2nd Degree Atrioventricular Block Research Articles

Effects of ketamine, propofol and isoflurane on electrocardiographic variables in clinically healthy dogs premedicated with medetomidine and midazolam.

The purpose of this study was to investigate the effects of three anesthetic agents, with premedication of medetomidine and midazolam, on electrocardiographic variables in dogs. Ten adult mixed breed dogs were used in a crossover design study, where they received ketamine, propofol and isoflurane treatments with a one-week washout period between them. In all three groups, medetomidine was administered first followed by midazolam after 15 min. Then, after 20 min, group 1 received ketamine intravenously (IV), group 2 received propofol (IV), and group 3 received isoflurane (inhalation). In all dogs, electrocardiographs were taken before and after premedication's, as well as every 15 min during anesthesia. Medetomidine significantly decreased heart rate and P wave amplitude and increased PR interval, R wave amplitude, QT interval, and T wave amplitude. Midazolam increased the amplitude of the R and T waves. Ketamine increased the heart rate and PR interval. Propofol increased the heart rate for up to 15 min, decreased the PR interval for up to 30 min, and the QT interval for up to 45 min. Isoflurane increased the heart rate and decreased the amplitude of R and T waves. The results showed that the drugs used in this study did not have many side effects on electrocardiographic variables and could be used without serious concern. The most important side effects observed were a severe reduction in heart rate and 1st degree atrioventricular (AV) block and, to a lesser extent, 2nd degree AV block caused by medetomidine and midazolam which were masked by the anesthetics.

Impact of referral diagnosis on diagnostic yield in 1-day vs 7-day and 14-day extended wear holter

Abstract Background Use of Extended Wear Holter (EWH) with monitoring durations up to 14 days has become common in clinical practice. When ordering a monitor, a referral diagnosis (RefDx) is provided to indicate the reason for the study. We previously presented data showing EWH monitors, irrespective of RefDx, provided a 2x diagnostic yield (DY) at 7d and 2.5x DY at 14d when compared to 1d Holter. Purpose To determine the impact of RefDx on DY for clinically significant arrythmias (CSA) using ePatch EWH monitoring for 1d, 7d, and 14d. Methods From October - December 2021, retrospective data was analyzed for RefDx (ICD-10 diagnosis code) and DY of CSA for ePatch with 1d, 7d, and 14d of analyzable data. RefDx were categorized as Common and Uncommon. Common RefDx included ICD-10 codes which represented at least 1.5% of total referrals on 1d monitors, while all RefDx with <1.5% were grouped together as Uncommon. CSA was defined as Bradycardia < 40 bpm, Pause ≥ 3 seconds, ≥ 2nd Degree AV Block, AF > 30 sec, SVT > 160 bpm for ≥ 3 beats, and VT > 100 bpm for ≥ 3 beats. DY was calculated as the percentage of patients with at least one CSA over the monitoring duration. Patients with Chronic AF were excluded from this analysis. Results RefDx for patients who wore ePatch for 1d (n=21,505), 7d (n=9,252), and 14d (n=11,269) are shown in the Table. Irrespective of monitoring duration, the most frequent RefDx was Palpitations (>35%). For each RefDx, the DY for any CSA at 1d vs 7d, 1d vs 14d, and 7d vs 14d was statistically significant (see Figure). Across all RefDx, DY increased 1.7x - 2.8x when comparing 1d to 7d, 1.9x - 4.2x when comparing 1d to 14d, and 1.1x – 1.5x when comparing 7d to 14d. For 1d, the lowest DY was for RefDx Chest Pain (13%) while the highest was for RefDx Bradycardia (43%). The DY benefit of extending monitoring from 1d to 7d was normally distributed across RefDX, while the DY benefit of extending monitoring from 7d to 14d was greatest (1.5x) for Chest Pain, and the DY benefit of extending from 1d to 14d was greatest (≥3.4x) for Chest Pain, Tachy Unspecified, Palpitations, Syncope/Collapse, and Dizziness/Giddiness. Notably, the most common RefDx of Palpitations demonstrated a DY of only 17% at 1d that increased 2.5x at 7d and 3.4x at 14d. Conclusion The impact of extending monitoring duration from 1d to either 7d or 14d was that a disparity in additive DY was observed when analyzing by RefDx. The 5 RefDx with the lowest DY for 1d of monitoring showed increases of ≥2.5x DY at 7d and ≥3.4x Dy at 14d of monitoring. Conversely, the 3 RefDx with the highest DY for 1d of monitoring showed <2X DY at 7d and <2.2x DY at 14d. Our data suggests that the RefDx can potentially be used to guide an optimal duration of telemetry monitoring.

