Wide Complex Arrhythmia-A Unique Presentation of an Unusual Syndrome.

The mechanisms of wide complex tachycardia can vary. We discuss the case of a wide complex tachycardia with multiple mechanisms due to a rare genetic abnormality in a 26-year-old Caucasian man with a past history of spontaneous pneumothorax and syncope.

Conduction system pacing versus conventional pacing in patients undergoing atrioventricular node ablation: Nonrandomized, on-treatment comparison.

Background: Atrioventricular node ablation (AVNA) with right ventricular or biventricular pacing (conventional pacing; CP) is an effective therapy for patients with refractory atrial fibrillation (AF). Conduction system pacing (CSP) using His bundle pacing or left bundle branch area pacing preserves ventricular synchrony. Objective: The aim of our study is to compare the clinical outcomes between CP and CSP in patients undergoing AVNA. Methods: Patients undergoing AVNA at Geisinger Health System between January 2015 and October 2020 were included in this retrospective observational study. CP or CSP was performed at the operators' discretion. Procedural, pacing parameters, and echocardiographic data were assessed. Primary outcome was the combined endpoint of time to death or heart failure hospitalization (HFH) and was analyzed using Cox proportional hazards. Secondary outcomes were individual outcomes of time to death and HFH. Results: AVNA was performed in 223 patients (CSP, 110; CP, 113). Age was 75 ± 10 years, male 52%, hypertension 67%, diabetes 25%, coronary disease 40%, and left ventricular ejection fraction (LVEF) 43% ± 15%. QRS duration increased from 103 ± 30 ms to 124 ± 20 ms (P < .01) in CSP and 119 ± 32 ms to 162 ± 24 ms in CP (P < .001). During a mean follow-up of 27 ± 19 months, LVEF significantly increased from 46.5% ± 14.2% to 51.9% ± 11.2% (P = .02) in CSP and 36.4% ± 16.1% to 39.5% ± 16% (P = .04) in CP. The primary combined endpoint of time to death or HFH was significantly reduced in CSP compared to CP (48% vs 62%; hazard ratio 0.61, 95% confidence interval 0.42-0.89, P < .01). There was no reduction in the individual secondary outcomes of time to death and HFH in the CSP group compared to CP. Conclusion: CSP is a safe and effective option for pacing in patients with AF undergoing AVNA in high-volume centers.

Clinical outcomes of left bundle branch area pacing compared to His bundle pacing.

INTRODUCTION: His bundle pacing (HBP) is the most physiologic form of pacing and has been associated with reduced risk for heart failure hospitalization (HFH) and mortality compared to right ventricular pacing. Left bundle branch area pacing (LBBAP) is a safe and effective alternative option for patients needing ventricular pacing. The aim of this study was to compare the clinical outcomes between LBBAP and HBP among a large cohort of patients undergoing permanent pacemaker implantation. METHODS: This observational registry included consecutive patients with AV block/AV node ablation who underwent de novo permanent pacemaker implantations with successful LBBAP or HBP between April 2018 and October 2020. The primary outcome was the composite endpoint of time to death from any cause or HFH. Secondary outcomes included the composite endpoint among patients with prespecified ventricular pacing burden and individual outcomes. RESULTS: The study population included 359 patients who met the inclusion criteria (163 in the HBP and 196 in the LBBAP group). Paced QRSd during LBBAP was similar to HBP (125 ± 20.2 vs. 126 ± 23.5 ms, p = .643). There were no statistically significant differences in the primary composite outcome in LBBAP (17.3%) compared to HBP (24.5%) (hazard ratio [HR]: 1.15, 95% CI: 0.72-1.82, p = .552). Secondary outcomes of death (10% vs. 17%; HR: 1.3, 95% CI: 0.73-2.33, p = .38) and HFH (10% vs. 12%; HR: 1.02, 95% CI: 0.54-1.94, p = .94) were not different among both groups. CONCLUSIONS: There were no statistically significant differences in the clinical outcomes of death or HFH in LBBAP when compared to HBP.

