Dual-chamber Pacemaker Implantation Research Articles

THROW YOUR LEAD OVER THE OBSTACLE: A CHALLENGING CRT UPGRADING

Abstract High percentage of right ventricular pacing could lead to pacing induced cardiomyopathy in a non–negligible proportion of patients. Cardiac resynchronization therapy upgrading could represent an option to improve ventricular function, reducing heart failure hospitalizations. A 82 yo male was admitted to hospital with symptomatic heart failure. He had history of complete AV block treated with dual chamber pacemaker implantation five years earlier following coronary artery bypass graft surgery, bioprosthetic aortic valve replacement and septal myectomy. He had also history of cardiac arrest occurred in the context of acute coronary syndrome treated with PCI so that ICD implant was not considered at that time, and two more HF hospitalizations in previous years. Progressive LVEF decline was documented since PM impantation until last echo showed severe left ventricular dysfunction (EF 20% from baseline EF 60%). The ECG showed sinus rhythm and wide paced QRS (206 ms) with 100% pacing percentage. A CRT device upgrading was planned. Baseline venography initially showed pervious axillary–subclavian left axis, but unfortunately the guidewire encountered a complete occlusion before entering the superior vena cava. Nevertheless, dye contrast injection documented the presence of a proximal collateral branch (fig A) having a vertical course in the thorax and reaching the lateral wall of the left ventricle with an extrapericardic course then entering the right heart through inferior vena cava. Using a IM 5Fr sheath (usually used by interventional cardiologists to cannulate internal mammary artery) we could reach this branch, inserting a guidewire and finally advancing a quadripolar lead (Fig B–C) which reached the lateral left ventricular wall. LV capture was confirmed when pacing from the three proximal poles, while the distal one caused phrenic nerve capture. The quadripolar lead was connected to the LV port of a three chamber PM along with previous implanted leads thus obtaining biventricular pacing. QRS paced was 50 ms shorter than baseline. No peri–procedural complications occurred. Lead–related venous occlusion might represent an obstacle to CRT upgrade requiring high technical expertise. The presence of a complete venous occlusion might cause procedural failure, particularly in hospitals without surgical facility. In this case, the presence of a collateral branch reaching the lateral wall of the left ventricle allowed to successfully complete the CRT upgrade.

EVALUATION OF EARLY OUTCOMES OF PERMANENT PACEMAKER IMPLANTATION IN HYPERTENSIVE PATIENTS WITH BRADYARRHYTHMIAS

Objective: This study aims to describe the clinical characteristics and the features of bradyarrhythmias on 24-hour Holter monitoring and to evaluate the early outcomes of permanent pacemaker implantation in hypertensive patients with bradyarrhythmias. Subjects and method: This cross-sectional study was conducted on 57 subjects with hypertension and bradyarrhythmias who were indicated for permanent pacemaker implantation. Results: The most common clinical symptoms recorded were fatigue, dizziness, and chest pain, accounting for 47.4%, 45.6%, and 42.1% respectively. The majority of patients had sinus node dysfunction (73.7%) and most underwent dual-chamber permanent pacemaker implantation (87.7%). The 24-hour Holter monitoring results showed that 42.1% had sinus atrial block - sinus pause in the sinus node dysfunction group and 15.8% of patients had third-degree atrioventricular block (AV block) in the AV block group. A good treatment outcome was observed in 72.0% of cases. Age > 70 (OR: 6.1; 95% CI: 1.2-30.1), female gender (OR: 4.2; 95% CI: 1.2-15.4), and single-chamber pacemaker (OR: 8.9; 95% CI: 1.5-52.1) were associated with a higher risk of moderate to poor treatment outcomes. Conclusion: Permanent pacemaker implantation generally tends to have good short-term outcomes. However, it should be noted that older age, female, and single-chamber pacemaker implantation in association with worse outcomes.

