LV Pacing Research Articles

Association between biventricular pacing and incidence of ventricular arrhythmias in the early post-operative period after left ventricular assist device implantation.

Cardiac resynchronization therapy (CRT) and left ventricular assist devices (LVAD) improve outcomes in heart failure patients. Early ventricular arrhythmias (VA) are common after LVAD and are associated with increased mortality. The association between left ventricular pacing (LVP) with CRT and VAs in the early post-LVAD period remains unclear. This was a retrospective study of all patients undergoing LVAD implantation from 1/2016 to 12/2019. Patients were divided into those with CRT and active LVP (CRT-LVP) immediately post-LVAD implant versus those without CRT-LVP. Implantable cardiac defibrillator electrograms were reviewed and early VAs were defined as sustained ventricular tachycardia (VT)/ventricular fibrillation occurring within 30 days of LVAD implantation. Of 186 included patients (mean age 53 years, 75% male, mean body mass index 28), 72 had CRT devices, 63 of whom had LV pacing enabled after LVAD implant (CRT-LVP group). Patients with CRT-LVP were more likely to have VA in the early postoperative period (21% vs. 4%; p = .0001). All 9 patients with CRT in whom LVP was disabled had no early VA. Among those with early VA, patients with CRT-LVP were more likely to have monomorphic VT (77% vs. 40%; p = .07). In multiple logistic regression, CRT-LVP pacing remained an independent predictor of early VA after adjustment for history of VA and AF. Patients with CRT-LVP after LVAD implant had a higher incidence of early VA (specifically monomorphic VT). Epicardial LV pacing may be proarrhythmic in the early postoperative period after LVAD.

Anodal Capture for Multisite Pacing with a Quadripolar Left Ventricular Lead: A Feasibility Study.

Background: Up to 40% of patients are CRT non-responders. Multisite pacing, using a unique quadripolar lead, also called multipoint/multipole pacing (MPP), is a potential alternative. We sought to determine the feasibility of intentional anodal capture using a single LV quadripolar lead, to reproduce MPP without the need of a specific algorithm (so-called “pseudo MPP”). Methods: Consecutive patients implanted with a commercially available CRT device and a quadripolar LV lead in our department were prospectively included. The electric charge (Q, in Coulomb) of RV and LV pacing spikes were calculated for all available LV pacing configurations at the threshold. The best MPP was defined as the configuration with the lowest consumption (QRV + Qbest LV1 + Qbest LV2). The best “pseudo MPP” (QRV + QLV1–LV2 with anodal capture) and best BVp (QRV + Qbest LV) were also calculated. A theoretical longevity was estimated for each configuration at the threshold without a safety margin. Results: A total of 235 configurations were tested in 15 consecutive patients. “Pseudo-MPP” was feasible in 80% of patients with 3.1 ± 2.6 vectors available per-patient and LVproximal-LVdistal (most distant electrodes) vectors were available in 47% of patients. Each MPP pacing spike electrical charge was comparable to “pseudo-MPP” (18,428 ± 6863 µC and 20,528 ± 5509 µC, respectively, p = 0.15). Theoretical longevity was 6.2 years for MPP, 5.6 years for “pseudo-MPP” and 13.7 years for BVp. Conclusions: “Pseudo MPP” using intentional anodal capture with a quadripolar left ventricular lead, mimicking conventional multisite pacing, is feasible in most of CRT patients, with comparable energy consumption. Further studies on their potential clinical impact are needed.

Machine Learning Prediction of Cardiac Resynchronisation Therapy Response From Combination of Clinical and Model-Driven Data.

Background: Up to 30–50% of chronic heart failure patients who underwent cardiac resynchronization therapy (CRT) do not respond to the treatment. Therefore, patient stratification for CRT and optimization of CRT device settings remain a challenge.Objective: The main goal of our study is to develop a predictive model of CRT outcome using a combination of clinical data recorded in patients before CRT and simulations of the response to biventricular (BiV) pacing in personalized computational models of the cardiac electrophysiology.Materials and Methods: Retrospective data from 57 patients who underwent CRT device implantation was utilized. Positive response to CRT was defined by a 10% increase in the left ventricular ejection fraction in a year after implantation. For each patient, an anatomical model of the heart and torso was reconstructed from MRI and CT images and tailored to ECG recorded in the participant. The models were used to compute ventricular activation time, ECG duration and electrical dyssynchrony indices during intrinsic rhythm and BiV pacing from the sites of implanted leads. For building a predictive model of CRT response, we used clinical data recorded before CRT device implantation together with model-derived biomarkers of ventricular excitation in the left bundle branch block mode of activation and under BiV stimulation. Several Machine Learning (ML) classifiers and feature selection algorithms were tested on the hybrid dataset, and the quality of predictors was assessed using the area under receiver operating curve (ROC AUC). The classifiers on the hybrid data were compared with ML models built on clinical data only.Results: The best ML classifier utilizing a hybrid set of clinical and model-driven data demonstrated ROC AUC of 0.82, an accuracy of 0.82, sensitivity of 0.85, and specificity of 0.78, improving quality over that of ML predictors built on clinical data from much larger datasets by more than 0.1. Distance from the LV pacing site to the post-infarction zone and ventricular activation characteristics under BiV pacing were shown as the most relevant model-driven features for CRT response classification.Conclusion: Our results suggest that combination of clinical and model-driven data increases the accuracy of classification models for CRT outcomes.

