Cardiac Resynchronization Therapy Pacing Research Articles

Delta QRS and outcomes post CRT in the Resynchronization-Defibrillation for Ambulatory Heart Failure Trial

BackgroundFor patients with left ventricular systolic dysfunction and prolonged QRS duration, cardiac resynchronization therapy (CRT) can improve cardiac electromechanical synchrony and prevent adverse clinical outcomes. ObjectiveThis study sought to investigate the role of delta QRS duration (ΔQRSd) in predicting clinical response to CRT. MethodsThe RAFT (Resynchronization-Defibrillation for Ambulatory Heart Failure Trial) study randomized 1798 patients to CRT with defibrillator or implantable cardioverter-defibrillator alone. Those who received CRT and had electrocardiograms available at baseline and after CRT implantation were included in this analysis. ΔQRSd was calculated as the absolute difference between QRS duration at baseline and with CRT pacing. The primary outcome was the composite of death and heart failure hospitalization. ResultsThere were 813 patients included in this analysis. The median age was 67 years, and 125 patients (15.2%) were female. The median ΔQRSd was −2 ms (−20 to 18 ms), and 447 (55%) patients had a ΔQRSd ≤0 after implantation. ΔQRSd was an independent predictor of the composite outcome for patients with CRT (hazard ratio, 1.012; 95% confidence interval, 1.008–1.017). CRT recipients with ΔQRSd >0 had higher rates of the composite outcome than patients randomized to implantable cardioverter-defibrillator alone. ConclusionFor patients receiving CRT for heart failure with left ventricular systolic dysfunction and QRS prolongation, ΔQRSd was an independent predictor of long-term mortality and heart failure hospitalization.

Utility of Cardiac Magnetic Resonance in Assessing Arrhythmic Risk in Patients With Nonischemic Cardiomyopathy Undergoing Biventricular Pacing

ABSTRACTBackgroundNonischemic cardiomyopathy (NICM) is responsible for approximately one‐third of heart failure and is associated with significant morbidity and mortality. Recent data suggested the lack of mortality reduction from adding a defibrillator to cardiac resynchronization therapy (CRT) in all patients with NICM. Myocardial fibrosis detected by cardiac magnetic resonance late gadolinium enhancement (CMR‐LGE) can help risk stratify patients who would benefit from adding a defibrillator to CRT in this patient population.ObjectivesWe aim to assess the relationship between the presence of myocardial fibrosis detected by CMR‐LGE and the rate of major arrhythmic events (MAE) that included sustained ventricular tachycardia (VT), appropriate cardiac resynchronization therapy‐defibrillator (CRT‐D) intervention, ventricular fibrillation (VF), and sudden cardiac death (SCD) in patients with NICM undergoing CRT and to compare all‐cause mortality and heart failure improvement between patients receiving cardiac resynchronization therapy‐pacing (CRT‐P) versus those receiving CRT‐D based on the presence of myocardial fibrosis.MethodsAll consecutive patients with NICM satisfying a guideline‐directed indication for CRT implantation were included in the study after excluding patients who refused to consent, patients with acute decompensated heart failure, and those contraindicated for a cardiac magnetic resonance (CMR). Patients were divided into two groups based on the presence of fibrosis in cardiac MRI: the LGE/CRT‐D group and the No LGE/CRT‐P group. They were then followed for 1 year.ResultsSixty patients were enrolled. Sixteen patients (26.6%) developed MAE during the study duration, among those patients, seven had myocardial fibrosis (receiving CRT‐D as per protocol), while nine had no myocardial fibrosis (receiving CRT‐P as per protocol), (41.2% vs. 20.9%, p = 0.045). The presence of CMR‐LGE, regardless of the extent and distribution, predicted MAE with an odds ratio of 2.6 (CI = 1.78–8.9, p = 0.04). The presence of ≥7.5% of myocardial fibrosis by CMR was associated with 54% sensitivity and 100% specificity for MAE in the study population. All‐cause mortality was significantly higher in the No LGE/CRT‐P group versus the LGE/CRT‐D group (15 [34.9%] vs. 2 [11.8%], p = 0.076).ConclusionIn patients with NICM candidates for biventricular pacing, the presence of LGE on CMR, irrespective of the extent or segmental pattern, is independently associated with an MAE and is associated with worse heart failure outcomes. However, the absence of LGE did not rule out MAE, and implanting CRT‐P based on lack of fibrosis may result in higher all‐cause mortality.

