Degree Atrioventricular Block Research Articles

The QRS frontal plane axis changes during left bundle branch block after transcatheter aortic valve replacement.

Left bundle branch block (LBBB) is common after transcatheter aortic valve replacement (TAVR) and associated with a left or normal QRS axis. We aim to assess the QRS frontal plane axis shift changes during LBBB after TAVR and determine if the risk of procedure-related high degree atrioventricular block (AVB) is affected by QRS axis shift changes. In a retrospective single-center study of 720 consecutive patients who underwent TAVR, 141 (19.6%) with normal baseline QRS duration developed a new LBBB after TAVR and constituted the study group. Most patients (59.6%) were females and the mean age of the cohort was 81.2±6 years. As compared with the baseline QRS axis before TAVR, the occurrence of LBBB was associated with a leftward QRS axis shift (by 40±28.3°) in 73% of the study patients and a rightward (by 18.6±19.4°) or no change in QRS axis in 25.6% and 1.4% of the study patients, respectively. A left QRS axis (-30°) was observed in 14.9% and 38.3% of the study patients before and after TAVR, respectively. The group of patients exhibiting a rightward or no QRS axis shift had a greater incidence of high degree AVB than the group of patients exhibiting a leftward QRS axis shift (18.4%vs. 6.8%, p=.056). Although post TAVR-LBBB is associated with a leftward QRS axis shift in most patients, a non-negligible proportion of patients (27%) exhibited a rightward or no QRS axis shift. The latter group tend to have a higher risk of developing high degree AVB.

Ten years follow-up of the largest oral Chagas disease outbreak: Cardiological prospective cohort study.

Chagas disease (ChD) is the most important endemy in Latin America. Some patients, develop chronic Chagasic cardiopathy (CCC) years after the acute phase. It is unknown if patients infected by the oral route have higher risk of developing early CCC. A prospective cohort study was conducted to assess morbidity and mortality during 10 years observation in 106 people simultaneously infected and treated in the largest known orally transmitted ChD outbreak in 2007. A preschooler died during the acute phase, but thereafter was no mortality associated to ChD. All acute phase findings improved in the first-year post-treatment. Each person was evaluated 8.7 times clinically, 6.4 by electrocardiogram (ECG)/Holter, and 1.7 by echocardiogram. Based on prevalence, the number of people who had any abnormalities (excluding repolarization abnormalities and atrial tachycardia which decreased) was higher than 2007, since they were found at least once between 2008-2017. However, when we evaluated incidence, except for clinical bradycardia and dizziness, it was observed that the number of new cases of all clinical and ECG findings decreased at the end of the follow-up. Between 2008-2017 there was not incidence of low voltage complex, 2nd degree AV block, long QT interval, left bundle branch block or left ventricular dysfunction that allowed the diagnosis of CCC. Total improvement prevailed over the persistence of all clinical and ECG/Holter findings, except for sinus bradycardia. Incomplete right bundle branch block, sinus bradycardia and/or T-wave inversion were diagnosed persistently in 9 children. The second treatment did not have significant influence on the incidence of clinical or ECG/Holter findings. At the end of the 10-year follow-up, there were not clinical or ECG/Holter criteria for classifying patients with CCC. The incidence of arrhythmias and repolarization abnormalities decreased. However, special attention should be paid on findings that not revert as sinus bradycardia, or those diagnosed persistently in all ECG as sinus bradycardia, incomplete right bundle branch block or T-wave inversion. Early diagnosis and treatment may have contributed to the rapid improvement of these patients. In ChD follow-up studies prevalence overestimates the real dimension of abnormalities, the incidence looks as a better indicator.

SAT484 High Degree AV Block And Sinus Arrest: Cardiovascular Manifestations Of Myxedema Coma