Prediction of pacemaker-induced cardiomyopathy using a convolutional neural network based on clinical findings prior to pacemaker implantation

Risk factors for pacemaker-induced cardiomyopathy (PICM) have been previously reported, including a high burden of right ventricular pacing, lower left ventricular ejection fraction, a wide QRS duration, and left bundle branch block before pacemaker implantation (PMI). However, predicting the development of PICM remains challenging. This study aimed to use a convolutional neural network (CNN) model, based on clinical findings before PMI, to predict the development of PICM. Out of a total of 561 patients with dual-chamber PMI, 165 (mean age 71.6 years, 89 men [53.9%]) who underwent echocardiography both before and after dual-chamber PMI were enrolled. During a mean follow-up period of 1.7 years, 47 patients developed PICM. A CNN algorithm for prediction of the development of PICM was constructed based on a dataset prior to PMI that included 31 variables such as age, sex, body mass index, left ventricular ejection fraction, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, left atrial diameter, severity of mitral regurgitation, severity of tricuspid regurgitation, ischemic heart disease, diabetes mellitus, hypertension, heart failure, New York Heart Association class, atrial fibrillation, the etiology of bradycardia (sick sinus syndrome or atrioventricular block) , right ventricular (RV) lead tip position (apex, septum, left bundle, His bundle, RV outflow tract), left bundle branch block, QRS duration, white blood cell count, haemoglobin, platelet count, serum total protein, albumin, aspartate transaminase, alanine transaminase, estimated glomerular filtration rate, sodium, potassium, C-reactive protein, and brain natriuretic peptide. The accuracy, sensitivity, specificity, and area under the curve of the CNN model were 75.8%, 55.6%, 83.3% and 0.78 respectively. The CNN model could accurately predict the development of PICM using clinical findings before PMI. This model could be useful for screening patients at risk of developing PICM, ensuring timely upgrades to physiological pacing to avoid missing the optimal intervention window.

Atrial Pacing Negatively Affects Left Atrial Morphological and Functional Parameters Similarly to Atrioventricular Dyssynchrony.

Background and Objectives: Atrioventricular (AV) dyssynchrony as well as atrial and ventricular pacing affect left atrial (LA) function. We conducted a study evaluating the effect of atrial and ventricular pacing on LA morphological and functional changes after dual-chamber pacemaker implantation. Materials and Methods: The study prospectively enrolled 121 subjects who had a dual-chamber pacemaker implanted due to sinus node disease (SND) or atrioventricular block (AVB). Subjects were divided into three groups based on indication and pacemaker programming: (1) SND DDDR 60; (2) AVB DDD 60 and (3) AVB DDD 40. Subjects were invited to one- and three-month follow-up visits. Three subsets based on pacing burden were analyzed: (1) high atrial (A) low ventricular (V); (2) high A, high V and (3) low A, high V. LA function was assessed from volumetric parameters and measured strains from echocardiography. Results: The high A, low V group consisted of 38 subjects; while high A, high V had 26 and low A, high V had 23. A significant decrease in reservoir and contractile LA strain parameters were only observed in the high A, low V pacing group after three months (reservoir 25.9 ± 10.3% vs. 21.1 ± 9.9%, p = 0.003, contractile -14.0 ± 9.0% vs. -11.1 ± 7.8, p = 0.018). While the re-established atrioventricular synchrony in the low A, high V group maintained reservoir LA strain at the baseline level after three months (21.4 ± 10.4% vs. 22.5 ± 10.4%, p = 0.975); in the high A, high V group, a further trend to decrease was noted (20.3 ± 8.9% vs. 18.7 ± 8.3%, p = 0.231). Conclusions: High atrial pacing burden independently of atrioventricular dyssynchrony and ventricular pacing impairs LA functional and morphological parameters. Changes appear soon after pacemaker implantation and are maintained.

Comparing the impact of left bundle branch area pacing and traditional left ventricular pacing on right heart function following dual-chamber pacemaker implantation

