Atrioventricular Interval Research Articles

Abstract 4136984: Low Occurence of Fetal Extranodal Findings and AV Interval Prolongation in Prospectively Followed High Titer Anti-Ro Pregnancies

. Background: Third-degree atrioventricular block (AVB) is the most common manifestation of Anti-Ro antibody associated fetal cardiac disease. Extranodal findings of isolated cardiac echogenicity, valvulitis with insufficiency and AV interval prolongation have been reported but not described in large prospective series. Aims: To report the occurrence and outcomes of extranodal findings in subjects followed prospectively since 2020 in STOP BLOQ (Surveillance and Treatment to Prevent Fetal AV block Likely to Occur Quickly) and the Registry for Neonatal Lupus (RNL). Methods: We reviewed fetal echo reports from pregnant STOP BLOQ and RNL Anti-Ro antibody subjects. Pregnancies with high (>1000 EU for anti-Ro52 or 60) antibody titers measured in a core research lab underwent surveillance with home fetal heart rate monitoring (FHRM) 3x/day and weekly or bi-weekly fetal echos from 17- 26 gestational weeks. Low titer subjects underwent echo or no surveillance based on local site protocol. We evaluated cardiac function, effusions, cardiac echogenicity and its location, any tricuspid (TV) or mitral (MV) insufficiency trivial or >trivial) and AV conduction times (<150, 150-170 or >170 ms) Results: Echo reports were available in 622 prospectively followed pregnancies (376 high (40/376 with a previously affected child) and 246 low-titer pregnancies. All had subjectively normal ventricular function and none had effusions. Seven fetuses, 2 low and 5 high titer at 19 (range 16.7-21.7) weeks demonstrated cardiac echogenicity (n=6), AV or semilunar valve insufficiency (n=2) or AV interval 150-170 ms (n=2) (Table). Subjects 1 and 2, both high titer and treated with prophylactic Plaquenil (400 mg/d before 10 gestational weeks), had prior fetal AVB. Subject #1 had normal AV conduction but MV and TV echogenicity and moderate insufficiency of both valves which resolved in days after IVIG and dexamethasone (dex) treatment, but 3° AVB developed at 19 weeks after dex wean. Subjects 2-7 received no treatment and extranodal findings did not progress to cardiac dysfunction or AVB. During the same time period, 10 high titer subjects developed 2° or 3° AVB. Conclusion: Anti-Ro associated extranodal findings are rare, occurring in 1% of pregnancies overall and in 5% of pregnancies with a previously affected child. Unlike AVB, extranodal findings can occur in low titer pregnancies. The role of treatment for isolated extranodal findings in the absence of cardiac dysfunction is unclear.

Hypertension and Device-Based Therapies for Resistant Hypertension: An Up-to-Date Review.

Hypertension is the most prevalent modifiable risk factor associated with cardiovascular mortality. The World Health Organization (WHO) estimates that hypertension directly or indirectly causes the death of at least nine million people globally every year. The number of people living with hypertension (blood pressure (BP) of ≥140 mmHg systolic or ≥90 mmHg diastolic or on medication) doubled between 1990 and 2019, from 650 million to 1.3 billion. Despite a plethora of antihypertensivedrugs widely available, a sizable part of the antihypertensive population stays uncontrolled. The unmet need of controlling BP in this population may be addressed, in part, by developing new drugs and devices/procedures to treat hypertension and its comorbidities. Several device-based approaches have been introduced to lower BP, and most of these strategies aim to modulate autonomic nervous system activity. Importantly, when considering a device-based treatment, each patient's underlying pathophysiology is considered, and the procedural risks are weighed against the cardiovascular risk attributed to the elevated BP.In November 2023, the FDA approved two renal denervation (RDN) devices. This manuscript discusses current interventional devices and procedures recently approved (RDN) and others in the clinical testing stage for arterial hypertension intervention or management.As we list below, all others have shown promising results and are being evaluated on a larger clinical trial.The new device-based classes are as follows: catheter-based RDN, baroreflex amplification, arteriovenous (AV) malformation, carotid body (CB) ablation, pacemaker-based cardiac neuromodulation, electro-acupuncture, and deep brain stimulation. Baroreflex amplification uses peripheral neuromodulation, while AV malformation leverages AV anastomosis. CB ablation modulates chemoreceptors, and pacemaker-based neuromodulation adjusts atrioventricular intervals. Electro-acupuncture proves potential, and deep brain stimulation offers central nervous system intervention.

Evaluation of ventricular pacing suppression algorithms in dual chamber pacemaker: Results of "LEADER" study.