Posterior right ventricular outflow tract septal pacing using His-bundle catheter guidance – Is it the closest we get to LV pacing?

Posterior right ventricular outflow tract septal pacing using His-bundle catheter guidance – Is it the closest we get to LV pacing?

Cardiac Magnetic Resonance Assessment of Response to Cardiac Resynchronization Therapy and Programming Strategies

ObjectivesThe objective was to determine the feasibility and effectiveness of cardiac magnetic resonance (CMR) cine and strain imaging before and after cardiac resynchronization therapy (CRT) for assessment of response and the optimal resynchronization pacing strategy. BackgroundCMR with cardiac implantable electronic devices can safely provide high-quality right ventricular/left ventricular (LV) ejection fraction (RVEF/LVEF) assessments and strain. MethodsCMR with cine imaging, displacement encoding with stimulated echoes for the circumferential uniformity ratio estimate with singular value decomposition (CURE-SVD) dyssynchrony parameter, and scar assessment was performed before and after CRT. Whereas the pre-CRT scan constituted a single “imaging set” with complete volumetric, strain, and scar imaging, multiple imaging sets with complete strain and volumetric data were obtained during the post-CRT scan for biventricular pacing (BIVP), LV pacing (LVP), and asynchronous atrial pacing modes by reprogramming the device outside the scanner between imaging sets. Results100 CMRs with a total of 162 imaging sets were performed in 50 patients (median age 70 years [IQR: 50-86 years]; 48% female). Reduction in LV end-diastolic volumes (P = 0.002) independent of CRT pacing were more prominent than corresponding reductions in right ventricular end-diastolic volumes (P = 0.16). A clear dependence of the optimal CRT pacing mode (BIVP vs LVP) on the PR interval (P = 0.0006) was demonstrated. The LVEF and RVEF improved more with BIVP than LVP with PR intervals ≥240 milliseconds (P = 0.025 and P = 0.002, respectively); the optimal mode (BIVP vs LVP) was variable with PR intervals <240 milliseconds. A lower pre-CRT displacement encoding with stimulated echoes (DENSE) CURE-SVD was associated with greater improvements in the post-CRT CURE-SVD (r = −0.69; P < 0.001), LV end-systolic volume (r = −0.58; P < 0.001), and LVEF (r = −0.52; P < 0.001). ConclusionsCMR evaluation with assessment of multiple pacing modes during a single scan after CRT is feasible and provides useful information for patient care with respect to response and the optimal pacing strategy.

B-PO05-211 PROGRAMMING CHALLENGES DURING LEFT VENTRICULAR PACING. A CASE OF PACEMAKER-MEDIATED TACHYCARDIA

Multichamber pacing may be associated with complex interactions between pacing timing cycles. Review of a case of pacemaker mediated tachycardia (PMT) during LV pacing. Data was collected by retrospective review. A patient with a history of coronary artery disease and bypass surgery, heart failure and primary prophylaxis dual chamber defibrillator (ICD) underwent upgrade to a biventricular ICD (Boston Scientific Vigilant X4 G247) due to new left bundle branch block and heart failure symptoms. Postoperative programming was identical (DDDR 50/130/130 bpm; PVARP 240-280 ms) except for shortened AV delay with simultaneous RV/LV pacing. During an admission to an outside hospital, AV delay was shortened (SAV: 100 ms, PAV 150 ms) and pacing mode was changed to LV only. In follow-up, numerous PMT episodes were noted in the device memory (Panel A) and also during device interrogation but only with LV-only pacing. Retrograde P wave during LV pacing fell outside the programmed PVARP because retrograde left bundle branch block caused transseptal retrograde conduction via the right bundle branch with delay in LV to RA interval. Timing from RV apex to RA (Panel B, red arrow, 240 ms) was the same during RV pacing and during LV pacing (panel C) but because PVARP is initiated with the first paced ventricular chamber, the V to A time prolonged with LV-only pacing (Panel C, blue arrow, 420 ms) beyond PVARP. Programming very long PVARP limits upper tracking rate so in this case we switched to biventricular pacing which shortened the QRS duration and also eliminated PMT episodes. In CRT devices, PVARP should be reassessed when LV only pacing is programmed.

