Arrhythmic Storm Research Articles

P476 TOLERATED SUSTAINED VENTRICULAR FIBRILLATION IN LVAD RECIPIENT: THE WALKING DEAD

Abstract A 73–year–old man comes to the cardiac surgery clinic, due to the onset of an arrhythmic storm. In 1999, the patient was diagnosed with dilated cardiomyopathy with finding of a pathogenic mutation of the MYH7 gene by NGS panel analysis. Because of severely reduced systolic function despite OMT and left conduction delay, he underwent CRT–D implant in class IA. The patient‘s course was characterized by multiple exacerbations and a worsening course of ventricular dysfunction (EF 20%), such as to configure a picture of advanced heart failure, INTERMACS III (frequent flyer). Approximately 6 months later, the patient was admitted with signs of hypoperfusion refractory to inotrope therapy and significant congestion. In consideration of age, frailty and irreversible renal dysfunction, the patient was excluded from the transplant list. Therefore, he was a candidate for mechanical support as destination therapy, through the implantation of the Heart Mate III. At admission, the patient was monitored with evidence of ventricular fibrillation (image 1) and relative hemodynamic stability. The vital parameters reported a BP of 90/76 mmHg, FC not evaluable and SpO2 of 80%. For this reason, in anesthesiological assistance, asynchronous external defibrillation (200 J) was performed with restoration of the pacing rhythm. The monitoring of the LVAD showed a series of alerts: a reduction of the Pump Flow and phases of reduction of the Pulse Index (image 2). Event monitoring of the CRT–D revealed that the patient developed an arrhythmic storm, with appropriate but ineffective several shocks. The 8 shocks were followed by the interruption of the device therapies, but the patient, despite the ventricular fibrillation, had preserved perfusion. Medical therapy was optimized (mexiletine add–on) and CRT–D was rescheduled. Conclusions The presence of LVAD ensures a satisfactory cardiac output during arrhythmias that would lead to hemodynamic compromise. For this reason it is possible to identify patients who autonomously come to our observation in "cardiac arrest".

P9 INCESSANT ARRHYTHMIC STORM, EFFECTIVELY TREATED BY VENTRICULOPLASTY

Abstract Arrhythmic storm is an emergency characterized by cardiac electrical instability leading to multiple episodes of sustained ventricular arrhythmias in a short period of time. Patients have multiple comorbidities that require multidisciplinary interventions to achieve clinical stability. The genesis of arrhythmic storm involves a complex interaction between a predisposing arrhythmogenic substrate, triggering factors, autonomic nervous system, and patient comorbidities. Antiarrhythmic drug therapy plays a key role and has been shown to be associated with a significant reduction in VT recurrence. Transcatheter ablation in patients refractory to drug therapy has been shown to reduce arrhythmic recurrences, ICD shocks, and improve patients‘ cumulative survival over time. Rare cases of arrhythmic storm refractoriness treated by plastic ventricle for the purpose of excluding scar are reported in the literature. We present the case of a 62–year–old man, Caucasian race, suffering from chronic ischemic heart disease with hypokinetic–dilated evolution carrying CRT–D, diabetic, obese, dyslipidemic, undergoing multiple percutaneous revascularizations. Sent to our hospital from a peripheral hospital for arrhythmic storm refractory to maximal antiarrhythmic therapy treated with multiple internal and external DC shocks. During hospitalization, the patient underwent SEF and attempted ATC which was ineffective in the following days due to recurrence of numerous episodes of TVS. In view of the clinical picture and refractoriness to therapy, it was decided to perform coronary examination which found subocclusion of the 1st diagonal branch treated by implantation of medicated stent. On ventriculography, the presence of severe pseudoaneurysmal formation supplied at the level of the anterior wall of the left ventricle was confirmed. It was decided to transfer the patient to cardiac surgery to perform ventriculoplasty surgery. In the following days, the patient underwent surgery through exclusion of the aneurysm by patching in pericardium in CEC. Procedure was free of complications. On follow–up echocardiogram dilated left ventricle with severe left ventricular dysfunction with findings of cardiac aneurysm exclusion. In the following days, the patient presented no further arrhythmic episodes.