There is limited research on the intra-individual efficacy of ventricular pacing minimization algorithms developed by Biotronik-the Ventricular Pace Suppression algorithm (VpS) and the Intrinsic Rhythm Support plus algorithm (IRSplus) (BIOTRONIK SE & Co. KG, Berlin, Germany). We performed a randomized pilot trial that evaluated the efficacy of two algorithms in patients with symptomatic sinus node dysfunction (SND) who received a dual-chamber pacemaker. The trial was conducted in 11 tertiary hospitals in South Korea. The patients were randomized to either the VpS or IRSplus algorithm group after a 3-month period of fixed atrioventricular (AV) delay. The primary outcome was the ventricular pacing percentage (Vp%) at each follow-up visit. The secondary outcomes were the occurrence of heart failure (HF) and atrial fibrillation (AF) during the study period. Data from 131 patients were analyzed. Initially, their average Vp% over 3 months with a fixed AV interval was 14.1 ± 19.4%. Patients were randomly assigned to VpS and IRSplus groups, with 66 and 65 in each. Algorithms reduced average Vp% to 4.0 ± 11.3% at 9 months and 6.7 ± 14.9% at 15 months. These algorithms were more effective for patients with paced AV delay (PAVD) ≤300 ms compared to those with PAVD >300 ms. Both algorithms were equally effective in reducing Vp%. Clinical AF or HF hospitalization was not observed during the study period. The VpS and IRSplus algorithms are effective and safe in minimizing unnecessary ventricular pacing in patients with SND.

The role of atrial pacing site in reducing filling pressures by accelerated pacing in virtual HFpEF patients

Abstract Background Patients with heart failure with preserved ejection fraction (HFpEF) and pacemakers have been shown to benefit from moderately accelerated pacing rates compared to the standard 60bpm. HFpEF patients often present with prolonged P-wave duration (PWD) and atrial fibrillation. Right atrial appendage pacing (RAAP) lengthens PWD, RA septal (RASP) has a neutral effect, while Bachmann’s bundle pacing (BBP) normalizes or shortens PWD compared to sinus rhythm. The mechanical and hemodynamic effects of atrial pacing site selection remain unknown. Aim To investigate the impact of RAAP, RASP and BBP on cardiac mechanics and hemodynamics in an established cohort of virtual HFpEF patients undergoing accelerated pacing. Method HFpEF with prolonged PWD was simulated using the validated CircAdapt computational model of the human cardiovascular system. First, left ventricular (LV) diastolic dysfunction was simulated by decreasing LV myocardial relaxation rate and compliance, such that mean left atrial (LA) pressure (mLAP) was 15mmHg. Second, PWD was prolonged by prescribing a gradual electrical activation delay from RA to LA of 140ms. We then simulated atrial pacing with three different lead positions (Fig.1, left) and gradually increased pacing rate with a constant 120-ms paced atrioventricular (AV) delay. The CircAdapt model computed regional LA strain and mLAP with RAAP, RASP, and BBP. Cardiac output (5L/min) and mean arterial pressure (92mmHg) were kept constant in all simulations. Results Simulated BBP demonstrated the most synchronous LA mechanical activation and function, characterized by uniform segmental LA strain patterns and highest LA reservoir strain (LASR) (Fig.1, middle, with colored arrows highlighting the mechanical dyssynchrony). Hemodynamically (Fig.1, right), BBP acutely decreased mLAP (-1.0mmHg) at the initial heart rate of 60bpm, while RAAP increased it (+0.3mmHg). As pacing rate accelerated, BBP reduces filling pressure (mLAP: -2.8mmHg), more than RASP (-1.8mmHg) or RAAP (-1.2mmHg) at 80bpm. At high pacing rates, RASP and RAAP adversely increase mLAP, due to the prolonged atrial contraction duration and shorter LV filling time. Conclusion Our simulations of different atrial pacing sites in virtual HFpEF patients suggest that BBP yields the most synchronous LA activation pattern and a more substantial reduction in filling pressures with accelerated atrial pacing compared to RASP. Reduction in mLAP with accelerated pacing was attenuated with RAAP. While our study concentrated on a specific paced AV interval, the favorable outcomes observed with BBP could be further improved by including different, rate-adaptive, AV protocols.Fig 1.

Atrioventricular Interval Modulation (AVIM) therapy for ambulatory systolic blood pressure (aSBP) reduction with a dual chamber pacemaker: comparison of conduction system vs. right ventricular pacing