Abstract Disclosure: J. Bosques-Lorenzo: None. P. Rivera: None. J. Colon-Castellano: None. Y. Otero-Dominguez: None. Bosques-Lorenzo Jaymilitte, Rivera-Cariño Patricia, Colon-Castellano Janet, Otero-Dominguez Yomaira. Background: Myxedema coma is a rare and life-threatening complication of severe hypothyroidism. The most common presenting symptoms are altered mentation, hypothermia, edema, and respiratory depression. The cardiovascular system is often involved, in the form of sick sinus syndrome, bradycardia, low voltage QRS complex, QT prolongation, and rarely cardiac arrest. Here we present a case of myxedema coma complicated with high degree AV block and sinus arrest. Clinical Case: A 84 year-old man with history of hypothyroidism on levothyroxine 125 mcg, presented to the ER due to disorientation, bilateral leg edema, and abdominal discomfort for 3 days. Vital signs revealed a temperature of 97.5 F, HR of 60bpm, BP 174/88 mmHg, and oxygen saturation of 100% at room air. Physical exam was pertinent for bilateral lower extremity edema, facial puffiness, macroglossia, slow mentation, and scattered rales on lung auscultation. Laboratories showed an elevated TSH (296.8 uIU/mL), with low total T3 and free T4 (45.03 ng/dL and 0.228 ng/dL respectively) with a myxedema score of 45. Altered renal parameters as per BUN and creatinine levels (83.4 mg/dL and 5.75 mg/dL) without electrolytes disturbances and elevated CPK (1250 U/L). Infectious process was ruled out. Chest X-ray showed vascular congestion. Echocardiogram showed a small pericardial effusion. Patient was admitted to ICU and started on IV Levothyroxine, along with hydrocortisone. Liothyronine was initially not available. On second admission day, the patient developed hypothermia (94.3 F) which was managed with passive warming. Telemetry monitoring recorded multiple episodes of bradycardia raging from 30 to 50 bpm, high-degree AV block, and one episode of sinus arrest of 15 seconds with self-resolution. Altered mentation persisted for which endotracheal intubation was performed to secure airway. A temporary transvenous pacing was placed emergently. Levothyroxine dose was further adjusted and liothyronine was initiated. After a few days of treatment, patient demonstrated clinical improvement that was supported with follow up thyroid function test. Patient was extubated and transitioned to oral levothyroxine. Nevertheless, he remained dependent of transvenous pacing for which permanent pacemaker placement was coordinated. Conclusion: Cardiovascular complications in myxedema coma are associated with poor prognosis with a mortality approaching 80%. Few cases of sinus or cardiac arrest associated to Myxedema coma have been reported in the literature. In this case, the patient developed high-degree AV block with concomitant sinus arrest despite prompt initiation of intravenous thyroid hormone. Prompt identification of cardiovascular involvement can prevent cardiovascular morbidity and mortality in myxedema coma. Presentation Date: Saturday, June 17, 2023

A retrospective audit of young adults who received permanent pacemakers at a teaching hospital in the Western Cape, South Africa.

While most pacemaker implantations occur in older individuals, younger patients also receive pacemakers. In these, degenerative conduction system disease is less likely to be the cause of atrioventricular block (AVB), with other diseases being more common. There is, however, a paucity of data on this group as well as on younger pacemaker recipients that have undergone pacemaker implantation for reasons other than AVB. The aim of this study was to perform an audit of young adult permanent pacemaker recipients. This was a retrospective record review, conducted in the Division of Cardiology at Tygerberg Hospital, Cape Town, South Africa. We included 169 adult patients between the ages of 18 and 60, who received permanent pacemakers between 2010 and 2020. A subgroup analysis of patients 55 years and younger was also performed. Third degree AVB was the most common indication for pacemaker implantation (n = 115; 68%), followed by high degree AVB (n = 23; 13.6%) and sick sinus syndrome (SSS; n = 14; 8.3%). A specific underlying cause for conduction system abnormalities was found in only 25.4% of patients (n = 43), with most of them being 55 years or younger (n = 32; 30.8% of patients ≤ 55 years). Specific causes that were identified included prosthetic valve implantation and/or valve repair (n = 14; 8.3%), myocardial infarction (n = 6; 3.6%), cardiac sarcoidosis (n = 5; 3.0%), coronary artery bypass grafting (n = 3; 1.8%), cardiomyopathy (n = 2; 1.2%), muscular dystrophy (n = 2; 1.2%), congenital heart disease (ventricular septal defect; atrioventricular septal defect; Tetralogy of Fallot; bicuspid aortic valve; n = 6; 3.6%), acute myocarditis (n = 1; 0.6%), atrial myxoma removal (n = 1; 0.6%), planned AV node ablation (n = 2; 1.2%), and following a previous stab in the chest (n = 1; 0.6%). Given that the mean age of our study population was high, the low number of identified underlying causes in the whole cohort (≤60 years) may reflect some AVB due to age related degeneration of the conductions system in the patients 56 to 60 years age, but also raises the possibility that these patients may be less likely to be extensively investigated for an underlying cause than those ≤55 years, where diseases such as sarcoidosis were more readily confirmed. As access to advanced diagnostic tools improves, the percentage of young pacemaker recipients with an underlying cause identified may increase.