Conduction system pacing compared with biventricular pacing for cardiac resynchronization therapy in patients with heart failure and mildly reduced left ventricular ejection fraction: Results from International Collaborative LBBAP Study (I-CLAS) Group

BackgroundCardiac resynchronization therapy (CRT) is a guideline-recommended therapy in patients with heart failure with mildly reduced ejection fraction (HFmrEF, 36%–50%) and left bundle branch block or indication for ventricular pacing. Conduction system pacing (CSP) using left bundle branch area pacing or His bundle pacing has been shown to be a safe and physiologic alternative to biventricular pacing (BVP). ObjectiveThe aim of this study was to compare the clinical outcomes between BVP and CSP for patients with HFmrEF undergoing CRT. MethodsConsecutive patients who underwent BVP or CSP with HFmrEF between January 2018 and June 2023 at 16 international centers were included. The primary outcome was the composite end point of time to death or heart failure hospitalization (HFH). Secondary end points included change in left ventricular ejection fraction (LVEF) and individual end points of death and HFH. ResultsA total of 1004 patients met inclusion criteria: BVP, 178; CSP, 826 (His bundle pacing, 154; left bundle branch area pacing, 672). Mean age was 73 ± 13 years; female, 34%; and LVEF, 42% ± 5%. Paced QRS duration in CSP was significantly narrower compared with BVP (129 ± 21 ms vs 144 ± 19 ms; P < .001). LVEF improved during follow-up in both groups (49% ± 10% vs 48% ± 10%; P = .32). CSP was independently associated with significant reduction in the primary end point of time to death or HFH compared with BVP (22% vs 34%; hazard ratio, 0.64; 95% confidence interval, 0.43–0.94; P = .025). ConclusionCSP was associated with improved clinical outcomes compared with BVP in this large cohort of patients with HFmrEF undergoing CRT. Randomized controlled trials comparing CSP with BVP will be necessary to confirm these results.

Ineffective cardiac resynchronization pacing is associated with poor outcomes in a nationwide cohort analysis

BackgroundDelivery of cardiac resynchronization therapy (CRT) requires left ventricular myocardial capture to achieve clinical benefits. ObjectiveWe sought to determine whether ineffective pacing affects survival. MethodsIneffective ventricular pacing (VP) was defined as the difference between the percentage of delivered CRT (%VP) and the percentage of effective CRT in CRT devices. Using the Optum de-identified electronic health record data set and Medtronic CareLink data warehouse, we identified patients implanted with applicable devices with at least 30 days of follow-up. Kaplan-Meier and Cox proportional hazards models assessed the impact of %VP and % ineffective VP on survival. ResultsAmong 7987 patients with 2.1 ± 1.0 years of follow-up, increasing ineffective VP was associated with decreasing survival: the highest observed survival was in the quartile with <0.08% ineffective VP and the lowest survival was in the quartile with >1.47% ineffective VP (85.1% vs 75.7% at 3 years; P < .001). As expected, patients with more than the median %VP of 97.7% had better survival than did patients with <97.7% VP (84.2% vs 77.8%; P < .001). However, patients who had >97.7% VP but >2% ineffective VP had similar survival to patients with <97.7% VP but ≤2% ineffective VP (81.6% vs 79.4%; P = .54). A multivariable Cox proportional hazards model demonstrated that <97.7% VP (adjusted hazard ratio 1.29; 95% confidence interval 1.14–1.46; P < .001) and >2% ineffective VP (hazard ratio 1.35; 95% confidence interval 1.18–1.54; P < .001) were both significantly associated with decreased survival. ConclusionIneffective VP is associated with decreased survival. In addition to maximizing the percentage of delivered CRT pacing, every effort should be made to minimize ineffective VP.

The use of left bundle branch pacing as a bail-out in case of CRT pacing failure: a case series

Abstract Introduction LBBB pacing has emerged as a novel alternative to CS pacing for cardiac resynchronization therapy in patients with heart failure. Purpose We hereby present a series of four cases wherein the use of LBB pacing, although not initially planned as first choice, was able to overcome a variety of different limitations of traditional CRT pacing. Presentation Patient #1 was an 81-year old man with a history of ischemic HF and AF who was admitted with recurring episodes of sustained ventricular tachycardia (VT) below the detection zone of the CRT-D that had been implanted 11 years ago. Interrogation of the device revealed fracture in the RV lead, intact values of the RV defibrillation coil and inability to capture from an LV lead in an anterior vein. Following initial stabilization the patient underwent successful LBB lead implantation combined with a new RV pace-sense lead as backup due to acceptable but non-optimal LBB lead values attributed to ischemic septal scarring. We were able to retain the previous CRT-D device by relegating the LBB lead to the atrial port and with the use of DDDR programming with custom AV delay values in order to achieve LBB pacing with RV pacing as backup. Patient #2 was a 51-year old man with a history of ischemic HF and permanent AF with a previously implanted CRT-D who was also admitted due to episodes of VT. Device interrogation revealed high threshold of an LV lead located in an anterior vein. The patient underwent supplementary LBB lead implantation which was then connected to the atrial port of the pre-existing CRT-D device, providing primarily LBB pacing with RV pacing backup through the use of custom DDDR programming same as in the previous case. Patient #3 was a 71–year old man with newly-diagnosed ischemic cardiomyopathy and multiple episodes of hemodynamically unstable VT that persisted even after successful reperfusion, necessitating VT ablation. The patient had narrow QRS at baseline and was not eligible for CRT-D, however after medical therapy to suppress ventricular arrhythmias the patient seemed prone to developing LBBB-like QRS widening. The decision was made to proceed with standard ICD implantation and combine a standard defibrillation lead with an LBB lead through the use of a DF1 port, so as to be able to provide LBB pacing as needed in the future. Patient #4 was a 62-year old man with a history of hypertrophic cardiomyopathy and HF with extensive apical scar scheduled for CRT-D implantation. CS venography during implantation revealed a single lateral vein draining the apical LV, lead was implanted but with no capture. An LBB pacing lead was successfully implanted and used instead of the LV lead in the conventional CRT-D set up. Conclusion In this case series we demonstrate that LBB pacing is a viable option as a bail-out in various cases of CRT pacing failure, including both septal scar and hypertrophy, as well as different anatomical substrates and CRT status.LBB pacing characteristics summary