Abstract Background AVIM is a pacing algorithm incorporated into dual-chamber pacemakers to treat hypertension. AVIM delivers repeating sequences of short and longer atrioventricular delays leading to reduced preload and afterload. The therapy lowers blood pressure while simultaneously modulating the autonomic nervous system. The marked blood pressure reducing capability of AVIM has been already confirmed by a previous randomized clinical trial using conventional right ventricular (RV) pacing. Nevertheless, whether a similar blood pressure reduction could be also achieved by AVIM when conduction system pacing (CSP) is applied instead of RV pacing has not been investigated yet. Considering the facts that CSP using Left Bundle Branch Area Pacing (LBBAP) has been found to elicit more synchronous ventricular contraction and improved hemodynamics compared to RV pacing and AVIM is associated with a signficant burden of ventricular pacing, it is tempting to hypothesize that AVIM with CSP could be particularly beneficial. Purpose To compare the effects of AVIM therapy when delivered via an LBBAP location with the effects when delivered using a traditional RV lead location. Methods This single-center study evaluated subjects indicated for a dual chamber pacemaker who also had uncontrolled hypertension despite a stable dose of ³ 1 antihypertensive drug. Leads were placed in the RV or the LBBAP position. Subjects entered a run-in period of 4 weeks in which baseline office (oSBP)and 24-hour aSBP were measured. Subjects with baseline aSBP >130 mmHg and oSBP>140 mmHg at week 4 were included in the study. AVIM therapy was activated and a 24-hour aSBP was performed immediately after activation. Results Using a dedicated CSP pacemaker lab setup, CSP was performed in 5 patients with the Select Secure electrode (model 3830-69 cm) delivered via a fixed curve sheath (C315HIS). During the run in phase, in 3 out of the 5 CSP-AVIM patients, high blood pressure did not reach the level of inclusion and therefore these patients were not used for further analysis. In the remaining two patients, AVIM was activated. These two patients had a V6 stimulus-peak time of 69 ms and 61 ms, while V1 stimulus peak time was: 121ms and 109ms respectively. The effect of AVIM on 24-hour aSBP in the activated CSP-AVIM patients was compared to the average effect seen in patients from the same center enrolled in the prior randomized study with leads in the RV. Table 1 shows individual aSBP values for the two patient groups. Results suggest that delivery of AVIM therapy through leads in either position generates a significant reduction in blood pressure: -24.1 mmHg vs. -15.4 mmHg when the lead is placed in LBBAP or RV positions respectively. Conclusion These results demonstrate a significant reduction in aSBP in both lead locations. Additional studies evaluating larger sample sizes are required to assess if specific lead positions are preferable.Table 1

Cardiac Safety of Ozanimod Use, a Novel Sphingosine-1-Phosphate Receptor Ligand, in COVID-19 Patients Requiring Oxygen: Secondary Analysis of the COZI Randomized Clinical Trial

BackgroundOzanimod is a novel immune modulator that could be useful in viral pulmonary infections by reducing lung inflammation. It is an S1P receptor ligand known to induce bradycardia and more serious adverse cardiac effects, such as atrioventricular block and QT interval prolongation. We present a substudy of the COVID-19 Ozanimod Intervention (COZI) trial in which ozanimod was administered in acute pulmonary infection patients, to assess cardiac safety. MethodsIn this pilot randomized open-label trial, COVID-19 patients requiring oxygen support were randomized into 2 groups: standard-of-care + ozanimod (OZA) vs standard-of-care alone (SOC). All patients were monitored with a 14-day electrocardiogram monitor (CardioSTAT, Icentia, Quebec, QC) during their hospitalization. We evaluated the cardiac effects of ozanimod on heart rate (HR), PR interval length, and QT interval duration. ResultsA total of 42 patients were analyzed: 23 in the SOC group and 19 in the OZA group. Mean hourly HR over the first 10 days of treatment decreased in the OZA group, compared with that in the SOC group (P < 0.0001). The maximum decrease in HR occurred on day 3. The maximum decrease in HR occurred on day 3, without a significant difference between groups: 49 beats per minute (interquartile range, 42-59) in the OZA group, and 54 beats per minute (48–60) in the SOC group, P = 0.45. No high-degree atrioventricular block was recorded. QT and PR interval median values were within the normal range in both groups, without a significant difference. ConclusionsThe maximal reduction in HR occurred 3 days after the onset of ozanimod treatment in patients hospitalized for COVID-19, but it did not remain significant over the 10-day treatment period. No relevant cardiac adverse event was observed.

HE EFFECT OF PROBENECID ON α-1-ADRENOCEPTOR STIMULATION INDUCED PROARRHYTHMIC CONDUCTION IN THE ATRIOVENTRICULAR NODE OF RAT HEART