Clinical outcomes of left bundle branch area pacing compared to right ventricular pacing: Results from the Geisinger-Rush Conduction System Pacing Registry.

BACKGROUND: Left bundle branch area pacing (LBBAP) has been shown to be a feasible option for patients requiring ventricular pacing. OBJECTIVE: The purpose of this study was to compare clinical outcomes between LBBAP and RVP among patients undergoing pacemaker implantation METHODS: This observational registry included patients who underwent pacemaker implantations with LBBAP or RVP for bradycardia indications between April 2018 and October 2020. The primary composite outcome included all-cause mortality, heart failure hospitalization (HFH), or upgrade to biventricular pacing. Secondary outcomes included the composite endpoint among patients with a prespecified burden of ventricular pacing and individual outcomes. RESULTS: A total of 703 patients met inclusion criteria (321 LBBAP and 382 RVP). QRS duration during LBBAP was similar to baseline (121 ± 23 ms vs 117 ± 30 ms; P = .302) and was narrower compared to RVP (121 ± 23 ms vs 156 ± 27 ms; P <.001). The primary composite outcome was significantly lower with LBBAP (10.0%) compared to RVP (23.3%) (hazard ratio [HR] 0.46; 95%T confidence interval [CI] 0.306-0.695; P <.001). Among patients with ventricular pacing burden >20%, LBBAP was associated with significant reduction in the primary outcome compared to RVP (8.4% vs 26.1%; HR 0.32; 95% CI 0.187-0.540; P <.001). LBBAP was also associated with significant reduction in mortality (7.8% vs 15%; HR 0.59; P = .03) and HFH (3.7% vs 10.5%; HR 0.38; P = .004). CONCLUSION: LBBAP resulted in improved clinical outcomes compared to RVP. Higher burden of ventricular pacing (>20%) was the primary driver of these outcome differences.

His-Purkinje Conduction System Pacing in Atrioventricular Block: New Insights Into Site of Conduction Block.

OBJECTIVES: This study aims to assess the safety and feasibility of achieving His-Purkinje conduction system pacing (HPCSP) in consecutive patients with atrioventricular block (AVB) and to describe the site of conduction block in patients with infranodal AVB. BACKGROUND: HPCSP has evolved as the preferred form of physiologic pacing. Left bundle branch area pacing (LBBAP) has emerged as an effective alternative to His bundle pacing (HBP). METHODS: Consecutive patients with AVB referred for pacemaker implantation were included in the study. HBP or LBBAP was attempted in all patients. Site of conduction block was identified as nodal or infranodal (intra-Hisian or infra-Hisian) AVB. RESULTS: HPCSP was attempted in 333 consecutive patients with AVB and was successful in 322 (97%) patients. HBP was achieved in 140 patients, LBBAP in 179 patients, and both in 3 patients. Site of conduction block was nodal in 55% and infranodal in 45% (intra-Hisian 89%; infra-Hisian 4%; indeterminate 7%). QRS duration at baseline was 111 ± 27 versus 129 ± 31 (P < 0.001) compared to 126 ± 24 vs 125 ± 21 milliseconds (P = 0.75) during HBP and LBBAP, respectively. HBP thresholds at implant were higher compared to LBBAP (1.2 ± 0.7 V at 0.9 milliseconds vs 0.6 ± 0.3 V at 0.5 milliseconds; P < 0.001) but remained stable during follow-up. Lead revision was required in 3% and 2% of patients with HBP and LBBAP, respectively. CONCLUSIONS: HPCSP pacing was successfully performed in 97% of unselected patients with AVB irrespective of the site of conduction block. True infra-Hisian block (distal His-Purkinje conduction disease) is rare. HBP and LBBAP were complementary in achieving stable and low capture thresholds.

Left Bundle Branch Area Pacing for Cardiac Resynchronization Therapy: Results From the International LBBAP Collaborative Study Group.