Impact of left bundle branch block morphology in predicting response to left bundle branch area pacing for cardiac resynchronization therapy

Abstract Background Left bundle branch area pacing (LBBAP) is a novel pacing technique with an emerging role in resynchronization therapy [1-4]. QRS morphology has shown to significantly influence cardiac resynchronization therapy (CRT) response [5-6]. Purpose The aim of this study was to assess whether different left bundle branch block (LBBB) definitions are associated with response to LBBAP resynchronization therapy. Methods 40 consecutive CRT candidates with previously unsuccessful biventricular (BiV) pacing or in which effective CRT could not be achieved with BiV pacing based on anatomical or functional criteria were selected for this study. Both ischemic and non-ischemic heart failure (HF) patients were included. Patients were divided into two groups according to LBBB morphology. Group 1 included 20 patients (45% ischemic HF) with strict LBBB definition according to Strauss criteria [7], while 20 patients in Group 2 (55% ischemic HF) had conventional LBBB morphology. Response to CRT was defined for (1) reduction in QRS duration; (2) increase in left ventricular ejection fraction (LVEF) ≥ 5% and (3) decrease in left ventricular end systolic volume (LVESV) ≥ 15%. Results LBBAP was successfully achieved in all patients (mean age: 72.0 years; male: 29). The mean baseline QRS duration before implantation was 178.6±13.8 in the Group 1 and 170.8±29.4 in the Group 2, without a statistically significant difference. Over a mean follow-up of 5.6 months, LBBAP resulted in QRS narrowing in both groups, with a greater reduction in Group 1 (-40.6 ms) compared to Group 2 (-15.1 ms), (p 0.002). Pre-implantation ventricular systolic function did not show significant differences between the two groups, with a mean of 30.1±3.5% in the Strauss LBBB group and 31.0±6.0% in the conventional LBBB group. After implantation LVEF was 42.1±8.5 % in the true LBBB patients and 33.2±7.5 in the conventional LBBB group. Echocardiographic response was observed in 65% of patients with a statistically significant difference between Group 1 (90% of responders) and Group 2 (40% of responders), (p 0,001). HF etiology did not impact the response to LBBAP CRT. Conclusions Strict LBBB definition is associated to a greater electrocardiographic and echocardiographic response in patients receiving LBBAP CRT compared to conventional LBBB criteria.\

Left bundle branch pacing and cardiac remodeling in HF patients with type 2 diabetes mellitus: epigenetic pathways and clinical outcomes.

Left bundle branch (LBB) pacing could achieve cardiac resynchronization therapy (CRT) in patients who cannot be resynchronized via the placement of the left ventricle (LV) lead into the coronary sinus. LBB pacing could improve cardiovascular outcomes in heart failure (HF) patients with LBB block who are affected by type 2 diabetes mellitus (T2DM). LBB pacing could increase the number of CRT responders and lead to the best clinical outcomes in HF patients with T2DM, inducing cardiac remodeling and improving left ventricle ejection fraction (LVEF) via microRNA (miR) modulation. In a multicenter observational study, we enrolled 334 HF patients with LBB block and an indication to receive LBB pacing for CRT. In these patients, we evaluated the CRT responder rate, clinical outcomes, and miR expression at 1 year of follow-up. At 1 year of follow-up, we had 223 responders (66.8%), 132 hospitalizations for HF (39.5%), 24 cardiac deaths (7.2%), and 37 all-cause deaths (11.1%), with a higher rate of HF hospitalizations (77 (69.4%) vs 55 (24.7%), p < 0.05), and cardiac deaths (13 (11.7% vs 11 (4.9%), p < 0.05) in non-responders vs responders. At the end of follow-up, we found the lowest expression of miR-26, miR-29, miR-30, miR-92, and miR-145 in LBB-pacing non-responders vs responders (p < 0.05), and a direct correlation between miR-30 (0.340, [0.833-1.915]; p 0.001), the 6-minute-walking test (6MWT; 0.168, [0.008-0.060]; p 0.011), angiotensin-receptor-neprilysin inhibitors (ARNI; 0.157, [0.183-4.877]; p 0.035), sodium-glucose-transporter-2 inhibitors (0.245, [2.242-7.283]; p 0.001), and LVEF improvements. C reactive protein (CRP) inversely correlated with LVEF improvement (-0.220, [-(0.066-0.263)]; p 0.001). ARNI (1.373, CI 95% [1.007-1.872], p 0.045), miR-30 (2.713, CI 95% [1.543-4.769], p 0.001), and 6MWT (1.288, CI 95% [1.084-1.998], p 0.001) were predictors of LBB pacing responders at 1 year of follow-up. LBB-pacing responders evidenced miR modulation, which was linked to significant improvement of the cardiac pump. Specifically, miR-30 was linked to cardiac pump improvement and predicted responders at 1 year of follow-up in patients with T2DM.