Cardiac tissue contains adrenergic receptors (AR) not only of the beta type, but also of the alpha type (α-AR). Both types of ARs play signifi cant role in regulation of cardiomyocytes electrophysiology in diff erent parts of the heart, including the atrioventricular node (AVN). An augmentation of α1-AR mediated component of adrenergic signaling results in impaired conduction of excitation in the heart and onset of various rhythm disturbances including AVNassociated arrhythmias. The activation of α1-AR facilitates anionic transmembrane transport causing electrophysiological changes in myocytes. Current study is aimed to the investigation of the eff ects of anion/chloride blockade on α1-AR-mediated proarrhythmic alteration of AVN functioning. Functional characteristics of AVN including AVN conduction time, AVN refractoriness and the AVN conduction alterations were examined via recording of surface electrograms in Langendorff -perfused isolated rat heart (Wistar, 250 ± 30 g). Phenylephrine was used as α1-AR agonist. Probenecid demonstrating anion/chloride transmembrane conductance blocking activity was used to modify Phe-induced α1-AR-mediated eff ects in AVN. The activation of α1-AR by Phe results in a signifi cant increase in the duration of AV intervals (N = 10, p &lt; 0.001) and eff ective refractory period (ERP) in the AVN (by 9.8% ± 1.2%, n = 10, p &lt; 0.001). Also, Phe induces AV-blocks of conduction and oscillations in atrioventricular delay (N = 10) at the stimulation rates close to ERP. Probenecid signifi cantly reduces the magnitude of AVD oscillations during non-stationary conduction in the AV node. In addition, probenecid attenuates ERP prolongation caused by Phe (107 ± 4 ms, N = 6) and 114.2 ± 5.35 ms (N = 10) in presence of only Phe and Phe with probenecid, respectively, returning its values toward typical for normal conditions. In conclusion, probenecid maintains physiological mode of AVN conduction when α1-AR are stimulated. This also suggests that chloride ion channels and anion carriers may contribute to the α1-AR-mediated AVN arrhythmias.

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.

Optimization of atrioventricular delay using Doppler ultrasound and left ventricular catheterization in patients implanted with His bundle pacing devices

Background: Currently, there is a lack of guidance on selecting the optimal method for optimizing the AV interval. Objective: To evaluate the technical characteristics of His bundle pacing and compare relation optimal ventricular conduction intervals using cardiac catheterization and echocardiogram. Method: Interventional prospective study. Result: A total of 56 patients underwent His bundle pacing (HBP) with a success rate of 78.5%. The average age was 57.8 ± 19.25, and 68.1% (30 cases) were female. Selective His pacing and non-selective respectively was successfully achieved in 22 out of 44 cases (50%) and 95.4% with pacing threshold was measured at an average of 0.82 ± 0.38 volts and 1.37 ± 0.83 volts with a pulse width of 1ms. The accuracy comparing AV optimization varied in the following order: VTImitral valve &gt; VTIaortic valve &gt; DFTmitral valve for AVsense optimization and VTImitral valve &gt; DFTmitral valve &gt; VTIaortic valve for AVpace optimization. After AV optimization, myocardial contractility increased by an additional 18.6% for AVsense and 26% for AVpace. Conclusion: His bundle pacing procedure success rate of 78.5%. AV optimization results enhancement in left ventricular contractility from 18.6 to 26%. Key words: His bundle pacing, cardiac resynchronization, heart failure, pacemaker, conduction disease, AV optimization, AV coupling.

High-density open window mapping vs conventional mapping in accessory pathways ablation

Abstract Background and purpose High density (HD) mapping is associated with a reduction in fluoroscopy time compared to conventional mapping in accessory pathway (AP) ablation. The Open Window (OW) technique (CARTO 3, Biosense Webster) is a new tool that automatically uses conventional electrophysiology criteria for AP location, as shorter local EGM AV interval (extended early meets late tool), earliest local activation time (LAT) and annotation at unipolar signal (wavefront annotation). However, no studies comparing its feasibility to conventional mapping have been conducted. Therefore, the aim of the present study was to assess the feasibility and the clinical implications of high-density OW mapping when compared to conventional HD mapping. Methods A prospective, unicentric cohort study was conducted that included consecutive patients which were referred to our institution for AP ablation with OW mapping technique and compared to a recent retrospective cohort of patients who underwent conventional HD mapping. Total fluoroscopy time, total mapping time and the rate of recurrence of the AP were compared between groups. A schematic step by step graphic of the workflow procedure is represented in figure 1. Results A total of 33 consecutive patients (32.28 ± 18 years, 58% males) were included in the OW group and compared with a cohort of 29 patients (29.6 ± 18 years, 52% males) who underwent conventional HD mapping. An example of Right Superior AP ablation is showed in figure 2. No differences in the location of the AP were observed (p=NS). OW mapping was associated to a lower mapping time (29.3 vs 37.8 min; p=0.04), lower fluoroscopy time (14.3 vs 21.3 min; p= 0.04) and lower radiofrequency time (p=0.007). After a median follow up of6 months, there were no differences in the rate of recurrence of the AP conduction between groups (p=NS). Conclusions In our experience, OW mapping was a feasible tool for AP location associated to a lower mapping time, lower radiofrequency time and lower X-ray exposure time with no differences in recurrence rate when compared to conventional HD mapping. However, more studies should be performed to corroborate these conclusions.Step by Step WorkflowRight Superior AP ablation

