History Of Sudden Cardiac Death Research Articles

The role of the arrhythmologist in a sports cardiology centre: the devil is in the detail

Abstract Funding Acknowledgements Type of funding sources: None. Introduction The role of the arrhythmologist in a sports cardiology centre (SCC) is to provide comprehensive care to athletes with cardiac arrhythmias. Objective To determine the proportion of athletes with arrhythmias examined at a SCC. To define the differences in care between an athlete with and without arrhythmia. Methods Retrospective analysis of the registry of all athletes of one SCC. Identification of patients=athletes with arrhythmias, description of key differences in access to arrhythmology subunits. Cohort: Between 1/2020-6/2022, a total of 115 cases of athletes, 100 males and 15 females (13%), aged 26 (+/-11 years), were examined and definitively closed at SCC. Twenty-two athletes (19%) received care for cardiac rhythm disorders. Duration of sports activity was at the borderline of statistical significance in demographic parameters (see Table No. 1), with 15 (+/-11) vs 12 (+/-8) years for athletes with non-arrhythmic diagnoses (p=0.085). Results In the statistical comparison of the groups without and with arrhythmias (Table No. 2), we see a statistically significantly higher proportion of athletes presenting because of symptoms and with pathological findings of the pre-participation screening, with a higher proportion of family history of sudden cardiac death, with a higher proportion of coronary CT use and an extraordinary statistical significance of cardiac MRI use. Conversely, there is no statistically significant difference in diagnosis and impact on sports eligibility. The sports cardiologist must be particularly cautious in the diagnosis and treatment of ventricular extrasystoles, which have a different "diagnostic-eligibility" pathway for athletes. Similarly, they must listen to the medical history more than non-athletes and be willing and able to use various sports monitor records. In invasive methods of diagnosing and treating arrhythmias, it is necessary to understand when arrhythmias occur in real life and try to mimic the diagnostic conditions of this situation (e.g., when inducing clinical arrhythmias that an athlete has in real life during the peak moments of a match or race). Last but not least, the sports cardiologist must communicate the potential changes that may occur by ablative treatment of the arrhythmia (e.g., a decrease in maximal heart rate after AVNRT ablation on the so-called slow pathway, or, e.g. a possible increase in resting heart rate after pulmonary vein isolation with radiofrequency or laser energy). Conclusion Athletes with arrhythmias are different in many aspects, and the role of the arrhythmologist in the sports cardiology team is to be prepared to respect these differences in an effort to provide the best possible care for the athlete.

Added value of 12-lead 24-hour ambulatory ECG monitoring in the identification of a spontaneous type 1 Brugada pattern and its prognostic role. A sub-study of the BHF RASE Brugada project

Abstract Funding Acknowledgements Type of funding sources: Foundation. Main funding source(s): British Heart Foundation Background A spontaneous type 1 Brugada (spT1-BrS) pattern is a recognised marker of arrhythmic risk. However, its fluctuations may underestimate the risk in subjects with concealed T1-BrS at presentation. Aim To investigate the yield of repeat resting and high-lead 12-lead ECG and the additional role of 12-lead 24-hour Holter monitoring with leads V1 and V2 in standard and high precordial ECG positions (12-HPL Holter), and evaluate the prognostic role of spT1-BrS in a large, single-centre, cohort of BrS patients. Methods Three-hundred and eighty-one subjects with BrS enrolled in our Registry from 2008 to December 2021 and with at least 3 months follow-up data were included in this study. Seventy-seven had spT1-BrS pattern at presentation (Group 1), and 304 did not (Group 2). All received lifestyle recommendations and had regular follow-up appointments with 12-lead ECG; the majority of them were also screened with 12-HPL Holter. Medical notes and tracings were reviewed to identify a dynamic spT1-BrS and events at f-up (SCD/appropriate ICD shock). Results The mean age at presentation was 44±15 years; 52% of participants were males. All had at least 2 resting ECGs recorded; in 281 subjects at least one 12-HPL Holter was available (total 643, median 2, range 1-8). Over a median follow-up of 66 months (IQR 75), 37 subjects in Group 2 showed a spT1-BrS at least once: 10 during a repeat resting ECG, 2 during/after exercise tolerance test, 25 at 12-HPL Holter. The average time at spT1 appearance during follow-up was 23 months (range 1- 225). Those with a newly detected spT1-BrS were more frequently males and less likely to have a familial history of sudden cardiac death (Table 1). Excluding subjects with previous aCA/documented VT, 6 events occurred at f-up, all in subjects with spT1 (Figure 1). Univariate models showed that the presence of a spT1-BrS pattern was consistently associated with increased risk of events (at presentation: HR 10, 95% C.I. 1.8-54; at follow-up: HR 5.3, 95% C.I. 1.6-17). Conclusions A spontaneous T1-BrS can be detected in up to 12% of subjects with concealed BrS at presentation using 12-HPL Holter monitoring. Its presence is consistently associated with arrhythmic risk at f-up up, regardless of the time at detection. Prolonged ambulatory ECG monitoring is fundamental for risk stratification in this population.