Abstract 15099: Sex Disparities in Patients With Cardiac Sarcoidosis Undergoing Implantable Cardioverter-Defibrillators Implantation in the United States

Introduction: In patients with cardiac sarcoidosis (CS), implantable cardioverter-defibrillators (ICDs) are utilized to avoid sudden cardiac death. We aimed to compare the sex disparities in CS patients undergoing ICD implantation.Hypothesis:Higher ICD implantation would be observed in male CS patients as compared to females. Methods: Males and females with CS receiving ICD were identified and compared from the 2016-2020 National Inpatient Sample (NIS) database whilst adjusting for confounders via logistic regression models. Results: Of the 760 cardiac sarcoidosis patients undergoing ICD implantation, 505 (66.4%) were males and 255 (33.6%) were females. Around 94.1% of all procedures (715 cases) were conducted in urban teaching centres. In comparison to females, males were younger (55.0 vs 56.9 years, p<0.01) with higher prevalence of diabetes (31.7% vs 21.6% p<0.01) and chronic kidney disease (CKD) (16.8% vs 7.8% p<0.01) and a lower occurrence of reported depression (5.0 vs 19.6 p<0.01). Atrial fibrillation (AF) (23.5% vs 11.9%, p<0.01), sick sinus syndrome (SSS) (7.8% vs 4.0%, p=0.024) and ventricular fibrillation (VF) (15.7% vs 9.9%, p=0.02) were more prevalent in female CS receiving ICD. The percentages of ICD use in those with a history of hypertension, smoking, obesity, lipid disorder, previous myocardial infarction, supraventricular tachycardia, ventricular tachycardia, 2nd degree AV block and complete AV block were similar for both male and female CS patients. Following ICD implantation, the mean length of stay and mean hospital charges were comparable between the two groups. Incidence of acute kidney injury (AKI) post-ICD was more common in males (23.8% vs 15.7%, p=0.01) (Table 1). Conclusion: AF, SSS and VF are more prevalent in female CS patients with ICD. However, ICD use in CS patients is generally more common in males who also have a greater prevalence of diabetes, CKD and post-ICD AKI.

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 < 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.

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.

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

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.

Frequency of Reversibility of Complete Heart Block in Acute Myocardial Infarction

Objective The aim of current study was to evaluate the frequency of reversibility of complete heart block in patients of acute myocardial infarction. Methods Total one hundred and thirty eight patients with complaint of syncope and atypical chest pain presented at emergency ward of Punjab Institute of Cardiology, Lahore. All patients underwent conventional coronary angiogram to roll out the ischemic etiology of underlying bradyarrhythmias. Among them more than 90% patients have mild coronary artery disease and they were kept on medical management. But all patients remained TPM dependant for two weeks which were then treated with permanent pacemakers. Results Results of the current study revealed that the mean age of patients was 51.48 ± 15.46 with minimum age 18 and maximum was 65 years. Out of 138 patients, 84(61%) were male while 54(39%) were female., 52(37.7%) patients diagnosed of diabetes mellitus, 75(54.3%) patients of hypertension and 58(42.03%) patients were smoker, 41(29.7%) have family history, 47(34.1%) patients have dyslipidemia and only 50(36.2%) obese patients. Patients divided into two groups; patients with complete heart block in the age grouped between 16-35 years, only 6(4.3%) as compare with age grouped 36-65 years only 10(7.2%) have complete heart block, male 8(5.8%), only 5(3.6%) hypertensive patients and 4(2.9%) diabetic patients suffering complete heart block, 2(1.4%) patients presented during 1-12 hours compare with 7(5.1%) presented between 13-24 hours, results showed statistically insignificant as p-value > 0.05. 2nd Degree AV Block and complete heart block showed significant difference between troponin level as p-value <0.05 in patients diagnosed with ACS. Conclusion Atrioventricular block is frequently reversible in people with AMI. As a result, in situations with AMI permanent pacemaker installation should be postponed.

