Right Ventricular Pacing Research Articles

Initial Experiences of Left Bundle Branch Area Pacing in Daegu, South Korea – New Procedure with Familiar Tools

Implantation of a permanent pacemaker is a safe and effective treatment for symptomatic bradycardia. Conventionally, ventricular lead is placed at the right ventricular (RV) muscles. Therefore, this causes interventricular dyssynchrony, and long-term high RV pacing (RVP) burden is associated with an increased risk of heart failure and atrial fibrillation. Hence, attempts to directly pace the cardiac conduction system have been made, and finally, a technique called left bundle branch area pacing (LBBAP) has emerged. In our country, the clinical experience of LBBAP is in the early stages. Especially, LBBAP using standard stylet-driven leads (SDL), a major procedural method performed in our country, is also in the early stages, and there are only a few reports about this method worldwide. Herein, we are reporting our initial experiences of LBBAP with SDL. Compared to conventional RVP performed during the same period, LBBAP required an initial learning period a more extended procedure, and fluoroscopy time. However, the paced QRS duration was significantly shorter in the LBBAP group (LBBAP group 120.6 ± 13.0 msec, RVP group 165.2 ± 16.0 msec, <i>p</i> < 0.001). It is fascinating that simply adding a ventricular lead delivery sheath can create a whole new outcome, even at centers that are only familiar with the standard tools. Our experience will be helpful in arrhythmia centers that aim to start LBBAP for the first time.

Rate and nature of complications of conduction system pacing compared with right ventricular pacing: Results of a propensity score–matched analysis from a multicenter registry

Conduction system pacing (CSP) using His bundle pacing (HBP) or left bundle branch area pacing (LBBAP) has emerged as an alternative to right ventricular pacing (RVP). Comparative data on the risk of complications between CSP and RVP are lacking. This prospective, multicenter, observational study aimed to compare the long-term risk of device-related complications between CSP and RVP. A total of 1029 consecutive patients undergoing pacemaker implantation with CSP (including HBP and LBBAP) or RVP were enrolled. Propensity score matching for baseline characteristics yielded 201 matched pairs. The rate and nature of device-related complications occurring during follow-up were prospectively collected and compared between the 2 groups. During a mean follow-up duration of 18 months, device-related complications were observed in 19 patients: 7 in RVP (3.5%) and 12 in CSP (6.0%) (P = .240). On dividing the matched cohort into 3 groups with similar baseline characteristics according to pacing modality (RVP, n = 201; HBP, n = 128; LBBAP, n = 73), patients with HBP showed a significantly higher rate of device-related complications than did patients with RVP (8.6% vs 3.5%; P = .047) and patients with LBBAP (8.6% vs 1.3%; P = .034). Patients with LBBAP showed a rate of device-related complications similar to that of patients with RVP (1.3% vs 3.5%; P = .358). Most of the complications observed in patients with HBP (63.6%) were lead related. Globally, CSP was associated with a risk of complications similar to that of RVP. Considering HBP and LBBAP separately, HBP showed a significantly higher risk of complications than did both RVP and LBBAP whereas LBBAP showed a risk of complications similar to that of RVP.

A New Electromechanical Wave Imaging Dispersion Metric for the Characterization of Ventricular Activation in Different Cardiac Resynchronization Therapy Pacing Schemes.

Conventional biventricular (BiV) pacing cardiac resynchronization therapy (CRT) is an established treatment for heart failure patients. Recently, multiple novel CRT delivering technologies such as His-Bundle pacing have been investigated as alternative pacing strategies for optimal treatment benefit. Electromechanical Wave Imaging (EWI), a high frame-rate echocardiography-based modality, is capable of visualizing the change from dyssynchronous activation to resynchronized BiV-paced ventricles in 3D. This proof-of-concept study introduces a new EWI-based dispersion metric to further characterize ventricular activation. Patients with His-Bundle device implantation (n = 4), left-bundle branch block (n = 10), right-ventricular (RV) pacing (n = 10), or BiV pacing (n = 15) were imaged, as well as four volunteers in normal sinus rhythm (NSR). EWI successfully mapped the ventricular activation resulting from His-Bundle pacing. Additionally, very similar activation patterns were obtained in the NSR subjects, confirming recovery of physiological activation with His pacing. The dispersion metric was the most sensitive EWI-based metric that identified His pacing as the most efficient treatment (lowest activation time spread), followed by BiV and RV pacing. More specifically, the dispersion metric significantly (p < 0.005) distinguished His pacing from the other two pacing schemes as well as LBBB. The initial findings presented herein indicate that EWI and its new dispersion metric may provide a useful resynchronization evaluation clinical tool in CRT patients under both novel His-Bundle pacing and more conventional BiV pacing strategies.