Second degree AV block in a dog with cardiac hemangiosarcoma in the interventricular septum

AbstractA 13‐year‐old, male, neutered Maltese presented for lethargy and anorexia. Clinical examination identified bradycardia and a grade 2/6 systolic left basilar murmur. A six‐lead electrocardiogram revealed high‐degree, 4:1 second‐degree atrioventricular block, with a rate of 40 beats per minute. Echocardiography revealed a large mass in the interventricular septum, an atypical location for a cardiac mass, as a potential cause of the arrhythmia. An epicardial pacemaker was placed and a mass within pericardium was biopsied. Histopathology revealed hemangiosarcoma. The patient was treated with chemotherapy and radiation therapy and was euthanased 2 months following diagnosis.

Unusual manifestation of atypical type I second degree atrioventricular block.

A 25year-old woman exhibited atypical type I second degree atrioventricular block characterized by constant PR intervals except the PR interval of the beat after the block. This was attributed to vagally induced AV block with failure of the vagal effect to depress the sinus node.

Incidence of atrioventricular block after isolated coronary artery bypass grafting: a systematic review and pooled-analysis.

Atrioventricular block (AVB) is a serious complication following coronary artery bypass grafting (CABG) surgery, and its high-grade form may necessitate the implantation of a permanent pacemaker (PPM). AVB is associated with increased morbidity and mortality rates. This study aims to estimate the incidence of AVB and subsequent PPM implantation after isolated CABG surgery. We searched electronic databases of PubMed, Embase, and Scopus from inception to 18 November 2022. Clinical trials and observational studies reporting the incidence of post-CABG AVB or subsequent PPM implantation in adult patients were included. The total incidence for all included outcomes was calculated using the inverse variance method, and the I2 statistic was reported to evaluate the heterogeneity of studies. A total of 28 studies met the inclusion criteria. Four studies [3 cohorts, 1 randomized controlled trial (RCT)] reported AVB without specifying its type; one (cohort) reported different degrees of AVB, 20 (12 cohorts, 8 RCTs) reported complete heart block (CHB) (or AVB requiring temporary pacing), and nine (8 cohorts, 1 RCT) reported the number of PPM inserted due to AVB. The pooled incidence of AVB, CHB (or AVB requiring temporary pacing), and PPM due to AVB was 1.16%, 1.73%, and 0.58%, respectively. Meta-regression analysis revealed that age, gender, diabetes, hypertension, hyperlipidemia, or smoking were not significantly associated with AVB, CHB, or PPM implantation. This study highlights the incidence of AVB and the need for PPM implantation following CABG surgery. The findings emphasize the importance of postoperative monitoring and surveillance to improve patient outcomes. https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022377181, identifier PROSPERO CRD42022377181.

The 'scan and treat' clinic; early evaluation of an advanced clinical practitioner (ACP) led combined echocardiography and outpatient cardiology clinic

Abstract Funding Acknowledgements Type of funding sources: None. Background There is increasing recognition that traditional models of hospital-based outpatient care in England are inefficient, unsustainable and do meet patient’s needs and preferences (RCP 2018). The National Health Service (NHS) ‘getting it right fist time’ (GIRFT) report for cardiology makes a number of recommendations including; increasing the utilisation non-medical roles such as Advanced Clinical Practitioners (ACPs), reducing face to face appointments, and triaging referrals with tests performed ahead of clinic appointments (NHS, 2021). We developed a novel clinic combining formal echocardiography with clinical assessment by a single British Society of Echocardiography (BSE) accredited ACP at medium sized district general hospital (DGH) in the west Midlands, England. No clinics of this type were identified in the literature, although there are studies demonstrating the efficacy of physiologist led valve clinics (Wasing et al., 2009) and cardiologist led ‘one stop’ clinics (Falces et al., 2008) Purpose To evaluate the case mix and early outcomes of the first 6 months of the scan and treat clinic. Methods Patient demographics, reason for referral and clinic actions were collected prospectively on an excel spreadsheet. A single un-blinded cardiologist reviewed the electronic patient records and echo images of 10 randomly selected patients from the first 3 months to assess the accuracy and appropriateness of documented diagnoses and treatment plans. Results 72 patients were seen over 11 clinics between July and December 2022. There was a low (6%) non-attendance rate, although a further 5 patients (7%) did not require an echo, due to booking errors. The most common reason for referral was suspected heart failure (33%) (table 1). Combined Heart Failure (HFrEF, HFmrEF, HFpEF) was also the most common primary diagnosis in the clinic (32%) (figure 1). There was a low rate of non-cardiac diagnoses (19%) and normal echocardiograms (33%) (figure 1). Clinic actions included prescribing (54%), cardiac monitors (24%), further imaging (15%) and blood tests (11%). The Cardiologist reviewer reported appropriate diagnosis and treatment of 10 radomly selected cases. Of 7 patients followed up in a cardiologist clinic before 10/01/2023, 5 had no significant changes in treatment or diagnosis, 1 patient had a pacemaker for asymptomatic 2nd degree AV block and another had Bisoprolol stopped due to side effects. Conclusion These preliminary results suggest the ‘scan and treat’ clinic is a viable alternative to traditional general cardiology clinic for patients who also require echocardiography. This review has a number of limitations including limited short term follow up, un-blinded cardiologist review and is not generalizable. This kind of initiative may help modernise and improve cardiology outpatient services. Further research is required to assess the efficacy of similar non-cardiologist led ‘one-stop’ clinic designs.Table 1Figure 1

Arrhythmia Resolution After Successful Parathyroidectomy for Primary Hyperparathyroidism.