Objective: To compare the effects of left bundle branch area pacing (LBBaP) versus traditional right ventricular pacing (RVP) on left ventricular function in patients after dual-chamber pacemaker implantation. Methods: A retrospective cohort study was conducted on patients who underwent dual-chamber pacemaker implantation from March 2017 to April 2021 in Beijing Anzhen Hospital. The patients were divided into the LBBaP group and RVP group based on the placement of the ventricular lead. Follow-up was conducted until March 2022, comparing baseline and follow-up echocardiographic parameters, pacing parameters, and the incidence and timing of complications between the two groups. The complications included ventricular electrode perforation, dislocation, pericardial effusion, tricuspid valve perforation, etc. Results: A total of 163 patients aged (68.3±13.5) years were included, including 82 (50.3%) men, with 80 patients in the LBBaP group and 83 in the RVP group. Baseline left ventricular end-diastolic diameter ((50.49±4.95) mm vs. (47.43±8.15) mm, P=0.01) and left atrium (LA) ((33.14±5.94) mm vs. (30.18±3.92) mm, P=0.001) in the LBBaP group were significantly higher than those in the RVP group. Follow-up LA diameter ((37.10±6.70) mm vs. (40.10±8.90) mm, P=0.016) showed a statistically significant difference in the LBBaP group compared to the RVP group. There was no statistically significant difference between the two groups in baseline QRS duration(P=0.490). Postoperative QRS duration in the LBBaP group was significantly lower ((110.69±24.01) ms vs. (139.65±29.85) ms, P<0.010). Intraoperative threshold in the LBBaP group was significantly higher ((0.83±0.32) V/0.48 ms vs. (0.71±0.23) V/0.48 ms, P=0.004), while impedance was lower ((754.53±205.59) Ω vs. (905.41±302.75) Ω, P<0.01). Comparing with the RVP group, postoperative ventricular pacing ratio (VP) ((87.39±20.92) % vs. (79.49±25.76) %, P=0.034), threshold ((0.90±0.38) V/0.48 ms vs. (0.69±0.27) V/0.48 ms, P<0.01) in the LBBaP group were higher, and impedance ((507.45±77.37) Ω vs. (620.52±197.29) Ω, P<0.01) in the LBBaP group was lower. Postoperative follow-up period was 5 to 51 months, with a median follow-up time of 17 months. No statistically significant difference in overall complications between the LBBaP and RVP groups was found (13.8% (11/80) vs. 7.2% (6/83), P>0.05). The median time to occurrence of complications after surgery was significantly earlier in the LBBaP group (29.74 (95%CI 27.21-32.26) months vs. 46.17 (95%CI 42.48-49.86) months, P=0.030). Conclusion: LBBaP demonstrates more stable pacing parameters, substantial improvement in clinical left ventricular function, with a relatively higher threshold compared to traditional RVP, and complications occurs relatively early.

His bundle pacing in a patient with atrioventricular conduction abnormalities, persistent atrial flutter at high thromboembolic and bleeding risk after hybrid coronary revascularization and left atrial appendage closure - case report

We present a case of a 78-year-old patient with persistent atrial &amp;#64258; utter, history of atrial &amp;#64257; brillation and atrioventricular conduction disturbances, including &amp;#64257; rst-degree atrioventricular block (AVB) and paroxysmal complete AVB. Echocardiography revealed mildly reduced left ventricular ejection fraction (LVEF, 44%). The patient had high thromboembolic risk, had previous ischemic stroke, suffered from chronic coronary artery disease treated with hybrid coronary revascularization (minimally invasive direct coronary artery bypass grafting and subsequent percutaneous coronary intervention) as well as left atrial appendage closure. Because of high bleeding risk, double antiplatelet therapy (acetylsalicylic acid and clopidogrel) combined with low dose of low-molecular-weight heparin after cardiac surgery were introduced. Due to persistent atrial &amp;#64258; utter, complete AVB, lack of intraventricular conduction abnormalities, mildly reduced LVEF and expected high right ventricle pacing burden, the patient was referred for dual-chamber pacemaker implantation using conduction system pacing (CSP), preferentially His bundle pacing (HBP). The procedure was performed with good outcome and CSP was utilized via HBP. After reassessment of thromboembolic and bleeding risk, the patient was discharged home on reduced dose of dabigatran. Short-term follow-up showed stable HBP parameters along with no additional symptoms. Despite good short-term outcomes and no complications in studied patient, large randomized controlled trials are needed to verify long-term safety and ef&amp;#64257; cacy of HBP to optimize clinical care of patients with atrioventricular conduction abnormalities using a personalized approach.&amp;nbsp;

Subacute right ventricular perforation from a passive fixation pacemaker lead - a multidisciplinary diagnostic and management work-up

Cardiac implantable electronic devices (CIEDs) implantation procedure has a complication rate of 5-6% according to most studies. Lead perforation is a possible and serious adverse event which can present with a spectrum of symptoms from asymptomatic to sudden death. Diagnostic tools in case of suspected lead perforation are X-ray, transthoracic echocardiography, pacemaker interrogation and computed tomography with the last one being the gold standard. Lead extraction could be done endovascularly or surgically. Transvenous removal is a possible option for active &amp;#64257; xation leads, while removal of passive &amp;#64257; xation leads is preferably done surgically, because of the bulky tip of the lead, which could damage the heart chambers and the vessels. In this article, we present a case of a massive ventricular perforation from a passive &amp;#64257; xation lead, further complicated by a cardiac tamponade. Surgical removal was the treatment of choice with subsequent implantation of a permanent dual-chamber pacemaker.&amp;nbsp;

Pacing mode survival in patients with single chamber atrial pacemaker for sinus node dysfunction