OBJECTIVES: The aim of this study was to assess the feasibility and outcomes of left bundle branch area pacing (LBBAP) in patients eligible for cardiac resynchronization therapy (CRT) in an international, multicenter, collaborative study. BACKGROUND: CRT using biventricular pacing is effective in patients with heart failure and left bundle branch block (LBBB). LBBAP has been reported as an alternative option for CRT. METHODS: LBBAP was attempted in patients with left ventricular ejection fraction (LVEF) <50% and indications for CRT or pacing. Procedural outcomes, left bundle branch capture, New York Heart Association functional class, heart failure hospitalization, echocardiographic data, and lead complications were recorded. Clinical (no heart failure hospitalization and improvement in New York Heart Association functional class) and echocardiographic responses (≥5% improvement in LVEF) were assessed. RESULTS: LBBAP was attempted in 325 patients, and CRT was successfully achieved in 277 (85%) (mean age 71 ± 12 years, 35% women, ischemic cardiomyopathy in 44%). QRS configuration at baseline was LBBB in 39% and non-LBBB in 46%. Procedure and fluoroscopy duration were 105 ± 54 and 19 ± 15 min, respectively. LBBAP threshold and R-wave amplitudes were 0.6 ± 0.3 V at 0.5 ms and 10.6 ± 6 mV at implantation and remained stable during mean follow-up of 6 ± 5 months. LBBAP resulted in significant QRS narrowing from 152 ± 32 to 137 ± 22 ms (p < 0.01). LVEF improved from 33 ± 10% to 44 ± 11% (p < 0.01). Clinical and echocardiographic responses were observed in 72% and 73% of patients, respectively. Baseline LBBB (odds ratio: 3.96; 95% confidence interval: 1.64 to 9.26; p < 0.01) and left ventricular end-diastolic diameter (odds ratio: 0.62; 95% confidence interval: 0.49 to 0.79; p < 0.01) were independent predictors of echocardiographic response. CONCLUSIONS: LBBAP is feasible and safe and provides an alternative option for CRT. LBBAP provides remarkably low and stable pacing thresholds and was associated with improved clinical and echocardiographic outcomes.

Cardiac troponin release following left bundle branch pacing.

Left bundle branch pacing (LBBP) has emerged as an alternative to His bundle pacing (HBP) to achieve physiologic ventricular stimulation. The extent of myocardial injury during permanent LBBP implantation is currently not known. The aim of the study was to prospectively assess the extent of myocardial injury during LBBP implantation. Cardiac troponin (cTn) levels were measured at baseline and 6-12 h following permanent LBBP. The number of attempts to achieve LBBP was documented. Troponin levels were measured in a control population undergoing other electrophysiology procedures including HBP, other devices involving right ventricular (RV) pacing, radiofrequency ablation for atrial fibrillation (AF) and supraventricular tachycardia (SVT). Significant elevation of troponin (SET) was defined as threefold increase above the upper reference limit (URL) for cTn. Between December 2019 and April 2020, 204 were prospectively enrolled: LBBP in 98 and Control group 106 (SVT, 55; AF, 20; HBP, 17; other devices, 14). SET (>3× URL) was seen in 49.4% of patients in the LBBP group compared to 58.4% in the control group (p = .23). Peak troponin levels were greater in the control group compared to the LBBP group (230.3 ± 320.1 vs. 87.4 ± 71.3 pg/ml; p = .0001). Compared to LBBP (49.4%), SET was observed less frequently following HBP (17.5%; p = .01), and other device implantation (29%; p = .15). Patients requiring >2 attempts (n = 33) had significantly higher incidence of SET compared to <2 attempts (n = 56; 66.7% vs. 39.3%; p = .01). LBBP implantation is associated with myocardial injury. Asymptomatic troponin release following LBBP is less than or comparable to other interventional electrophysiology procedures.

Permanent His Bundle Pacing in Patients With Congenital Complete Heart Block: A Multicenter Experience.