PO-04-101 SIMPLIFIED CARDIONEUROABLATION TECHNIQUE FROM THE RIGHT ATRIUM ONLY

Functional bradyarrhythmias are caused by parasympathetic hyperactivity in the absence of an organic lesion of the cardiac conduction system. This leads to various types of blocks (atrioventricular block, sinus arrest) and the development of symptoms such as dizziness, severe weakness or syncope. At the moment, ablation of ganglionated plexi is practiced in the world to suppress vagal hyperreactivity and serves as an alternative to pacemaker implantation. Is to develop and study a new simplified technique of cardioneuroablation in patients with vasovagal bradyarrhythmias. Our method consists of the following steps: 1. Carotid sinus stimulation. We used frequent stimulation of the carotid sinus region through the jugular vein with a frequency of 3000 pulses per minute. 2. Ablation. In case of Atrio Ventricular Block we created ablation line from foramen ovale to coronary sinus. And for Sinus Node Disfunction – create ablation line in medial part of the confluence of the superior vena cava into the right atrium. 3. Carotid sinus stimulation to evaluate the result of ablation. In case of insufficient effect, additional ablation line were performed. The inclusion criterion was the transient nature of the heart rhythm disorder. We included 27 patients with symptomatic bradyarrhythmias in the study. Among them, 15 women and 12 men. Mean age 42±6.3 years. On the 24-hour ECG monitor, episodes of sinus node arrest were recorded in 10 patients, and atrioventricular blockades of various degrees were recorded in 17 patients. All operations were performed under general anesthesia. In all cases, stimulation of the corotid sinus induced atrioventricular block or sinus arrest for more than 3 seconds At follow-up for an average of 10.2±1.3 months, patients did not report symptoms. During the follow-up on daily ECG monitoring no blockade was recorded, except for one patient who had 2 episodes of 2nd degree AV block, type 1, at night. All patients noted an improvement in well-being and no syncope was noted during follow up. There were no complications. Cardioneuroablation is currently an alternative to pacemaker implantation. A simplified version of cardioneuroablation has shown significant efficacy, which may lead to a greater spread and use of this ablation technique and to mitigate the risks associated with excessive damage to the ganglia or the risks associated with pacemaker implantation.

Bilateral interstitial pneumonia and 2nd degree atrioventricular block as complications after COVID-19 infection

Objective: The epidemiological and clinical manifestations, pathogenesis, and complications in patients in the acute phase of coronavirus infection are described in detail. On the other hand, the term "prolonged COVID" was introduced in early 2020, representing a multisystemic disease that can occur even after a mild course of acute disease. Case presentation: We present the case of a 61-year-old woman who reported severe dyspnea and was previously tested positive for coronavirus. The patient experienced worsening of the health condition again, and a chest X-ray showed changes that correspond to bilateral interstitial pneumonia, and high degree atrioventricular block (AV) was verified on an electrocardiographic record (ECG). After treatment with dual antibiotic therapy and implantation of a permanent electrostimulator (pacemaker), her condition significantly improved. Conclusion: Approximately 10% of patients with COVID-19 may have symptoms persisting beyond three weeks, which presents as post-COVID syndrome. Primary healthcare professionals have a key role in the management of these patients. Research is needed to reveal the pathogenesis, clinical spectrum, and prognosis of post-COVID syndrome.

Aberrant QRS morphologies during atrial tachycardia: What is the mechanism?

A 12-lead electrocardiogram was obtained in a 73-year-old woman after laparoscopic gastric bypass surgery (Figure 1). The electrocardiogram reveals an ectopic atrial tachycardia with a cycle length of 360 ms. There is 2nd degree AV block in a 3:2 pattern. The second PR interval of each 3:2 period is longer than the first, so the block is of the Wenckebach (Mobitz 1) type. In every other Wenckebach cycle, the second QRS is conducted with right bundle branch block aberrancy. What is the mechanism of this pattern of aberrancy?

504 ACUTE HEART DISFUNCTION IN PATIENT WITH PACEMAKER, ATRIAL FIBRILLATION AND OLD MYOCARDIAL INFARCTION: WHAT IS THE REASON?