BackgroundSingle chamber atrial pacemaker should be sufficient for patients with sinus node dysfunction (SND) with normal atrioventricular (AV) conduction. However, most patients undergo dual chamber pacemaker implantation because of concern of new onset AV block. The annual incidence of new AV block has been reported from 0.6 to 4.4 % in various studies. ObjectivesOur aim is to assess mode survival in sinus node dysfunction with normal AV conduction patients implanted with AAIR. MethodsPatients who underwent single chamber atrial pacemaker implantation for SND with normal AV conduction between January 2014 and December 2021 were followed up for pacemaker device change, new onset AV block, bundle branch block, atrial fibrillation (AF), lead complications, reoperation and mortality rate. ResultsA total of 113 patients underwent single chamber atrial pacemaker implantation for SND during the study period. Mean age was 55.6 ± 12.7 years. During a mean follow up of 48.7 ± 24.9 months, none of the patients required pacemaker device change to VVIR/DDDR. Nine patients underwent reoperation, 5 for lead dislodgment, 1 for high threshold, 1 for pocket site erosion and 3 for pulse generator change. None developed AV block or AF with slow ventricular rate. Only 4 patients developed AF (3 paroxysmal,1 permanent). There were 3 deaths during follow up and none were sudden deaths. ConclusionSingle chamber atrial pacing is an acceptable mode of pacing in patients with SND in developing countries. Development of AV conduction abnormalities is rare in this relatively younger population.

Abstract 16153: Electrocardiographic Correlations With Cardiac Magnetic Resonance in Left Bundle Branch Area Pacing

Introduction: As the use of left bundle branch area pacing (LBBAP) continues to increase, there remains uncertainty about the mechanical effects of achieving selective LBB capture. Hypothesis: The hypothesis was that cardiac magnetic resonance (CMR) strain and functional parameters would be similar with and without LBBAP, and mechanical function would be more favorable with surface ECG parameters indicative of LBB capture. Methods: CMR was performed at 3T in two centers in the first year after implantation of dual-chamber pacemakers with LBBAP. Imaging sets were obtained with dual-chamber LBBAP (DOO mode) and, in patients with intact atrioventricular (A-V) conduction, atrial-only pacing (AOO mode), including strain imaging with displacement encoding with stimulated echoes (DENSE). Results: In 17 patients, the median LVEF with LBBAP was 50% (IQR 48-52%). The median LVEF and RVEF were similar with LBBAP on (DOO mode) and off (AOO mode) (p=0.27 and p=0.37, respectively); however, there were differences in synchrony (CURE-SVD) (p=0.0081), mean septal Ecc (p=0.011), and mean LV free wall Ecc (p=0.011) that favored atrial-only pacing with A-V conduction vs. sequential LBBAP (Figure 1). A shorter interval between R wave peaks in ECG leads V6 and V1 (V6-V1 interpeak interval), shown to be associated with selective LBB capture, was the best predictor of a greater LVEF with LBBAP (p=0.0016). A shorter paced QRS duration predicted greater global Ecc (p=0.044) and more synchrony by the CURE-SVD (p=0.027) (Figure 2). Conclusions: LBBAP reproduces biventricular function by CMR with some differences noted in CMR strain, and selective LBB capture was associated with a greater LVEF by CMR.

Abstract 13553: Traumatic Right Atrium Perforation Causing Pneumopericardium and Pneumothorax, Treated Conservatively

Background: Pneumopericardium after pacemaker implantation is an extremely rare complication. Patients can present with symptoms such as chest pain, shortness of breath, or be completely asymptomatic. We present a case of a 68-year-old male who underwent dual chamber pacemaker implantation complicated by a pneumopericardium and contralateral pneumothorax. Case Report: A 68-year-old male with a past medical history of coronary artery disease status post percutaneous coronary intervention to the obtuse marginal artery and left circumflex, hypertension and benign prostatic hyperplasia presented with syncope while driving. Telemetry showed symptomatic long pauses up to 6.2 seconds and a dual chamber pacemaker implantation was recommended via the left subclavian vein approach. It was noted that the patient had multiple attempts to place the right atrium lead. Two days after the procedure, the patient developed severe right-sided chest pain and an electrocardiogram showed diffuse ST segment elevations consistent with pericarditis. A chest computed tomography (CT) showed a large right-sided pneumothorax and pneumopericardium and a chest tube was placed. The pacemaker was interrogated and showed a stable function and the patient was managed conservatively. A repeat CT chest showed significant improvement in both the pneumopericardium and the pneumothorax and the patient did well on follow up. Discussion: Ipsilateral pneumothorax and cardiac perforation are not uncommon following pacemaker implantation; however, contralateral pneumothorax and pneumopericardium are extremely rare. In our patient, it appears that the right atrium lead perforated through the right atrium into the right pleural space creating a fistula between the pericardial and pleural spaces. This was not detected on the initial chest x-ray and was only seen on subsequent CT chest imaging. Treatment of pneumopericardium usually involves lead revision or extraction; however, conservative therapy can be successfully attempted with close monitoring, as in our case.