The prevalence of primary hyperparathyroidism (PHPT) is increasing as routine laboratory testing for calcium and parathyroid hormone becomes more prevalent due to heightened awareness of the disease. PHPT affects multiple organ systems including the cardiovascular system. This case report highlights a patient with first degree atrio-ventricular block pre-operatively that resolved after resection of her parathyroid adenoma. This case emphasizes the importance of treating asymptomatic hyperparathyroidism to optimize cardiac function.

Problematic definitions of Mobitz type II second degree AV block: Historical aspects.

Problems with the definition of type II second degree AV block are best understood by reviewing the historical aspects that include Mobitz's original description, the contributions of the Chicago Arrhythmia School and the growing importance of excluding slowing of the sinus rhythm.

Incidence and outcome of arrhythmias and electrical disease in patients with Trisomy 18.

Patients with Trisomy 18 have a high incidence of cardiac anomalies and are associated with early death. Because of early mortality, electrical system disease and arrhythmia has been difficult to delineate and the incidence remain unknown. We sought to describe the association and clinical outcomes of electrical system disease and cardiac tachy-arrhythmias in patients with Trisomy 18. This was a retrospective, single institutional study. All patients with Trisomy 18 were included in the study. Patient characteristics, congenital heart disease (CHD), conduction system and clinical tachy-arrhythmia data were collected on all patients. Outcomes including cardiac surgical interventions, electrical system interventions and death were collected until the time of study. Patients with tachy-arrhythmias/electrical system involvement were compared to those without to identify potential associated variables. A total of 54 patients with Trisomy 18 were included in analysis. The majority of patients was female and had associated CHD. AV nodal conduction system abnormalities with either first or second degree AV block were common (15%) as was QTc prolongation (37%). Tachy-arrhythmias were common with 22% of patients having at least one form of tachy-arrhythmia and associated with concomitant conduction system disease (p = 0.002). Tachy-arrhythmias were typically treatable with monitoring or medication with eventual resolution without need for procedural intervention. Although early death was common, there were no causes of death associated with tachy-arrhythmia or conduction system disease. In conclusion, patients with Trisomy 18 have a high incidence of conduction system abnormalities and burden of clinical tachy-arrhythmias. Although frequent, electrical system disease did not affect patient outcome or difficultly of care delivery.

FREQUENCY OF HIGH DEGREE ATRIOVENTRICULAR BLOCK IN PATIENTS WITH ACUTE ANTERIOR WALL MYOCARDIAL INFARCTION

Atrioventricular (AV) block is an AV conduction disorder that can manifest in various settings, with varying symptomaticity and severity. Complications of acute ST-elevation myocardial infarction (STEMI) as AV blocks are often observed. The first degree of atrioventricular block is the most common and requires no treatment. The second-degree block is sub-classified in Mobitz type I and Mobitz type II. This study aimed to determine the frequency of high-degree atrioventricular block in acute anterior wall myocardial infarction cases. The current cross-sectional analysis was conducted at the Department of Cardiology, Rehmat-ul-Lil-Alameen Institute of Cardiology, Lahore, from 19-02-2021 to 18-08-2021. A total of 311 patients were enrolled in the study. Cases underwent an electrocardiogram, and high degree AV Block was labeled per operational definitions. The results were noted and recorded on the same proforma. The overall mean age of the patients was 55.6±8.4 years. Gender distribution of patients shows a higher frequency of 57.9% males compared to 42.1% females with a female-to-male ratio of 1:1.4. High degree of atrioventricular block was found among 5.8% of the total patients. Around 5.8% of AWMI patients presented with high-grade AV block in this study are in-concomitant with other studies. No association of risk factors (p-value >0.05) was presented regarding age, gender, DM, hypertension, dyslipidemia, family history of CAD, and smoking in this study.