OBJECTIVES: This study retrospectively assessed the safety and efficacy of permanent His bundle pacing (HBP) in patients with congenital complete heart block (CCHB). BACKGROUND: HBP has become an accepted form of pacing in adults. Its role in CCHB is not known. METHODS: Seventeen patients with CCHB who underwent successful HBP were analyzed at 6 academic centers between 2016 and 2019. Nine patients had de novo implants, and 8 patients had previous right ventricular (RV) leads. Three RV paced patients had reduced left ventricular ejection fractions at the time of HBP. Implant/follow-up device parameters, New York Heart Association functional class, QRS duration, and left ventricular ejection fraction data were analyzed. RESULTS: Patients' mean age was 27.4 ± 11.3 years, 59% were women, and mean follow-up was 385 ± 279 days. The following parameters were found to be statistically significant between implant and follow-up, respectively: impedance, 602 ± 173 Ω versus 460 ± 80 Ω (p < 0.001); and New York Heart Association functional class, 1.7 ± 0.9 versus 1.1 ± 0.3 (p = 0.014). In patients with previous RV pacing, HBP resulted in a significant decrease in QRS duration: 167.1 ± 14.3 ms versus 118.3 ± 13.9 ms (p < 0.0001). In de novo implants, HBP resulted in increases in QRS duration compared with baseline: 111.1 ± 19.4 ms versus 91.0 ± 4.8 ms (p = 0.016). Other parameters exhibited no statistically significant differences. During follow-up, 2 patients required lead revision due to elevated pacing thresholds. CONCLUSIONS: HBP seems to be safe and effective, with improvement in clinical outcomes in patients with CCHB. Larger studies with longer follow-up periods are required to confirm our findings.

His bundle pacing capture threshold stability during long-term follow-up and correlation with lead slack.

AIMS: His bundle pacing (HBP) is the most physiologic form of pacing. Long-term HBP capture threshold stability and its relation to lead characteristics at the time of implantation have not been adequately described. The aim of this study was to characterize HB capture threshold in follow-up and to identify potential lead characteristics predictive of lead capture instability. METHODS AND RESULTS: Consecutive patients with successful HBP for bradycardia indications were identified from the Geisinger HBP registry. His bundle capture thresholds, baseline comorbidities, and radiographic lead slack characteristics were analysed. An increase in HB capture threshold ≥1 V above implant values at any time during follow-up was tracked. Forty-four of the 294 studied (15%) experienced HB capture threshold increase by ≥ 1 V. Threshold increase was seen early (41% by 8 weeks, 66% by 1 year). Eighteen (6%) patients required lead revision in follow-up. Abnormal slack shape was associated with a trend toward capture threshold increase [hazard ratio (HR) 2.07; 95% confidence interval (CI) 0.9-4.6; P = 0.08]. Non-perpendicular angle of lead insertion on radiography was associated with the capture threshold increase (HR 2.81, 95% CI 1.4-5.8; P < 0.01). CONCLUSION: His bundle capture threshold remains stable in the majority (85%) of patients. Implant characteristics may predict the threshold rise. Further evaluation of the aetiology of threshold increase and design changes in lead and delivery systems may lead to chronically stable capture thresholds.

His-Purkinje Conduction System Pacing Following Transcatheter Aortic Valve Replacement: Feasibility and Safety.

