BiV Pacing Research Articles

Impact of Multidirectional Pacing on Activation and Repolarization Parameters to Localize Ischemic Ventricular Tachycardia Circuits.

In ventricular tachycardia (VT), optimal substrate mapping strategies identifying arrhythmogenic sites are not established. This study sought to evaluate multidirectional pacing on the distribution of specific conduction and repolarization metrics to localize re-entrant VT sites in a porcine infarct model. Substrate maps were created in 13 pigs with chronic myocardial infarction using the Advisor HD Grid (Abbott) during right ventricular (RV), left ventricular, biventricular pacing (BIV), and sinus rhythm (SR). Critical VT sites of early-, mid-, and late-diastolic signals were delineated. Vulnerable sites to re-entry were defined as sites of latest activation timing within and post-QRS complex, largest activation and activation-recovery interval gradients. Distances between the 20 most vulnerable sites and diastolic VT points were measured, and identification of VT points was assessed using the area under the receiver-operating characteristic curve. A total of 34 VTs were mapped, and 48 sinus and pacing maps were obtained (10 BIV, 13 left ventricular, 13 RV, 12 SR). Late potential mapping in SR was taken as the established clinical standard for comparison. Latest activation time with BIV pacing provided the closest localization for VT isthmus (median 5.5mm; IQR: 7.15mm; P< 0.005). The gradient of activation-recovery interval using RV pacing had closest localization for VT exit and entrance (median 10.6mm; IQR: 5.0mm; P< 0.005 and 9.4mm; IQR: 8.0mm; P< 0.05). Global sensitivity and specificity analysis showed that gradient of activation-recovery interval in SR achieved the highest area under the receiver-operating characteristic curve, with similar results from the gradient of activation timing. Multidirectional pacing in combination with conduction and repolarization parameters enables better localization of VT diastolic critical sites vs SR late potentials.

MANAGEMENT OF REMOTE MONITORING FOR IMPLANTABLE DEVICES CONTROLS: SINGLE CENTER EXPERIENCE

Abstract Background Nowadays the benefits of remote monitoring (RM)of cardiac implantable electronic devices (CIEDs) are Known: an improved both device surveillance and patient clinical management and a decrease in office follow up. So RM is used as supplement in clinic follow up for patients with CIED.However despite decades to RM utilization there are challenges in managing patients with RM including large number of trasmissions and lack of trained staff. There are many different model of care to RM management. Methods We describe our model of care to management CIED recipients with RM considering data collected from January 2021 to November 2023. Results Our model of care consists of 4 electrophysiologists Physicians and 4 Tecnicians. RM enrollment is performed at scheduled in office visit after ten days from hospital discharge after device implantation. implantable cardiac device(ICD)recipients with RM are annualy followed in office and biennal for pacemaker (PM) recipients and they send every three months transmissions. Trained tecnicians gives home monitor, take care of patients education and collected and screen transmissions. Tecnicians inform immediately physicians in case of urgent alert (shock or antitachicardia pacing therapy (ATP), sustained ventricular tachycardia(TV), ventricular fibrillation (Fv) indicator of elective replacement (ERI), lead releted alert or noise). Physician contact patients the same day (exept Saturday and Sunday). In addiction Physicians twice a week review less urgent and scheduled transmissions and call the patients by phone for visit in office for patients with low rate of biventricular pacing, detection of atrial fibrillation. We have 1000 patients with RM: 746 ICD recipients (103 Biotronik, 150 Abbott, 200 Boston scientific, 293 medtronic), 50 implantable cardiac monitor (ICM) recipients and 204 PM recipients. We analyze 12721 transmissions.Considering ICD recipient we detect 96 episode of ATP and 31 of shock. Shock of ICD was registered in 52 patients (6,9%)We received 1982 atrial fibrillation (AF) detection, with 35 for new detectable AF.The most of transmisisone were for low bIV pacing. We contacted these patients by phone about clinical status and in some case we called them in office. Conclusions Our model of care allows to control a large number of trasmissions with fast management of urgent alert trasmissions.

Abstract 18182: Inappropriate Shocks After Mitraclip™ Placement: Should Reassessment of Post-Procedural ICD Sensitivity Be Routine Practice?

Case Description: A 53 year old African American woman with non-ischemic cardiomyopathy (EF 10%) with intolerance to GDMT (allergies) and severe secondary MR. An ICD was placed years ago. Given LBBB and QRS 146ms, she underwent a BiV(biventricular pacing)-ICD upgrade with symptomatic improvement, but persisting exertional intolerance. TEE showed a favorable anatomic profile for transcatheter edge-to-edge MV repair and a MitraClip™ was placed. Post-procedure, the severity of MR decreased significantly (from severe to mild), however there was no sizable improvement in LV EF. Also, there were no significant EKG changes. Three months later, she experienced multiple inappropriate shocks (IAS). Device interrogation revealed T-wave oversensing (TWOS). TWOS was noted on multiple vectors with LV only pacing, but was solely associated with fusion complexes on BiV pacing. R wave sensing threshold was increased. Patient was switched to BiV only pacing and AV delay(paced and sensed) was decreased to avoid fusion beats. Patient did well and no further IAS were noted at 4 months follow-up. Discussion: ICDs (+/- CRT) are vital in preventing SCD in advanced CHF. Currently, transvenous technology is excellent at avoiding TWOS, however our case represents a challenging dilemma where repolarization may have changed post-operatively after MitraClip™ placement. T wave amplitude is dynamic and real time monitoring of sensing threshold is needed. This becomes especially important after structural heart procedures like MV TEER that can induce subclinical electroanatomic changes. While MitraClip™ can reduce ventricular arrhythmias with favorable remodeling, inappropriate sensing of devices is a small but real risk. Consequently, there are no established guidelines on routine post-procedural device interrogation. Preemptive reassessment of T wave safety margin and monitoring of sensing thresholds and lead placement may be useful following structural heart interventions.