B-IN01-06 PERSONALIZED APPROACH FOR CARDIAC RESYNCHRONIZATION THERAPY (CRT) IMPLANTATION GUIDED BY REAL-TIME NON-INVASIVE 3D ELECTROCARDIOGRAPHIC MAPPING

The optimal approach for CRT implantation is not established. To evaluate the feasibility of CRT implantation under electrocardiographic mapping guidance. Thirty consecutive patients with left ventricular ejection fraction (LVEF) ≤35% and conduction delay (9 LBBB and 21 non-LBBB) were recruited. A 252-electrode vest (CardioInsight, Medtronic) was worn by the patient during the procedure to measure the total activation time (TAT) when different pacing combinations of biventricular pacing (BVP), His-bundle pacing (HBP) and/or left bundle branch pacing (LBBP) were tested. The combination that resulted in the shortest TAT would be chosen. Clinical response was defined by ≥1 NYHA class improvement and echocardiographic response by LV end-systolic volume reduction ≥15% and/or LVEF improvement ≥10% at 6-months follow-up. Final pacing configurations involved LBBP in 40%, HBP in 33%, BVP in 13% and RV or LV pacing alone in 13% of patients. Mean QRS duration shortened from 164±18ms to 128±18ms and LVEF improved from 26±6% to 39±14% (both p <0.01). Clinical and echocardiographic response rates were 80% and 73%, respectively. Super echocardiographic responder rate (final LVEF >45%) was 33%. Mean TAT (57ms vs. 87ms) was significantly lower and TAT reduction (42% vs. 12%) was significantly greater with final pacing-configuration compared to BVP, respectively (both p<0.01). Personalized approach for CRT implantation using real-time non-invasive electrocardiographic mapping was feasible and associated with better resynchronization results compared to BVP.

B-PO03-190 COMPARISON OF ADAPTIVE AND NON-ADAPTIVE PACING MODES WITH BIVENTRICULAR STIMULATION ON TIME-TO-PEAK DERIVATIVE OF LEFT VENTRICULAR PRESSURE

Time-to-peak dP/dt (Td) is marker of mechanical resynchronization. Td links the time domain (dyssynchrony) to the mechanical domain (pressure) as the dyssynergic muscular contractions resulting from electrical dyssynchrony delays pressure development and hence the timing Td. Td shortens with resynchronization. In this study we investigated the acute changes in Td with standard BIVP and fusion with intrinsic conduction, single or multiple LV electrodes and different VV-intervals. 19 patients with sinus rhythm and LBBB undergoing CRT implantation were studied. We measured pressures with an indwelling LV pressure sensor catheter. Td was calculated as the time from onset of pacing to peak dP/dt and averaged in 10 subsequent beats at each stage of pacing. We used quadripolar LV pacing leads positioned in what was considered an optimal mid/basal posterolateral/ lateral branch of the coronary sinus and sequential pacing (DDD) was performed; Adaptive (A) and Non-Adaptive (NA) BIVP was performed at LV distal [LVdist], proximal electrode [LVprox] and at both electrodes as multipoint pacing [MPP]. VV-timing: LV pacing was performed relative to QRS onset (either as a result of intrinsic activation or RV pace, mean±SD): 1. LV only 76±21ms before QRS activation with minimal fusion with RV activation (LVonly); 2. 28±14ms before QRS activation (Pre); 3. 12±15ms after (Post) QRS activation. Average Td (data pooled) with RVP was 173±2ms, MPP 144±0.4ms and BIVP 150±0.4ms. Analyzing pacingmode (A,NA), VV-timing (LVonly,Pre,Post) and electrode (LVdist,LVprox,MPP) we found that Td was shorter (p<0.01) with A(Post) for all electrode combinations [LVdist] 143±4ms, [LVprox] 140±4ms and [MPP] 134±4ms, while Td with A(Pre) was shorter with [MPP] 139±4ms only. NA(Post)[MPP] at 145±4ms and NA(Post)[LVdist] at 146±4ms provided the shortest Td (p<0.01) of the NA pacing modes, and Td with NA(Post)[MPP] was shorter (p<0.01) than all NA pacing modes. A(post)[MPP] provided the shortest Td of all (134±4ms, p<0.01). Td shortens the most with LV MPP timed to near simultaneous intrinsic RV activation, indicating a beneficial mechanical effect from Adaptive MPP compared to standard biventricular pacing modes.