Abstract Patient (pt) 78 years old, ex smoker, with hypertension, dyslipidemia, iperuricemia and overweight. Myocardial inferior infarction with mechanical rivascularization and implant of drug eluting stent on right coronary artery in 2012. Residual ejection fraction of 47% with inferior hypocinesia. Pacemaker DDD implant for 2nd degree atrioventricular block in 2013. Atrial fibrillation from July 2021. Acute nocturnal heart failure with hypoxiemia (PO2 76%) and necessity of non invasive ventilation in November 2021 without worsening of coronary tree at coronarography and echocardiografic finding of EF 47% with inferior and posterior hypocinesia. Troponin I hs 53.6 pg/ml BNP 378 ng/ml. None relevant arrhytmias at pacemaker control. After hospital admission pt done polisonnography with finding of severe obstructive nocturnal apneas and need of CPAP (continous positive airways pressure). Conclusions in literature obstructive sleep apnea syndrome (OSAS) can cause heart failure, cardiac ischemic disease and hypertension. In this case a long obstructive apnea could have caused severe desaturation with hypoxiemia and then an acute episode of heart failure.

Abstract 13783: Near-Real Time Extended Ambulatory ECG Monitoring in Patients With Syncope Unveils a Spectrum of Arrhythmias and High Incidence of Atrial Fibrillation

Introduction: Patients (pts) with a history of syncope are at high risk for sudden death with a reported 1-year mortality rate of 30%. Triaging relevant arrhythmias (ars) in a timely manner in this population is critical to allow for potential life-saving interventions. For example screening atrial fibrillation (AF) studies of pts with no known AF, reported an AF detection of 4.5% to 5.3%. It is unknown if these findings extend to a syncope population. A recent syncope study reported most significant ars occurred outside the typical window of a hospital stay. Therefore, this study aims to analyze a proprietary Zio AT database containing arrhythmia findings of pts monitored for the diagnosis of syncope. Methods: Data retrospectively analyzed 10,643 pts from US institutions with a syncope indication for monitoring. Pts with recordings between July 2017 to December 2021 were analyzed. All ars transmitted via cellular gateway during the wear period and full ECG download at end of wear were analyzed with a validated proprietary AI algorithm, then followed by a certified cardiographic technician review. Ars were defined as: AF, ≥30 seconds at any heart rate; SVT, ≥90 bpm for ≥4 S beats; Pause, ≥3 second; AV Block, any 3rd or 2nd degree AV Block (Mobitz I or II); VT, ≥100 bpm for ≥4 V beats or PVT, TdP, VF. Detected ars were characterized by duration, episode counts, rates, and/or burden (where applicable). Results: Of the 10,643 pts studied (49% female, mean age 65.4 years, mean wear 11.9 ± 3.6 days), 8,442 (79%) had at least 1 arrhythmia detected, with 3,107 (29%) having 2 or more arrhythmia types. Most common ars detected in this patient population were SVT (69%; 7365/10643), VT (26%; 2716/10643), and AF (9.5%; 1015/10643). AV Blocks (3.6%; 382/10643) and Pauses (6.2%; 662/10643) were not uncommon. Surprisingly, the most common arrhythmia to trigger a notification alert was AF/AFL (8.5%). Average time until first AF detection was 1.4 ± 2.8 days for all AF subjects and 2.8 ± 3.5 days for paroxysmal AF subjects. Conclusions: In this large retrospective study, ambulatory ECG monitoring with ZIO AT in syncope indicated pts revealed an unexpectedly high incidence of AF and SVT. Further analysis of this group may help clinicians focus a heightened awareness of atrial ars in this population.