Invasive risk stratification and implantable loop recorders in brugada syndrome: a single centre experience

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Risk stratification in Brugada syndrome (BrS) is challenging. Cardiogenic syncope, family history of sudden cardiac death and ECG markers are useful variables in determining patient risk. Invasive risk stratification is sometimes needed in those with an intermediate risk phenotype. Implantable loop recorders (ILR) may be considered in those patients with no inducible ventricular arrythmias during programmed ventricular stimulation (PVS). Objective The aim of this study was to retrospectively evaluate the outcome of BrS patients referred for PVS and ILR implantation. Methodology Demographic, clinical and follow-up data of BrS patients seen in clinic were retrospectively analysed from hospital databases. A p vale of <0.05 was considered significant. Results 129 patients have been diagnosed with BrS since launching the inherited arrhythmia clinic service (53.5% males). 15 (high risk patients) had an ICD (n=13, 10.1%) or PM (n=2, 1.6%) implanted because of a hospital cardiac arrest, ventricular arrhythmias, high grade AV Block or cardiogenic syncope. 26 (20.2%) were placed in the intermediate risk category, (65.4% males). Patients were offered an electrophysiology study (EPS/PVS) or an ILR depending on the clinical indication (Figure 1). Most were male (65.4%), with a mean age of 41.8±17.7 years at the time of risk stratification. 6 had a likely or definite pathogenic mutation (n=5 19.2% SCN5A, n=1 3.8% MYBPC3). This group had a median Shanghai score of 4.0±0.9. Gender (p=0.429), age (p=0.246), genotype (p=0.273) and shanghai score (p=0.746) did not differ between strategies. Most (n=12, 9.3%) were offered an EPS/PVS from the offset. Ventricular arrhythmias were induced in 1 (8.3%), an ICD was then implanted. The rest were implanted with an ILR on the day. Patients not offered an EPS (n=14, 10.9%) were initially implanted with an ILR because of insufficient grounds to proceed with an EP study. Patients with an ILR (n=25, 19.4%) were followed up for a median 39 ± 21 months. ILR monitoring identified actionable events in 3 (12.0%) patients. One (4.0%) needed a pacemaker for sick sinus syndrome. Two (8.0%) recorded non-sustained ventricular arrhythmias. Both were subjected to an EPS/PVS, one needed an ICD. None of the patients who had an EPS initially had any significant events during follow up. Conclusion ILR implantation has a role in risk stratifying intermediate risk patients who do not fulfil criteria for EPS referral. This may also be considered in intermediate risk patients who are not keen on an invasive risk assessment with EPS.

P167 CARDIAC ARREST IN SUSPECTED LONG QT: APPROACH TO ARRHYTHMIC MITRAL VALVE PROLAPSE

Abstract Mitral valve prolapse is a common condition. It affects 1–3% of the population. Clinical manifestations range from the absence of symptoms to sudden cardiac death. The arrhythmogenic mechanism is related to fibrotic changes in myocardial posterior caused by valve prolapse. ECG abnormalities indicative of high risk are inverted or biphasic T waves, ST depression, QT prolongation or dispersion, and BEV originating from the left outflow tract or papillary muscles. The echocardiogram allows the identification of mitral prolapse and disjunction of the mitral annulus (MAD), while MRI shows fibrosis. ICD implantation should be considered in high–risk patients with documented ventricular arrhythmias. Clinical case A 29–year–old woman with a family history of sudden cardiac death reported a state of absolute well–being until September 2022 when she presented with syncope with referred pulse failure for which she underwent cardiac massage, without defibrillation, by family members. At the arrival of 118 the patient presented bigeminal ventricular extrasystole with superior axis and BBsx type morphology (Fig.1). When she arrived at the hospital, ECG showed long QT (484 ms) associated with hypokalemia (2.8 mmol / l). During hospitalization, the coronary angiography was normal, while the cardiac MRI showed a globular and dilated left ventricle with preserved EF, thickening of the mitral leaflets, prolapse of both leaflets more evident at the level of P2/P3, MAD more evident in P3 with separation maximum end–systolic of 12 mm and absence of edema (Fig. 2). The patient underwent ICD implantation. In the presence of hypertelorism, prognathism, and flat feet, even in the absence of anomalies affecting the aorta and epiaortic vessels, scarring defects or ease to joint sprain, genetic screening was started for channelopathies and collagen diseases. Conclusions The approach to the patient with cardiac arrest and typical facies must be based on a systemic overview of the patient, whose phenotypic characteristics may suggest involvement of connective tissue diseases. In the future, the cardiologist must develop adequate knowledge to fully collect the information that the patient provides not only during instrumental examinations but also during an adequate clinical objective examination and facies, possibly supported by artificial intelligence.

P162 ARRHYTHMIC MITRAL VALVE PROLAPSE OCCURRING AS ABORTED SUDDEN CARDIAC DEATH

Abstract Mitral valve prolapse (MVP) is the common valvular heart disease, with a prevalence about 1–3% in the population. MVP is characterized on echocardiography by an abnormal systolic displacement of mitral valve leaflets into left atrium (LA) ≥ 2 mm above the mitral annulus. We described a clinical case of a 15 years–old boy with a first clinical presentation of out–of–hospital cardiac arrest related to ventricular fibrillation (VF) with a successful resuscitation after 2 DC shocks. Retrospectively, an episode of loss of awareness reported as post–minational. No familiar history of sudden cardiac death (SCD) or MVP was noticed. In the emergency room, the patient was hemodynamically unstable and was sedated and intubated. The surface electrocardiogram (ECG) showed sinus rhythm, QRS with fragmentation, and frequent monomorphic isolated premature ventricular contractions (PVCs) with RBBB/LAFB configuration.Frequent monomorphic PVCs with bigeminy was observed during continuous ECG monitoring, so the patient was treated with magnesium sulphate and metoprolol. The patient was subsequently weaned from ventilation support, presenting good gas exchange and without neurological sequalae. The 24h Holter monitoring showed an average of 53 bpm, extremely rare supraventricular extrasystoles, high incidence of monomorphic PVCs (23% of the total beats) with 4 couplets. Transthoracic echocardiography documented normal size and thickness with systolic function (GLS –21%, mild asynchrony of posterior basal segments), bi–leaflet prolapse associated to mild–moderate mitral regurgitation, and mitral annular disjunction (MAD) of 6.2 mm. The late gadolinium enhancement cardiac magnetic resonance showed bi–leaflet prolapse with mild insufficiency and maximum MAD 9 mm, mild LA dilatation, and slightly dilated both ventricles, without regional wall motion abnormalities; no scar or fibrosis at the late gadolinium enhancement was observed. According to guidelines, the patient received a subcutaneous implantable cardiac defibrillator for the secondary prevention of SCD and maintained under betablockers in order to control the arrhythmic burden. The genetic sampling did not show any pathogenetic mutation potentially related to cardiomyopathies or channelopathies. This case show an arrhythmic MVP complex with probably posterior papillary muscle source. The early PVCs with R/T constituted a possible trigger of VF. The betablocker therapy exhibited a full suppression of extrasystolic burden.