ID: 216922 Lumbar Medial Branch Nerve Stimulation With SPRINT Demonstrating No Pacemaker Interference: A Case Report

A 93-year-old male with significant cardiac history including CAD, aortic valve stenosis s/p TAVR, symptomatic bradycardia, paroxysmal atrial fibrillation, second degree AV block on anticoagulation with an implanted Biotronik cardiac pacemaker was evaluated for chronic low back pain. Patient previously completed conservative modalities and multiple interventional procedures including epidural steroid injections and lumbar medial branch blocks with minimal relief. He was not a surgical candidate. The risks and potential benefits of SPRINT peripheral nerve stimulation (PNS) were discussed given his age, cardiac history, and ongoing anticoagulation. Currently, SPRINT is contraindicated in patients with active cardiac implanted devices including pacemakers and defibrillators.

Optimizing atrial sensing parameters in leadless pacemakers: main findings of the OptiVALL study

Abstract Funding Acknowledgements Type of funding sources: None. Backgroung: The MARVEL2 study demonstrated the feasibility of leadless pacemakers in delivering atrioventricular (AV) synchronous pacing with an accelerometer-based algorithm, for up to 5 h. Purpose To assess the AV synchrony (AVS) the device can provide under daily activities and across different heart rate (HR) ranges, and to describe what programming changes are needed to achieve proper atrial tracking and AVS. Methods The OptiVALL study is a single-centre and prospective study of consecutive patients implanted with MICRA AV. Follow-up was routinely performed at 24 hours and at 1, 3, 6 and 12 months. The pacing mode was programmed to VDD in all patients and AV conduction mode switch (VVI +) was deactivated. In each visit a device check was carried out and reprogramming of the atrial sensing parameters was performed according to the manual atrial mechanical tests, as well as information from device counters and rate histograms. A 24-h Holter monitoring was placed at 3-months follow-up and ECG recorded tracings were automatically and blindly analyzed with an ECG delineation system. Cardiac cycles were defined as synchronous if a ventricular event followed the P-wave by ≤300 ms. AVS was calculated by dividing the number of synchronous cycles by the total number of cardiac cycles. The primary efficacy endpoint was defined as AVS≥ 85% of total cardiac cycles during the 24-h Holter-ECG monitor. AVS was also calculated for each HR range of 10 bpm. Results Thirty-two patients (18 males, mean age 78.8 ±15.1, 16 patients with 3rd degree AV block, 15 patients with 2nd degree AV block, 1 patient with bifascicular block) underwent successful Micra AV implant, of whom 31 remained in VDD mode at some visit throughout the follow-up, and 26 remained in VDD mode at 3 months follow-up. Device reprogramming of nominal parameters was needed in all patients at follow-up (table). The automatic A3 window end was disabled, and a fixed and short value was set in 100% of patients. Lower HR was set to 40 bpm in 88.5% (n=23) of patients. Auto A4 threshold and auto A3 threshold were modified in 6 and 3 patients respectively and vector was changed in 3 patients. An ambulatory 24-h Holter monitor was performed 112.8±37.5 days after the implant in the 26 patients who remained in VDD. A comparison between nominal parameters and programming at ambulatory 24-h Holter monitoring is displayed in the table. Total ECG recorded time was 550.8 hours and 2,291,953 cardiac cycles were analyzed. Average ambulatory AVS was 87.3±6.3% (median: 87.6%) and 20 out of 26 patients showed an AVS≥85% of cardiac cycles. AVS across the different heart rate ranges was good and remained ≥85% until 90 bpm (figure) with a substantial drop only with HR over 110 bpm. Conclusions High ambulatory AVS in outpatients with leadless pacemakers can be feasible, although may require manual reprogramming of atrial sensing parameters, especially the A3 window end setting.

Active monitoring for atrial fibrillation (AMALFI): a streamlined randomised controlled trial of remote screening for subclinical atrial fibrillation