Abstract 14365: In-Hospital Outcomes of Septal Myectomy versus Alcohol Septal Ablation for Hypertrophic Cardiomyopathy - An Update and Insights From the National Inpatient Sample

Introduction: Septal Myectomy (SM) and Alcohol Septal Ablation (ASA) improve symptoms in patients with Hypertrophic Cardiomyopathy (HCM), however, outcomes data in this population is predominantly from specialized centers. Methods: The National Inpatient Database was queried from 2011- 2019 for relevant ICD-9 and -10 diagnostic and procedural codes. Baseline characteristics and in-hospital outcomes of patients with HCM who underwent SM vs. ASA were compared. A p-value <0.001 was considered statistically significant. Results: We identified 17,245 patients who underwent septal reduction therapies, of whom 62.5% underwent SM and 37.5% underwent ASA. Patients who underwent SM had higher all-cause mortality (OR:2.2 [1.7-2.9]), post procedure ischemic stroke (OR: 2.4 [1.8-3.2]), acute kidney injury (OR: 1.9 [1.7-2.2]), vascular complications (OR: 4 [2.8-5.7]), ventricular septal defect (OR: 4.6 [3.5-6.1]), aortic dissection/aneurysm (OR: 1.6 [1.3-2.1]), cardiogenic shock (OR: 2 [1.5-2.6]), sepsis (OR:5.2 [3.3-8.1]), and left bundle branch block (OR: 3.2 [2.8-3.7]) (p<0.001 for all), compared to ASA. Patients who underwent ASA had higher post procedure complete heart block (OR: 1.2 [1.1-1.4]), 2 nd -degree AV Block (OR: 2 [1.4-3]), right bundle branch block (OR: 6.4 [5.3-7.8]), ventricular tachycardia (OR:2 [1.8-2.3]), supraventricular tachycardia (OR: 1.4 [1.2-1.7]), and more commonly required pacemaker (OR: 1.4 [1.2-1.6]) or implantable cardioverter-defibrillator (OR: 1.3 [1.1-1.5]) (p<0.001 for all) insertion compared to SM. Conclusions: This nationwide analysis evidenced patients undergoing SM had higher in-hospital mortality and periprocedural complications compared to ASA, however, those undergoing ASA had higher post-procedure conduction abnormalities and pacemaker or ICD implantation. The implications of these findings warrant further investigation in regards to patient selection strategies for these therapies.

Abstract 15832: Optogenetic Stimulation of Intrinsic Cardiac Autonomic Neurons Reveals the Interaction Between Catecholaminergic and Cholinergic Pathways

Autonomic tone, through the interaction of catecholaminergic and cholinergic pathways, is a powerful modulator of cardiac function. Until recently, selective activation of cardiac autonomic pathways has required administration of exogeneous neurotransmitters or careful placement of electrodes to stimulate specific neural populations. Optogenetics enables broader exploration of autonomic interactions through the selective expression of channelrhodopsin (ChR2) in neural populations. Our objective was to simultaneously activate catecholaminergic and cholinergic pathways, by exogenous perfusion of neurotransmitter and photostimulation of opposing autonomic neurons, to test the hypothesis that simultaneous activation will reveal the fast kinetics of cholinergic modulation of catecholaminergic increases in heart rate (HR). Norepinephrine (NE) and acetylcholine (ACh) were administered to perfused transgenic mouse hearts that expressed ChR2 within sympathetic tyrosine hydroxylase neurons (TH+ChR2) or parasympathetic choline acetyltransferase (ChAT+ChR2) neurons. Intrinsic neurons were photostimulated by illuminating the SA node with a 465nm high power microLED. The ECG was recorded to measure beat-to-beat changes in HR. Moderate doses of exogeneous NE increased HR 26.77±5.61% (n=3) and high doses increased HR 59.74±8.77% (n=3). At all NE doses, photostimulation of ChAT+ChR2 neurons immediately reduced HR to values equivalent to, or lower than, pre-NE HR. Arrhythmias were not observed. In companion studies, moderate doses of exogeneous ACh reduced HR 19.98±4.68% (n=7) and high doses reduced HR 51.31±4.07% (n=7). HR increases caused by TH+ChR2 neuron photostimulation were diminished by exogenous ACh in a dose-dependent manner. Increased dosing of exogeneous ACh, with simultaneous TH+ChR2 neuron photostimulation, dramatically shortened the onset of 2 nd degree AV block and increased its severity. At high concentrations of exogeneous ACh, non-sustained arrhythmias were observed upon the cessation of TH+ChR2 neuron photostimulation. These results provide new insight into the kinetics of intrinsic cardiac autonomic interactions and reveal powerful modulation of catecholaminergic activity by cholinergic activation.

Apical versus septal pacing - can we chose the localization of ventricular lead in order to prevent upgrade to cardiac resynchronization therapy?