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.

Abstract 18855: Comparison of Hospital Outcomes in Sick Sinus Syndrome Patients With and Without Pacemaker- A Nationwide Inpatient Sample Analysis

Introduction: Sick sinus syndrome refers to degenerative fibrosis of the sinoatrial node, leading to bradyarrhythmias with or without tachyarrhythmias. Pacemaker implantation is a common therapeutic intervention in patients with symptomatic sick sinus syndrome (SSS). We aimed to analyze the periprocedural outcomes for patients with SSS who undergo pacemaker implantation. Hypothesis: Pacemaker implantation is associated with lower odds of mortality in patients with sick sinus syndome. Methods: Retrospective cohort study with data from 2016-18 combined National Inpatient Sample database. ICD-10 codes used to include admissions with SSS and dichotomized based on permanent dual chamber pacemaker implantation. The primary and secondary outcomes were studies between the two cohorts. Multivariate linear and logistic regression were used to adjust for confounders Results: Out of 190,625 sick sinus syndrome, admissions in 2016-18 NIS database, 115,195 (60%) received a permanent pacemaker. Permanent pacemaker implantation in SSS patients was associated with lower adjusted odds of inpatient mortality (aOR 0.22, 95% CI 0.17-0.29, p&lt;0.001), decrease in mean LOS by 0.31 days (5.55 vs 5.86, p&lt;0.001) and higher adjusted THC by a difference of 35,489 USD (116,474 USD vs 80,985 USD, p&lt; 0.001). Secondary outcomes are shown in Fig. Conclusions: Pacemaker implantation in sick sinus syndrome patients is associated with 80% decrease in mortality, shorter length of stay, and significantly lower odds of inpatient complications including sepsis, pulmonary embolism, ventricular fibrillation, acute kidney injury when compared to patients without a pacemaker.

Abstract 15412: Unusual Case of Cardiac Sarcoidosis Unmasked by COVID 19

Background: COVID-19 can present with a constellation of symptoms and cardiac dysfunctions. It can mimic cardiac sarcoidosis clinically which can lead to diagnostic challenges and treatment delays. We describe a case of cardiac sarcoidosis which was unmasked by a recent COVID-19 infection. Case: A 72-year-old Caucasian male with history of post-traumatic epilepsy as a child and otherwise no significant health issues until March 2022 when he had COVID-19 infection presented with worsening fatigue, dizziness, lightheadedness, abnormal eye movements, brain fog and inability to exercise since his COVID infection. Prior to this, he was very active and was riding his bike 50 miles a week. He underwent extensive neurological work up including CT head/neck/temporal bone, MRI brain and continuous EEG that was unrevealing. Echocardiogram showed normal left and right ventricular size and function with no significant valvular abnormalities. 2-week Holter monitor revealed bradycardia with HR 30 beats per minute and sinus pauses with longest of 3.9 seconds. Cardiac MRI was obtained which showed late gadolinium enhancement (LGE) in the basal septum (Image). Subsequent, PET scan revealed mid myocardial FDG uptake with preserved perfusion involving the proximal segments of the heart raising the possibility of early inflammation related to cardiac sarcoidosis or other inflammatory process. He underwent dual chamber pacemaker implantation for sinus pauses. Decision making: Cardiac MRI with LGE in basal septum and PET scan showing increased FDG uptake along with bradycardia and pauses leading to pacemaker implantation led to the diagnosis of cardiac sarcoidosis. He was treated with prednisone with repeat PET scan in 3 months. Conclusion: It remains unclear if COVID 19 plays a role in inducing inflammatory process of sarcoidosis. Further studies are required to understand the cardiac sequalae of COVID 19 infection and association with sarcoidosis.