Abstract 14310: Evaluation of Ventricular Pacing Suppression Algorithmsin Dual Chamber Pacemaker: Results of 'Leader' Study

Introduction: Several algorithms have been proposed to reduce unnecessary right ventricular (RV) pacing, and their operations are based on two different mechanisms: (i) atrioventricular (AV) hysteresis (AVH) and (ii) DDD to AAI pacing mode change. Hypothesis: The purpose of our study was to evaluate the efficacy and safety of two ventricular pacing suppression algorithms: Intrinsic Rhythm Support (IRS) plus algorithm (using AVH, IRSplus) and VP suppression (DDD to AAI mode change) algorithm (VpS). Methods: This was a multicenter, randomized study conducted in 11 tertiary hospitals in South Korea. Patients with sinus node dysfunction and receiving dual-chamber permanent pacemaker implantation were included in this study. After the implantation, patients maintained a fixed AV interval for three months. The AV conduction time was determined as the "atrial pacing to ventricular sensing interval" observed from the marker channel during the PPM implantation was set as the sensed AV delay. The paced AV delay was set to be the sensed AV delay+30ms. Subsequently, patients were randomly assigned to either the VpS or IRSplus algorithm group and were followed for 12 months with assessments every 6 months. Results: A total of 118 patients were enrolled, and the total RV pacing percentage (Vp%) of the patients during the 3 months with a fixed AV interval was 10.9±16.0 on average. They were randomly assigned to VpS and IRSplus groups, with 62 and 56 patients in each group. Six months later, the average Vp% was 14.6±18.8 to 2.7±6.0, P&lt;0.001 and 6.8±10.9 to 1.1±4.0, P&lt;0.001 for the VpS and IRSplus groups, respectively. This trend was maintained for additional 6 months (VpS group: 4.6±9.5; IRSplus group: 1.2±3.8). The effects of algorithms were more pronounced in groups with an intrinsic PR interval of &lt; 200ms, and the IRSplus showed better efficacy (Figure). Conclusions: The two ventricular pacing suppression algorithms were effective in reducing Vp% compared to the fixed AV interval.

Electrophysiological evidence of crossmodal correspondence between auditory pitch and visual elevation affecting inhibition of return

Inhibition of return (IOR) has proved to be weakened by audiovisual integration because of the increased perceptual salience of targets. Although other audiovisual interactions, such as crossmodal correspondence, have also been shown to facilitate attentional processes, to the best of our knowledge, no study has investigated the interaction between crossmodal correspondence and IOR. The present study employed Posner’s spatial cueing paradigm and manipulated the cue validity, crossmodal correspondence congruency and time interval of auditory and visual stimuli (AV interval) to explore the effect of crossmodal correspondence on the IOR effect. The behavioral results showed a reduced IOR effect under the correspondence congruency condition in contrast to the correspondence incongruency condition at the AV interval of 200 ms, whereas at an AV interval of 80 ms, the decreased IOR effect under crossmodal correspondence congruency was eliminated. The electrophysiological results showed a reduced amplitude difference in P2 between valid and invalid cue conditions when the crossmodal correspondence effect decreased the IOR effect. The present study provided the first evidence of the weakened effect of the crossmodal correspondence effect on the IOR effect, which could be eliminated by audiovisual integration.

Use of Polynomial Reference Ranges for Atrioventricular Intervals Assessed by Fetal Echocardiography in Anti-Ro/SSA Antibody-Positive Pregnancies to Exclude Fetal Heart Blocks: A Pilot Study

Introduction: Maternal anti-Ro/SSA antibodies can cause fetal atrioventricular blocks (AVB). This pilot study aims to apply previously published echocardiographic reference ranges of the fetal atrioventricular (AV) intervals in the setting of anti-Ro/SSA antibody-positive pregnancies in order to exclude a 1° AVB. Materials and Methods: Between January 2018 and September 2022, we included all women with known anti-Ro/SSA antibodies followed up at the prenatal ultrasound department of the University Hospital of Bern. AV intervals were serially measured by two previously reported methods and plotted against previously created reference ranges. Results: We included 23 pregnancies from 17 anti-Ro/SSA antibody-positive women with connective tissue diseases. 443 AV interval measurements were recorded between 16+3 and 38+4 weeks of gestation. 14 (3.2%) AV-intervals measured >150 ms, none measured >170 ms and 8 (1.8%) were found to be >95th percentile. In none of the pregnancies, serial AV-prolongations were noted. The postnatal electrocardiograms demonstrated normal sinus rhythm without AVB in all children. Conclusion: AV intervals of pregnancies followed up for anti-Ro/SSA antibodies without neonatal AVB lie within our published polynomial reference ranges. While diagnosing a 1° AVB remains controversial, more data are needed to prove that our reference ranges are helpful exclude a 1° AVB.