Comparison of the safety and efficiency of temporary cardiac pacing methods during left bundle branch pacemaker implantation: Femoral vein pacing versus atrial spiral pacing with electrodes placed at the ventricle.

Left bundle branch pacemakers (LBBPs) can better maintain ventricular electrical synchronization than traditional right ventricular pacing (RVP). Temporary cardiac pacing (TCP) is needed to ensure the safety of the operation in patients undergoing LBBP. Currently, there are two methods of installing TCP in conventional permanent pacemaker implantation. To evaluate the safety and efficiency of replacing femoral vein pacing with atrial spiral pacing in the right ventricle for temporary cardiac pacing (TCP) during left bundle branch pacemaker (LBBP) implantation. A total of 179 patients who underwent TCP during LBBP were selected for retrospective analysis from April 2019 to 2021 and divided into two groups: the atrial spiral electrode group (n = 76) and the femoral vein electrode group (n = 103). The following were observed: operation time; radiation dose; radiation time; operation expenses; hospitalization time; pacemaker parameters immediately after the operation and at 1 week, 1 month, 3 months, and 6 months after the operation; operation complications and femoral vein puncture point complications were observed in the two groups. Compared to the femoral vein electrode group, the atrial electrode group had significantly lower operation times ([116.86 ± 24.63] versus [128.94 ± 25.27] min, p < 0.05), radiation doses ([805.07 ± 132.94] versus [846.42 ± 87.37] mgy, p < 0.05), and decreased risk of a displaced or dislodged temporary pacing electrode during the operation ([0.00%] versus [4.85%], p < 0.05). The atrial electrode group did not have significant operation costs or material costs associated with femoral vein temporary pacing electrode implantation. In addition, the atrial electrode group did not have an increased risk of pacemaker-related infections, and the parameters of the pacemaker were unaffected. However, some puncture point complications appeared in the femoral vein electrode group (8 cases of local subcutaneous hematoma, 3 cases of pseudoaneurysms, 3 cases of arteriovenous fistula). The replacement of the femoral vein pacing electrode with an atrial spiral pacing electrode in the right ventricle for TCP during LBBP implantation was safe and effective.

Clinical impact of right ventricular pacing burden in patients with post-transcatheter aortic valve replacement permanent pacemaker implantation.

Patients who undergo permanent pacemaker (PPM) implantation after transcatheter aortic valve replacement (TAVR) have a worse outcome. The aim of this study was to identify risk factors of worse outcomes in patients with post-TAVR PPM implantation. This is a single-centre, retrospective study of consecutive patients who underwent post-TAVR PPM implantation from 11 March 2011 to 9 November 2019. Clinical outcomes were evaluated by landmark analysis with cut-off at 1 year after the PPM implantation. Of the 1389 patients underwent TAVR during the study duration and a total of 110 patients were included in the final analysis. Right ventricular pacing burden (RVPB) ≥ 30% at 1 year was associated with a higher likelihood of heart failure (HF) readmission [adjusted hazard ratio (aHR): 6.333; 95% confidence interval [CI]: 1.417-28.311; P = 0.016] and composite endpoint of overall death and/or HF (aHR: 2.453; 95% CI: 1.040-5.786; P = 0.040). The RVPB ≥30% at 1 year was associated with higher atrial fibrillation burden (24.1 ± 40.6% vs. 1.2 ± 5.3%; P = 0.013) and a decrease in left ventricular ejection fraction (-5.0 ± 9.8% vs. + 1.1 ± 7.9%; P = 0.005). The predicting factors of the RVPB ≥30% at 1 year were the presence of RVPB ≥40% at 1 month and the valve implantation depth measured from non-coronary cusp ≥4.0 mm (aHR: 57.808; 95% CI: 12.489-267.584; P < 0.001 and aHR: 6.817; 95% CI: 1.829-25.402; P = 0.004). The RVPB ≥30% at 1 year was associated with worse outcomes. Clinical benefit of minimal RV pacing algorithms and biventricular pacing needs to be investigated.