Noninvasive Electrical Mapping Compared with the Paced QRS Complex for Optimizing CRT Programmed Settings and Predicting Multidimensional Response

The aim was to test the hypothesis that left ventricular (LV) and right ventricular (RV) activation from body surface electrical mapping (CardioInsight 252-electrode vest, Medtronic) identifies optimal cardiac resynchronization therapy (CRT) pacing strategies and outcomes in 30 patients. The LV80, RV80, and BIV80 were defined as the times to 80% LV, RV, or biventricular electrical activation. Smaller differences in the LV80 and RV80 (|LV80-RV80|) with synchronized LV pacing predicted better LV function post-CRT (p = 0.0004) than the LV-paced QRS duration (p = 0.32). Likewise, a lower RV80 was associated with a better pre-CRT RV ejection fraction by CMR (r = − 0.40, p = 0.04) and predicted post-CRT improvements in myocardial oxygen uptake (p = 0.01) better than the biventricular-paced QRS (p = 0.38), while a lower LV80 with BIV pacing predicted lower post-CRT B-type natriuretic peptide (BNP) (p = 0.02). RV pacing improved LV function with smaller |LV80-RV80| (p = 0.009). In conclusion, 3-D electrical mapping predicted favorable post-CRT outcomes and informed effective pacing strategies.Graphical

The role of conduction system pacing in patients with atrial fibrillation.

Conduction system pacing (CSP) has emerged as a promising novel delivery method for Cardiac Resynchronisation Therapy (CRT), providing an alternative to conventional biventricular epicardial (BiV) pacing in indicated patients. Despite increasing popularity and widespread uptake, CSP has rarely been specifically examined in patients with atrial fibrillation (AF), a cohort which forms a significant proportion of the heart failure (HF) population. In this review, we first examine the mechanistic evidence for the importance of sinus rhythm (SR) in CSP by allowing adjustment of atrioventricular delays (AVD) to achieve the optimal electrical response, and thus, whether the efficacy of CSP may be significantly attenuated compared to conventional BiV pacing in the presence of AF. We next evaluate the largest clinical body of evidence in this field, related to patients receiving CSP following atrioventricular nodal ablation (AVNA) for AF. Finally, we discuss how future research may be designed to address the vital question of how effective CSP in AF patients is, and the potential hurdles we may face in delivering such studies.

Comparison of myocardial depolarization spreading after resynchronization with left bundle branch area pacing versus biventricular pacing

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Left bundle branch area pacing (LBBAP) is an emerging new method of cardiac resynchronization therapy (CRT) in patients with left bundle branch block (LBBB). Studies comparing LBBAP with standard biventricular pacing (BiV) have shown similar post-operative shortening of QRS duration and left ventricular activation times. Calculation of equivalent dipole (ED) trajectories from 12-lead high-resolution ECG (hrECG) provides additional insight into myocardial depolarization and may be used for further assessment of left ventricular activation. Purpose The aim of this study was to determine myocardial depolarization patterns with assessment of ED trajectories in patients undergoing CRT with LBBAP or BiV and to compare them to myocardial depolarization patterns of healthy controls. Methods Twenty-five heart failure patients in sinus rhythm and LBBB with indication for CRT were randomized in LBBAP or BiV pacing group. Five-minute supine 12-lead hrECG recordings before and one month after implantation were assessed. LBBAP group was compared to BiV group and both groups were compared to the control of healthy subjects with normal surface ECG. The QRS duration was measured manually by two independent electrophysiologists and averaged. ED trajectories were constructed with the use of inverse algorithm method. The length of ED trajectory was defined as a line between the start and the end of the ED trajectory and its orientation with azimuth and elevation angles. (Figure 1). Results Eleven patients received LBBAP and 14 BiV. There were no differences in baseline characteristics (72% male, 64% non-ischemic cardiomyopathy) between groups. The average baseline QRS duration was 174±20 ms in LBBAP and 180±17 ms in BiV group (p=0.42). QRS duration decreased to 134±14 ms after LBBAP (p&amp;lt;0.01) and 137±11 ms after BiV pacing (p&amp;lt;0.01) and was comparable in both groups (p=0.59). There was also no difference in absolute (p=0.72) or relative (p=0.72) QRS shortening. The absolute and relative ED shortening did not differ (p=0.43 and p=0.38, respectively). At follow-up, analysis of ED trajectories showed a significant difference in elevation angle in both groups (p&amp;lt;0.01). The elevation angle in LBBAP group (6±30°) was significantly different from the angle in BiV group (-44±33°) (p &amp;lt; 0.01), pointing more toward apex of the heart (Figure 2). Furthermore, elevation angle in LBBAP was more similar (absolute difference 49°) to healthy subjects than the elevation angle in BiV group (absolute difference 103°) (p&amp;lt;0.01). There was no intergroup difference in azimuth angle (p=0.07). Conclusion Compared to BiV pacing, resynchronization with LBBAP produces significantly different ED trajectory orientation, which was more comparable to orientation in healthy controls. While both resynchronization methods result in similar QRS narrowing, LBBAP may provide more physiological depolarization of the left ventricle in comparison to BiV.