Comparisons of long-term clinical outcomes with left bundle branch pacing, left ventricular septal pacing, and biventricular pacing for cardiac resynchronization therapy

BackgroundLeft bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP) are referred to as left bundle branch area pacing. ObjectiveThis study investigated whether long-term clinical outcomes differ in patients undergoing LBBP, LVSP, and biventricular pacing (BiVP) for cardiac resynchronization therapy (CRT). MethodsConsecutive patients with reduced left ventricular ejection fraction (LVEF <50%) undergoing CRT were prospectively enrolled if they underwent successful LBBP, LVSP, or BiVP. The primary composite end point was all-cause mortality or heart failure hospitalization. Secondary end points included all-cause mortality, heart failure hospitalization, and echocardiographic measures of reverse remodeling. ResultsA total of 259 patients (68 LBBP, 38 LVSP, and 153 BiVP) were observed for a mean duration of 28.8 ± 15.8 months. LBBP was associated with a significantly reduced risk of the primary end point by 78% compared with both BiVP (7.4% vs 41.2%; adjusted hazard ratio [aHR], 0.22 [0.08–0.57]; P = .002) and LVSP (7.4% vs 47.4%; aHR, 0.22 [0.08–0.63]; P = .004]. The adjusted risk of all-cause mortality was significantly higher in LVSP than in BiVP (31.6% vs 7.2%; aHR, 3.19 [1.38–7.39]; P = .007) but comparable between LBBP and BiVP (2.9% vs 7.2%; aHR, 0.33 [0.07–1.52], P = .155). Propensity score adjustment also obtained similar results. LBBP showed a higher rate of echocardiographic response (ΔLVEF ≥10%: 60.0% vs 36.2% vs 16.1%; P < .001) than BiVP or LVSP. ConclusionLBBP yielded long-term clinical outcomes superior to those of BiVP and LVSP. The role of LVSP for CRT needs to be reevaluated because of its high mortality risk.

Left bundle branch pacing lead for sensing ventricular arrhythmias in implantable cardioverter-defibrillator: A pilot study (LBBP-ICD study)

BackgroundLeft bundle branch pacing (LBBP) has been suggested as an alternative modality for biventricular pacing in cardiac resynchronization therapy (CRT)–eligible patients. As it provides stable R-wave sensing, LBBP has been recently used to provide sensing of ventricular arrhythmia in patients receiving implantable cardioverter-defibrillator (ICD) with CRT. ObjectiveThe aim of this study was to analyze the long-term safety and efficacy of the LBBP lead for appropriate detection of ventricular arrhythmia and delivery of antitachycardia pacing (ATP) in patients requiring defibrillator therapy with CRT. MethodsCRT-eligible patients who underwent successful LBBP-optimized ICD and LBBP-optimized CRT with defibrillator were enrolled. The LBBP lead was connected to the right ventricular-P/S port after capping the IS-1 connector plug of the DF-1–ICD lead. LBBP-optimized ICD or LBBP-optimized CRT with defibrillator was decided on the basis of correction of conduction system disease. Documented arrhythmic episodes and therapy delivered were analyzed. ResultsThirty patients were enrolled. The mean age was 59.7 ± 10.5 years. LBBP resulted in an increase in left ventricular ejection fraction from 29.9% ± 4.6% to 43.9% ± 11.2% (P < .0001). During a mean follow-up of 22.9 ± 12.5 months, 254 ventricular arrhythmic events were documented. Appropriate events (n = 225 [89%]) included nonsustained ventricular tachycardia (VT) (n = 212 episodes [94%]), VT (n = 8 [3.5%]), and ventricular fibrillation (n = 5 [2.5%]). ATP efficacy in terminating VT was 75%. Eleven percent of episodes (n = 29) were inappropriately detected because of T-wave oversensing. Inappropriate therapy (ATP) was delivered for 14 episodes (5.5%). Three patients (10%) had worsening of tricuspid regurgitation. ConclusionSensing from the LBBP lead for arrhythmia detection is safe as ∼90% of the episodes were detected appropriately. Future studies with a dedicated LBBP-defibrillator lead along with algorithms to avoid oversensing can help in combining defibrillation with conduction system pacing.