Long-term follow-up of selective and non-selective His bundle pacing leads in patients with atrioventricular block.

His bundle pacing (HBP) is a novel treatment with limited knowledge on long-term outcome. We aimed to assess long-term safety and effectiveness of HBP in patients with atrioventricular block treated with HBP and a back-up right ventricular pacing (RVP) lead. We included 38 patients from a completed single-center, randomized controlled cross-over trial designed to compare left ventricular (LV) function after 12months of HBP vs. RVP conducted between September 2007 and August 2011. Lead performance beyond the 2-year study period was assessed based on a retrospective review of capture thresholds, sensing, impedance, energy consumption, and rate of HBP interruption. Patients were followed for a mean of 7 ± 4years. Both at baseline and during follow-up, HBP leads displayed significantly higher capture thresholds than RVP leads (P < 0.001), multifold higher energy consumption (P < 0.001), and lower sensing amplitudes (P < 0.001). During follow-up, 17 (53%) HBP leads were deactivated or abandoned. The principal cause for HBP interruption was high pacing thresholds in patients with preserved LVEF during RVP. Device longevity was shorter than that of contemporary cohorts treated with dual-chamber pacing or CRT, and time to first device exchange was 6.8 ± 1.5years. No lead dislodgements occurred, but four patients (10%) developed device-related infections requiring device extraction. HBP was interrupted in > 50% of patients during long-term follow-up. The principal cause was unacceptably high capture thresholds and no significant difference in LV function with HBP compared with RVP. Device longevity was shorter, and infection rates were higher than anticipated.

Clinical, procedural and lead outcomes associated with different pacing techniques: a network meta-analysis

BackgroundHis- Purkinje system pacing (HPSP) techniques have been proposed as alternative to biventricular pacing (BVP) and right ventricular pacing (RVP). ObjectiveTo compare data regarding clinical, procedural and lead outcomes associated with different pacing techniques. MethodsAn accurate search of online scientific libraries (from inception to May, 12,022) was performed. Thirty-three studies were included in the meta-analysis involving 4386 patients, of whom 1324 receiving RVP, 1032 patients receiving BVP, 1069 patients receiving his-bundle pacing (HBP) and 968 patients receiving left bundle branch pacing (LBBP). ResultsLBBP provided a statistically significant increase in LVEF relative to HBP (0.4473 [0.0584; 0.8361] p = 0.0242) and BVP (0.6733 [0.4734; 0.8732] p < 0.0001) in patients with cardiac resynchronization therapy indication. LBBP and HBP significantly decreased QRS duration as compared to BVP, with largest QRS narrowing obtained by LBBP (−0.4951 [−0.9077; −0.0824] p = 0.0187). As compared to LBBP, HBP was associated with a significant increase of pacing threshold (p = 0.0369) and significant reduction of R-wave amplitude over time (p = 0.027). LBBP was associated with significant reduction in RR of hospitalization for HF (HFH) as compared to both BVP (p = 0.0343) and HBP (p = 0.0476), whereas, as compared to RVP, the risk of lead issues was significantly higher with BVP (p = 0.0424) and HBP (p = 0.0298), but not for LBBP (p = 0.425). ConclusionsAs compared to other pacing techniques, LBBP significantly improved LVEF, narrowed QRS duration and reduced HFHs, with steadily lower capture thresholds and higher R-wave amplitude, and without increasing lead issues.

Novel non-invasive ECG imaging method based on the 12-lead ECG for reconstruction of ventricular activation: A proof-of-concept study.