B-PO01-100 PERSONALIZED APPROACH FOR CARDIAC RESYNCHRONIZATION THERAPY (CRT) IMPLANTATION GUIDED BY REAL-TIME NON-INVASIVE 3D ELECTROCARDIOGRAPHIC MAPPING

The optimal approach for CRT implantation is not established. To evaluate the feasibility of CRT implantation under electrocardiographic mapping guidance. Thirty consecutive patients with left ventricular ejection fraction (LVEF) ≤35% and conduction delay (9 LBBB and 21 non-LBBB) were recruited. A 252-electrode vest (CardioInsight, Medtronic) was worn by the patient during the procedure to measure the total activation time (TAT) when different pacing combinations of biventricular pacing (BVP), His-bundle pacing (HBP) and/or left bundle branch pacing (LBBP) were tested. The combination that resulted in the shortest TAT would be chosen. Clinical response was defined by ≥1 NYHA class improvement and echocardiographic response by LV end-systolic volume reduction ≥15% and/or LVEF improvement ≥10% at 6-months follow-up. Final pacing configurations involved LBBP in 40%, HBP in 33%, BVP in 13% and RV or LV pacing alone in 13% of patients. Mean QRS duration shortened from 164±18ms to 128±18ms and LVEF improved from 26±6% to 39±14% (both p <0.01). Clinical and echocardiographic response rates were 80% and 73%, respectively. Super echocardiographic responder rate (final LVEF >45%) was 33%. Mean TAT (57ms vs. 87ms) was significantly lower and TAT reduction (42% vs. 12%) was significantly greater with final pacing-configuration compared to BVP, respectively (both p<0.01). Personalized approach for CRT implantation using real-time non-invasive electrocardiographic mapping was feasible and associated with better resynchronization results compared to BVP.

B-PO03-067 PACEMAKER EXIT-BLOCK AFTER RADIOABLATION FOR VT CAUSING INAPPROPRIATE ICD SHOCKS AND BRADYCARDIC ARREST

Stereotactic body radiation therapy (SBRT) is an emerging tool for the treatment of VT where catheter ablation has failed or is technically not feasible. Knowledge of the acute and chronic electrophysiologic sequelae, including changes in functioning of device therapy, is an evolving area. We report the first known case of inappropriate ICD shocks and severe bradycardia due to exit-block in a pacemaker dependent patient as a late-onset phenomenon following successful SBRT for VT. NA NA A 54-year-old female with a history of scar-related VT despite amiodarone therapy and chemical sympathectomy underwent successful SBRT for VT seven months prior. She was pacemaker dependent (CRT-D) with stable thresholds post-SBRT. She presented to hospital with multiple episodes of conscious ICD shocks due to R-wave double counting and misclassification as VF from interventricular conduction delay or RV loss of capture (LOC). At testing, LV and RV pacing thresholds were measured to be stable however. She later experienced severe bradycardic episodes due to intermittent LV and RV LOC that was stabilised by programming her CRT to maximum output. Definitive treatment was with insertion of a new transcutaneous RV lead and removal of LV lead. This is the first known case of delayed-onset exit-block occurring following SBRT for VT with sequelae of inappropriate ICD shocks and profound bradycardia due to dynamic conduction delay, variable pacing threshold and interplay with CRT programming. It is important that the electrophysiology team is aware of these issues.

Excitation and Contraction of the Failing Human Heart In Situ and Effects of Cardiac Resynchronization Therapy: Application of Electrocardiographic Imaging and Speckle Tracking Echo-Cardiography

Despite the success of cardiac resynchronization therapy (CRT) for treating heart failure (HF), the rate of nonresponders remains 30%. Improvements to CRT require understanding of reverse remodeling and the relationship between electrical and mechanical measures of synchrony. The objective was to utilize electrocardiographic imaging (ECGI, a method for noninvasive cardiac electrophysiology mapping) and speckle tracking echocardiography (STE) to study the physiology of HF and reverse remodeling induced by CRT. We imaged 30 patients (63% male, mean age 63.7 years) longitudinally using ECGI and STE. We quantified CRT-induced remodeling of electromechanical parameters and evaluated a novel index, the electromechanical delay (EMD, the delay from activation to peak contraction). We also measured dyssynchrony using ECGI and STE and compared their effectiveness for predicting response to CRT. EMD values were elevated in HF patients compared to controls. However, the EMD values were dependent on the activation sequence (CRT-paced vs. un-paced), indicating that the EMD is not intrinsic to the local tissue, but is influenced by factors such as opposing wall contractions. After 6 months of CRT, patients had increased contraction in native rhythm compared to baseline pre-CRT (baseline: −8.55%, 6 months: −10.14%, p = 0.008). They also had prolonged repolarization at the location of the LV pacing lead. The pre-CRT delay between mean lateral LV and RV electrical activation time was the best predictor of beneficial reduction in LV end systolic volume by CRT (Spearman’s Rho: −0.722, p &lt; 0.001); it outperformed mechanical indices and 12-lead ECG criteria. HF patients have abnormal EMD. The EMD depends upon the activation sequence and is not predictive of response to CRT. ECGI-measured LV activation delay is an effective index for CRT patient selection. CRT causes persistent improvements in contractile function.