PO-05-192 LOCAL HETEROGENEITY OF LATE GADOLINIUM ENHANCEMENT PREDICTS VENTRICULAR ARRHYTHMIA IN HYPERTROPHIC CARDIOMYOPATHY

Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death in young people. Despite recent advances in risk stratification using cardiac magnetic resonance (CMR) imaging, risk prediction remains suboptimal. Improved risk stratification is therefore warranted. Whether local heterogeneity of Late Gadolinium Enhancement (LGE) signal is associated with ventricular arrhythmia remains unknown. To determine whether local heterogeneity of LGE signal on CMR predicts ventricular arrhythmia and appropriate shocks after implantable cardioverter defibrillator (ICD) implantation in patients with HCM. Local heterogeneity was quantified by LGE-CMR signal dispersion score and compared with cardiovascular outcomes in 179 HCM patients who underwent ICD implantation. The primary outcome was appropriate ICD shocks. During a median follow-up time of 7.3 years the event rate was 0.015 per person year. History of ventricular arrhythmia (HR 9.413, p<0.001) and sudden cardiac death (HR 13.82, p<0.001) were associated with receiving an appropriate ICD shock in both univariable and multivariable analyses. History of syncope, family history of sudden cardiac death, non-sustained ventricular tachycardia, left ventricular wall thickness and presence of LGE were not associated with the primary outcome. When compared to patients without ICD shock, patients who received ICD shocks had higher burden of LGE gray zone (16.8±7.5% vs 25.8±3.5% p<0.001) and scar (10.5±6.7% vs 18.7±4.3% p<0.001) on CMR. Importantly, patients with ICD shocks had a higher dispersion score (1.20 vs 0.97, respectively), signifying higher degree of LGE signal heterogeneity (p=0.047). Dispersion score, a marker of local LGE signal heterogeneity of scar and gray zone was associated with a higher burden of ICD shocks in HCM patients who received ICDs. Mechanistically, local LGE signal heterogeneity could represent complex scar. These results may contribute to improved risk stratification for ventricular arrhythmia in HCM patients.

PO-04-075 TRANSVENOUS CARDIAC DEFIBRILLATOR WITHOUT INTERACTION WITH THE MAGNETIC TITANIUM BEADS SYSTEM FOR GASTROESOPHAGEAL REFLUX DISEASE

Gastroesophageal reflux is increasingly treated with LINX®, a flexible bracelet of magnetic titanium beads (not MRI compatible) that is laparoscopically implanted to wrap around the gastroesophageal junction for providing tone/support aiding passive relaxation of a weak lower esophageal sphincter with peristalsis. The FDA currently cautions against concurrent use of the LINX® system with cardiac implantable electronic devices (CIEDs) given that the risk of electromagnetic interference (EMI) is unknown, and safety has not been established. We assessed the safety of a transvenous ICD in a patient with the LINX® system. Case Report 59 year old male who previously had the LINX® system implanted after hiatal hernia repair for refractory reflux. Shortly after, he was then diagnosed with apical hypertrophic cardiomyopathy with obstruction (NYHA Class I, genetic testing revealed VUS in CSRP3). Given non-sustained VT on cardiac event monitoring, family history of sudden cardiac death (SCD) and late gadolinium enhancement on cardiac magnetic resonance imaging with a calculated 5-year SCD risk 4.1%, he was recommended ICD implantation for primary prevention. Patient underwent an uneventful transvenous dual chamber defibrillator implantation. Although we do not routinely perform (DFT) testing at our institution, given the coexisting LINX® system in close proximity to the RV lead, we elected to proceed with DFT Testing, which was successful (1 induction: T-wave shock from sinus to VF, 30J delivered successfully to sinus with 7s charge time, no ATP, 70 ohms impedance). Patient underwent routine remote device interrogations and at 1-year follow up (which included an in-person device interrogation), continues to have normal lead parameters (sensing, impedance, threshold), minimal atrial or ventricular pacing, and no recurrent arrhythmias including NSVT (was started on verapamil). Specifically, patient received no inappropriate shocks, and no high frequency noise episodes were detected. We present the first case report of a patient who had a concomitant dual chamber ICD that was implanted shortly after a LINX device placement. We demonstrate normal DFTs at implant and no device interaction at 1 year follow-up, suggesting that ICD implantation without removal of the LINX device might be reasonable. Decision-making for cardiac device implantation decisions in such patients should consider additional theoretical risks until additional data with more patients is available.