Current non-invasive electrocardiographic imaging (ECGi) methods are often based on complex body surface potential mapping, limiting the clinical applicability. The aim of this pilot study was to evaluate the ability of a novel non-invasive ECGi method, based on the standard 12-lead ECG, to localize initial site of ventricular activation in right ventricular (RV) paced patients. Validation of the method was performed by comparing the ECGi reconstructed earliest site of activation against the true RV pacing site determined from cardiac computed tomography (CT). This was a retrospective study using data from 34 patients, previously implanted with a dual chamber pacemaker due to advanced atrioventricular block. True RV lead position was determined from analysis of a post-implant cardiac CT scan. The ECGi method was based on an inverse-ECG algorithm applying electrophysiological rules. The algorithm integrated information from an RV paced 12-lead ECG together with a CT-derived patient-specific heart-thorax geometric model to reconstruct a 3D electrical ventricular activation map. The mean geodesic localization error (LE) between the ECGi reconstructed initial site of activation and the RV lead insertion site determined from CT was 13.9 ± 5.6 mm. The mean RV endocardial surface area was 146.0 ± 30.0 cm2 and the mean circular LE area was 7.0 ± 5.2 cm2 resulting in a relative LE of 5.0 ± 4.0%. We demonstrated a novel non-invasive ECGi method, based on the 12-lead ECG, that accurately localized the RV pacing site in relation to the ventricular anatomy.

Update in LV Only Fusion CRT Pacing: Annals and Future Perspectives.

Triple-chamber cardiac devices are utilized for cardiac resynchronization therapy (CRT) and is the standard-of-care therapy for heart failure (HF) patients in the current guidelines. In the setting of biventricular (BIV) pacing it involves a mandatory implantation of right ventricular (RV) lead that allows simultaneous BIV pacing with 0 ms VV (ventricular to ventricular) interval. Nevertheless, it seems that response to CRT is not related to RV lead position. RV pacing is known for deleterious effects on RV/Left Ventricle (LV) function and should not be used in persons with normal atrioventricular conduction (AV) and sinus rhythm. As it compensates for the additional asynchrony induced by unnecessary stimulation of RV pacing, only pacing the left ventricle (LV) may result in improved cardiac resynchronization therapy (CRT) outcomes and a decrease in the number of individuals who do not respond to the procedure. Furthermore, leadless LV fusion CRT pacing without RV lead could be a potential CRT therapy alternative to BIV pacing in nonischemic heart failure patients with preserved AV conduction. The aim of our study is to made an update in cardiac resynchronization therapy with LV only fusion pacing.

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Right ventricular cardiac resynchronization therapy in patients with right ventricular conduction delay and heart failure

Reducing cardiac tamponade caused by temporary pacemaker perforation in transcatheter aortic valve replacement

BackgroundCardiac tamponade caused by temporary right ventricular (RV) pacemaker perforation is a rare but serious complication in transcatheter aortic valve replacement (TAVR). AimsTo study the incidence of temporary pacemaker related cardiac tamponade in TAVR, and the relation to the type of pacemaker lead used in periprocedural temporary transvenous pacing. MethodsA single center registry of transfemoral TAVRs in 2014–2020. Main inclusion criterion was peri-operative use of a temporary RV pacing lead. Main exclusion criteria were a preoperatively implanted permanent pacemaker or the exclusive use of left ventricular guidewire pacing. Incident cardiac tamponade was classified as pacemaker lead related, or other. Patients were grouped according to type of temporary RV pacing wire. Results810 patients were included (age 80.5 ± 7.3 [mean ± standard deviation], female 319, 39.4%). Of these, 566 (69.9%) received a standard RV temporary pacing wire (RV-TPW), and 244 (30.1%) received temporary RV pacing through a permanent, passive pacemaker lead (RV-TPPL). In total, 18 (2.2%) events of cardiac tamponade occurred, 12 (67%) were pacemaker lead related. All pacemaker lead-related cardiac tamponades occurred in the group who received a standard RV-TPW and none in the group who received RV-TPPL (n = 12 [2.1%] vs. n = 0 [0%], p = 0.022). No difference in cardiac tamponade due to other causes was seen between the groups (p = 0.82). ConclusionsThe use of soft-tip RV-TPPL was associated with a lower risk of pacemaker related cardiac tamponade in TAVR. When perioperative pacing is indicated, temporary RV-TPPL may contribute to a significant reduction of cardiac tamponade in TAVR.