OBJECTIVES: This study aimed to assess the feasibility and success rates of permanent His-Purkinje conduction system pacing (HPCSP) in patients requiring pacing after transcatheter aortic valve replacement (TAVR). BACKGROUND: TAVR is associated with increased risk for atrioventricular block. HPCSP has the potential to reduce electromechanical dyssynchrony associated with right ventricular pacing. The feasibility and safety of HPCSP in this population are unknown. METHODS: Consecutive patients requiring pacemakers after TAVR in whom His bundle pacing (HBP) and/or left bundle branch area pacing (LBBAP) was attempted at 5 centers were included in the study. Implant success rates, pacing characteristics, QRS duration, and left ventricular ejection fraction were assessed. Any procedure-related complications, lead revisions, heart failure hospitalizations, and deaths were documented. RESULTS: HPCSP was successful in 55 of 65 (85%) patients studied. HBP was successful in 29 of 46 patients (63%), and LBBAP was successful in 26 of 28 (93%) patients in whom it was attempted. HBP was more successful in patients with Sapien valves than in those with CoreValves (69% vs. 44%; p < 0.05). LBBAP was associated with lower pacing thresholds and higher R-wave amplitudes at implantation compared with HBP (0.64 ± 0.3 at 0.5 ms vs. 1.4 ± 0.8 at 1 ms; p < 0.001; 14 ± 8 mV vs. 5.5 ± 5.6 mV; p < 0.001). Pacing thresholds remained stable and left ventricular ejection fraction remained unchanged during a mean follow-up of 12 ± 13.7 months. CONCLUSIONS: HPCSP is feasible in the majority of patients requiring pacemakers post-TAVR. Success rates of HBP were lower in patients with CoreValves compared to Sapien valves. LBBAP was associated with higher success rates and lower pacing thresholds compared with HBP.

Clinical Outcomes of Selective Versus Nonselective His Bundle Pacing.

OBJECTIVES: The aim of the study was to evaluate the clinical outcomes of nonselective (NS) His bundle pacing (HBP) compared with selective (S) HBP. BACKGROUND: HBP is the most physiologic form of ventricular pacing. NS-HBP results in right ventricular septal pre-excitation due to fusion with myocardial capture in addition to His bundle capture resulting in widened QRS duration compared with S-HBP wherein there is exclusive His bundle capture and conduction. METHODS: The Geisinger and Rush University HBP registries comprise 640 patients who underwent successful HBP. Our study population included 350 consecutive patients treated with HBP for bradyarrhythmic indications who demonstrated ≥20% ventricular pacing burden 3 months post-implantation. Patients were categorized into S-HBP or NS-HBP based on QRS morphology (NS-HBP n = 232; S-HBP n = 118) at the programmed output at the 3-month follow-up. The primary analysis outcome was a combined endpoint of all-cause mortality or heart failure hospitalization. RESULTS: The NS-HBP group had a higher number of men (64% vs. 50%; p = 0.01), higher incidence of infranodal atrioventricular block (40% vs. 9%; p < 0.01), ischemic cardiomyopathy (24% vs. 14%; p = 0.03), and permanent atrial fibrillation (18% vs. 8%; p = 0.01). The primary endpoint occurred in 81 of 232 patients (35%) in the NS-HBP group compared with 23 of 118 patients (19%) in the S-HBP group (hazard ratio: 1.38; 95% confidence interval: 0.87 to 2.20; p = 0.17). Subgroup analyses of patients at greatest risk (higher pacing burden or lower left ventricular ejection fraction) revealed no incremental risk with NS-HBP. CONCLUSIONS: NS-HBP was associated with similar outcomes of death or heart failure hospitalization when compared with S-HBP. Multicenter risk-matched clinical studies are needed to confirm these findings.

Long term performance and safety of His bundle pacing: A multicenter experience.

INTRODUCTION: Several single-center short-term studies have demonstrated the feasibility, safety, and positive clinical outcomes of permanent His bundle pacing (HBP). We performed a retrospective study to evaluate long-term technical and safety performances of HBP in a large population of pacemaker patients from two different centers. METHODS AND RESULTS: The analysis includes 844 patients (345 female, mean age = 75 ± 9 years) who underwent successful permanent HBP for pacemaker indications from 2004 to 2016. The main endpoints were long term electrical performances including pacing threshold, sensing, impedance, and freedom from pacing related complications. The pacing indication was AV Block in 348 (41.2%) patients, sinus node disease in 147 (17.4%), any bradycardia indication in patients with atrial fibrillation in 335 (39.7%) patients and need for cardiac resynchronization therapy in 14 (1.7%) patients. Mean pacing capture thresholds and sensed R waves were 1.6 V and 5.8 mV, respectively at implant and 2.0 V and 6.1 mV at chronic follow-up. During the median follow up of 3 years (interquartile range = 1-6 years), HBP was free of any complication in 91.6% of patients. In the first 368 patients, HBP was achieved using a deflectable curve delivery system, while in 476 using the fixed curve sheath. A significant difference was found in the thresholds (2.4 ± 1.0 V and 1.7 ± 1.1 V, P < .001, respectively) and complications (11.9% and 4.2%, P < .001, respectively) between the two groups. CONCLUSIONS: Permanent HBP was safe and effective during long-term follow-up. The fixed curved delivery sheath offered significantly better electrical parameters and reliability over time. The results of this multicenter study are consistent with recent studies.