Electrical delays in quadripolar leads with cardiac resynchronization therapy.

Pacing at sites of late intraventricular activation (QLV) or long interventricular conduction (right ventricle [RV]-left ventricular [LV]) have been associated with improved cardiac resynchronization therapy (CRT) outcomes. Quadripolar leads improve CRT outcomes by allowing for electrical repositioning to optimize pacing sites. However, little is known regarding the effect of such repositioning on electrical delay. Determine the relationship between different electrical bipoles from a quadripolar lead and measures of electrical delay. Forty-six patients underwent CRT with a quadripolar lead. The RV-LV and QLV intervals were measured for both the proximal and distal bipoles and the difference (Δ) between bipoles for each measure were calculated. Multivariate analyses were performed to identify predictors of electrical delays. This was a typical CRT population with a mean age of 65 years and ejection fraction of 27%, with left bundle branch block(LBBB) present in 70%. The regression model for ΔQLV was significant (p = .05), with both gender (p = .008) and LBBB status (p = .020) significant predictors. The overall regression model for ΔRV-LV was not significant. ΔQLV and ΔRV-LV were significant among LBBB patients. Among non-LBBB, only ΔRV-LV was significant (mean: 7.2 ms, p = .006). ΔRV-LV versus ΔQLV were strongly correlated in LBBB (R2 = .92) but not non-LBBB (R2 = .06). In LBBB, ΔRV-LV and ΔQLV are closely correlated suggesting that the proximal bipole and thus basal LV pacing sites should be selected when feasible. Greater variation in activation pattern is present in non-LBBB, so pacing sites should be individualized.

A STUDY ON GLOBAL LONGITUDINAL STRAIN IN PREDICTING PACING INDUCED LEFT VENTRICULAR DYSFUNCTION OVER TIME IN POST PERMANENT PACEMAKER PATIENTS

OBJECTIVE:The goal of this study is to predict the long term LV function in RV apical paced patients. BACKGROUND:We have used the GLS measured by 2D STE, as a tool to predict the patients who are at high risk of developing pacing induced LV dysfunction (PIVD) or pacing induced cardiomyopathy (PCMP). METHOD: A prospective study conducted in the cardiology department of Government Rajaji Hospital, Madurai, including 47 patients of AV block or sinus node dysfunction with preserved ejection fraction undergoing RV apical pacing. This study population was followed up with serial trans thoracic 2D echocardiography with GLS by STE for a period of 12 months for the development of PIVD (PCMP). RESULTS: Of the study population, 42.5% (n=20) developed PIVD at 12 months and these patients had a signicant fall in their GLS values at one month post pacing. (GLS -16.94% vs -17.60%; p=0.02). CONCLUSION: GLS, a novel echocardiographic parameter can be used as a tool in predicting the decline in ejection fraction following pacemaker implantation with potential to predict the development of PIVD. GLS at one month post pacing had a high predictive accuracy for identifying those who developed PIVD later in the follow up.

Are His bundle pacing or His bundle plus coronary sinus pacing superior to conventional cardiac resynchronization therapy in improving heart failure? Results from a controlled study