Strain echocardiography in predicting LV dysfunction in RV apical pacing

Right ventricular (RV) pacing is associated with a reduction in left ventricular (LV) systolic function, thought to be mediated by pacing-induced ventricular dyssynchrony. The prevalence of heart failure after RV pacing is reported to range from 31±3%. We studied 60 subjects with high-grade atrioventricular block and Complete Heart Block (CHB) scheduled to undergo right ventricular apical pacing. 2D echocardiography was done at baseline, 1 month and 12 months. Pacing-induced cardiomyopathy was defined as a reduction in LVEF to <45%. Strain was evaluated off-line from digitally stored images using all advanced software package (cardiac wall motion quantification (CMQ); Toshiba Medical Systems). Longitudinal strain for individual myocardial segments was measured from the apical four-chamber, two-chamber and long axis views (16 segment AHA/ASE model). None had LV dysfunction at baseline based on 2D and strain echo imaging. Subsequently 18 patients were detected to develop low GLS score (less than -14.5) at 1 month. On subsequent follow up at 1 year, all 18 patients developed LV dysfunction on 2D Echocardiography. Thus Strain imaging with GLS score helped in early detection of LV dysfunction in RV apical pacing subjects. Pacing-induced cardiomyopathy had significant association with high grade AV block with pacemaker dependency. It had no significant associations with other comorbidities like diabetes, hypertension, ischemic heart disease or with the type of medication intake. However there was a statistically significant association with heart failure.

Echocardiographic Evaluation of the Effect on Left Ventricular Function Between Left Bundle Branch Pacing and Right Ventricular Pacing.

The purpose of this study was to assess the left ventricular function effects of permanent left bundle branch pacing (LBBP) versus traditional right ventricular pacing (RVP). Consecutive patients receiving pacemaker implantation were included and divided into left bundle branch block (LBBB) group and right ventricular pacing (RVP) group. Baseline characteristics were collected, and they received 1-year follow-up. Electrocardiogram (ECG) characteristics and pacing parameters were assessed before and after implantation. Cardiac function parameters such as left ventricular ejection fraction (LVEF) and tricuspid regurgitation (TR) were recorded and compared. Of 78 patients included, 45 patients received LBBP (mean age, 72.7 ± 12.2 years; male, 55.6%) and 33 patients underwent RVP (mean age 72.9 ± 11.8 years; male, 63.6%). The pacing parameters were satisfactory during the implantation and remained stable during mid-term follow-up. During the follow-up period, LBBP patients had a greater decrease in LVEDD and LVESD. The TR in the LBBP group was significantly improved as compared to the RVP group (P=0.016). Permanent LBBP achieves favorable cardiac hemodynamic effects with good stability and safety. LBBP may reduce severe TR at 1-year follow-up, and LBBP may be an option for patients with severe TR.

Initial Experience with Left Bundle Branch Area Pacing in Patients with Atrioventricular Block and Impaired LV Function.

Chronic right ventricular (RV) pacing can exacerbate heart failure in patients with a low left ventricular ejection fraction (LVEF). Left bundle branch area pacing (LBBAP) has emerged as a novel physiological pacing technique; however, information remains limited on its use among patients with a low EF. This study investigated the safety and short-term clinical outcomes of LBBAP among patients with impaired left ventricular (LV) function. This retrospective analysis of pacemakers at Chosun University Hospital, South Korea, included all patients with impaired LV function (EF<50%) who underwent pacemaker implantation for atrioventricular blockage from 2019-2022. Clinical characteristics, 12-lead electrocardiography findings, echocardiography findings, and laboratory parameters were evaluated. Composite outcomes were defined as all-cause mortality, cardiac death, and hospitalization due to heart failure during the 6-month follow-up. Altogether 57 patients (25 men; mean age, 77.4±10.8 y; LVEF, 41.5±3.8%) were divided into LBBAP (n=16), biventricular pacing (BVP; n=16), and conventional RV pacing (RVP; n=25) groups. In the LBBAP group, the mean paced QRS duration (pQRSd) was narrower (119.5±14.7 vs. 140.2±14.3 vs. 163.2±13.9; p<0.001) and cardiac troponin I level was elevated post-pacing (1.14±1.29 vs. 0.20±0.29 vs. 0.24±0.51, p=0.001). Lead parameters were stable. One patient was hospitalized, and four died (one patient each from heart failure admission, myocardial infarction, unexplained death, and pneumonia in RVP vs. one from intracerebral hemorrhage in BVP) during the follow-up period. In conclusion, LBBAP is feasible in patients with impaired LV function without acute or significant complications and provides a remarkably narrower pQRSd with a stable pacing threshold.