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): National Institute for Health and Care Research Oxford Biomedical Research Centre ECG patches (and respective monitoring data analysis) were granted free of charge by the manufacturer (iRhythm) Background Incidence of stroke could be reduced by detection of subclinical atrial fibrillation (AF) and appropriate anticoagulation. Opportunistic screening by pulse-taking or ECG is recommended by some international guidelines. In contrast, there is uncertainty regarding the benefits and harms of systematic screening across populations and/or using longer monitoring durations. Purpose To assess if screening using a one-off single-lead continuous non-invasive ECG patch worn for 14 days increases AF detection at 2.5 years compared to standard care, and whether this approach is cost-effective. Methods AMALFI is an ongoing mail-based open-label randomised controlled trial of remote AF screening in England. Streamlined design includes integration with national electronic health data and care pathways for participant identification, invitation, and management. The target population are individuals aged ≥65 years with CHA2DS2VASc score of ≥3 in men and ≥4 in women, and with no prior history of AF or allergy to latex. Participants in the intervention arm self-apply the ECG patch and return it for analysis after 14 days. AF findings (duration ≥30 seconds at any rate) are communicated to primary care physicians, with further clinical management at their discretion. Participants in the control arm receive usual care (which is expected to include opportunistic AF screening). The primary outcome is the proportion of participants with newly-detected AF recorded in primary care electronic health records in each group at 2.5 years after randomisation. Results From 2019 to 2022, AMALFI invited 22,188 people, of whom 5,040 (23%) were randomised. Baseline characteristics included age 77±6 years, 47% female, and median CHA2SD2VASc score 3 (Table 1). Of 2520 individuals randomised to the intervention, 2127 (84%) wore and returned the patch. Median wear time was 13.9 days and median proportion of time analysable was 98.8%. AF was present in 102 patch reports, representing 4.8% of reports received and 4% of the intervention arm (in line with a priori estimates for power calculations for the primary outcome); median AF burden was 11.3%. AF was present at commencement of recording in 40% of these reports, by the end of the first day in 58%, and by the end of the first week in 83% (Figure 1). Incidental findings included supraventricular tachycardia (in 90% of reports), non-sustained ventricular tachycardia (VT; in 32%), sustained VT (in 0.1%), Mobitz II/high-grade/3rd degree AV block (in 1.1%), and pauses >6s (in 0.3%). Conclusion AMALFI’s innovative design facilitated recruitment and demonstrates that a remote ECG patch-based AF screening strategy is feasible, resulting in a new diagnosis of AF in ~4% of individuals selected due to moderate-to-high clinical stroke risk. Longer term follow-up will provide data on the incremental value and cost-effectiveness of AF diagnosis by systematic screening compared to routine opportunistic detection.

Usefulness of parahisian pacing for risk prediction of pacemaker implantation after TAVI

Abstract Funding Acknowledgements Type of funding sources: None. Background Conduction disturbances determining pacemaker implantation are a significant concern in patients undergoing Transcatheter Aortic Valve Implantation (TAVI), a procedure that is nowadays spreading even in the low-risk population. OBJECTIVE The aim of the study was to evaluate the role of the parahisian pacing, a method to directly identify the conduction system anatomical variability, in predicting the iatrogenic damage risk conditioning pacemaker implantation after TAVI. Methods Between October 2021 and November 2022 we prospectively collected clinical features, ECG, procedural and imaging data (cardiac CT and echocardiography) of every patient who underwent electrophysiological study for pre-existing or worsening conduction disorders within 48 hours after TAVI procedures in our centre. After having recorded the HV interval, parahisian stimulation at decreasing energy output was performed (CL 600 ms, 25V to 0.5V x 2 ms) with definition of the loss of capture pattern related to the three anatomical variations of His bundle described by Kawashima (1). Fisher’s exact test was used for statistical analysis; p-value <0.05 was considered statistically significant. Results Out of 110 TAVI performed, a total of 31 patients with conduction disorders have been studied. Patients who developed permanent 3rd degree AV block after the procedure were excluded. Mean age was 82.6±4.4 years; 21 patients (67.7%) were males. 11 patients (35.5%) had a pre-existing conduction disorder worsened after TAVI, 13 patients (41.9%) developed newly-onset LBBB; 8 (25.8%) also developed 1st degree AV block. The total number of patients who underwent PM implantation was 16 (51.6%). The anatomical variables (membranous septum <3mm and/or septal cusps calcifications) and type of valve implanted were not significantly associated with PM implantation (p = NS). An HV interval <70 ms was registered in 20 (64.5%) patients (Fig. 1); 7 of them underwent PM implantation as they developed paroxysmal 3rd degree AV block. These 7 patients all had type 2 or type 3 pattern during parahisian stimulation. None of the patients undergoing PM implantation presented a type 1 pattern during parahisian stimulation. A significant protective value (p = 0.02) for PM implantation in patients with type 1 pattern was observed (Fig. 2). Conclusions Parahisian stimulation can be a useful tool to define the conduction system anatomical variability. It can also be helpful to predict the conduction system damage risk during TAVI, conditioning PM implantation. Our data need to be confirmed in a larger population.