Abstract Funding Acknowledgements Type of funding sources: None. BACKGROUND His bundle pacing (HBP), alone or optimized in association with coronary sinus pacing (HBP + LV) has recently been proposed as an alternative to conventional cardiac resynchronization therapy (CRT). However, there is lack of controlled studies that assessed clinical outcome. METHODS We did a single-centre, propensity-score matched, case-control study of comparison of HBP and HBP + LV versus conventional CRT in patients with heart failure (HF) and standard indications for CRT. The study group patients (n = 27) were consecutively enrolled in the years 2019. The control group patients (n = 27) were selected, by propensity score matching, among those CRT implantations performed, in the years 2015-2018. RESULTS In the active group, HBP alone was preferred in 12 (44%) patients, HBP + LV pacing in 12 (44%) patients and HBP failed in 3 (11%) patients. In the control group, conventional CRT was achieved in 26 (96%) patients and failed in one. Paced QRS width was shorter in the active than in the control group (128 ± 18 ms vs 148 ± 27 ms, p = 0.004). During a mean of 9.6 months of follow-up, in the intention-to-treat analysis, a composite clinical outcome of death, hospitalization for HF or worsening HF occurred in 3 (11%) in the active group and in 4 (15%) in the control group, p = 0.58. No difference was also observed with softer endpoints: NYHA class (1.9 ± 0.7 versus 2.1 ± 0.7), subjective improvement (74% versus 74%) and LV ejection fraction (40.7% versus 40.7%). CONCLUSION Compared with standard CRT, a shorter QRS width can be obtained with HBP alone or HBP + LV but we were unable to show a better clinical outcome. There is urgent need for large, randomized trials. Results by intention-to-treat analysisVariableActive groupN = 27Control groupN = 27PFollow-up, months9.7 ± 4.89.5 ± 4.50.90QRS width, ms128 ± 18148 ± 270.004Combined primary endpoint3 (11%)4 (15%)0.58• Death for HF10• Hospitalization for HF24• Worsening HF-1Subjective improvement20 (74%)20 (74%)1.24NYHA class1.9 ± 0.72.1 ± 0.70.15LV ejection fraction (%)40.7 ± 11.540.7 ± 12.21.00HF = heart failure; NYHA = New York Heart Association; LV = left ventricleAbstract Figure. Flow of active group patients

Echocardiographic but not clinical response to CRT is an independent predictor of a better survival free from arrhythmic events

Abstract Funding Acknowledgements Type of funding sources: None. Background Cardiac resynchronization therapy (CRT) is of proven benefit in heart failure patients, improving mortality and reducing hospital admissions. There is however uncertainty if the arrhythmic risk is reduced in responders. Purpose We aimed to assess if patients with a CRT implanted for primary prevention had less arrhythmic episodes if they responded to this therapy and if echocardiographic and clinical responses to CRT differ regarding the occurrence of ventricular arrhythmias. Methods We prospectively enrolled patients that underwent CRT implant for primary prevention according to ESC guidelines. Patients were classified as responders if they fulfilled one of four criteria (echocardiographic or clinical) at six months after implant: a 5% absolute improvement in LV ejection fraction (LVEF), a 15% improvement in LVEF, a 15% decrease in LV end-diastolic volume or a decrease in NYHA class. During follow-up with device interrogation, arrhythmic ventricular events (AVE) were classified as appropriate ICD therapies or sustained ventricular tachycardia either occurring in ICD monitoring zones or undetected by the device due to a slower rare, but clinically documented. All patients were further classified according to type of pacing, biventricular or LV only. Demographic characteristics of patients were also assessed. Results We enrolled 73 patients, 58 (79.5%) male, median age of 72 (65-77) years. Median LVEF was 28 (22-35) % (p = 0.95 between groups), ischemic etiology in 36 (46.6%, p = 1.00). The two groups with and without AVE did not differ significantly regarding clinical, echocardiographic, and electrocardiographic characteristics (table). CRT echocardiographic response criteria were met by 50 (68.5%) of patients and clinical criteria by 53 (72.6%) patients. AVE occurred in 15 (20.5%) patients. In univariate regression analysis, echocardiographic response was associated with reduced AVE (OR 0,14; p = 0,005). Clinical response to CRT was not associated with AVE (p = 0.07). LV only pacing was associated with a higher probability of AVE (OR 5.1; p = 0.038). In Cox regression multivariate analysis, response to CRT was the only independent predictor of better survival free from AVE (HR 0.28;CI 95%, p = 0.044) and LV only pacing was not associated with more episodes of ventricular arrhythmias (p = 0.17). Conclusions: Echocardiographic, but not clinical response to CRT therapy, is the only independent predictor of a higher survival free from arrhythmic events. In spite controversies regarding the arrhythmogenic role of LV pacing, this was not associated with higher ventricular arrhythmic events. Abstract Figure.

The year in cardiovascular medicine 2020: arrhythmias.

of the progress in arrhythmias in 2020. RACE4 and ALL-IN indicated that integrated nurse-led care improves outcomes in AF patients.3,4 The same was reported for early rhythm control therapy15 and cryoablation as initial AF treatment.25,26 Subcutaneous ICD was non-inferior to classical transvenous ICD therapy in PRAETORIAN.54 One mechanistic study showed that autoantibodies against misexpressed actin, keratin, and connexin-43 proteins create a blood-borne biomarker profile enhancing diagnosis of Brugada syndrome.50 Another mechanistic study indicated that transseptal LV pacing yields similar improvement in contractility as His bundle pacing whilst being more easy to execute.44 In PRE-DETERMINE a simple-to-use ECG risk score improved risk prediction in patients with ischemic heart disease possibly enhancing appropriate ICD therapy in high risk patients.58.