PO-04-053 OUT-OF-HOSPITAL CARDIAC ARREST ASSOCIATED WITH EARLY REPOLARIZATION

Early repolarization syndrome (ERS) is characterized by J-point elevation presenting as slurring or notching of the terminal part of the QRS complex. Of the several congenital and acquired disorders that encompass J-wave syndromes, ERS has been linked to increased risk of developing polymorphic VT and idiopathic VF that can lead to sudden cardiac death. To describe a patient who presented after a cardiac arrest with initial ECG criteria consistent with Type III ERS who recieved a dual-chamber ICD. n/a We present a case of a 42-year-old man without any prior history that presented to the emergency room after successful resuscitation from out-of-hospital cardiac arrest due to VF. After noticing agonal respiration during early morning hours, his wife called emergency medical services (EMS) and promptly performed cardiopulmonary resuscitation. Upon arrival, EMS found the patient to be in VF. He was shocked once by an automatic external defibrillation leading to ROSC with restoration of sinus rhythm. In the ED, his initial vitals were 122/93 mmHg, 104 bpm, 95% oxygen saturation on room air, and temperature of 36.4 °C. He denied any family history of sudden cardiac death. Wife reported prior history of nocturnal agonal respirations. Initial diagnostic work-up was significant for a leukocytosis of 19,000 and serial high-sensitivity cardiac troponins of 130, 305, and 364 with a 0/3-hour delta change of 234. A12-lead ECG upon presentation is shown in Figure 1 without previous ECGs available for comparison. An emergent coronary angiography was performed which revealed no significant coronary obstruction or anomaly. With both his ECG findings and a Shanghai Score of 7, a diagnosis of Type III ERS was highly suspected. Further diagnostic testing included a TTE showing left ventricular dysfunction with an ejection fraction of 40-45%. CMR showed no delayed gadolinium enhancement. Ultimately, a dual-chamber ICD was implanted during the admission. Follow-up ECGs revealed resolution of slurred terminal QRS complexes. He was discharged on beta blocker and low-dose losartan with close outpatient follow-up with electrophysiology. ECG changes of ERS can be dynamic and may sometimes be concealed, particularly in the setting of an out-of-hospital cardiac arrest. It is important to identify early repolarization patterns due to the adverse prognostic significance especially of Type III ERS which is associated with the highest level of risk for development of malignant arrhythmia.

Whole-exome sequencing and electrophysiological study reveal a novel loss-of-function mutation of KCNA10 in epinephrine provoked long QT syndrome with familial history of sudden cardiac death

Congenital long QT syndrome (LQTS) is one type of inherited fatal cardiac arrhythmia that may lead to sudden cardiac death (SCD). Mutations in more than 16 genes have been reported to be associated with LQTS, whereas the genetic causes of about 20% of cases remain unknown. In the present study, we investigated a four-generation pedigree with familial history of syncope and SCD. The proband was a 33-year-old young woman who experienced 3 episodes of syncope when walking at night. The electrocardiogram revealed a markedly epinephrine-provoked prolonged QT interval (QT = 468 ms, QTc = 651 ms) but no obvious arrhythmia in the resting state. Three family members have died of suspected SCD. Whole-exome sequencing and bioinformatic analysis based on pedigree revealed that a novel missense mutation KCNA10 (c.1397G＞A/Arg466Gln) was the potential genetic lesion. Sanger sequencing was performed to confirm the whole-exome sequencing results. This mutation resulted in the KV1.8 channel amino acid residue 466 changing from arginine to glutamine, and the electrophysiological experiments verified it as a loss-of-function mutation of KV1.8, which reduced the K+ currents of KV1.8 and might result in the prolonged QT interval. These findings suggested that KCNA10 (c.1397G＞A) mutation was possibly pathogenic in this enrolled LQTS family, and may provide a new potential genetic target for diagnosis and counseling of stress-related LQTS families as well as the postmortem diagnosis of SCD.

Brugada syndrome: epidemiology, diagnosis, and management

Enrika Mačiulaitytė1, Eglė Ignatavičiūtė1, Jolanta Laukaitienė2 1Lithuanian University of Health Sciences, Faculty of Medicine, Kaunas, Lithuania 2Hospital of Lithuanian University of Health Sciences Kauno klinikos, Department of Cardiology, Kaunas, Lithuania Abstract Background. Brugada syndrome (BrS) is a rare pathology characterized by ST segment elevation in the right precordial leads in the absence of established structural heart disease. BrS is potentially life-threatening due to the increased risk of ventricular tachyarrhythmias and sudden cardiac death. Aim: to review the epidemiology, diagnostics, risk stratification, and management of Brugada syndrome. Methods. The literature used for this review was selected using “Google Scholar” and “Pubmed” databases. The search was performed using the following keywords and their combinations: “Brugada syndrome”, “sudden cardiac arrest”, “arrhythmias”, “epidemiology”, “diagnosis”, “management”. Results. BrS usually occurs in middle-aged men, with a global prevalence of 0.5 per 1000 population. BrS should be suspected in individuals with ventricular tachyarrhythmias, cardiac arrest, or a positive family history of sudden cardiac death and 1 of 3 characteristic electrocardiographic (ECG) criteria. Currently, it is recommended to limit genetic analysis to the predominant gene (SCN5A). Assessing the risk of ventricular fibrillation and sudden cardiac death remains the main challenge. Although cardioverter-defibrillator (ICD) implantation remains the first-choice treatment for high-risk patients, drug treatment with quinidine, and radiofrequency ablation (RDA) also effectively reduce the risk of arrhythmias (respectively, 90% and 87%). Conclusions. BrS is a rare pathology, more common in Southeast Asia. BrS is diagnosed by spontaneous or drug-induced ECG changes, although in clinical practice, symptoms or a positive family history are also important. Risk assessment in BrS patients remains challenging. The main treatment methods for BrS patients are ICD implantation, medical treatment, and RDA. Keywords: Brugada syndrome, sudden cardiac arrest, arrhythmias. Full article https://doi.org/10.53453/ms.2023.2.15