Invasive electrophysiology study guided loop recorder implantation in myotonic dystrophy type 1: a prospective single-center study

Abstract Funding Acknowledgements Type of funding sources: None. Introduction In one third of the patients with myotonic dystrophy type 1 (DMT1) the cause of death is of cardiac origin. The most common cardiac manifestations are arrhythmias and conduction disturbances. Purpose Due to its extreme long monitoring properties, implantable loop recorders (ILRs) are highly suitable to detect rare cardiac arrhythmias. To date, there are only limited data using ILRs in DMT1. We aimed to evaluate the role of the invasive electrophysiology study (EPS)-guided loop recorder implantation in patients with DMT. Methods In our prospective study 18 genetically confirmed DMT1 patients underwent non-invasive cardiac examination including transthoracic echocardiography, 24-hour Holter monitoring and surface ECG. In addition, EPS was performed in all cases to evaluate the risk of sudden cardiac death and infra-Hisian conduction properties. Based on the performed non-invasive diagnostic evaluation and EPS findings, patients were divided into low, intermediate and high-risk groups. For patients with normal investigation results and normal HV interval (<55 ms) only annual cardiac follow-up visits were planned (low-risk group). Patients with increased PR interval (>240 ms), QRS duration (>120 ms), or slightly prolonged HV interval (55-70 ms) underwent implantable loop recorder (ILR) implantation (intermediate-risk group). Permanent pacemaker (PM) or implantable cardiac defibrillator (ICD) was implanted in patients with 2nd/3rd degree atrioventricular block (AVB), significantly prolonged HV interval (>100 ms) or if sustained ventricular tachyarrhythmia could be induced during EPS. All patients were followed for at least 3 years. Results According to our study criteria, 8 patients could be categorized as "intermediate risk", 7 of them received implantable loop recorder (ILR). 1 ILR had to be removed 3 weeks after implantation due to skin infarction. During three-years of follow-up, 2 patients had many asymptomatic atrial high-rate episodes, but no 2nd or 3rd degree AVB, significant asystole or malignant ventricular arrhythmia were detected. Conclusions Our single-center prospective study examined the EPS-guided ILR implantation for the risk stratification of DMT1 patients for the first time. A more extensive, multicenter study is warranted to define optimal management of DMT1 patients with slightly impaired infrahisian conduction.

Familial cardiolaminopathy due to a previously undescribed LMNA gene mutation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Cardiolaminopathies are rare genetic alterations, which present diverse mechanical and electrical alterations. OBJECTIVE To present a family carrying an LMNA gene mutation that although not described manifest clinical and electrocardiographic characteristics of the disease. Methods We present the case of two sisters and one brother, aged 65, 57 and 51 years, respectively. At the beginning of their fourth decade, all of them debuted with atrial flutter associated with second and third degree atrioventricular block. Two of them (one or the sisters and the brother) underwent ablation of isthmus-dependent atrial flutter. However, in both, the flutter recurred and no new interventional treatment was further offered. The male subject received a pacemaker implant for treatment of AV block; some years later, he presented a cerebrovascular event and subsequently a recurrence, both while in oral anticoagulation and, actually remains with moderate motor deficit and dysarthria. The youngest woman suffered an embolic cerebrovascular event when she was 50 y/o; she remained asymptomatic in relation to the rhythm disorder and refused a pacemaker. The oldest sister who is asymptomatic, received a pacemaker when she was 45 y/o and now is anticoagulated. By echocardiography, all siblings presented left ejection fraction in between 40 and 50% with decreased strain values and normal left ventricular geometry. Results Recently in our country it is possible to carry out a genetic test, for which the three were subjected to it. In this family, the genetic testing was done using a comercial kit for 172 genes. The result was a Frameshift Indels (non misense) mutation NM_170707.3 c.1526del p.(Pro509LeufsTer39) Exon:9/12, in all three. The caveat is that this LMNA gene mutation has not been previously described. In light of these results, the youngest woman with total AV block and sequelae of cerebrovascular disease and mild left ventricular dysfunction, received an implantable cardiac defibrillator (ICD) implant for primary prevention of sudden death and her siblings are undergoing an upgrade to ICD. Conclusion The mutation found in this family is unique and for the first time reported in the LMNA gene in the world. Genetic diagnosis is limited in our country, which makes it difficult to determine this type of pathology. However, given the clinical presentation of an electrical disorder in all the siblings of a family, in this particular case, it was mandatory to perform this test. These results allow us to better understand the prognosis and intervene appropriately to prevent sudden death, even though there is no treatment to avoid the progression of the disease.