Visualization of the SyncAV® Algorithm for CRT Optimization by Non-invasive Imaging of Cardiac Electrophysiology: NICE-CRT Trial.

(1) Background: Periodic repetitive AV interval optimization using a device-based algorithm in cardiac resynchronization therapy (CRT) devices may improve clinical outcomes. There is an unmet need to successfully transform its application into clinical routine. (2) Methods: Non-invasive imaging of cardiac electrophysiology was performed in different device programming settings of the SyncAV® algorithm in 14 heart failure patients with left bundle branch block and a PR interval ≤ 250 milliseconds to determine the shortest ventricular activation time. (3) Results: the best offset time (to be manually programmed) permitting automatic dynamic adjustment of the paced atrioventricular interval after every 256 heart beats was found to be 30 and 50 milliseconds, decreasing mean native QRS duration from 181.6 ± 23.9 milliseconds to 130.7 ± 10.0 and 130.1 ± 10.5 milliseconds, respectively (p = 0.01); this was followed by an offset of 40 milliseconds (decreasing QRS duration to 130.1 ± 12.2 milliseconds; p = 0.08). (4) Conclusions: The herein presented NICE-CRT study supports the current recommendation to program an offset of 50 milliseconds as default in patients with left bundle branch block and preserved atrioventricular conduction after implantation of a CRT device capable of SyncAV® optimization. Alternatively, offset programming of 30 milliseconds may also be applied as default programming. In patients with no or poor CRT response, additional efforts should be spent to individualize best offset programming with electrocardiographic optimization techniques.

Afterload dependence of right ventricular pacing-induced left ventricular dysfunction in patients with aortic stenosis undergoing transcatheter aortic valve implantation

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): TKP2021-EGA-23 János Bolyai Research Scholarship of the Hungarian Academy of Sciences. Introduction Recent experimental data indicates that patients with left bundle branch block are particularly sensitive to increased arterial afterload. Nevertheless, whether the detrimental hemodynamic consequence of right ventricular pacing (RVP) is also associated with afterload dependency has not been investigated yet. Purpose Hence, the present preliminary study aimed to examine the acute effect of RVP on left ventricular (LV) function in patients with aortic stenosis before (with elevated arterial afterload) and after (without elevated arterial afterload) transcatheter aortic valve implantation (TAVI). Methods Patients with a previously implanted permanent pacemaker (PM) and significant aortic stenosis referred for TAVI at the Heart and Vascular Center of our university were screened for this observational study. Only those patients who had an intrinsic, regular, narrow QRS rhythm (including junctional escape rhythm) were included. Four patients with a DDD PM (with sick sinus syndrome and maintained AV conduction) and two patients with a VVI PM (with atrial fibrillation and AV block) were enrolled. Echocardiography was performed immediately before TAVI and on the second postoperative day. The ultrasound measurements were carried out during intrinsic, narrow QRS rhythm (80/min AAI pacing in patients with DDD PM and 30/min backup VVI pacing to allow the narrow QRS escape rhythm in patients with VVI PM) and during frequency-matched RVP with wide QRS (&amp;gt;150ms) (DDD pacing with a short AV interval ensuring ventricular capture or VVI pacing, respectively). From the sonographic recordings, speckle-tracking echocardiography-derived global myocardial work index (GMWI) was calculated by commercially available software to assess LV function. Results TAVI resulted in decreased mean aortic gradient (35.4±3.6 mmHg vs. 5.3±1.4 mmHg before vs. after TAVI, P&amp;lt;0.001) indicating successful alleviation of the increased arterial afterload. Compared to the intrinsic, narrow QRS rhythm, RVP reduced GMWI before and after TAVI as well. Nevertheless, a significant reduction was only noted when the increased afterload was present (pre-TAVI GMWI: 1710±169 vs. 1170±199mmHg%, P=0.008), while following pressure unloading only a strong tendency could be observed (post-TAVI GMWI: 1127±76 vs. 865±83mmHg%, P=0.065). Conclusion Our preliminary results indicate that RVP-induced LV dysfunction might be afterload dependent. Hence, in patients with aortic stenosis and a high percentage of ventricular pacing, afterload reduction could entail a great clinical benefit.