Exploratory use of intraprocedural transesophageal echocardiography to guide implantation of the leadless pacemaker.

Fluoroscopy is the standard tool for transvenous implantation of traditional and leadless pacemakers (LPs). LPs are used to avoid complications of conventional pacemakers, but there still is a 6.5% risk of major complications. Mid-right ventricular (RV) septal device implantation is suggested to decrease the risk, but helpful cardiac landmarks cannot be visualized under fluoroscopy. Transesophageal echocardiography (TEE) is an alternative intraprocedural imaging method. The purpose of this study was to explore the spatial relationship of the LP to cardiac landmarks via TEE and their correlations with electrocardiographic (ECG) parameters, and to outline an intraprocedural method to confirm mid-RV nonapical lead positioning. Fifty-six patients undergoing implantation of LP with TEE guidance were enrolled in the study. Device position was evaluated by fluoroscopy, ECG, and TEE. Distances between the device and cardiac landmarks were measured by TEE and analyzed with ECG parameters with and without RV pacing. Mid-RV septal positioning was achieved in all patients. TEE transgastric view (0°-40°/90°-130°) was the optimal view for visualizing device position. Mean tricuspid valve-LP distance was 4.9 ± 0.9 cm, mean pulmonary valve-LP distance was 4.2 ± 1 cm, and calculated RV apex-LP distance was 2.9 ± 1 cm. Mean LP paced QRS width was 160.8 ± 28 ms and increased from 117.2 ± 34 ms at baseline. LP RV pacing resulted in left bundle branch block pattern on ECG and 37.8% QRS widening by 43.5 ± 29 ms. TEE may guide LP implantation in the nonapical mid-RV position. Further studies are required to establish whether this technique reduces implant complications compared with conventional fluoroscopy.

Leadless biventricular left bundle and endocardial lateral wall pacing versus left bundle only pacing in left bundle branch block patients.

Biventricular endocardial (BIV-endo) pacing and left bundle pacing (LBP) are novel delivery methods for cardiac resynchronization therapy (CRT). Both pacing methods can be delivered through leadless pacing, to avoid risks associated with endocardial or transvenous leads. We used computational modelling to quantify synchrony induced by BIV-endo pacing and LBP through a leadless pacing system, and to investigate how the right-left ventricle (RV-LV) delay, RV lead location and type of left bundle capture affect response. We simulated ventricular activation on twenty-four four-chamber heart meshes inclusive of His-Purkinje networks with left bundle branch block (LBBB). Leadless biventricular (BIV) pacing was simulated by adding an RV apical stimulus and an LV lateral wall stimulus (BIV-endo lateral) or targeting the left bundle (BIV-LBP), with an RV-LV delay set to 5ms. To test effect of prolonged RV-LV delays and RV pacing location, the RV-LV delay was increased to 35ms and/or the RV stimulus was moved to the RV septum. BIV-endo lateral pacing was less sensitive to increased RV-LV delays, while RV septal pacing worsened response compared to RV apical pacing, especially for long RV-LV delays. To investigate how left bundle capture affects response, we computed 90% BIV activation times (BIVAT-90) during BIV-LBP with selective and non-selective capture, and left bundle branch area pacing (LBBAP), simulated by pacing 1cm below the left bundle. Non-selective LBP was comparable to selective LBP. LBBAP was worse than selective LBP (BIVAT-90: 54.2 ± 5.7ms vs. 62.7 ± 6.5, p < 0.01), but it still significantly reduced activation times from baseline. Finally, we compared leadless LBP with RV pacing against optimal LBP delivery through a standard lead system by simulating BIV-LBP and selective LBP alone with and without optimized atrioventricular delay (AVD). Although LBP alone with optimized AVD was better than BIV-LBP, when AVD optimization was not possible BIV-LBP outperformed LBP alone, because the RV pacing stimulus shortened RV activation (BIVAT-90: 54.2 ± 5.7ms vs. 66.9 ± 5.1ms, p < 0.01). BIV-endo lateral pacing or LBP delivered through a leadless system could potentially become an alternative to standard CRT. RV-LV delay, RV lead location and type of left bundle capture affect leadless pacing efficacy and should be considered in future trial designs.