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Right ventricular apical pacing (RVAp) may be deleterious to ventricular function and hemodynamics due to pacing induced dyssynchrony. In the last decades, some studies showed that RVAp has been associated with heart failure, deterioration of left ventricular function and high mortality. Some patients (pts) may need, during the follow up (FUP), an upgrade to cardiac resynchronizaon therapy (CRT). New techniques have emerged such as RV lead implantation in the high septum or outflow RV tract (RVOT) and, more recently, His bundle/LB pacing. Purpose To compare the need for upgrade to CRT in patients with RVAp versus septal/RVOT pacing. Methods Retrospective single-center study of consecutive pts that implanted pacemakers in a tertiary center between January 1995 and December 2020. We collected data regarding pacing indication, RV pacing site (apex versus septum/RVOT) and need for an upgrade to CRT during follow up (FUP). Our primary endpoint was upgrade to CRT during the FU period. In the model, the impact of localization of the implanted lead on the survival free from upgrade was estimated assuming a neutral effect on mortality. Statistical analysis was performed using T-student test and logistic regression. Results We included 8761 pts, 60.2% (n=5275) were male, with a mean age of 76.5±10.7 years. The main indications for pacemaker implantation were (1) complete atrioventricular (AV) block (2239, 25.6%), (2) sick sinus syndrome (2211, 25.2%), (3) atrial fibrillation with AV block or bradycardia with significant pauses (17.4%) and (4) Mobitz II 2nd degree AV block (1467, 16.7%). RVAp was performed in 1746 (20%) patients and RVOT/septal pacing in 6933 patients (80%; RVOT in 657 (9,5%)). During FUP, 26 (1,5%) RVAp pts and 52 (0,8%) RVOT/septal pacing pts underwent upgrade to CRT, in a total of 78 pts (CRT-P in 54 patients and CRT-D in 24 patients). We observed that patients with RVAp had twice the risk of CRT upgrade during FUP (OR: 2,0 (IC 95% 1,25-3,21), p=0,004) when compared to patients with RVOT/septal pacing. Conclusions Patients with RVAp presented a 2-fold higher risk for upgrade to CRT when compared to patients with RVOT/septal pacing in our center. This retrospective analysis shows that lead implantation in the septum/RVOT should be preferred instead of the apex to reduce pacing induced dyssynchrony and need for CRT upgrade.

C83 USE OF CANGRELOR IN A 63 YEARS OLD MEN SUFFERING FROM ACUTE INFERIOR ST–ELEVATION MYOCARDIAL INFARCTION AND SEVERE IDIOPATHIC THROMBOCYTOPENIC PURPURA: A CASE REPORT

Abstract A 63–year–old man suffering from systemic arterial hypertension, thalassemic trait, recent right ureteral stent implantation, dysthyroidism and thrombocytopenia presented to the Emergency Department with acute chest pain and ST elevation in inferior leads and 2nd degree atrioventricular block. He suffered from idiopathic thrombocytopenic purpura since February 2020, with baseline platelet level (PLT) <10,000/mm³ requiring treatment with deltacortene 5 mg, tranexamic acid 1000 mg x 3/day and fostamatimib 100 mg x 2/day. Upon arrival in the Cardiology Intensive Care Unit (UTIC) an echocardiogram was performed and confirmed inferior myocardial infarction. First laboratory results were significant for PLT of 9,000/mm³ and Troponin I peaked at 31,838 pg/mL. The patient received Acetylsalicylic acid (ASA) 300 mg iv then was urgently transported to the Cath–Lab. Coronary angiography revealed mid right coronary artery occlusion, subsequently underwent primary percutaneous coronary intervention with multiple pre–dilations and placement of dual 3.5x28mm and 4.0x28mm TiNO bioactive metal stent with excellent angiographic results. A temporary Pacemaker was implanted. It was started Cangrelor bolus 30 µ/kg followed by infusion at 4 µ/kg/min for 6 hours associated with unfractionated sodium heparin at a reduced dosage of 50 IU/kg during the procedure and with a subsequent switch to Clopidogrel after an oral bolus of 300 mg. After 24 hours, the patient removed the temporary PMK for resolution of the AV block. The haematologist consultant advised to increase fosfatimib to 150 mg x 2/day and recommended the use of Human Immunoglobulin iv from the second day of hospitalization for 2 days. The patient was discharged on the seventh day, asymptomatic, with dual antiplatelet therapy (DAPT) with ASA 100 mg and Clopidogrel 75 mg daily and did not experience any bleeding during hospitalization. At a one–month follow–up, the patient is symptomatic and continued to tolerate ASA and Clopidogrel with stable PLT of 11,000/mm³. In treating for STEMI, the treatment regimen consists of DAPT that increases risks for bleeding. In patients with thrombocytopenia, the risk for bleeding is multiplied and there are no clinical trials where patients with low platelet count are included, all therapeutic decisions must be made based on clinician’s experience and experts’ consensus. The use of Cangrelor proved to be safe and effective during STEMI even in patient with severe thrombocytopenia.