Interaction between atrial-ventricular and ventricular-ventricular delay in CRT

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): United Hospital Medical Education and Research Committee, United Hospital Foundation. Background Appropriate programming of atrial-ventricular delay (AVD) and ventricular-ventricular delay (VVD) is critical for delivery of optimal cardiac resynchronization therapy (CRT). However, there is debate over how to determine optimal programming for a given patient. This is complicated by the use of 2 distinct methods of defining the activation timing at a given AVD and VVD used by different device manufacturers. Purpose To describe how electrical dyssynchrony is affected by changes in AVD, VVD and the method used to program AVD and VVD. Methods We measured electrical synchrony at multiple combinations of AVD/VVD in 41 patients with underlying left bundle branch block (LBBB) using a novel methodology called electrical dyssynchrony mapping (EDM). Electrical dyssynchrony was quantified by cardiac resynchronization index (CRI), calculated as % change in area under the curve between combinations of 9 anterior and 9 posterior surface electrograms. Results EDM (Figure 1) shows CRI at multiple combinations of atrial-to-RV-paced, (A-RVp, y-axis) and atrial-to-LV-paced (A-LVp, x-axis) intervals. VVD changes to produce LV preactivation are shown at short and long AVDs using the methods of 2 different CRT device manufacturers: Method 1: fixing A-RVp and shortening A-LVp; and Method 2: fixing A-LVp and lengthening A-RVp. During simultaneous BiV pacing, CRI at short AVD (61.7±20.9) was significantly (p&amp;lt;0.001) greater than at long AVD (46.9±14.0). On average, CRI was significantly greater at short AVD than at long AVD during LV preactivation of 20 or 40 ms (Figure 2). At short AVD, Method 2 resulted in slightly but significantly better CRI at VVD 20 and 40 ms. At long AVD, Method 1 resulted in large and significantly better CRI at VVD 20 and 40 ms. Conclusions The interaction between AVD and VVD is complex, and the electrical resynchronization achieved when programming depends on both the AVD at which VVD is programmed, and the programming algorithm used by the device manufacturer. At longer AVDs, Method 1 yields significantly better resynchronization than Method 2 when programming VVD. Studies assessing effects of AVD and VVD programming that involve patients with CRT devices from different manufacturers need to modify programming parameters appropriately in order to accurately interpret results. Methods For programming VVD and EDM

EN-452414-1 IMPACT OF MULTI-DIRECTIONAL PACING ON LATE SIGNAL ACTIVATION, ACTIVATION SLOWING AND REPOLARIZATION GRADIENTS TO LOCALIZE RE-ENTRANT VENTRICULAR TACHYCARDIA CIRCUITS IN A PORCINE INFARCT MODEL.

Optimal signal parameters and substrate mapping strategies for identifying key arrhythmogenic sites in ventricular tachycardia (VT) ablation are not established. To evaluate multi-directional pacing on the distribution of late signal activation, activation slowing and repolarization gradients in relation to critical sites of re-entrant VT, in a porcine infarct model. Electrophysiology studies were performed 4 weeks post-infarction in 13 pigs using the EnSite Precision system (Abbott, IL, USA), and the Advisor HD Grid (Abbott) multi-electrode catheter. Substrate maps were created during right ventricular (RV), left ventricular (LV), and biventricular pacing (BIV), and sinus rhythm (SR). Sites of early, mid-, and late-diastolic signals of induced VT’s were delineated. Off-line analysis compared these critical VT sites to algorithmically identified 20 most vulnerable sites of latest activation timing within and post-QRS, and the largest activation (GradAT) and activation recovery interval gradients (GradARI). 34 VTs were mapped with at least one diastolic recorded component, with a mean tachycardia cycle length of 236.5 ± 32.4 ms. 48 sinus rhythm and pacing maps were obtained, 10 using BIV pacing (mean points 375 ± 263), 13 using LV pacing (mean points 610 ± 334), 13 from RV pacing (mean points 603 ± 263) and 12 in sinus rhythm (mean points 1078 ± 654). Late potential (LP) mapping in sinus rhythm was taken as the established clinical standard for statistical comparison with all other protocols, displayed in Figure 1. GradARI using RV pacing provided the closest localization for VT exit and entrance, with a median distance of 10.6mm (IQR 5.0mm, p <0.05) and median 9.4mm (IQR 8.0mm, p <0.05) compared to LP in sinus rhythm, respectively. LAT with BIV pacing provided closest VT isthmus localization for VT isthmus, with a median of 5.5mm (IQR 7.15mm, p <0.05) compared to LP in sinus rhythm (Figure 1). A global sensitivity and specificity analysis was performed on all points. GradARI mapping in SR reported the highest AUC (area – under curve) for early diastolic VT signals (AUC 0.96, sensitivity 93%, specificity 91%), mid-diastolic signals (AUC 0.92, sensitivity 84%, specificity 88%) and late diastolic signals (AUC 0.92, sensitivity 88%, specificity 84%). Sites with the largest ARI gradients in sinus rhythm best predict critical sites of VT in this model, with the most effective protocol being RV pacing examining ARI gradients.