High-density open window mapping vs conventional mapping in accessory pathways ablation

Abstract Funding Acknowledgements Type of funding sources: None. Background and purpose High density (HD) mapping is associated with a reduction in fluoroscopy time compared to conventional mapping in accessory pathway (AP) ablation. The Open Window (OW) technique (CARTO 3, Biosense Webster) is a new tool that automatically uses conventional electrophysiology criteria for AP location, as shorter local EGM AV interval (extended early meets late tool), earliest local activation time (LAT) and annotation at unipolar signal (wavefront annotation). However, no studies comparing its feasibility to conventional mapping have been conducted. Therefore, the aim of the present study was to assess the feasibility and the clinical implications of high-density OW mapping when compared to conventional HD mapping. Methods A prospective, unicentric cohort study was conducted. Consecutive patients which were referred to our institution for AP ablation with OW mapping technique were included and compared to a recent retrospective cohort of patients who underwent conventional HD mapping. Total fluoroscopy time, total mapping time and the rate of recurrence of the AP were compared between groups. Results A total of 29 consecutive patients (32.28 ± 18 years, 58% males) were included in the OW group and compared with a cohort of 29 patients (29.6 ± 18 years, 52% males) who underwent conventional HD mapping. An example of Right Superior AP ablation is showed in figure 1. No differences in the location of the AP were observed (p=NS). OW mapping was associated to a lower mapping time (29.3 vs 37.8 min; p=0.04), lower fluoroscopy time (14.3 vs 21.3 min; p= 0.04) and lower radiofrequency time (p=0.007). After a median follow up of 6 months, there were no differences in the rate of recurrence of the AP conduction between groups (p=NS). A schematic step by step graphic of the workflow procedure is represented in figure 2. Conclusions In our experience, OW mapping was a feasible tool for AP location associated to a lower mapping time, lower radiofrequency time and lower X-ray exposure time with no differences in recurrence rate when compared to conventional HD mapping. However, more studies should be performed to corroborate these conclusions.

Optimizing diastolic filling by pacing in nonobstructive hypertrophic cardiomyopathy

Treatment options for symptomatic patients with nonobstructive hypertrophic cardiomyopathy (nHCM) are limited. The purpose of this study was to determine the effect of sequential atrioventricular (AV) pacing, from different right ventricular (RV) sites with varying AV delays, on the diastolic function and functional capacity of patients with nHCM. Twenty-one patients with symptomatic nHCM and normal left ventricular (LV) systolic function were prospectively enrolled. Inclusion criteria included PR interval >150 ms, E/e' ≥15, and an indication for implantable cardioverter-defibrillator (ICD) implantation. Doppler echocardiographic study was performed during dual-chamber pacing at various AV intervals. Pacing was performed at 3 RV sites: RV apex (RVA), RV midseptum (RVS), and RV outflow tract (RVO). The site and sensed AV delay (SAVD) at which optimal diastolic filling occurred were chosen based on diastolic filling period and E/e'. During ICD implantation, the RV lead was implanted at the site identified by the pacing study. Devices were programmed in DDD mode at the optimal SAVD. During follow-up, diastolic function and functional capacity were assessed. Among the 21 patients (age 47.8 ± 7.7 years; 81.0% male), baseline E/A and E/e' were 2.4 ± 0.6 and 17.2 ± 2.2, respectively. There was an improvement in diastolic function (E/e') in 18 patients (responders) when pacing from the RVA (12.9 ± 3.4; P <.001) than from the RVS (16.6 ± 2.3) and RVO (16.9 ± 2.2). Among responders, optimal diastolic filling occurred at SAVD of 130-160 ms with RVA pacing. Nonresponders had longer duration of symptoms (P = .006), lower LV ejection fraction (P = .037), and higher late gadolinium enhancement burden (P <.001). During 13.5 ± 1.5 months of follow-up, there was an improvement (Δ) in diastolic function (E/e' -4.1 ± 0.5), functional capacity (New York Heart Association functional class -1.5 ± 0.3), and reduction in N-terminal pro-brain natriuretic peptide level (-55.6 ± 12.3 pg/mL) compared to baseline. Pacing at an optimized AV delay from the RVA improves diastolic function and functional capacity in a subset of patients with nHCM.

PO-04-017 'LEFT' BROKEN AFTER EXERCISE: A CASE OF PAINFUL LBBB SYNDROME SUCCESSFULLY TREATED WITH LEFT BUNDLE BRANCH AREA PACING