Feasibility study on cardiac resynchronization in the treatment of heart failure by single left bundle branch pacing

To examine the feasibility of single left bundle branch pacing for cardiac resynchronization therapy (CRT) by carrying out a frequency adaptive atrioventricular delay (RAAVD) algorithm and automatic optimization of the single left bundle branch pacing atrioventricular interval (AVI) based on the right atrioventricular interval (RAS–RVS). Thirty-six patients with CRT class Ia indications according to the European Society of Cardiology 2016 guidelines and implanted with RAAVD functional three-chamber pacemakers were prospectively enrolled in this study. Patients were divided into a single left bundle branch pacing group (n = 21) and a standard biventricular pacing group (n = 15). The optimization of the two groups was performed under standard cardiac colour Doppler ultrasound, followed by the comparison of the QRS width, cardiac function improvement, and echocardiography indicators. The ratio of AVI to the right atrial-right ventricular interval (RAS–RVS) after single LV pacing optimization was defined as the single left bundle branch pacing coefficient (LUBBPε). In comparison to the BVP, the QRS was significantly narrowed (P = 0.017), accompanied by a significantly increased proportion of patients with NYHA class I and II, as well as the 6MWT. Compared with standard biventricular pacing, LVEDD was significantly shortened (P = 0.045), accompanied by significantly improved LAD, AVVTI, EA distance/RR, IVMD, and TS-SD after the operation. RAS–RVS was 156 ± 33 ms, the optimized AVI was 102 ± 10 ms, and LUBBPε was calculated to be 0.66 ± 0.06. Depending on the LUBBPε, a three-chamber pacemaker with a single left bundle branch pacing system was developed based on RAS–RVS-optimized AVI automatically. A three-chamber pacemaker with single left bundle branch pacing can achieve CRT based on RAS–RVS, reaching the optimal AVI of 66% of RAS–RVS.

Conduction system pacing: overview, definitions, and nomenclature.

Pacing from the right ventricle is associated with an increased risk of development of congestive heart failure, increases in total and cardiac mortality, and a worsened quality of life. Conduction system pacing has become increasingly realized as an alternative to right ventricular apical pacing. Conduction system pacing from the His bundle and left bundle branch area has been shown to provide physiologic activation of the ventricle and may be an alternative to coronary sinus pacing. Conduction system pacing has been studied as an alternative for both bradycardia pacing and for heart failure pacing. In this review, we summarize the clinical results of conduction system pacing under a variety of different clinical settings. The anatomic targets of conduction system pacing are illustrated, and electrocardiographic correlates of pacing from different sites in the conduction system are defined. Ultimately, clinical trials comparing conduction system pacing with standard right ventricular apical pacing and cardiac resynchronization therapy pacing will help define its benefit and risks compared with existing techniques.

Comparative study of the effects of left ventricular and biventricular pacing on indices of cardiac function and clinical status of heart failure patients: preliminary results of READAPT study

Abstract Nonresponse to cardiac resynchronization therapy (CRT) has been related with right ventricular dysfunction. Preferential left ventricular pacing (pLVP) can overcome iatrogenic right ventricular dysfunction by achieving left ventricle resynchronization and by allowing for intrinsic activation of the right side, with ramifications extending beyond cardiac output and atrial fibrillation occurrence. Moreover, the AdaptivCRT® algorithm also automatically adjusts interventricular (V-V) delay every minute, optimizing it by means of comparing relative activation delay between right and left ventricles (electrically – driven optimization). In the present study we evaluated the effects of a pLVP algorithm on 50 heart failure patients (all Caucasians, 49% male; 66 +/- 8 years old; 46% ischemic cardiomyopathy; 41% diabetics; NYHA II-III) following randomization to standard biventricular pacing and pLVP, on echocardiographic and cardiopulmonary exercise test indices of functional status, as well as a self-reported quality of life questionnaire. Device programming was based on echocardiography-evaluated maximization of stroke volume and subsequent interventricular and atrioventricular delay adjustments delegated to the device. The follow-up consisted of 6 and 12-months visits; after the 1rst month of optimizing maximum CRT response. Results Significant comparative effects of LVP over optimized CRT were noted regarding RV systolic velocity in TDI even from 6-months from baseline (6% increase, p=0.01); while end-systolic diameter of left ventricle was increased by 4% in 6-months in CRT group (p=0.01), while no significant difference was observed in LVP group. At 12 months endsystolic volume was significantly decreased (16%, p=0.01) and left ventricular systolic longitudinal strain was improved in 12 months in LVP group compared to CRT group (p- for interaction =0.001). Additionally, in cardiorespiratory exercise test LVP group showed improved inotropic reserve compared to CRT group according to maximum SBP achieved (20% increase, p&amp;lt;0.01 for interaction); while all other cardiorespiratory indices shoed borderline significant changes at 12 -months. Minnesota score was significantly reduced in LV-P group by 70% at 6-months; whereas no significant change was observed in CRT group (p for interaction &amp;lt;0.01). Conclusions In the preliminary findings of READAPT study, it seems that LV pacing optimized by a standardized echocardiographic protocol in patients with preserved AV conduction, LBBB, can achieve a higher percentage of synchronized LV pacing associated with improved patient quality of life; right ventricular function and endsystolic volume at 6 and 12-months of follow-up, over echo-optimized CRT pacing.