Abstract 16250: Latent His-Purkinje Disease Unmasked by Beta Blocker Overdose

Background Symptomatic bradycardia usually has a single mechanism and treatment modality. Identifying the culprit mechanism can be challenging, especially when faced with concurrent pathologies. We present a case of severe symptomatic bradycardia where appropriate management of one mechanism unmasked a second mechanism, with a need for pacemaker placement. Case Presentation A 56-year-old patient presented with beta blocker overdose and severe bradycardia. The initial ECG showed sinus bradycardia with a sinus cycle length of 2060ms and 2:1 AV conduction, with each conducted P wave preceded by a long-coupled junctional escape beat. Atropine resulted in shortening of the junctional escape interval but had no effect on the sinus rate. There was now 1:1 AV conduction, with each P wave being preceded by a faster junctional escape beat. Glucagon resulted in acceleration of the sinus rate to a cycle length of ~820ms (73 bpm) with return of 1:1 AV conduction, a PR interval of 200ms, and no junctional beats. Conducted beats showed a right bundle branch block and left axis deviation. The dependence of AV conduction on a preceding QRS complex within a certain window of time highly suggested infranodal conduction disease manifesting as phase 4 AV block. While normal sinus rates and 1:1 AV conduction were restored with glucagon, the presence of infranodal disease warranted dual chamber pacemaker implantation. In follow-up, with atrial pacing support, there was &lt; 1% ventricular pacing. Discussion Two causes of bradycardia were simultaneously present - sinus bradycardia due to beta blocker overdose, and 2nd degree AV block due to His-Purkinje disease. Phase 4 AV block is a mechanism of paroxysmal AV block (PAVB) in patients with diseased His-Purkinje system. Spontaneous depolarization occurs in diseased fibers during prolonged periods of ventricular pause, such as with slowing of the sinus rate. The sodium channels are blocked during phase 4 of the action potential and therefore the conduction system is incapable of depolarizing due to low resting membrane potentials. In this case, AV 1:1 conduction can only be restored with a premature ventricular contraction. This is an overall under-recognized entity and should be managed with pacemaker implantation.

Abstract 12244: Gender Differences in Leadless Pacemaker Peri-Procedural Adverse Events, Long-Term Device Functions, and Clinical Outcomes

Introduction: Some studies suggested gender differences in procedural complication rates and long-term outcomes for trans-venous pacemakers. Little is known about gender differences associated with leadless pacemaker (LP) implantation. Methods: We reviewed all Medtronic Micra LP implants at our institution from 9/2014 to 9/2022. Device parameters (R wave sensing, impedance, and capture threshold), right ventricular pacing burden (RVP), left ventricular ejection fraction (LVEF), and 30-day adverse events post implant were obtained. Results: Among 489 patients, 50.9% were men. Mean follow-up was 1.7 ± 1.5 years. Women were older than men at the time of LP implant (78.1 ± 14.7 vs 75.5 ± 15.3 years old, p=0.04). There were no significant differences in R wave sensing and RVP between genders. Impedance and LVEF were higher in women and capture thresholds were higher in men at both baseline and last follow up. Despite significant differences in device parameters between genders, differences were small and not clinically relevant in most cases (Figure). Mean number of device deployments required at implant was similar: women 1.3 ± 0.6 vs men 1.4 ± 0.9, p=0.16). Implant related complications were similar between women and men: access site hematoma (5 vs 9, p=0.42), pseudoaneurysm (0 vs 2, p=0.49), cardiac perforation (2 vs 1, p=0.62), 30-day re-hospitalization (16 vs 25, p=0.19) and 30-day mortality (16 vs 17, p=0.99). LVEF decreased over time in both genders (Figure). During follow-up, 4 women and 6 men required transvenous cardiac resynchronization therapy (CRT) implantation (p=0.75) and 4 women vs 2 men required transvenous dual chamber pacemaker implantation (p=0.44). Conclusion: Outcomes of leadless pacemaker implantation are similar between women and men. Long-term device function is excellent in both genders. However, about 3% of all patients required device upgrade, highlighting the need for close electrophysiology follow-up after LP implant in both genders.