807 MATERNAL ANTI-RO/SSA AUTOANTIBODIES AND PROLONGED PR INTERVAL IN A COMPETITIVE ATHLETE

Abstract Background Prolongation of the PR interval is a common finding among competitive athletes. However, further investigations should be performed when the PR interval is markedly prolonged. We report the case of a young male athlete with a late progressive congenital form of autoimmune-mediated atrioventricular block. Case presentation A 26-year-old male athlete was referred to our center because of a significant prolongation of the PR interval (PR=400 ms), firstly found at the age of 7 years in a preparticipation screening and then confirmed when he was 10 years old. He has been playing soccer for 6 hours/week without symptoms or limitations. His personal remote medical history was unremarkable, he did not have a family history of sudden cardiac death, channelopathies, or cardiomyopathies. Vital parameters and physical examination were normal. Blood test results were within the limits, with negative inflammation indexes and normal thyroid function. Ambulatory 12-lead ECG monitoring, including a training session to assess the chronotropic response to exercise, showed a 1st and 2nd type 1 AV block with narrow QRS without pauses and a shortening of the PR interval during the training session, also confirmed by exercise testing. After three months of detraining, no variation in the PR interval was observed. Echocardiography and cardiac magnetic resonance were normal, as well as genetic testing. Finally, we assessed the autoimmunity status of the patient and his mother, given the potential association between damage induced by anti-Ro/SSA antibodies and AV block and we found maternal seropositivity only, compatible with a late progressive congenital form of autoimmune AV bock. Accordingly, no circulating anti-Ro/SSA-autoantibodies were found in the athlete and we did not recommend immuno-modulating therapy. Considering the absence of symptoms and of cardiac, laboratory and genetic abnormalities, no circulating autoantibodies in the patient and the stability of the PR interval, the athlete was deemed eligible for sports competition. We advised him yearly follow-up visits to exclude the possibility of conduction disturbance progression. During the follow-up period he has continued to practice competitive sports without events. Discussion According to current recommendations, 1st degree AV block (up to 399 ms) and 2nd degree type 1 AV block can be considered physiological adaptations to exercise, especially if they disappear during exercise and detraining. Otherwise, further investigations are recommended to exclude abnormalities associated with sudden cardiac death in athletes, such as structural heart diseases, primary electrical diseases and autoimmunity. The most recognized form of autoimmune AV block is congenital (neonatal lupus). Growing evidence supports the existence of a late progressive congenital form, in which the conduction system injury is mediated by transplacental passage of antibodies produced by the mother and cross-reacting with calcium channels in the fetus, with a subclinical presentation in utero/at birth/in the neonatal phase and a manifest conduction disease later in life. Finally, autoimmune AV block can be acquired, in this case autoantibodies are found in the patient only and immuno-modulating therapy can be considered. In our case, maternal only seropositivity supported the hypothesis of a late progressive congenital form.

1013 RADIOFREQUENCY CATHETER ABLATION OF IDIOPATHIC VENTRICULAR FIBRILLATION: A CURRENT SINGLE-CENTRE EXPERIENCE

Abstract Short-coupled idiopathic ventricular fibrillation (SC-IVF) is a rare, life-threatening arrhythmia, accountable for 5–10% of out-of-hospital cardiac arrests (OHCA). Catheter ablation of the short-coupled premature ventricular contraction (PVC) that triggers VF has been shown to prevent VF recurrences in outdated case series. Aim To evaluate the clinical outcome and summarize the recent experience of 3D electrophysiological mapping and radiofrequency catheter ablation (RFCA) of SC-IVFs in a tertiary high-volume referral centre. Methods from January 2016, we enrolled all consecutive patients diagnosed with SC-IVF and treated by RFCA. Structural heart disease was excluded in all patients by means of echocardiography, cardiac magnetic resonance, coronary angiography, and exercise test. Brugada syndrome and long QT syndrome were excluded by Ajmaline and Epinephrine tests, respectively. The CARTO system was used to construct detailed 3D electroanatomic maps of the right and left ventricle. Mapping and ablation were performed with a standard 3.5- irrigated tip catheter. The PVCs were localized by mapping the earliest bipolar electrogram relative to the onset of the ectopic surface QRS (confirmed by QS complex in the unipolar configuration). Pace mapping was used in patients with infrequent PVCs. The origin of PVCs from fascicles/Purkinje network was indicated by initial sharp potentials preceding the ectopic QRS complex. The procedural end point was the abolition of all clinical PVCs. Outcome (freedom from SC-PVCs and VF episodes) was assessed by Holter monitoring and defibrillator memory interrogation. Results eleven consecutive patients [8 men, 3 women; median age 41 (± 5 years)] were enrolled. 10/11 patients (91%) were asymptomatic prior the index VF event, while 1 patient (9%) experienced recurrent syncope. An aborted OHCA was the index event in all patients. Arrhythmic storm was observed at the index presentation in 2 patients (18%). No patient had family history of sudden cardiac death. All patients were implanted with an ICD after the index event. The delay in SC-IVF diagnosis was 3 (± 2 years) from the index event. 2 patients (18%) had ≥ 2 SC-PVC morphologies. The mean coupling interval (CI) of the SC-PVCs ranged from 230 to 330 msec (mean 303 ± 26 msec). The CI/QT ratio ranged from 0.6 to 1 (mean 0.81 ± 0.15). 10 patients underwent RFCA for recurrent VF/ICD shocks and 1 patient for refractory electrical storm. RFCA was based on activation mapping, pace-mapping, and both in 1 (9%), 1 (9%), and 9 (82%) patients, respectively. The sites of ablation were LV Purkinje, RV Purkinje, RV non-Purkinje (RV outflow tract and tricuspid annulus), and LV non-Purkinje (LV Summit) in 3 (27%), 4 (36%), 3 (27%), and 1 (9%) patient, respectively. The first ablation was acutely successful in all patients. 1 patient experienced recurrence of SC-PVCs and VF episodes after 5 days from the first ablation and underwent a second RFCA. There were no peri-procedural complications. After a median follow-up of 22 months (ranging from 6 to 39 months) all patients were free from sustained ventricular arrhythmia recurrences: 10 patients (91%) were free from VF and PVCs; 1 patient (9%) had recurrent SC-PVCs without VF episodes. Conclusions this retrospective study explored the effectiveness of RFCA combined with the advanced electroanatomic mapping in a current cohort of patients with history of OHCA diagnosed with SC-IVF. RFCA of SC-PVCs was safe and highly effective in abolishing VF episodes in all patients.