Electrocardiographic imaging demonstrates electrical synchrony improvement by dynamic atrioventricular delays in patients with left bundle branch block and preserved atrioventricular conduction.

Cardiac resynchronization therapy programmed to dynamically fuse pacing with intrinsic conduction using atrioventricular (AV) timing algorithms (e.g. SyncAV) has shown promise; however, mechanistic data are lacking. This study assessed the impact of SyncAV on electrical dyssynchrony across various pacing modalities using non-invasive epicardial electrocardiographic imaging (ECGi). Twenty-five patients with left bundle-branch block (median QRS duration (QRSd) 162.7 ms) and intact AV conduction (PR interval 174.0 ms) were prospectively enrolled. ECGi was performed acutely during biventricular pacing with fixed nominal AV delays (BiV) and using SyncAV (optimized for the narrowest QRSd) during: BiV + SyncAV, LV-only single-site (LVSS + SyncAV), MultiPoint pacing (MPP + SyncAV), and LV-only MPP (LVMPP + SyncAV). Dyssynchrony was quantified via ECGi (LV activation time, LVAT; RV activation time, RVAT; LV electrical dispersion index, LVEDi; ventricular electrical uncoupling index, VEU; and biventricular total activation time, VVtat). Intrinsic conduction LVAT (124 ms) was significantly reduced by BiV pacing (109 ms) (P = 0.001) and further reduced by LVSS + SyncAV (103 ms), BiV + SyncAV (103 ms), LVMPP + SyncAV (95 ms), and MPP + SyncAV (90 ms). Intrinsic RVAT (93 ms), VVtat (130 ms), LVEDi (36 ms), VEU (50 ms), and QRSd (163 ms) were reduced by SyncAV across all pacing modes. More patients exhibited minimal LVAT, VVtat, LVEDi, and QRSd with MPP + SyncAV than any other modality. Dynamic AV delay programming targeting fusion with intrinsic conduction significantly reduced dyssynchrony, as quantified by ECGi and QRSd for all evaluated pacing modes. MPP + SyncAV achieved the greatest synchrony overall but not for all patients, highlighting the value of pacing mode individualization during fusion optimization.

A systematic review and meta-analysis of upgrade to biventricular or conduction system pacing approaches

Abstract Introduction Chronic RV pacing has been recognised as being harmful to cardiac function. Patients undergoing a de novo pacemaker implant with even mild LV impairment are recommended to instead receive a physiological pacing strategy (biventricular or conduction system pacing [CSP]). No corresponding guideline recommendation exists for patients who already have a pacemaker. Methods We undertook a random-effects meta-analysis of all RCTs and observational studies covering device upgrade to biventricular pacing or conduction system pacing. Results 6 RCTs assessing effect of upgrade to BiV pacing randomising 161 patients were eligible for analysis. Eligible observational studies included 46 of BiV upgrade and 7 of CSP upgrade totalling 2795 patients. Mean LVEF improved by +8.3% from 34.4% in BiV upgrade RCTs (p=0.001) and +8.3% from 25.7% in BiV upgrade observational studies (p&amp;lt;0.001). In observational studies of upgrade to CSP, LVEF increased by +10.1% from 38.4% (p=0.001) despite less severe LV impairment at baseline (p=0.004 vs mean EF in BiV RCTs and p&amp;lt;0.0001 vs mean EF in BiV observational studies). LVESV decreased significantly by −25.4 ml, −23.7 ml, and −19.8 ml in BiV RCTs, BiV observational studies and CSP observational studies. Significant changes were also seen in NYHA class (decreased by −0.4, −0.8 and −1.0 respectively). Minnesota Heart Failure Score (−6.9 points) and peak oxygen uptake (+1.1 ml/kg/min) increased significantly in RCTs of BiV upgrade. This was also seen in observational studies of BiV upgrade (−21.0 points and +2.63 ml/kg/min respectively). Conclusions RCTs and observational studies of upgrade to BiV pacing show significant physiological and symptomatic benefit. Observational studies of CSP upgrade show similar benefit with significant improvements in LVEF, LVESV and NYHA class in patients with an even milder degree of baseline LV impairment. Funding Acknowledgement Type of funding sources: None.