SAT579 Newly Diagnosed Graves' Disease With Complete Heart Block In Elderly Patient. A Case Report

Abstract Disclosure: M.M. Eid: None. T. Zahra: None. J. Vargas-Jerez: None. Introduction: Hypothyroidism is the most common thyroid disorder in elderly. The prevalence of hyperthyroidism in elderly is 0.5-3% and mainly caused by toxic thyroid nodules. Graves’ disease is an autoimmune disorder mediated by TSH receptor antibody (TSHR AB), presents commonly with hyperthyroidism in middle age female(1). Complete heart block in elderly can be due to conduction system fibrosis, Ischemic/structural heart diseases, medications, electrolyte disturbance and hypothyroidism(2). Case 72yo, Female with history of DM and HTN. Denied smoking, alcohol, drug and allergy. Irrelevant family history. Medications include amlodipine, metformin and atorvastatin. She was referred to endocrinology clinic for low TSH (was normal last year). Review of system was negative, denied tremor, palpitation, anxiety, weight loss, bowel movement/mood/sleep change, vision/swallowing problem. Physical examination: ABP150/80, Heart Rate(HR) 75/min. Mild lid lag, no exophthalmos. No tremor. Thyroid gland: diffusely enlarged non tender, no bruit. Normal cardiopulmonary and abdomen examination. Laboratory work up TSH less than 0.01 normal 0.2 to 4.20 uIU/ml , FT4 3.5 normal 0.9 to1.8 ng/dl, FT3 6 normal 2 to 4.4 pg/ml. Repeat lab confirmed TSH suppression and high FT4 ,FT3. TSHR antibody 7.66 normal less than 1.75 IU/L, Thyroid stimulating immunoglobulin 5.05 normal less than 0.5 IU/L ,HBA1C 6.6, Normal liver and kidney function tests and Complete blood count. She was diagnosed with Graves’ disease, kept on Methimazole 10mg/day. 2 weeks later, she presented to the ED after syncope at home. Initial EKG showed complete heart block HR 35/min and right bundle branch block (RBBB), ABP 110/65. Hours later EKG showed transient first degree heart block HR 75/min, RBBB and left axis deviation, then complete heart block with HR 30/min. Normal Troponin, potassium 4.2 mmol/L, sodium 141 mmol/L, calcium 9.2mg/dl, TSH 0.015 uIU/ml,FT4 3 ng/dl. Negative Anti-Lyme IgG and IgM. Normal Echocardiogram. She underwent uneventful Dual chamber pacemaker implantation with close endocrinology follow up. Conclusion: Graves’ Disease has variable presentations in elderly. Hyperthyroidism causes tachyarrhythmia due to the positive chronotropic effect of thyroid hormones. Bradyarrhythmia in our case is most likely due to conduction system fibrosis and could be related to the inhibitory effect of TSHR AB in elderly in contrary to the simulating effect in young patients. It is still rare to diagnose symptomatic bradyarrhythmia with uncontrolled hyperthyroidism(1).

Combined effects of high atrial septal pacing and reactive atrial antitachycardia pacing for reducing atrial fibrillation in sick sinus syndrome.

It is unknown whether atrial fibrillation (AF) burden varies by pacing site in patients with reactive atrial antitachycardia pacing (rATP). We aimed to compare AF burden in patients with high atrial septal pacing (HASp) via delivery catheter and right atrial appendage pacing (RAAp) in patients with sick sinus syndrome (SSS). We retrospectively identified 109 patients with a history of paroxysmal AF and SSS who had received dual-chamber pacemaker implantation between January 2017 and December 2019, of whom 39 and 70 patients had HASp and RAAp, respectively. rATP was initiated after a 1-month post-implantation run-in period. Patients with HASp had a significantly shorter P-wave duration during atrial pacing than those with RAAp (99.3 ± 10.4 vs. 116.0 ± 14.3 ms, p < .001). During the 3-year follow-up period, the incidence of an AF lasting longer than 1 or 7 days was significantly lower (hazard ratio [HR], 0.45; p = .016; HR, 0.24; p = .004) than in those with RAAp. The median time of AF/AT per day in the follow-up periods was significantly shorter in the HASp group than in the RAAp group (10 vs. 18 min/day, p = .018). Atrial lead division did not occur in the HASp group during the follow-up period. HASp via delivery catheter is as safe as RAAp, and HASp combined with rATP is effective for reducing AF burden in patients with SSS and paroxysmal AF.

Feasibility and short-term outcomes of left bundle pacing in paediatric patients: a case series