Cardiac Arrhythmias in Patients with COVID-19 Infection – A Single Center Study

Background: Corona virus disease (COVID-19) has been associated with different cardiac complications including cardiac arrhythmias. Arrhythmias carries a great influence on the outcomes. The pathophysiology of these manifestations remain elusive. This study was aimed to observe the incidence and outcome of cardiac arrhythmia in patients with COVID-19 infection from July 2020 to May 2021. Method: We conducted an observational study of patients ³18 years of age with a clinical diagnosis of COVID -19 infection attending Bangabandhu sheikh Mujib Medical University (BSMMU) with and without cardiac arrhythmias from July 2020 to May 2021. Patients were labeled as having arrhythmia if they had sinus bradycardia (heart rate <40 bpm), A-V block, Atrial fibrillation (AF), atrial flutter (AFL), supraventricular tachycardia (SVT), nonsustained VT, sustained VT, ventricular fibrillation (VF). We excluded those patients presented with Acute Coronary syndrome & cardiogenic shock. Different clinical data including demographics, comorbidities (like Hypertension, Diabetes mellitus, Chronic kidney disease, IHD), baseline electrocardiographic and echocardiographic findings, antiviral therapy, use of any proarrhythmic drugs. Results: Data was collected from 2264 patients from BSMMU with COVID-19 infection. Among them 158 patients (6.97%) had cardiac arrhythmia, 78 (48.91%) had hypertension, 37 (23.41%) ischaemic heart disease, 31 (19.62%) diabetes, 14 (8.88%) had CKD. Out of 158 patients 53.79% had sinus bradycardia (heart rate £40bpm); 16(10.1%) had first degree AV block; 14 (8.86 %) had 2nd or 3rd degree AV block; 27 (17.08%) had AF; 7 (4.40%) had AFL; 6 (3.7%) had SVT; and 3 (1.89%) of had NSVT. Only one of S. bradycardia patient required temporary pacemaker. 80 (93.75%) did not require any specific treatment and 4 ( 6.25%) was ventilated. 14 (8.86%) had advance AV block, 11 (78.57%) was discharged, 1 (7.14%) required permanent pacemaker and 3 (21.42%) needed mechanical ventilation in addition to standard treatment. 40 (25.31%) had AF/AFL/SVT; all of them were treated with different antiarrhythmic drugs. 40.0% needed mechanical ventilation and 60.0% discharged safely. 3 (1.89%) had NSVT or VT, 2 (66.67%) of them needed mechanical ventilation and 1 (33.33%) was discharged safely. 87.32% patient was discharged safely and 16.4% was ventilated. Among 26 ventilated patients 15 (57.69%) was expired. Out of them 11 (68.75% of 16 patient) had atrial tachyarrhythmia, 2 (100% of 2 patient) had ventricular tachyarrhythmia and 2 (16.67% of 12 patient) had bradyarrhythmia. Conclusion: COVID-19 infection made a profound negative effect on the lives of millions of people across the world. More than 3 millions of people already died. Lots of patients of COVID-19 infection developed cardiac arrhythmia and was associated with high morbidity and mortality. Appropriate monitoring by ECG with accurate and early identification of arrhythmia is important for better management and outcome. University Heart Journal 2022; 18(1): 61-64

Cardiac MRI Findings in Patients presenting With Advanced Conduction System Disease