1103 A SINGLE CENTER EXPERIENCE ON RIGHT VENTRICULAR VS. BIVENTRICULAR FAILURE ASSESSMENT GUIDED BY CMRI AND 3-D ECHOCARDIOGRAPHY

Abstract Background Currently, echocardiography represents the first-line diagnostic test for risk stratification in myocardial dysfunctions, cardiomyopathies (CM) and valvular heart diseases. Three-dimensional (3D) echo imaging improves the accuracy of cardiac chamber volumes evaluation in complex cardiac anatomies and eliminates the need for geometric modelling as well as the errors caused by foreshortened views. On the other side, cardiac magnetic resonance imaging (CMRi) has limited availability and relative high costs, whereas it provides the most accurate and reproducible measurement of atrial, biventricular global and regional systolic function, and can detect myocardial oedema, fibrosis, infiltration, and perfusion defects. Moreover, fibrosis detection by late gadolinium enhancement (LGE) contributes to ventricular tachyarrhythmias (VT) risk stratification. Our experience considers the diagnostic and prognostic role of an integrated approach guided by CMRi and 3-D echocardiography in two different subtypes of arrhythmogenic cardiomyopathy (ACM). Methods In December 2018, a sixty-six-year-old man, without familiar history of sudden cardiac death (SCD) or cardiomyopathies was admitted to emergency department for dyspnoea and chest pain. First ECG showed a VT with right bundle branch block morphology, rapidly cardioverted. In July 2019, a fifty-six-year-old woman, without family history of SCD or ACM, with previous sustained VT episode with right ventricular (RV) outflow tract pattern was admitted to our centre for further examinations. In both cases routine exams were carried out, and, in the suspicious of ACM, genetic tests, 3-D echo and CMRi were performed. Results in the first case, 3-D echo showed hypo-akinesia of left ventricular posterior-lateral wall, reduced ejection fraction (EF) 40%; enlargement of right chambers (RV end-diastolic volume, EDV, 194 ml; RV end-systolic volume, ESV, 152 ml) with reduced indices of systolic function (TAPSE 13 mm; FAC 25%; RV S’ 7 cm/s). CMRi showed global hypokinesia and free lateral wall bulging with RV EDV 235 ml; RV ESV 147 ml; RV EF 26% and reduced left ventricular EF 36%. In the second case, 3-D echo documented RV EDV 175 ml; RV ESV 64 ml with preserved systolic function (TAPSE 20 mm; FAC 47%; global longitudinal strain, GLS, -19%) and bulging of medio-distal free wall, normal EF 57%; GLS -22.7%. At CMRi there was evidence of slight RV dilatation (RV EDV 193 ml; RV ESV 88 ml) and hypokinetic, mildly-reduced global systolic function (EF 49%), images of LGE due to possible diffuse myocardial fibrosis of the free wall with morpho-functional anomalies of the RV. Both cases had negative genetic tests. ACM diagnosis was made according to Padua criteria, and programmed ventricular stimulation (sustained VT induction with hemodynamic instability) mandated cardioverter/defibrillator implantation in both cases. Conclusions In our experience, an integrated approach guided by CMRi and 3-D echocardiography in subtypes of ACM plays a pivotal role for assessing diagnosis by refining disease characterization through additional parameters. The non-invasive high-risk stratification was confirmed by electrophysiologic studies. Further studies for prognostic correlation between CMRi/advanced echocardiography and arrhythmic phenotype are mandatory.

Characterisation and long-term follow-up of children with Brugada syndrome: experience from a tertiary paediatric referral centre.

Brugada syndrome is an inherited condition, which typically presents in young adults. It can also be diagnosed in children, but data in this group remain scarce. This study aims to describe the clinical features, management, and follow-up of children with personal or family history of Brugada syndrome. Retrospective study of consecutive patients with Brugada history followed up in a tertiary paediatric referral centre between 2009 and 2021. Patients were assessed according to the phenotype: positive (with variable genotype) or negative (with positive genotype). Thirty patients were included (mean age at diagnosis 7 ± 6 years, 53% male). Within the positive phenotype (n = 16), 81% were male, and 88% had spontaneous type 1 ECG pattern. A genetic test was performed in 88% and was positive in 57%. Fourteen patients had a negative phenotype-positive genotype, 79% female, all diagnosed during family screening; 43% mentioned family history of sudden cardiac death. Although most of the patients were asymptomatic, the prevalence of rhythm/conduction disturbances was not negligible, particularly if a positive phenotype. No clinically significant events were reported in the negative phenotype patients. Three patients were hospitalised due to an arrhythmic cause, all in patients with a positive phenotype. In our study, the documentation of rhythm and conduction disturbances was not infrequent, especially in patients with a positive phenotype. Despite the significant family history, phenotype negative patients had no relevant events during follow-up. Nevertheless, the management of these patients is not clear cut, and a personalised therapeutic strategy with close follow-up is essential.