Similarly high success and low complication rates of catheter ablation for idiopathic premature ventricular contractions from the left and right ventricular outflow tract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Catheter ablation is the first line treatment for idiopathic premature ventricular contractions (PVCs) from the right ventricular outflow tract (RVOT) but not from the left ventricular outflow tract (LVOT), due to presumed lower success and higher complication rates in the LVOT. In this observational single center study we analyzed success rates and complication rates in patients undergoing catheter ablation for idiopathic PVCs with an inferior axis. Methods Patients undergoing catheter ablation for idiopathic PVCs with an inferior axis at Hannover Heart Rhythm Center between 2012 and 2020 were included. Patients were excluded if no activation mapping could be performed because of low PVC activity. Ablation success was defined as complete suppression of the index PVC at the end of the procedure. Results 108 patients (53% male, age 53 ± 17 years) with predominantly symptomatic (94%) PVCs with one (72%), two (20%) or more (8%) morphologies and a PVC count of 22063 ± 14426 /24h were included. 47 PVCs (44%) were located in the RVOT (21 anterior RVOT and 26 septal RVOT) and 39 PVCs (36%) in the LVOT (11 lateral LVOT, 5 septal LVOT, 8 RCC, 2 ACC, 13 LCC). 14 PVCs (13%) had the origin close to the CS/LV summit and 8 PVCs (7%) in the parahisian region. Overall success rate was 82%. Success rates for RVOT and LVOT origin were 98% (46/47 cases) and 97% (38/39 cases) respectively. No significant differences in procedure time (145 ± 68 vs. 158 ± 72 min), ablation time (441 ± 328 vs. 462 ± 307 sec), fluoroscopy time (496 ± 521 vs. 519 ± 473 sec) or minor complications (5 vs. 8) were observed for outflow tract PVCs, and no major complications occurred in this group. However, 3 major complications and significantly lower success rates were observed for non-outflow tract PVCs (0/8 for parahisian origin, 4/14 (29%) for CS/LV summit origin). 2 patients with a parahisian focus experienced higher degree AV block and 1 patient with an LV summit focus had a pericardial tamponade. Conclusion Catheter ablation of PVCs with LVOT origin can be performed with similarly high success and low complication rates compared to PVCs with RVOT origin, and therefore could be considered as first-line therapy like RVOT PVCs. On the other hand, identification of PVCs with a parahisian or CS/LV summit focus should be aspired before an ablation procedure, as these localizations are associated with poorer ablation outcome and higher complication rates.

Marked first-degree AV block may lead to complete AV block development

Abstract Funding Acknowledgements Type of funding sources: None. Background First-degree atrioventricular (AV) block (PR interval >200 ms) is considered a benign condition with rare progression to a higher degree AV block. The site of block is determined with electrophysiological (EP) study and measurement of His-ventricular (HV) interval, with normal values below 55 ms. Prolonged HV interval > 70 ms is predictive of higher-grade AV block development. Marked first-degree AV block with a PR > 300 ms may lead to symptoms such as fatigue, poor exercise tolerance and palpitations. When symptoms are correlated to the conduction delay, permanent pacemaker (PPM) implantation to restore AV synchrony should be considered. In the Framingham heart study, patients with first-degree AV block had a threefold higher risk of PPM implantation. However, there is no data on the HV intervals and the rate of progression of conduction disorder in patients with marked first-degree AV block. Purpose To assess the predictive value of HV interval measurement in patients with marked first-degree AV block for progression to a higher-degree conduction disorder. Methods We prospectively evaluated consecutive patients with symptomatic marked first-degree AV block that underwent a PPM implantation. His electrograms were recorded during the implantation, and HV intervals were measured from the first deflection of the His signal to the earliest onset of ventricular activation on a 12-lead surface ECG. Patients were followed for 6 months with three out-patient visits, during which the PPM was temporarily inhibited to check for intrinsic AV conduction. Results Seventeen patients were evaluated between January 2020 and September 2022. Ten patients (59%) were male, and 7 (41%) were female, with an average age of 61 ± 19 years. All patients had markedly prolonged PR interval (383 ± 47 ms) and narrow QRS complex (100 ± 16 ms). Three patients (17%) had intermittent type 1 second-degree AV block, right bundle branch block was recorded in two (12%) and left anterior fascicular block in four (24%) patients. Except for one patient with a corrected atrial septal defect, there were no echocardiographic signs of structural heart disease with a left ventricular ejection fraction of 61 ± 5%. The HV intervals were on the upper limit of normal values at 54 ± 6ms and no patient had an HV interval above 70 ms. Two patients (12%) developed complete AV block during follow-up: one female, and one male, 28 and 83 years old, respectively, with a PR interval 392 and 363 ms, QRS 104 and 94 ms, and HV 57 and 48 ms. None of the two had any additional conduction blocks at the time of PPM implant. Conclusion In our cohort of patients with symptomatic first-degree AV block (PR>300 ms), two patients (12%) developed complete AV block despite normal HV intervals at the time of implant. Closer monitoring, beyond only EP measurements, of patients with markedly prolonged PR intervals is warranted for the potential progression of conduction disorder.