Abstract P307: A Case Of Dual Tachycardia Presenting With Heart Failure Exacerbation

Dual tachycardia (DT) is the occurrence of simultaneous supraventricular tachycardia and ventricular tachycardia/fibrillation (VT/VF). With increasing interest in this uncommon arrhythmia due to difficulties with diagnosis and complexity of management, DT is identified in about 9% of double-chamber ICD interrogation. An 81 year old male with history of hypertension, ischemic cardiomyopathy status-post BiV AICD presented to ED with worsening exertional dyspnea, orthopnea and pedal edema. He was tachycardic (140 bpm) with bibasilar rales. BNP 655 pg/mL, cardiomegaly and pulmonary edema on chest x-ray. EKG revealed atrial fibrillation (AF) with rapid ventricular response. Echocardiogram revealed a reduced left ventricular ejection fraction &lt;20%. He was diuresed with furosemide, diltiazem infusion for rate control and heparin for anticoagulation. During admission, he developed two episodes of monomorphic VT in VF zone and was successfully cardioverted. During the initial episode, he was in AF and had a VT triggered by PVC which was successfully cardioverted to BiV Paced rhythm. However, he remained in AF which was converted to sinus rhythm after a second cardioversion. A repeat EKG revealed sinus rhythm with BiV paced rhythm. He was later transitioned to oral metoprolol, amiodarone to maintain rhythm control and apixaban. Dual tachyarrhythmia can be managed with medical therapy and/or catheter ablation. The termination of the trigger AF/PVC has been shown to reduce the recurrence of VT/VF episodes. Rhythm control for AF with antiarrhythmic therapy can reduce AF and PVC burden, improve BiV pacing, prevent ICD shocks and help reduce heart failure exacerbation.

Measurement of electrical dyssynchrony in CRT patients: 12-lead ECG versus 96-lead body surface map

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Grant agency AZV, Ministry of Health of the Czech Republic Background Quantification of electrical dyssynchrony would allow optimization of lead placement and timing in patients with CRT. The standard deviation of activation times (SDAT) derived from body surface maps (BSM) was proposed as a measure of electrical dyssynchrony in CRT patients. However, SDAT derived from standard 12-lead ECG would be clinically preferred. Objective To evaluate and compare the SDAT measured from BSM and 12-lead ECG for assessment of electrical resynchronization in patients with implanted CRT. Methods CRT patients with sinus rhythm and LBBB at baseline (n=19, 58% males; age 60±11 years; NYHA class II-III; QRS 160±29) were studied using 96-lead BSM. For each ECG lead, the activation time was automatically detected and SDAT was calculated using either 96 leads or standard 12 leads. Electrical dyssynchrony was assessed during native sinus rhythm and 6 different pacing modes (see figure). Results SDAT calculated from BSM and 12-lead ECG decreased during optimal BiV pacing as compared to sinus rhythm by 26% (p=0.006) and 30% (p=0.003), respectively. The two other BiV setups showed also a decrease in SDAT values. Importantly, a high degree of reliability was found between values of SDAT obtained from12-lead ECG and 96-lead BSM for different pacing modes, the intraclass correlation coefficient was 0.8 to 0.9 (95% CI 0.7 - 0.9, p&amp;lt;0.001). Conclusion SDAT assessment is considered an important metric of electrical dyssynchrony in CRT. Our results suggest that 12-lead ECG provides similar results as BSM and thus, allows simplification of the measurement. Further prospective studies are necessary to verify the clinical utility of SDAT from 12-lead ECG.

Usefulness of ventricular sense response in last-generation cardiac resynchronization therapy devices

ObjectivesHigh percentages of pacing were associated to maximal symptomatic and mortality benefit from cardiac resynchronization therapy (CRT). Loss of CRT pacing is linked to intrinsic ventricular activation preceding biventricular pacing (BiV), as it occurs in patients with atrial fibrillation (AF). Last generation CRT devices incorporate the ventricular sense response (VSR) mechanism to maintain biventricular pacing in patients with atrial arrhythmias. This work aimed to characterize electrical dyssynchrony differences among baseline, BiV and VSR pacing, and determine whether the VSR mode is as beneficial as the BiV mode in terms of electrical dyssynchrony. MethodsThirty-two patients implanted with CRT devices were retrospectively studied. All patients presented non-ischemic dilated myocardiopathy and complete left bundle branch block (LBBB). Every patient went through baseline, BiV and VSR pacing while recording the 12‑lead ECG. Electrical dyssynchrony was assessed by a dyssynchrony index (DIn) obtained from correlation analysis on the 12‑lead ECG. ResultsWhen comparing with baseline, VSR pacing improved QRS duration (178 ± 22 ms vs 158 ± 43 ms, baseline vs VSR, p < 0.05) and so did BiV pacing (178 ± 22 ms vs 142 ± 20 ms, baseline vs BiV, p < 0.05). However, electrical dyssynchrony only improved at BiV pacing (2.86±0.6 vs 0.54±0.8, baseline vs BiV, p < 0.05) while VSR showed average DIn values similar to those at baseline. ConclusionsVSR pacing did not improve the electrical synchrony while did shorten QRS duration in this sample population. Therefore, VSR paced beats would fall in the category of inefficient BiV and may not be the preferred alternative in patients with CRT and AF.