Abstract Funding Acknowledgements Type of funding sources: Other. Main funding source(s): Government Background Chronic RV apical pacing in pediatric patients can lead to LV dysfunction. Left bundle pacing has been shown to preserve LV function in adults. The feasibility and outcomes of left bundle pacing in pediatric patients are unknown. Objectives To study the feasibility, safety, and short-term outcomes of pediatric left bundle branch pacing (LBBp). Methods Patients &amp;lt; 18 years with class I or II indication for pacing were the study subjects. All patients had dual-chamber pacemaker implantation from the right or left side. We did the device implantation either under conscious sedation, or general anesthesia, after 6 hours of fasting and intravenous hydration with normal saline at 1 ml/kg/min. A venogram was performed on the ipsilateral to the implantation site from the cubital venous access with 5-10 ml of non-ionic contrast side to delineate the venous anatomy before the procedure. Venous access was obtained through two separate punctures of the extrathoracic axillary vein using an 18 G puncture needle and a 0.025 glide wire. The vein was sequentially SelectSecure 3830 4F lead, and C315HIS sheath was used for LBBp. An additional loop was added to the ventricular lead to account for the growth of the patient. The primary outcomes were successful, stable LBBp. The secondary outcomes were lead stability over three months with no implant-related complications or death. Result This case series has six patients of whom 2 were males and with a mean age of 9.5 years, and a mean body weight of 25.5 Kgs. All patients but one had undergone intracardiac repair (4 VSD, 1 ASD). The pacing indication was symptomatic AV block in five and sick sinus syndrome in one patient. At implant, the mean R wave was 12.83±4.8 mV, mean ventricular threshold was 0.6 ± 0.1 V at 0.5 ms pulse width, mean ventricular impedance of 737.3W ±131.5 ohms. The mean procedure time was 65± 20min, the mean fluoroscopy time was 14.63±13.3 min and the mean contrast volume was 30±20ml and the mean paced QRS duration was 98.5±16.5 ms and V5 LVAT 62.66±22.33ms. During follow follow-up of 4±3 months, the lead parameters were stable with a ventricular threshold of 0.8±0.1V at 0.5ms pulse width impedance of 689±130.2 ohms. There was no lead perforation, dislodgement, or death. Conclusion LBBp in the pediatric population is feasible and safe with good -lead stability and no complications in the near term.

Post-cardiac injury syndrome occurred two months after permanent dual-chamber pacemaker implantation

BackgroundPost cardiac injury syndrome (PCIS) is characterized by the development of pericarditis with or without pericardial effusion due to a recent cardiac injury. The relatively low incidence makes diagnosis of PCIS after implantation of a pacemaker easily be overlooked or underestimated. This report describes one typical case of PCIS.Case presentationWe present a case report of a 94-year-old male with a history of sick sinus syndrome managed with a dual-chamber pacemaker who presented with PCIS after two months of pacemaker implantation. He gradually developed chest discomfort, weakness, tachycardia and paroxysmal nocturnal dyspnea and cardiac tamponade after two months of pacemaker. Post-cardiac injury syndrome related to dual-chamber pacemaker implantation was considered based on exclusion of other possible causes of pericarditis. His therapy was drainage of pericardial fluid and managed with a combination of colchicine and support therapy. He was placed on long-term colchicine therapy to prevent any recurrences.ConclusionThis case illustrated that PCIS can occur after minor myocardial injury, and that the possibility of PCIS should be considered if there is a history of possible cardiac insult.

Impact of pacing mode and different echocardiographic parameters on cardiac output (PADIAC).

The extent of the hemodynamic benefit from AV-synchronous pacing in patients with sinus rhythm and AV block is not completely understood. Thus, we systematically investigated the association of an array of echocardiographic and epidemiological parameters with the change in cardiac output depending on the stimulation mode (AV-synchronous or AV-asynchronous pacing). Patients in sinus rhythm after previous dual chamber pacemaker implantation underwent a thorough basic echocardiographic assessment of diastolic and systolic left ventricular function, and atrial function (26 echo parameters, including novel speckle tracking strain measurements). Then, stroke volume was measured with AV-synchronous (DDD) and AV-asynchronous (VVI) pacing. Each patient represented their own control, and the sequence of stroke volume measurements was randomized. In this prospective single-center study (NCT04068233, registration August 22nd 2019), we recruited 40 individuals. The stroke volume was higher in all patients when applying AV-synchronous DDD pacing [median increase 12.8 ml (16.9%), P < 0.001]. No echo parameter under investigation was associated with the extent of stroke volume increase in a linear regression model. Of all epidemiological variables, a history of acute myocardial infarction (AMI) was associated with an attenuated stroke volume gain in a univariate and a multivariate regression model that adjusted for confounders. A- and S-wave velocities were reduced in the AMI group. In our cohort of patients, each subject benefited from AV-synchronous DDD pacing. No single echo parameter could predict the amount of stroke volume increase. The beneficial effect of AV-synchronous pacing on stroke volume was attenuated after prior acute myocardial infarction.ClinicalTrials.gov identifier (NCT number): NCT04068233.