Brugada ECG phenocopy in hypertrophic cardiomyopathy: The time matter

An Implantable Cardioverter-Defibrillator was implanted in an asymptomatic 56-year-old man, with type 2 Brugada pattern on ECG, inducible ventricular fibrillation at elective electrophysiological study, and a family history of sudden cardiac death. Seventeen years later, the patient was admitted to the hospital due to palpitations related to a typical atrial flutter. A transthoracic echocardiogram unexpectedly revealed a clinically manifest hypertrophic cardiomyopathy.

Multiple Xanthoma Tuberosum

A 43-year-old unmarried healthy woman presented at the dermatology clinic with xanthelasma (Panel A) and asymptomatic multiple rounded, grouped, and yellow to orange colored nodules, located on the hands and feet for 16 years (Panels B and C). The lesions were 15 mm in size; and were indurated, coalesced, and gradually grown. The patient had no history of diabetes mellitus, hypertension, heart problems, or any history of thyroid disease. On the other hand, she had a family history of sudden death when her brother died at the age of 28 years after a cardiac attack. The vital signs were normal. Full blood counts were normal. Fasting blood glucose was 98 mg/dl (reference range 70 to 99 mg/dl), triglycerides 174 mg/dl (reference range < 150 mg/dl), serum total cholesterol 216 mg/dl (reference range < 200 mg/dl), low density lipoprotein 259 mg/dl (reference range < 116 mg/dl), and high density lipoprotein 29.5 mg/dl (reference range > 55 mg/dl for females). Serum uric acid, liver enzymes, and thyroid function tests were within normal limits. The patient had no evidence of ischemic heart disease or pancreatitis. Treatment started with Rosuvastatin at 40 mg/day. The diagnosis is multiple xanthoma tuberosum (MXT). It is characterized by deposition of lipid at the subcutaneous tissue, particularly on the elbows, knees, face, knuckles, and toe joints. Equal prevalence is reported in males and females. The biopsy is not performed owing to the missing of the patient. This case shed light on MXT associated with abnormal serum lipoprotein levels and a family history of sudden cardiac death. The affected subjects with MXT need long-life follow-up to catch its serious cardiovascular complications as early as possible and treated them promptly.

Abstract 15510: Big Heart Problems: A Case of Reversible Nonischemic Cardiomyopathy Due to Severe Hypothyroidism

Introduction: Cardiomyopathy is a heterogeneous group of myocardial diseases that can result in mechanical and electrical dysfunction. Thyroid insufficiency can increase the risk of cardiovascular abnormalities through multiple mechanisms including ventricular arrhythmias, hypertension, and heart failure. Case Presentation: Our patient is a 40-year-old Hispanic female with a past medical history of papillary thyroid carcinoma with a right-sided hemithyroidectomy in 2019 who presented to the emergency department with a 1-week history of dyspnea and peripheral edema. She has a family history of sudden cardiac death in her father. She discontinued her levothyroxine 75 mcg once daily dose 6 months ago as she believed this was causing her headaches. Her vital signs were significant for a heart rate of 117 beats per minute and a blood pressure of 185/147 mmHg. Her lab work showed a thyrotropin level of 94.6 uIU/mL, free thyroxine of 0.57 ng/dL, troponin T of 22 ng/L, and proBNP of 2660 pg/mL. A transthoracic echocardiogram (TTE) demonstrated global left ventricular hypokinesis with a left ventricular ejection fraction (LVEF) of 30-35%. Her electrocardiogram (EKG) showed normal sinus rhythm and corrected QTc of 494 ms. She received levothyroxine and furosemide and was discharged with guideline directed medical therapy (GDMT). Her outpatient TTE demonstrated improved LVEF of 40-45% after two months of levothyroxine use and GDMT. Discussion: Hypothyroidism has many cardiometabolic effects that directly impact cardiac function. Impairments in cardiac contractility can result in diastolic heart failure leading to low cardiac output, low heart rate, and low stroke volume. Increased vascular permeability results in protein-rich pericardial and pleural effusions. Myxedema, or non-pitting edema can be seen in long-standing, severe hypothyroidism. An increased QTc interval occurs due to prolonged cardiac action potentials which predispose the heart to ventricular irritability. Treatment with levothyroxine can improve cardiac output and contractility, however this carries increased risk of cardiac arrhythmias and myocardial ischemia. Conclusion: Severe hypothyroidism should be considered in cases of isolated nonischemic cardiomyopathy.

Abstract 15535: A Case of Suspected Menstruation Induced QTc Prolongation Leading to Torsades De Pointes

