cardiovasc Interv 2014 ; 7 : 447 – 55 . Google Scholar Crossref Search ADS PubMed WorldCat Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions, please email: journals.permissions@oup.com. 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TI - Impact of electroanatomical mapping-guided lead implantation on procedural outcome of His bundle pacing
JF - Europace
DO - 10.1093/europace/euaa292
DA - 2021-03-08
UR - https://www.deepdyve.com/lp/oxford-university-press/impact-of-electroanatomical-mapping-guided-lead-implantation-on-0JgAgP09Zj
SP - 409
EP - 420
VL - 23
IS - 3
DP - DeepDyve
ER -