Abstract 10836: Outcomes of Biventricular Pacing versus Conventional Pacing (DDD Mode) in Patients with a Normal Left Ventricular Ejection Fraction

Introduction: Cardiac resynchronization therapy (CRT) is beneficial in patients with heart failure with reduced ejection fraction and normal sinus rhythm. However, its role in patients with pacing indication, narrow QRS, and normal ejection fraction remains controversial. Objectives: We aimed to evaluate the impact of biventricular pacing (BiV) versus conventional right ventricular (RV) pacing (DDD mode, ventricular pacing avoidance algorithm) in patients with normal ejection fraction. Methods: A comprehensive literature search in PubMed, Google Scholar, and Cochrane Review from inception to November 15, 2020, was performed. Outcomes studies were - major adverse cardiovascular events (MACE, composite of cardiovascular death, hospitalization for heart failure or any cardiovascular cause), cardiovascular mortality, change in left ventricular ejection fraction (LVEF, %), left ventricular end-systolic volume (LVESV, mL) and left ventricular end-diastolic volume (LVEDV, mL). Results: Four randomized trials (n=457, BiV group=229, mean age 71.6±4.4 years, RV pacing=228, mean age 70.3±4.38 years) met inclusion criteria. There was a significant reduction in MACE (RR 0.68, 95% CI 0.46-0.99, p=0.04), LVESV [mean difference (MD) -6.42, 95%CI -10.27- -2.57; p=0.001], LVEDV (MD -6.12,95% CI -9.30 to -2.94; p=0.0002) in patients with BiV pacing compared to RV pacing. There was no reduction in cardiovascular mortality and a trend towards improvement in LVEF (MD 3.99,95% -0.12-8.10; p=0.06) with BiV pacing compared to RV pacing during the follow-up period (1.95 years). Conclusion: BiV pacing may be a feasible option for permanent pacing in patients with normal LVEF and may attenuate untoward effects of conventional RV pacing on the left ventricular function.

Long-term reverse remodeling and clinical improvement by MultiPoint Pacing in a randomized, international, Middle Eastern heart failure study

PurposeCardiac resynchronization therapy (CRT) with multipoint left ventricular (LV) pacing (MultiPoint™ Pacing, MPP) has been shown to improve CRT response, although MPP response using automated pacing vector programming has not been demonstrated in the Middle East. The purpose of this study was to compare the impact of MPP to conventional biventricular pacing (BiV) using echocardiographic and clinical changes at 6-month post-implant.MethodsThis prospective, randomized study was conducted at 13 Middle Eastern centers. After de novo CRT-D implant (Abbott Unify Quadra MP™ or Quadra Assura MP™) with quadripolar LV lead (Abbott Quartet™), patients were randomized to either BiV or MPP therapy. In BiV patients, the LV pacing vector was selected per standard practice; in MPP patients, the two LV pacing vectors were selected automatically using VectSelect. CRT response was defined at 6-month post-implant by a reduction in LV end-systolic volume (ESV) ≥ 15%.ResultsOne hundred and forty-two patients (61 years old, 68% male, NYHA class II/III/IV 19%/75%/6%, 33% ischemic, 57% hypertension, 52% diabetes, 158 ms QRS, 25.8% ejection fraction [EF]) were randomized to either BiV (N = 69) or MPP (N = 73). After 6 months, MPP vs. BiV patients experienced greater ESV reduction (25.0% vs. 15.3%, P = 0.08), greater EF improvement (11.9% vs. 8.6%, P = 0.36), significantly greater ESV response rate (68.5% vs. 50.7%, P = 0.04), and significantly greater NYHA class improvement rate (80.8% vs. 60.3%, P = 0.01).ConclusionsWith MPP and automatic LV vector selection, more CRT patients in the Middle East experienced reverse remodeling and clinical improvement relative to conventional BiV pacing.

Upgrade of cardiac resynchronization therapy by utilizing additional His-bundle pacing in patients with inotrope-dependent end-stage heart failure: a case series.

BackgroundHis-bundle pacing (HBP) alone may become an alternative to conventional cardiac resynchronization therapy (CRT) utilizing right ventricular apical (RVA) and left ventricular (LV) pacing (BiVRVA+LV) in selected patients, but the effects of CRT utilizing HBP and LV pacing (BiVHB+LV) on cardiac resynchronization and heart failure (HF) are unclear.Case summaryWe presented two patients with inotrope-dependent end-stage HF in whom the upgrade from conventional BiVRVA+LV to BiVHB+LV pacing by the addition of a lead for HBP improved their HF status. Patient 1 was a 32-year-old man with lamin A/C cardiomyopathy, atrial fibrillation, and complete atrioventricular (AV) block. Patient 2 was a 70-year-old man with ischaemic cardiomyopathy complicated by AV block and worsening of HF resulting from ablation for ventricular tachycardia storm. The HF status of both patients improved dramatically following the upgrade from BiVRVA+LV to BiVHB+LV pacing.DiscussionEnd-stage HF patients suffer from diffuse intraventricular conduction defect not only in the LV but also in the right ventricle (RV). The resulting dyssynchrony may not be sufficiently corrected by conventional BiVRVA+LV pacing or HBP alone. Right ventricular apical pacing itself may also impair RV synchrony. An upgrade to BiVHB+LV pacing could be beneficial in patients who become non-responsive to conventional BiV pacing as the His–Purkinje conduction defect progresses.