Cardiac magnetic resonance-derived myocardial scar is associated with echocardiographic response and clinical prognosis of left bundle branch area pacing for cardiac resynchronization therapy.

Left bundle branch area pacing (LBBAP) is a novel approach for cardiac resynchronization therapy (CRT), but the impact of myocardial substrate on its effect is poorly understood. This study aims to assess the association of cardiac magnetic resonance (CMR)-derived scar burden and the response of CRT via LBBAP. Consecutive patients with CRT indications who underwent CMR examination and successful LBBAP-CRT were retrospectively analysed. Cardiac magnetic resonance late gadolinium enhancement was used for scar assessment. Echocardiographic reverse remodelling and composite outcomes (defined as all-cause death or heart failure hospitalization) were evaluated. The echocardiographic response was defined as a ≥15% reduction of left ventricular end-systolic volume. Among the 54 patients included, LBBAP-CRT resulted in a 74.1% response rate. The non-responders had higher global, septal, and lateral scar burden (all P < 0.001). Global, septal, and lateral scar percentage all predicted echocardiographic response [area under the curve (AUC): 0.857, 0.864, and 0.822; positive likelihood ratio (+LR): 9.859, 5.594, and 3.059; and negative likelihood ratio (-LR): 0.323, 0.233, and 0.175 respectively], which was superior to QRS morphology criteria (Strauss left bundle branch abnormality: AUC: 0.696, +LR 2.101, and -LR 0.389). After a median follow-up time of 20.3 (11.5-38.7) months, higher global, lateral and septal scar burdens were all predictive of the composite outcome (hazard ratios: 4.996, 7.019, and 4.741, respectively; P's < 0.05). Lower scar burden was associated with higher response rate of LBBAP-CRT. The pre-procedure CMR scar evaluation provides further useful information to identify potential responders and clinical outcomes.

Incidence of Radiotherapy Induced Cardiac Implantable Electronic Devices Malfunction: Australian-Based Observation Study.

To assess the incidence rate of cardiac implantable electronic devices (CIED) malfunction with radiotherapy (RT) and identify factors resulting in CIED malfunction. The working hypothesis is that CIED malfunction is associated with higher photon beam energy, treatment anatomical location, device type and dose to device. This retrospective review involved 441 patients with CIED treated with RT. Clinical information, RT (prescription, dose to device, beam energy, anatomical regions treated etc.) and CIED details (type, manufacturer, and device malfunction) were collected from electronic medical records. A total of 344 patients (78%) had a permanent pacemaker (PPM), 44 patients (10%) had implantable cardioverter defibrillator (ICD), 44 patients (10%) had CRT-defibrillator (CRT-D) and 9 (2%) had cardiac resynchronization therapy-pacing (CRT-P). The median prescribed dose was 36 Gy (IQR 1.8-80 Gy). 17 out of 441 patients (3.9%) experienced an CIED malfunction event. This group had a higher prescribed median dose of 42.5 Gy (IQR 20-77 Gy) and beam energy of 14 MV (12-18 MV). None of the malfunctions resulted in clinical symptoms. Median dose to CIED was 0.28 Gy (IQR 0-3.3). No patents received dose to device ≥2 Gy. Using logistic regression, the predictors of CIED malfunction were photon beam energy use ≥10 MV (OR 5.73; 95% CI, 1.58-10.76), anatomical location of RT above the diaphragm (OR 5.2, 95% CI, 1.82-15.2), and having an ICD (OR 4.6, 95% CI, 0.75-10.2). We have demonstrated that photon beam energies ≥10 MV, RT to above the diaphragm and ICD devices are significantly associated with CIED malfunction. The recorded CIED malfunctions in this study were minor malfunctions which did not result in any clinical symptoms. Stringent adherence to the local institution's CIED treatment guidelines, utilization of safety measures and careful choice of beam energy are recommended to minimize risk of symptomatic CIED malfunctions.

Conduction system pacing vs. biventricular pacing for cardiac resynchronization therapy in heart failure with reduced ejection fraction: An updated systematic review and meta-analysis