Extraction of the permanent His bundle pacing lead: Safety outcomes and feasibility of reimplantation.

BACKGROUND: Permanent His bundle pacing (HBP) is a physiological alternative to right ventricular pacing. However, concerns remain about the feasibility and safety of lead extraction from the His bundle region. OBJECTIVE: The aim of our study was to assess the safety and feasibility of extraction of chronically implanted permanent HBP leads in addition to report on the feasibility of reimplanting in the His bundle region. METHODS: Patients undergoing extraction of leads from the His bundle location for standard indications were studied. The primary outcomes were removal success rates, need for extraction tools, and feasibility of reimplantation in the His bundle region. RESULTS: Thirty patients (male 23 (27%); mean age 73.3 ± 14 years) with permanent HBP leads of at least 6-month duration were included. The indications for removal of the HBP leads were infection (n = 3), lead failure (n = 22), nonfunctional lead (n = 3), and upgrade to implantable cardioverter-defibrillator (n = 2). The mean duration of the implanted leads was 25 ± 18 months (range 6-72 months). Removal of HBP leads was successful in 8 of 8 patients (100%) with ≤12-month duration and 21 of 22 patients (95%) with >12-month duration. Extraction tools were used in 4 patients, while manual traction was successful in the remaining patients. Reimplantation in the His-Purkinje conduction system was successful in 19 of 22 patients (86%). CONCLUSION: In this largest study of HBP lead extractions, the overall success rate of extraction of chronically implanted HBP leads was high with a low complication rate. The need for mechanical extraction tools was low, and reimplantation in the His-Purkinje conduction system was feasible.

Prospective evaluation of feasibility and electrophysiologic and echocardiographic characteristics of left bundle branch area pacing.

BACKGROUND: His bundle pacing (HBP) is the most physiologic form of pacing but associated with higher thresholds and lower success in patients with His-Purkinje conduction disease. Recent reports have described transvenous left bundle branch area pacing (LBBAP). OBJECTIVE: We aimed to prospectively evaluate the feasibility and the electrophysiologic and echocardiographic characteristics of LBBAP. METHODS: Patients requiring pacing for bradycardia or heart failure indications (failed left ventricular [LV] lead) were prospectively enrolled. LBBAP was performed with a Medtronic 3830 lead. Presence of left bundle branch (LBB) potential, paced QRS morphology/duration, and peak LV activation time (pLVAT) were recorded at implant. Pacing threshold and sensing was assessed at implant and follow-up. Echocardiography was performed to assess the approximate lead location and impact on tricuspid valve function. RESULTS: LBBAP was successful in 93 of 100 (93%) patients. Mean age was 75 ± 13 years; men 69%, left bundle branch block 24%, right bundle branch block 25%, intraventricular conduction defect 8%. Indications for pacing were atrioventricular (AV) block 54%, sinus node dysfunction 23%, AV node ablation 7%, cardiac resynchronization therapy 11%, HBP lead failure 7%. Baseline QRS duration was 133 ± 35 ms. Paced QRS duration was 136 ± 17 ms. LBB potentials were observed in 63 patients with left bundle branch - ventricle (LBB-V) interval of 27 ± 6 ms. pLVAT was 75 ± 16 ms. Pacing threshold at implant was 0.6 ± 0.4 V @ 0.5 ms and R waves were 10 ± 6 mV and remained stable at median follow-up of 3 months. The lead depth in the septum was approximately 1.4 ± 0.23 cm. CONCLUSIONS: LBBAP was feasible in a high percentage of patients with low thresholds during acute follow-up. HBP and LBBAP may significantly increase the overall success of physiologic pacing.