Conduction system disturbance can be the first presentation of underlying structural heart disease, including infiltrative disorders such as sarcoidosis. Appropriate diagnosis may critically influence patient care, including immunosuppression and ICD therapy. We sought to investigate the clinical utility of cardiac MRI in this patient population. We evaluated all patients undergoing cardiac MRI between 2005–2021 at The Alfred for investigation of complete AV block or advanced distal conduction system disease (Mobitz II 2nd degree AV block, LBBB or bifascicular block). Patients with pre-existing devices were included in the analysis. We identified 122 patients (mean age 48±15 yrs, 57% male) fulfilling inclusion criteria. Complete heart block was the leading conduction abnormality (37%), followed by LBBB (17%) and Mobitz II second degree AV block (12%). Twenty-nine patients (24%) had a diagnosis of extra-cardiac sarcoidosis at the time of CMR referral. The majority of patients (80%) had normal LV systolic function (LVEF > 50%) on echocardiography. Left ventricular fibrosis (LGE) was seen in 33/122 (27%) patients. Cardiac sarcoid was the most common final diagnosis (n=16, 13%), of whom only 5 (31%) had known extracardiac sarcoid prior to CMR. Other diagnoses were: non-ischaemic cardiomyopathy (n=2), myocarditis (n=2), amyloid (n=1). Nearly a third of patients undergoing CMR for investigation of conduction disease had evidence of fibrosis. Cardiac sarcoid was diagnosed in nearly half of these patients, most of whom had no features of extra-cardiac sarcoid. Cardiac MRI may be an important adjunctive tool for investigation of conduction disease, particularly in younger patients.

Abstract 13743: Prevalence of Cardiac Rhythm Disturbances in Heart Failure Patients With and Without Cardiac Amyloidosis: A National Inpatient Sample Analysis

Background: Cardiac amyloidosis (CA) is well-known to affect electrocardiographic findings. However, the impact of CA on the prevalence of cardiac arrhythmias, particularly in heart failure (HF) patients, is unknown. Our aim was to assess the prevalence of arrhythmias in HF patients with and without CA. Methods: A retrospective cohort study was conducted using the Nationwide Inpatient Sample from 2017. About 5,074,059 patients who had acute, acute on chronic and chronic HF as primary or secondary diagnosis were identified and stratified based on the presence or absence of CA using ICD-10 codes. Both univariate regression and literature review were used to determine the covariates. Multivariate logistic regression analysis was used to adjust for confounders and analyze the variables. Results: Out of the 5,074,059 hospitalized patients with a primary and secondary diagnosis of HF, 7,980 individuals had CA. HF patients with CA had a higher prevalence of Atrial Fibrillation (AF) (52.6% vs 39.3%), Atrial Flutter (AFL) (9.4% vs 3.89%), Ventricular tachycardia (VT) (9.6% vs 4%), Supraventricular tachycardia (SVT) (3.9% vs 2.1%), right bundle branch block (RBBB) (2.9% vs 1.6%), 1st degree AV block (1AVB) (3.07% vs 1%), 2nd degree AV block (2AVB) (1.4% vs 0.4%), and 3rd degree AV block (3AVB) (1.25% vs 0.7%) than without. When adjusted to patient demographics, comorbidities, and hospital characteristics, HF patients with CA had higher risk of AF (aOR= 1.67, p<0.0001), AFL (aOR=2.9, p<0.0001), VT (aOR=2.08, p<0.0001), SVT (aOR=1.63, p<0.0001), RBBB (aOR=1.62, p=0.002), 1AVB (aOR=2.27, p<0.0001), and 2AVB (aOR=2.86, p<0.0001) compared to those without. However, there was no significant difference in the prevalence of Ventricular Fibrillation (VF) (aOR=0.92, p=0.82) in the same population. Conclusion: HF patients with CA are 67%, 190%, 108%, 63%, 62%, 127%, and 186% more likely to develop AF, AFL, VT, SVT, RBBB, 1AVB, and 2AVB respectively, than those without. However, HF patients with CA did not have a significant difference in the prevalence of VF, 3AVB, and LBBB. CA is an infiltrative disease process that is known to cause cardiac conduction disturbances. Limitations include the underdiagnosis of CA in our society as well as the non-specificity of ICD codes for CA.