Clinical Outcomes in Conduction System Pacing Compared to Right Ventricular Pacing in Bradycardia

BackgroundConduction system pacing (CSP) provides more physiological ventricular activation than right ventricular pacing (RVP). ObjectivesThis study evaluated the differences in clinical outcomes in patients receiving CSP and RVP. MethodsConsecutive patients with pacemakers implanted for bradycardia from 2016 to 2021 in 2 centers were prospectively followed for the primary composite outcome of heart failure (HF) hospitalizations, upgrade to biventricular pacing, or all-cause mortality, stratified by ventricular pacing burden (Vp) . ResultsAmong 860 patients (mean age 74 ± 11 years, 48% female, 48% atrioventricular block), 628 received RVP and 231 received CSP (95 His-bundle pacing, 136 left bundle branch pacing). The primary outcome occurred in 217 (25%) patients, more commonly in patients with RVP than CSP (30% vs 13%, P < 0.001). In multivariable analyses, CSP was independently associated with 47% reduction of the primary outcome (adjusted hazard ratio [AHR]: 0.53; 95% CI: 0.29-0.97; P = 0.04) and HF hospitalization alone (AHR: 0.40; 95% CI: 0.17-0.95; P = 0.04), among only patients with Vp >20%. The incidence of the primary outcome was highest among RVP with Vp >20% and lowest in CSP with Vp >20% (35% vs 10%, P < 0.001). Compared with RVP with Vp >20%, both CSP with Vp >20% (AHR: 0.51; 95% CI: 0.28-0.91; P = 0.02) and all patients with Vp ≤20% (AHR: 0.73; 95% CI: 0.54-0.99; P = 0.04) were independently associated with reduced primary outcome, driven primarily by reductions in HF hospitalizations (P < 0.05). Event-free survival was similar between CSP with Vp >20% and those needing ≤20% Vp. ConclusionsCSP significantly reduced adverse clinical outcomes for bradycardic patients requiring ventricular pacing and should be the preferred pacing modality of choice.

Abstract 14042: Cmr Demonstrates Key Differences in Patients Undergoing De Novo CRT versus CRT Upgrades

Introduction: Patients with cardiac resynchronization therapy (CRT) upgrades with right ventricular pacing (RVP) dependence may have a different prognosis after CRT and require a distinct implementation strategy. Hypothesis: Left ventricular (LV) size/function, optimal AHA segments for LV pacing, and survival post-CRT is different for patients with RV pacing undergoing CRT upgrade procedures. Methods: Cardiac magnetic resonance (CMR) with cine imaging, DENSE strain mechanical activation mapping, and scar imaging was performed prior to implants of CRT systems that were "de novo" (Group 1) or upgraded from pre-existing pacemakers or ICDs with RVP (Group 2) and without RVP (Group 3). Optimal LV pacing sites were identified based on latest activation. Patients were followed for clinical outcomes. Results: In 92 patients (23.5% female, 65.8 ± 10.7 years old), the baseline LVEDVI by CMR was significantly smaller in RVP upgrade (Group 2) patients (101.8 +/- 34.3 cc/m 2 ) compared with de novo (Group 1; 140.5 +/- 38.2 cc/m 2 ); p=0.001) and non-RVP upgrade patients (Group 3; 153.6 +/- 46.4 cc/m 2 ; p=0.001) (Figure 1). RVP upgrade patients also had the widest baseline QRS (178.2 +/- 26.6 ms v. 159.7 +/- 18.5 ms in Group 1 v. 154.5 +/- 20.1 ms in Group 3; p = 0.001) and were more likely to have latest mechanical activation in an anterior LV segment (50%) versus Group 1 (10%) and Group 3 (35%) patients (p = 0.0007). As shown in Figure 2, RVP upgrade patients had the worst survival (p = 0.007). Conclusion: Patients with RVP dependence undergoing CRT upgrades are more likely to have smaller baseline LV volumes by CMR, greater QRS durations, optimal pacing sites in anterior segments, and unfavorable survival.