Outcomes of His-bundle pacing upgrade after long-term right ventricular pacing and/or pacing-induced cardiomyopathy: Insights into disease progression.

BACKGROUND: His-bundle pacing (HBP) is a physiological alternative to right ventricular pacing (RVP). The outcomes of HBP in patients with longstanding atrioventricular block (AVB) and RVP are unknown OBJECTIVE: The purpose of this study was to retrospectively assess the feasibility of HBP in patients with chronic RVP and longstanding AVB and to evaluate its efficacy in reversing the adverse remodeling induced by RVP. METHODS: HBP was attempted in patients with longstanding AVB and chronic RVP and/or pacing-induced cardiomyopathy (PICM) in need for resynchronization therapy. The site of conduction block and feasibility of HBP was documented. Electrocardiographic and echocardiographic assessments at baseline and follow-up were recorded. RESULTS: HBP was successful in 79 of 85 patients (93%) with RVP for 77.6 ± 74.8 months (range 2-540 months). AV nodal block was present in 59 and infranodal block in 26. QRS duration increased from 123 ± 31 ms at baseline to 177 ± 17 ms (P <.001) during RVP and decreased to 115 ± 20 ms with HBP (P <.001). T-wave memory was observed in 53 of 79 patients with HBP and normalized in 2-12 weeks. HBP threshold was 1.47 ± 0.9 V @ 1 ms at implant and 1.9 ± 1.3 V @ 1 ms at last follow-up (25 ± 24 months). In 60 patients with PICM in whom left ventricular ejection fraction decreased from 54% ± 7.7% at baseline to 34.3% ± 9.6% (P <.001), ejection fraction improved to 48.2% ± 9.8% (P <.001) after HBP CONCLUSION: Despite a long duration of AVB and chronic RVP, HBP normalized QRS complexes and T waves with stable thresholds, suggesting that progression of distal conduction disease is uncommon in this population. Electrical and structural changes induced by chronic RVP were consistently reversed with HBP.

Low Fluoroscopy Permanent His Bundle Pacing Using Electroanatomic Mapping: A Feasibility Study.

BACKGROUND: Conventional permanent His Bundle pacing (PHBP) can be challenging and associated with high fluoroscopy exposure. The aim of this study was to assess the feasibility and safety of performing low fluoroscopy PHBP using 3-dimensional electroanatomic mapping and comparing outcomes with conventional fluoroscopy guided PHBP implants. METHODS: PHBP was performed at 2 centers using electroanatomic mapping-guided low fluoroscopy implantation in 10 patients using a novel protocol (group 1) and conventional fluoroscopy guided implantation in 20 patients (group 2). The primary end point was feasibility of achieving PHBP with low/zero fluoroscopy and safety end points included total radiation exposure (fluoroscopy time and dose area product), procedure-related complications associated with lead implantation or need for lead revisions. RESULTS: PHBP was successful in 9 of 10 patients (90%) in group 1 and 100% successful in the group 2 patients. The mean His lead fluoroscopy time was significantly lower in group 1 (0.2±0.2 minutes) compared with 8±7 minutes in group 2 ( P=0.002) as was the total fluoroscopy time (0.8±0.3 versus 13±8 minutes, P=0.003) and the dose area product (96±83 versus 1531±923 microGy/m2, P=0.003). The HB capture threshold was lower in group 1 (0.7±0.4 at 1 ms) compared with patients in group 2 (1.15±0.7 at 1 ms) P=0.04. There were no procedure-related complications or lead dislodgements in either group. There was an increase in HB capture threshold in 1 patient (5%) in group 2 at 1-month follow-up. CONCLUSIONS: Electroanatomic mapping-guided PHBP is feasible can be performed safely and results in a significant reduction in fluoroscopy duration and exposure.