The leading causes of new-onset left bundle branch block (LBBB) include coronary artery disease, hypertension, and cardiomyopathies. However, when the LBBB occurs in the absence of ischemia, in a rate-dependent manner, usually with exertion, it constitutes a painful left bundle branch block. Although there are multiple case reports of this entity, the mechanism, pathophysiology, and treatment are not well defined. We intend to raise awareness of this syndrome and highlight our unique treatment approach. NA A 57-year-old male presented to the cardiology clinic with exertional chest pain and palpitations. He underwent an exercise ECG test, surprisingly on stage 2 of Bruce protocol, at around a heart rate of 116 bpm; he started developing LBBB on every other beat. At a heart rate of 125 bpm, he developed persistent LBBB associated with similar symptoms, both of which persisted in the recovery phase (Figure 1). His Echocardiogram was normal. Invasive coronary angiography revealed normal coronaries. Previous case reports have shown that cardiac rehabilitation helps to delay the onset of LBBB to a higher heart rate; however, he opted for pacemaker implantation as he had severe exercise limitations. He underwent a biventricular-implantable pacemaker with right atrial, left bundle branch area, and coronary sinus (CS) left ventricular (LV) leads. The pacemaker was programmed DDD60 with a rate adaptive AV interval with a start rate of 80 bpm. This would enable the LBB area pacing above a heart rate of 80 bpm. Within one week of implantation, the patient had a complete resolution of his symptoms. A cardiopulmonary exercise test to assess VO2 with pacing programmed off and then on is scheduled as part of the follow-up. The symptoms of the painful LBBB syndrome can be quite severe, resulting in physical and psychological debilitation. Treatment with a physical exercise regimen has been successful as it delays the LBBB onset to a higher heart rate. However, the patient loses the benefit once they stop exercising. A definitive solution is a pacemaker; there are multiple case reports of His bundle and right ventricular pacing, which successfully treated this syndrome. In this case, we used a unique approach of pacing just the LBBB area; in addition, a CS LV lead was placed, which could be used for an earlier activation of the LV if the patient needs that in the future.

PO-04-100 ARTIFICIAL INTELLIGENCE TO IMPROVE PROCEDURAL SAFETY OF ATRIOVENTRICULAR NODAL RE-ENTRANT TACHYCARDIA ABLATION

During slow pathway modification for atrioventricular nodal reentrant tachycardia, heart block may occur if ablation cannot be stopped in time in response to high risk electrogram features (HREF). To develop an automatic algorithm to monitor for HREF and terminate ablation earlier than human reaction. Digital electrogram data from 327 ablation runs from February 2020 to June 2022 were included. They were divided into test and validation sets which contained 126 and 201 ablation runs respectively. A program was developed with insight gained from the test set. Simulation ablation videos were rendered using the validation set electrogram data. The videos were played to three independent electrophysiologists who each determined when to stop ablation. The timing of ablation termination, sensitivity, and specificity were compared between human and program. Reasons for ablation termination in the test set include short AA time, short VV time, AV block and VA block. Cutoffs for the program were decided as follows: 240ms for short AA time, 220ms for short VV time, 250ms for AV interval and 200ms for VA interval. The sensitivity and specificity for the program in the validation set were 95.2% and 91.1% respectively, which were comparable to that of human performance at 93.5% and 95.4%. If HREF were recognized by both human and program, ablations were terminated earlier by the program 90.2% of times, by a median of 574ms (interquartile range 412-807ms, p<0.001). Program-driven termination of slow pathway modification can supplement human judgement to improve ablation safety.Tabled 1AI compared with human in validation sets (PO-04-100)Operator 1Operator 2Operator 3Total human armAISensitivity0.9700.9840.8510.9350.952Specificity0.9610.9170.9850.9550.911AI lead time in milliseconds- Median (IQR)561 (405.5)542 (320.75)602 (473)574 (396)N/A- p value for median<0.001<0.001<0.001<0.001N/A- Mean +/- SD613.0 +/- 844.6609.8 +/- 1012.9824.1 +/- 1057.8673.7 +/- 969.9N/A- p value for mean<0.001<0.001<0.001<0.001N/A Open table in a new tab

The impact of chronotropic incompetence on atrioventricular conduction times in heart failure patients.

Intrinsic atrioventricular (AV) conduction is used to optimize AV intervals with cardiac resynchronization therapy (CRT) in most device algorithms. Atrial pacing and heart rate affect conduction times, but little is known regarding differeces among chronotropic incompetent(CI) and competent(CC) patients to guide programming. RAVE was a multicenter prospective trial of CRT patients. Heart rate was increased with incremental atrial pacing and with submaximal exercise. According to the maximal heart rate achieved during exercise, patients were classified as either CI or CC. For CI patients, an additional symptom-limited exercise with rate-adaptive pacing activated was performed. Intracardiac intervals were measured from the implantable lead electrograms in multiple postures. There were 12 subjects with CI and 24 with CC. With atrial pacing, AV interval immediately increased and gradually increased with incremental atrial pacing in all patients. However, the changes in the atrial to right ventricular (ARV) and atrial to left ventricular (ALV) intervals with increasing atrial pacing rates were about threefold greater in CI patients compared to CC patients (24.3 ± 28.9 vs. 7.2 ± 5.5ms/10bpm for ARV and 22.7 ± 25.6 vs. 7.1 ± 5.7ms/10bpm for ALV in the standing position, p < 0.05). In CI pacing with rate-adaptive pacing during exercise, AV interval changes with paced heart rate were variable. The AV response to overdrive atrial pacing at rest may provide a simple means of identifying chronotropic competence in CRT patients. For patients with CI, who often require rate-adaptive atrial pacing, rate-adaptive AV algorithms should be adjusted individually.