Conduction system pacing (CSP) is considered an effective and physiological form of pacing in patients requiring cardiac resynchronization therapy (CRT). To compare electrocardiographic (ECG), echocardiographic (ECHO) characteristics and clinical outcomes among patients with heart failure with reduced ejection fraction (HFrEF) undergoing CRT with CSP or biventricular pacing (BVP). This study protocol was registered in the PROSPERO registry (CRD42022375155) and the review was conducted per the PRISMA protocol. Four major databases were searched from inception till October 20, 2022, for relevant studies comparing CSP to BVP for CRT in patients with HFrEF. From a total of 10,072 references identified, 35 full-text were assessed and 18 studies (6 RCTs, 12 observational studies) were included in the review. Following left bundle branch area pacing (LBBAP), on average, paced QRS duration was 28 ms narrower in comparison to BVP (MD -27.69, CI -36.59 to -18.80), and a similar result was obtained with HBP vs. BVP as well. Left ventricular ejection fraction (LVEF) improvement was greater with CSP in comparison to BVP [LBBAP (MD 6.03, CI 4.16-7.91); HBP (MD 3.79, CI 0.46-7.11); HPSP (MD 6.60, CI 4.42-8.78). There were higher odds of being responders (OR 3.82, CI 1.88-7.75)/super responders (OR 2.08, CI 1.53-2.82) (per ECHO findings) in the CSP group, and overall mortality (OR 0.61, CI 0.40-0.93) and hospitalization for HF (HHF) (OR 0.37, CI 0.25-0.55) was lower in CSP group. Our analysis showed better ECG, ECHO, and clinical outcomes in terms of mortality and HHF with CSP compared to BVP.

Significance of effective cardiac resynchronization therapy pacing for clinical responses: An analysis based on the effective cardiac resynchronization therapy algorithm

High percent ventricular pacing maximizes cardiac resynchronization therapy (CRT) response. An effective CRT algorithm classifies each left ventricular (LV) pace as effective or ineffective on the basis of the detection of QS or QS-r morphology on the electrogram; however, the relationship between percent effective CRT pacing (%e-CRT) and responses is unclear. We aimed to clarify the association between %e-CRT and clinical outcomes. Of the 136 consecutive CRT patients, 49 using the adaptive and effective CRT algorithm with percent ventricular pacing > 90% were evaluated. The primary and secondary outcomes were heart failure (HF) hospitalization and prevalence of CRT responders, defined as patients with an improvement in LV ejection fraction of ≥10% or a reduction in LV end-systolic volume of ≥15% after CRT device implantation, respectively. We divided the patients into the effective group (n = 25) and the less effective group (n = 24) by the median value of %e-CRT (97.4%). During the median follow-up period of 507 days (interquartile range 335-730 days), the effective group had a significantly lower risk of HF hospitalization than did the less effective group as revealed by Kaplan-Meier analysis (log-rank, P = .016). Univariate analysis revealed %e-CRT ≥ 97.4% (hazard ratio 0.12; 95% confidence interval 0.01-0.95; P = .045) as a predictor of HF hospitalization. The effective group had a higher prevalence of CRT responders than did the less effective group (23 [92%] vs 9 [38%]; P < .001). Univariate analysis revealed that %e-CRT ≥ 97.4% (odds ratio 19.20; 95% confidence interval 3.63-101.00; P < .001) was a predictor of CRT response. High %e-CRT is associated with high CRT responder prevalence and low HF hospitalization risk.

Electrophysiologic effects of left bundle branch area pacing: comparing left ventricular septal pacing and left bundle branch pacing

Abstract Funding Acknowledgements Type of funding sources: Private company. Main funding source(s): Medtronic Background Left bundle branch area pacing(LBBAP) has been introduced as a more physiological pacing alternative to anti-bradycardia pacing and as an alternative to biventricular pacing in cardiac resynchronization therapy (CRT). LBBAP is the common denominator of left ventricular septal pacing(LVSP) and left bundle branch pacing(LBBP). In LVSP, there is only capture of the myocardium on the left side of the interventricular septum, whereas in LBBP there is additional capture of the left bundle branch(LBB) and subsequent Purkinje fibers. Purpose To investigate the electrophysiological differences between LBBP and LVSP. Methods Patients with a permanent pacemaker indication due to bradycardia or heart failure according to current guidelines were included and underwent LBBAP implantation. At baseline and during implantation, electrical activation parameters were recorded pacing at different sites (Right ventricle, LVSP and LBBP), using the standard 12-lead ECG and the ECG BELT. Electrophysiologic measures included: QRS duration, QRSarea calculated from the vectorcardiogram after conversion from the ECG using the Kors matrix, and standard deviation of activation time(SDAT) measured through the ECG BELT. Both QRS area and SDAT are known markers of ventricular dyssynchrony. Results 28 patients (17 male), with an age of 67±7 yrs underwent LBBAP. 21(75%) had a pacing indication for bradycardia with a baseline narrow QRS and 7(25%) for heart failure with a baseline LBBB. In 17 patients (61%) LBB capture was achieved. The remaining patients were treated with LVSP. In patients with baseline narrow QRS, both LVSP and LBBP showed a significant increase in QRS duration(p&amp;lt;0.001, p&amp;lt;0.001 resp.), without a significant difference in QRS duration between LVSP and LBBP(fig. 1 A). There was no significant difference in SDAT between LVSP and LBBP compared to baseline narrow QRS, and a significant SDAT reduction in patients with underlying LBBB (p=0.005, p&amp;lt;0.001 resp.) Furthermore, there was no significant SDAT difference between LVSP and LBBP(fig. 1 B). LVSP showed a small but significant increase in QRSarea compared to baseline narrow QRS (p=0.011) where LBBP showed no difference compared to baseline narrow QRS. Compared to baseline LBBB both LVSP and LBBP showed a significant QRSarea reduction (p=0.003, p&amp;lt;0.001 resp.). Moreover, there was a small but significant reduction in QRSarea when LBBP was achieved over LVSP(p=0.044) (fig. 1 C). Conclusion LVSP and LBBP showed a similar effect on ventricular synchrony in terms of SDAT, with levels of synchrony comparable to normal physiologic activation. Left bundle branch capture resulted in a small, but significant improvement in QRSarea over LVSP. Fig. 1 Relative changes in QRS duration(A), SDAT (B) and QRS area (C) compared to baseline narrow QRS (bradypacing) and baseline heart failure with LBBB. *p&amp;lt;0.05 compared to baseline, **p&amp;lt;0.05 for bradypacing and heart failure with LBBB combined.