AV delay optimisation in LV only CRT: constant fusion pacing is easier in patients with first degree AV block

Abstract Background LV only pacing is non-inferior to BiV pacing, and recent publications showed that DDD CRT without RV lead is safe in patients with normal atrioventricular (AV) conduction, although there are no device algorithms available for fusion pacing and PR interval variability is understudied in this population. Purpose To analyse AV behaviour in patients with DDD CRT and the impact to effective fusion maintenance. Methods Consecutive patients with right atrium/left ventricle leads DDD CRT pacing system were included. Prospective data were collected at every 6 months follow-up visits: device interrogation, exercise test (ET), echocardiography. CRT assessment during ET analysed loss of LV capture with special focus on maintaining constant fusion pacing during exercise. We defined 2 groups of patients: longer PR interval patients (200–250 ms) and normal PR interval patients (&amp;lt;200 ms). In case of LV loss of capture or unsatisfactory LV fusion pacing, device reprogramming was performed individualised for each patient and BB/ivabradine dose titration was done to achieve stability of PR spontaneous interval. Patients were rescheduled in no later one month to be reassessed by ET. Results 55 patients (29 male) aged 62±11 y.o. were included, 36 patients with normal PR and 19 patients with longer PR. During follow-up (45±19 months), a total of 235 ETs were performed with mean exercise load 118±35 watts. In the normal PR group, 14 patients (39%) had inadequate pacing or loss of LV capture during ET due to physiological shortening of PR interval vs. 4 patients (21%) in the longer PR group. Loss of LV capture by exceeding maximum tracking rate (MTR) was noted in 6 patients (17%) with normal PR vs. 2 patients (11%) with long PR. Post ET device optimisation included: reprogramming rate adaptive AV interval (23±8 ms decrease in normal PR patients vs. 12±7 ms in longer PR patients, p&amp;lt;0.0001) and individualised programming of MTR. BB/ivabradine optimisation was performed in 32% of patients with normal PR vs. 13% of patients with longer PR. Conclusions A lower rate of optimisations after ET was needed in patients with a slightly longer AV conduction to achieve stability of fusion pacing DDD CRT, without device algorithms. Larger studies are needed to assess AV conduction variability and the benefits of fusion pacing CRT in patients with longer PR interval. Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): University of Medicine and Pharmacy “Victor Babes”, Timisoara; Timisoara Institute of Cardiovascular Diseases

Electrical synchronization achieved by multipoint pacing combined with dynamic atrioventricular delay.

Multipoint pacing (MPP) improves left ventricular (LV) electrical synchrony in cardiac resynchronization therapy (CRT). SyncAV automatically adjusts atrioventricular delay (AVD) according to intrinsic AV intervals and may further improve synchrony. Their combination has not been assessed. The objective was to evaluate the improvement in electrical synchrony achieved by SyncAV combined with MPP in an international, multicenter study. Patients with LBBB undergoing CRT implant with a quadripolar lead (Abbott Quartet™) were prospectively enrolled. QRS duration (QRSd) was measured by blinded observers from 12-lead ECG during: intrinsic conduction, BiV pacing (conventional biventricular pacing, nominal static AVD), MPP (2 LV cathodes maximally spaced, nominal static AVD), BiV + SyncAV, and MPP + SyncAV. All SyncAV offsets were individualized for each patient to yield the narrowest QRSd during BiV pacing. QRSd changes were compared by ANOVA and post hoc Tukey-Kramer tests. One hundred and three patients were enrolled (65.7 ± 12.1years, 67% male, 37% ischemic, EF 26.4 ± 6.5%, PR 190.3 ± 39.1ms). Relative to intrinsic conduction (QRSd of 165 ± 16ms), BiV reduced QRSd by 11.9% to 145 ± 18ms (P < 0.001 vs intrinsic), and MPP reduced QRSd by 13.3% to 142 ± 19ms (P < 0.001 vs intrinsic). However, enabling SyncAV with a patient-optimized offset nearly doubled this QRSd reduction. BiV + SyncAV reduced QRSd by 22.0% to 128 ± 13ms (P < 0.001 vs BiV), while MPP + SyncAV reduced QRSd further by 25.6% to 122 ± 14ms (P < 0.05 vs BiV + SyncAV). SyncAV can significantly improve acute electrical synchrony beyond conventional CRT, with further improvement achieved by superimposing MPP.