Optimal programming of cardiac resynchronisation therapy with His bundle pacing based on aortic velocity time integral in patients with congestive heart failure and permanent atrial fibrillation

Abstract Background Cardiac resynchronisation therapy (CRT) in patients with permanent atrial fibrillation (AF) is usually less effective than in sinus rhythm patients. Recent evidence has shown that His bundle pacing (HBP) might be a valuable alternative to conventional pacing systems resulting in more physiologic electrical activation of the heart. Currently, there is a need to identify the optimal way of CRT + HBP programming in patients with congestive heart failure (CHF) and permanent AF to achieve high cardiac output and improve physical capacity and survival. Purpose The aim of this study was to evaluate the impact of CRT + HBP programming on cardiac output in the early post-operative measurements. Methods We included consecutive patients with: 1. permanent AF, 2. CHF in NYHA class III-IV, 3. bundle branch block with QRS &amp;gt;130 ms or QRS &amp;lt;130 ms and high expected requirement of ventricular pacing, 4. severely reduced left ventricular ejection fraction (LVEF) ≤35%, 5. CHF refractory to optimal medical therapy, 6. implanted CRT + HBP. All patients gave informed consent for CRT + HBP implantation and optimization of device programming. During the early post-operative phase, we aimed to optimize CRT + HBP settings in order to achieve the highest cardiac output assessed by repeated echocardiographic measurements of aortic velocity time integral at various pacing programs (Table 1). Then, we selected the optimal pacing settings of CRT + HBP for each individual patient. Results Study included 17 consecutive patients aged 71.5±6.3 years, 12 were male. Mean LVEF was 24% and median NYHA class was III. The most efficacious method of pacing in terms of aortic VTI was HBP combined with left ventricular pacing (LV) which resulted in median VTI of 22.5. HBP + LV was superior to right ventricular pacing (RV): VTI of 22.5 vs 18.5, P=0.003 and outperformed biventricular pacing: VTI 22.5 vs 18.7, P=0.019. Detailed results are shown in Figure 1. Conclusion His bundle pacing coupled with LV pacing proved to be the most advantageous pacing program setting with regard to cardiac output and it performed significantly better than RV pacing only or biventricular pacing. Our observation supports the use of His bundle pacing in CRT systems in patients with CHF and permanent AF. Figure 1 Funding Acknowledgement Type of funding source: None

Electrical characteristics of deep septal vs. left bundle branch (area) pacing

Abstract Background/Introduction Recent studies have described transvenous left bundle branch (LBB) pacing as a new conduction system pacing strategy. However, information on effect of pacing depth within the septum and the additional effect of LBB capture is unknown. Purpose To investigate the relation of electrocardographic characteristics with transseptal LV lead implantation depth and LBB capture. Methods 20 consecutive patients referred for pacemaker implantation were enrolled. The right atrial (RA) lead was positioned according to routine practice. The LV septal pacing lead (Medtronic 3830) was transvenously positioned against the right side of the interventricular septum and advanced in small steps of 1–2mm towards the left side of the septum. At each depth in the septum 12-lead ECG's were recorded during pacing, from which vectorcardiograms (VCG) were calculated. QRS duration and QRS area were measured, the latter being the integral of the QRSarea in X, Y and Z directions. Successful LBB capture was defined as paced right bundle branch block (RBBB) morphology, stable and short stimulus to LV activation time (LVAT; R in V5) and recorded LBB potential. Differences were compared among pacing conditions using repeated measures ANOVA with Bonferroni multiple comparisons procedure applied to pairwise comparisons. Statistical significance was assumed at p&amp;lt;0.05. Results LV septal lead implantation was successful in all patients. Left bundle branch capture was achieved in 10/20 patients (50%). Post-procedural LV pacing threshold, impedance and sensing was 0.7±0.1 V at 0.5 ms pulse width, 658±5 Ω and 13±10 mV, respectively. Compared to intrinsic rhythm, QRS duration was significantly increased by both RV septum (RVS; 124±5 vs. 161±3 ms) and LV septum pacing (LVS; 142±3 ms). QRS area increased significantly during RVS pacing as compared to intrinsic rhythm but decreased when moving from RVS to LVS to values close to intrinsic rhythm (panel A &amp; B). LVS-pacing derived QRS area was significantly lower in patients with LBB capture (36±6 mV*ms) compared to patients without LBB capture (deep septal pacing; 46±12 mV*ms). The reduction in QRS area between RVS and LVS pacing coincided with normalization of the QRS vector in the transverse plane (panel C), which is characterized electrocardiographically by predominantly negative-to-positive inversion of the QRS complex in the precordial leads (V1-V3). Conclusions Compared to RV septal pacing, LV septal pacing restores ventricular electrical synchrony, as determined by QRS area, and normalizes the activation vector in the transverse plane to a level comparable to intrinsic rhythm. Differences in resynchronization between left bundle branch pacing and deep septal pacing are small. LBBAP restores ventricular synchrony Funding Acknowledgement Type of funding source: None