PO-03-080 OPTIMIZING POST-IMPLANT CRT MANAGEMENT

Implementing a post-implant cardiac resynchronization therapy (CRT) clinic using a combined electrophysiology (EP) & heart failure (HF) advanced practice provider (APP) model may improve subspecialty collaboration & prevent delays in device & medical optimization. Some previously described models evaluate patients 6 months post-procedure. Early follow-up post-implant may further improve response. To determine if a 1 month post-implant device interrogation provides actionable data to improve CRT response at 6 months using a dual-APP multidisciplinary model. We designed a multidisciplinary clinic to formally evaluate patients after CRT device implant. The team involves an advanced HF APP, an EP APP & a HF nurse. Standard device clinic follow up is maintained with the addition of a device interrogation at 1 month to evaluate device function & CRT pacing. Interventions are made at 1 month as necessary. Patients are then seen in the multidisciplinary clinic 6 months following implant & undergo device interrogation, ECG, echocardiogram, & 6-minute walk test. Patients are simultaneously seen by the APPs & a unified plan of care is developed. The electronic medical records were reviewed prospectively for clinical characteristics pre-implant & at 1 & 6 months post-implant, which were summarized with descriptive statistics, including correlation between 1 month data & 6 month CRT response. CRT responders at 6 months were defined as having an LVEF improvement of ≥5% & a reduction in LVESVi ≥10%. Ninety-six patients seen in the clinic from September 2020 to April 2022 were evaluated. The mean age was 70 years; 66 (69%) were male; 40 (42%) had ischemic cardiomyopathy; 53 (56%) had no documented arrhythmia history prior to device implant; 13 (13.5%) were considered to have permanent atrial fibrillation (AF). Of these patients, 52 (54%) were considered CRT responders at 6 months. One month CRT pacing >95% correlated with 6 month CRT response (coefficient of 0.11, std error 0.04, p= 0.01). PVC burden >5% negatively correlated with CRT response (coefficient of 0.15, std error 0.15, p=.02). AF burden did not correlate with CRT response (coefficient of 0.01, std error 0.01, p=0.14). Multivariate analysis did not show these variables to be independently predictive of CRT response. An APP-led, early post-implant evaluation of CRT patients may provide an opportunity to improve six-month CRT response.

Conduction system versus biventricular pacing in heart failure with non-left bundle branch block.

The benefits of cardiac resynchronization therapy (CRT) with biventricular pacing (BiV) is significantly lower when applied to heart failure (HF) patients with non-left bundle branch block (LBBB) conduction delay. We investigated clinical outcomes of conduction system pacing (CSP) for CRT in non-LBBB HF. Consecutive HF patients with non-LBBB conduction delay undergoing CSP were propensity matched for age, sex, HF-etiology, and atrial fibrillation (AF) in a 1:1 ratio to BiV from a prospective registry of CRT recipients. Echocardiographic response was defined as an increase in left ventricular ejection fraction (LVEF) by ≥10%. The primary outcome was the composite of HF-hospitalizations or all-cause mortality. A total of 96 patients were recruited (mean age 70 ± 11years, 22% female, 68% ischemic HF and 49% AF). Significant reductions in QRS duration and LV dimensions were seen only after CSP, while LVEF improved significantly in both groups (p < 0.05). Echocardiographic response occurred more frequently in CSP than BiV (51% vs. 21%, p < 0.01), with CSP independently associated with four-fold increased odds (adjusted odds ratio 4.08, 95% confidence interval [CI] 1.34-12.41). The primary outcome occurred more frequently in BiV than CSP (69% vs. 27%, p < 0.001), with CSP independently associated with 58% risk reduction (adjusted hazard ratio [AHR] 0.42, 95% CI 0.21-0.84, p = 0.01), driven by reduced all-cause mortality (AHR 0.22, 95% CI 0.07-0.68, p < 0.01), and a trend toward reduced HF-hospitalization (AHR 0.51, 95% CI 0.21-1.21, p = 0.12). CSP provided greater electrical synchrony, reverse remodeling, improved cardiac function and survival compared to BiV in non-LBBB, and may be the preferred CRT strategy for non-LBBB HF.

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.