Abstract 10177: Pacing-Induced Cardiomyopathy: A Systematic Review and Meta-Analysis of Definition, Incidence, Risk Factors and Management

Introduction: Pacing-induced cardiomyopathy (PiCM) is a potential adverse sequela of right ventricular pacing. Definition varies between studies and the optimal management approach is uncertain. We aimed to characterize definition, incidence, risk factors and treatment strategies of PiCM. Methods: We performed a systematic review and meta-analysis of human studies that evaluated PiCM following pacemaker implantation identified through a literature search of PubMed and EMBASE up to March 2022. Included studies had fifty or more participants. We collected data regarding study definition of PiCM and calculated pooled prevalence across studies. Meta-analysis with random-effects modelling was used to assess association between risk factors and PiCM, reported as odds ratio (OR) with 95% confidence interval (CI). Results: Twenty-six studies (six prospective studies) with a total of 57993 patients (mean/median age 51-78 years, female 45%) were included in final analysis. Fifteen unique definitions of PiCM were reported; the most common definition was left ventricular ejection fraction (LVEF) &lt;50% and LVEF decline ≥10% after pacemaker insertion. Pooled prevalence of PiCM was 12% (95%CI, 11-14%; Figure 1). On meta-analyses, risk factors included male sex (OR 1.23 95%CI 1.12-1.35), baseline LVEF (OR 0.95 per 1% increase, 95%CI 0.93-0.97), paced QRS complex duration (OR 1.02 per msec, 95%CI 1.01-1.03) and right ventricular pacing (RVP) burden (OR 1.02 per 1% increase, 95%CI 1.01-1.02). Treatment strategies identified included cardiac resynchronisation therapy (five studies) and his bundle pacing (three studies). Conclusions: Definition of PiCM varied significantly between studies. More than one in ten patients with a pacemaker with RV pacing developed PiCM. Risk factors included male sex, baseline LVEF, paced QRS duration and RVP. The optimal management strategy is not yet established. Further research is needed to define and treat this understated complication.

Abstract 10991: Incidence of Pacing-Induced Cardiomyopathy in Leadless and Traditional Pacemakers: A Retrospective Analysis of 198 Patients

Introduction: Transvenous pacemaker (TVP) with right ventricular (RV) apical pacing over 40% has been associated with a 17-25% risk of Pacing-Induced Cardiomyopathy (PICM), defined as a decrease in ejection fraction (EF) by 10% or more. It’s been postulated that a septally placed Leadless Pacemaker (LP) causes less risk of PICM, but the exact incidence is unknown. Methods: We performed a single-center retrospective analysis of adults who received an LP or TVP between January 1, 2014 and April 1, 2022 and had echocardiograms before and after the pacemaker. This study’s outcomes were the RV pacing percentage, change in EF, the need for cardiac resynchronization therapy (CRT) upgrade, and follow-up duration. A Wilcoxon rank-sum test calculated the change in EF. RV time, defined as the duration from pacemaker to echocardiogram in months multiplied by the RV pacing percentage, served as a surrogate for how long the RV was paced. Results: A total of 614 patients were screened and 198 patients were included in the study, where 72 received LP and 126 received TVP. The median follow-up was 480 days. The average of the reported 161 patients with RV percentage pacing for LP was 63.43% and TVP was 71.30% (p=0.14). The incidence of PICM and CRT upgrade in the LP group was 44% and 9.7% in LP and TVP was 37% and 9.5% in TVP (p=0.3 and p&gt;0.9), respectively. After accounting for age, age, sex, LP vs TVP, atrioventricular nodal ablation, RV pacing percentage, and follow-up duration, univariate analysis showed that RV time was significantly different between pacemakers (LP 1,353.97 ± 1,420.56 months vs TVP 926.47 ± 1,395.17 months, p=0.009), but not with CRT (No CRT 1,211.37 ± 1,447.45 months vs CRT 919.34 ± 1,199.54 months, p=0.5). Conclusions: This analysis demonstrated that the incidence of PICM was high in both groups (LP 44% vs TVP 37%). Despite significantly more RV time in patients with LP, there was no difference in CRT upgrade.