Impact of chronic sequential LV-RV pacing with cardiac resynchronization therapy for patients with narrower (&amp;lt;130 ms) QRS complexes following evaluation of acute myocardial strain characteristics

Abstract Background Prior studies have shown acute improvement in myocardial strain patterns (SP) and strain rates (SR), left ventricular ejection fraction (LVEF), and long-term clinical improvement by Cardiac Resynchronization Therapy (CRT) preferential LV pacing. This relationship has not been studied in patients (pts) with narrower QRS. Objectives We aimed to evaluate myocardial speckle tracking SP and SR at different VV intervals in pts with narrow (&amp;lt;130 ms) and wide (&amp;gt;130 ms) QRS. Methods We assessed LVEF and speckle tracking myocardial SP and SR as per the American Society of Echocardiography (ASE) Dyssynchrony Writing Group methods in pts with CRT in acute settings at VV0, VV60 and LV-only pacing. For SP assessment, we used Bull's eye format display of the LV segments, and scores for SR, 2 = early stretch, late peak, 1= early stretch, early peak, and 0 = single peak at aortic closure. Results Total cohort of 271 pts; age 69.2±10.3 yrs (mean ± SD), male - 60%, divided into 2 groups; Gp A (QRS &amp;lt;130 ms, n=69) and Gp B (QRS &amp;gt;130 ms, n=202). QRS width and LVEF in Gp A and B were 120.1±12.3 ms and 152.1±12.9 ms, and 22.3±9.4% and 23.3±10.2% respectively. With VV0 increase in LVEF, 67±6.0% from baseline 22.3±9.4% was seen in Gp A compared to 43±6.5% from 23.3±10.2% in Gp B (p&amp;lt;0.01). With VV60 and LV-only pacing further rise in LVEF to 100.0±7.1% and 112.0±7.2% in Gp A and 80.2±8.0% and 93±8.1% in Gp B was seen. (Figure 1). Strain scores at different VV timings in both groups are shown in Table 1. Conclusions In pts with CRT, different VV timings show differences in acute myocardial speckle tracking SP and SR, and LVEF. These changes are markedly favorable with LV-only and sequential LV-RV pacing even in pts with narrower QRS. Our findings support chronic sequential LV-RV pacing programming in CRT pts with narrow QRS. Figure 1 Funding Acknowledgement Type of funding source: None

A hybrid machine learning approach to localizing the origin of ventricular tachycardia using 12-lead electrocardiograms

BackgroundMachine learning models may help localize the site of origin of ventricular tachycardia (VT) using 12-lead electrocardiograms. However, population-based models suffer from inter-subject anatomical variations within ECG data, while patient-specific models face the open challenge of what pacing data to collect for training. MethodsThis study presents and validates the first hybrid model that combines population and patient-specific machine learning for rapid “computer-guided pace-mapping”. A population-based deep learning model was first trained offline to disentangle inter-subject variations and regionalize the site of VT origin. Given a new patient with a target VT, an on-line patient-specific model -- after being initialized by the population-based prediction -- was then built in real time by actively suggesting where to pace next and improving the prediction with each added pacing data, progressively guiding pace-mapping towards the site of VT origin. ResultsThe population model was trained on pace-mapping data from 38 patients and the patient-specific model was subsequently tuned on one patient. The resulting hybrid model was tested on a separate cohort of eight patients in localizing 1) 193 LV endocardial pacing sites, and 2) nine VTs with clinically determined exit sites. The hybrid model achieved a localization error of 5.3 ± 2.6 mm using 5.4 ± 2.5 pacing sites in localizing LV pacing sites, achieving a significantly higher accuracy with a significantly smaller amount of training sites in comparison to models without active guidance. ConclusionThe presented hybrid model has the potential to assist rapid pace-mapping of interventional targets in VT.