Estrogen is known to produce changes in cardiac electrophysiology specifically in premenopausal women, increasing the risk of arrhythmias. We report a case of Torsades de Pointes (TdP) in a young premenopausal female. A 25-year-old female with a history of anxiety presented to the emergency room (ED) with several days of vomiting. While in the ED, she had an unwitnessed syncopal event, and was found to be in pulseless ventricular fibrillation (V-Fib) . She required one defibrillation to obtain return of spontaneous circulation (ROSC). Initial work up showed calcium 7.6 mg/dl, phosphorous 1.1 mg/dl, magnesium 2.4 mg/dl, potassium 4.0 mg/dl. Remainder of electrolytes were normal. Toxicology screen was positive for cannabinoids. Post ROSC EKG showed sinus tachycardia at a rate of 103bpm with a prolonged QTc of 531ms. Patient was not on any medications outpatient. On further discussion, patient reported no prior history of syncopal episodes, palpitations, and denied any family history of sudden cardiac death. She did report she was presently on her menses. Shortly after admission, she had recurrent polymorphic ventricular tachycardia which degenerated to TdP. She was loaded with magnesium. Echocardiogram showed an ejection fraction (EF) of 35-39% and global hypokinesis. Diagnostic left heart catheterization was performed revealing clean coronaries. Cardiac MRI revealed EF of 43% without any late gadolinium enhancement. Her QTc remained prolonged even with electrolyte normalization. She underwent successful ICD placement and remained event free during the remainder of the hospital course. She will undergo genetic work up for long QT syndrome. Female sex hormones, specifically estrogen, have been described in literature as pro-arrhythmic given its effects on QT prolongation and ion gated channels. Prior cases of menstruation dependent arrhythmias have speculated that the abrupt reduction in estradiol prior to menstruation is associated with increased cyclic adenosine monophosphate dependent arrhythmogenicity. This case highlights the multifactorial etiology of sudden V-Fib arrest in a young female, and the importance of understanding the role that sex hormones play in the underlying pathogenesis.

Arrhythmia detection using insertable cardiac monitors after a negative electrophysiology study in Brugada syndrome: observations from a multicenter Spanish registry

Abstract Background/Introduction Risk stratification in Brugada syndrome (BrS) remains controversial. In this respect, the role of electrophysiology study (EPS) has been subject of debate. It is common practice in some centers to implant an insertable cardiac monitor (ICM) after a negative EPS, especially in the presence of unexplained symptoms. However, the diagnostic value of this approach has never been specifically addressed. Purpose We aimed to describe the baseline characteristics and the main findings of a diagnostic work-up strategy using an insertable cardiac monitor (ICM) after a negative EPS in patients with BrS. Methods We retrospectively evaluated data from a multicenter registry including 56 BrS patients from 7 referral hospitals who received an ICM to help risk stratification. Only patients with a negative EPS (ie, non-inducible VT/VF) prior to ICM implantation were considered for this analysis. EPS protocols differed across hospitals (see Figure 1) Results A total of 26 patients from 5 different hospitals were studied. Mean age was 33.0±12.8 and 77% were male. Spontaneous type 1 pattern was present in 12 patients (46%). Positive genotype was found in 10 (38%) and family history of sudden cardiac death was present in 11 (42%). Previous symptoms were syncope/presyncope in 15 patients (58%) and palpitations in 3 patients (12%). The rest of the patients (30%) were asymptomatic. After a median follow-up of 33.4 months (IQR 16.5 and 43.1 months), none of the patients presented ventricular arrhythmias. ICM allowed the detection of other arrhythmias in 5 patients (19%), which led to specific therapeutic actions in all but 2 of them (see Table 1). ICM-detected arrhythmias correlated with previously reported symptoms only in one of the patients. Conclusion The results of this exploratory analysis support the notion that EPS in BrS has a high negative predictive value for risk stratification. ICM implantation after a negative EPS may allow the detection of incidental arrhythmias during follow-up. Despite the apparent low correlation of these findings with previously reported symptoms, this strategy may lead to important treatment decisions in a significant proportion of patients. Funding Acknowledgement Type of funding sources: None.

Characterization and long-term follow-up of children with brugada syndrome: experience from a tertiary paediatric referral centre

Abstract Introduction Brugada syndrome (BrS) is an autosomal dominant channelopathy, which typically presents in young adults. It can also be diagnosed in children, but data in this age group is scarce. Purpose To describe the clinical features, management and long-term follow-up of children with BrS history followed-up in a tertiary paediatric referral centre. Methods Single centre retrospective study of consecutive patients with history of BrS, defined as having a BrS positive phenotype (BrS(+)), or a negative phenotype-positive genotype (BrS(−)). They were all followed up in a paediatric heart rhythm clinic. Clinical and demographical data were collected and analysed according to the phenotype. Results 30 patients were included, with a median age at diagnosis of 7 years (IQR 1–13) and a mean follow-up time of 7±3 years. Sixteen patients were BrS(+), predominantly male (n=13, 81%). 88% (n=14) performed a genetic test, which was positive in 57% (n=8); the most frequent mutation was SCN5A (n=5). Family history of BrS was present in 56% (n=9) and almost one third had family history of sudden cardiac death (SCD). Most of the patients had a type 1 Brugada ECG pattern (n=14) and 2 patients presented a fever and drug induced pattern, respectively. Fourteen patients were BrS(−), mostly female (n=11, 79%) with a loss-of-function mutation in the SCN5A gene (n=10). They all had family members with BrS, mainly from the paternal side, and 43% (n=6) mentioned SCD history. Although most of the patients were asymptomatic, the prevalence of rhythm or conduction disturbances was not infrequent, particularly in BrS(+) patients (n=12, 75%). Also, in this group and during follow-up, 3 patients had documented supraventricular tachyarrhythmias, and 2 patients had syncope episodes, one of which required an implantable cardioverter-defibrillator. No events were reported in the BrS(−) patients. Nine patients (n=9/30, 30%) were hospitalized, 3 due to an arrhythmic event (all in the BrS(+) group). Overall, no sudden cardiac death event was reported during follow-up. Conclusion In our study, although the majority of the patients were asymptomatic, the occurrence of arrhythmic events was not negligible, especially in the BrS(+) patients. Despite the significant family history, patients with BrS(−) had no events reported during follow-up. Nevertheless, the management of these patients is not clear cut, and a personalized therapeutic strategy with close follow-up is essential. Funding Acknowledgement Type of funding sources: None.