Permanent His Bundle Pacing for Cardiac Resynchronization Therapy in Patients With Heart Failure and Right Bundle Branch Block.

Background Cardiac resynchronization therapy utilizing biventricular pacing is an effective therapy for patients with left ventricular (LV) systolic dysfunction, left bundle branch block, and heart failure. Benefits of biventricular pacing may be limited in patients with right bundle branch block (RBBB). Permanent His bundle pacing (HBP) has recently been reported as an option for cardiac resynchronization therapy. The aim of the study was to assess the feasibility and outcomes of HBP in patients with RBBB and heart failure. Methods HBP was attempted as a primary or rescue (failed LV lead implant) strategy in patients with reduced LV ejection fraction, RBBB, QRS duration ≥120 ms, and New York Heart Association class II to IV heart failure. Implant characteristics, New York Heart Association functional class, and echocardiographic data were assessed in follow-up. Results Mean age was 72±10 years, female 15%, with an average LV ejection fraction of 31±10%. HBP was successful in 37 of 39 patients (95%) with narrowing of RBBB in 78% cases. His capture and bundle branch block correction thresholds were 1.1±0.6 V and 1.4±0.7 V at 1 ms, respectively. During a mean follow-up of 15±23 months, there was a significant narrowing of QRS from 158±24 to 127±17 ms ( P=0.0001), increase in LV ejection fraction from 31±10% to 39±13% ( P=0.004), and improvement in New York Heart Association functional class from 2.8±0.6 to 2±0.7 ( P=0.0001) with HBP. Increase in capture threshold occurred in 3 patients. Conclusions Permanent HBP was associated with significant narrowing of QRS duration and improvement in LV function in patients with RBBB and reduced LV ejection fraction. Permanent HBP is a promising option for cardiac resynchronization therapy in patients with RBBB and reduced LV ejection fraction.

Clinical Outcomes of His Bundle Pacing Compared to Right Ventricular Pacing.

BACKGROUND: Right ventricular pacing (RVP) is associated with heart failure and increased mortality. His bundle pacing (HBP) is a physiological alternative to RVP. OBJECTIVES: This study sought to evaluate clinical outcomes of HBP compared to RVP. METHODS: All patients requiring initial pacemaker implantation between October 1, 2013, and December 31, 2016, were included in the study. Permanent HBP was attempted in consecutive patients at 1 hospital and RVP at a sister hospital. Implant characteristics, all-cause mortality, heart failure hospitalization (HFH), and upgrades to biventricular pacing (BiVP) were tracked. Primary outcome was the combined endpoint of death, HFH, or upgrade to BiVP. Secondary endpoints were mortality and HFH. RESULTS: HBP was successful in 304 of 332 consecutive patients (92%), whereas 433 patients underwent RVP. The primary endpoint of death, HFH, or upgrade to BiVP was significantly reduced in the HBP group (83 of 332 patients [25%]) compared to RVP (137 of 433 patients [32%]; hazard ratio [HR]: 0.71; 95% confidence interval [CI]: 0.534 to 0.944; p = 0.02). This difference was observed primarily in patients with ventricular pacing >20% (25% in HBP vs. 36% in RVP; HR: 0.65; 95% CI: 0.456 to 0.927; p = 0.02). The incidence of HFH was significantly reduced in HBP (12.4% vs. 17.6%; HR: 0.63; 95% CI: 0.430 to 0.931; p = 0.02). There was a trend toward reduced mortality in HBP (17.2% vs. 21.4%, respectively; p = 0.06). CONCLUSIONS: Permanent HBP was feasible and safe in a large real-world population requiring permanent pacemakers. His bundle pacing was associated with reduction in the combined endpoint of death, HFH, or upgrade to BiVP compared to RVP in patients requiring permanent pacemakers.