P1488Autonomic nervous system optimized cardiac resynchronization therapy

Abstract Introduction. Traditional Cardiac Resynchronization Therapy, CRT, relies on bi-ventricular, bi-V, pacing. For left bundle branch block, LBBB, patients with good atrial-right ventricular conduction, A-RVc, alternatives have been proposed that use left-ventricular only pacing, LVoP, with adaptive atrio-ventricular delay, AVD, that is updated every minute from A-RVc measurements. The key advantage is extended device longevity since the RV pacing pulse is not emitted. Purpose. In this paper we present a CRT alternative using fixed AVD LVoP + RV sense trigger (an LV pulse is triggered when an RV depolarization is sensed), RVsT, that can be used with LBBB patients with good A-RVc. Intrinsic RV depolarization is used. The longevity of the device is expected to approach that of a dual chamber device since AVD adaption is not needed. Method. 5 CRT patients with LBBB and good A-RVc, previously programmed to bi-V pacing, were reprogrammed to fixed AVD LVoP + RVsT. The devices are standard CRT pacemakers, CRT-P, with RVsT. They are normally operated in LVoP mode. In response to atrial tachycardia, mode switching to bi-V will be required. So, 3 chamber devices are still required. Results. Nightly at about 02:00 the CRT-P collects Ax-Vs (Ax = As &amp; Ap) statistics for 35 consecutive heart cycles with AVD of 300 ms, while the patient is asleep. A typical plot of these timing statistics at the time of reprogramming to LVoP is shown in Fig. 1. After a self-training period of 2 weeks to 9 months, these statistics coalesce in a narrow range of values, 20 ms wide, as illustrated in Fig. 2 for our super responder (2 weeks). This 20 ms wide pattern persisted for the next 9 months. In the case of the index patient this lasted 3+ years. This persistent A-RVc pattern across all 5 patient can only be explained by a tight dromotropic control by the Autonomic Nervous System, ANS. Fig. 3 illustrates RVsT. As the RVs arrives earlier than the LVp, there is no longer synchronicity improvement since the LVp now follows the RVs immediately. In Fig. 4, we see long periods with high %RVs associated with high heart rates. Increased hemodynamic demand can only be met by increased contractility. Thus inotropic modulation by the ANS is now active and effective. The patients were put on remote monitoring with nightly follow-ups. Over a period of 6.5 months RVs (pre LVp) statistics were collected. A daily median of 11% was reported for this patient. On a particular day, it can be as high as 50%. Dromotropic action to pull in the RVs cannot be explained without concurrent inotropic modulation. Conclusions. Traditional CRT leads to ineffective ANS modulation due to bi-V pacing for &amp;gt;95-98% of the cycles. In our 5 patients the fixed AVD LVoP + RVsT program has allowed nervous system remodeling and the ANS is back in control of hemodynamics. Thus we have ANS optimized CRT! It is an attractive CRT alternative for LBBB patients with good A-RVc since device longevity is also improved. Abstract Figure. Fixed delay LV-only + RVs trigger

P1168Redefining first degree AV block: constant fusion pacing CRT is easier in longer PR interval patients

Abstract Background LV only pacing is non-inferior to BiV pacing, and recent publications showed that DDD CRT without RV lead is safe in patients with normal atrioventricular (AV) conduction, although there are no device algorithms available for fusion pacing and PR interval variability is understudied in this population. Purpose: To analyse AV behaviour in pts with DDD CRT and the impact to effective fusion maintenance. Methods Consecutive pts with right atrium/left ventricle (RA/LV) DDD CRT pacing system were included. Prospective data were collected at every 6 months follow-up visits: device interrogation, exercise test (ET), echocardiography. CRT assessment during ET analysed loss of LV capture with special focus on maintaining constant fusion pacing during exercise. We defined 2 groups of pts: longer PR interval pts (200-250 ms) and normal PR interval pts (˂200 ms). In case of LV loss of capture or unsatisfactory LV fusion pacing, device reprogramming was performed individualised for each patient and BB/ivabradine dose titration was done to achieve stability of PR spontaneous interval. Patients were rescheduled in no later one month to be reassessed by ET. Results 55 pts (29 male) aged 62 ± 11 y.o. were included, 36 pts with normal PR and 19 pts with longer PR. During follow-up (45 ± 19 months), a total of 235 ETs were performed with mean exercise load 118 ± 35 watts. In the normal PR group 14 pts (39%) had inadequate pacing or loss of LV capture during ET due to physiological shortening of PR interval vs. 4 pts (21%) in the long PR group. Loss of LV capture by exceeding maximum tracking rate (MTR) was noted in 6 pts (17%) with normal PR vs. 2 pts (11%) with longer PR. Post ET device optimisation included: reprogramming rate adaptive AV interval (23 ± 8 ms decrease in normal PR pts vs. 12 ± 7 ms in longer PR pts, p &amp;lt; 0.0001) and individualised programming of MTR. BB/ivabradine optimisation was performed in 32% of pts with normal PR vs. 13% of pts with longer PR. Conclusions A lower rate of optimisations after exercise test was needed in pts with a slightly longer AV conduction to achieve stability of fusion pacing DDD CRT without device algorithms. Larger studies are needed to assess AV conduction variability and the benefits of fusion pacing CRT in pts with longer PR interval. Abstract Figure.