P165 ARRHYTHMIC STORM IN SUBACUTE MYOCARDIAL INFARCTION: A CASE REPORT

Abstract Introduction Ventricular arrhythmias (VA) represent a common complication of myocardial infarction (MI). Typically, they occur in two scenarios: during acute MI, related to ongoing ischemia, as ventricular tachycardia (VT) or ventricular fibrillation (VF), or in the context of a late phase of MI, related to the presence of a scar, as monomorphic VT (mVT). Despite the above, their occurrence may be atypical. Clinical Case 55–year–old man affected by obesity, diabetes and hypertension, admitted to our department for subacute MI. Coronarography showed three–vessel disease with indication for surgical revascularization. Thirty hours after admission, in absence of symptoms, occurrence of cardiovascular arrest due to mVT, which degenerated into VF. After resuscitation, ECG and Echo findings did not change compared to those observed at admission, excluding the presence of current ischemia. A blood gas analysis excluded dysionias. Few minutes later, arrhythmic recurrence of mVT degenerated into VF. This was refractory to electrical and antiarrhythmic therapy and stopped only after percutaneous left stellate ganglion block (LSGB) and deep sedation. Then, emergency surgical revascularization was performed. In the early postoperative days, during weaning attempts from sedation and ECMO support, that had become necessary due to hemodynamic instability after surgery, numerous recurrences of mVT, regressed only after deepening of sedation, multiple external shocks, antiarrhythmic polytherapy, and LSGB. A new coronarography documented patency of coronary artery bypass grafts. On 6th postoperative day, discontinuation of deep sedation and weaning from circulatory support without recurrence of VA. The patient was discharged from the intensive care unit and started on a rehabilitation pathway. Conclusions mVTs are commonly related to the presence of a scar, formed late after MI, or to the context of ongoing ischemia in acute MI. However, it should be remembered that even during the subacute phase of MI, arrhythmic instability might still occur. The responsible mechanisms are not completely known but it can be assumed that, even in the absence of a new ischemic event, the process of scar maturation may have led to a transient proarrhythmic substrate, responsible for the arrhythmic storm. Further studies are needed to clarify the mechanisms of arrhythmogenesis in the subacute phase of MI.

Hemorrhagic and ischemic complications of percutaneous transvalvular microaxial flow pump

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Percutaneous Transvalvular Microaxial Flow Pump for Mechanical Circulatory Support (p-MCS) is increasingly used for treating cardiogenic shock (CS). However, it associates complications due to the need for a peripheral access and anticoagulation. Purpose We aim to describe the bleeding and ischemic complications derived from p-MCS support and their possible causes. Methods Analytical and observational study of 31 consecutive patients (pts) admitted for CS to our Acute Cardiovascular Care Unit who were assisted by p-MCS from March 2020 to September 2022. We analyze demographic and other variables with the use of conventional statistic. Results The registry included 31 pts, 77,4% were males and the mean age was 56,5 years. The causes of CS were: 77,4 % acute myocardial infarct (AMI), 6,5 % arrhythmic storm, 12,9% acute heart failure and 3,2% mechanical complication of AMI. 21 were supported only by p-MCS (67,7%), 9 by p-MCS and Venoarterial Extracorporeal Membrane Oxygenation (29%) and 1 by p-MCS for right and left ventricle simultaneously (3.2%). According to Society for Cardiovascular Angiography and Interventions (SCAI) classification, 6,6% of pts were in stage B, 20% in C, 46,7% in D and 26,7% in E. The median support duration was 4 days. The mortality during support was 35% (11 pts) and at day 30, 42% (13 pts). 19,3% presented ischemia of the limb where the p-MCS was inserted. 1 case was mild and 5 were major and required surgery (two compartimental syndromes due to muscular necrosis included). Women presented higher rates of ischemia (57,1 vs 8,4%, p=0.005) and trend to be more severe (100% of the cases were major vs 50% in men, p=0,105). The pts who developed ischemia were older (62,1 vs 55,1 years, p=0.034). 40% of pts presented systemic bleeding: 2 (6,7%) were fatal, 6 (20%) major (defined by the drop of 2 points of hemoglobin, the need for 10 ml/kg blood transfusion or retroperitoneal, pulmonary or surgery-required hemorrhages) and 4 (13,3%) mild. The median of length support was 9 days in pts with systemic bleeding versus 3 days in pts without (p=0.016). Local (pericannula) bleeding appeared in 46,7% of the pts, resulting major (dressing change every 4 hours) in 8 (26,7%) and mild in 6 (20%). Regarding systemic ischemic events, 5 strokes (16.1%) were reported, without diferences between groups for the analyzed variables. Conclusions p-MCS is effective at the management of CS with a mortality at 30 days of 42%, which is acceptable considering the pathology severity. However, it implies risk of ischemic and hemorrhagic complications. In our registry, 46.7% of the pts presented local bleeding, 40% systemic bleeding, 19,3% limb ischemia and 16,3% stroke. Female sex and older age seem to be risk factors for developing ischemia, as well as longer duration of support for systemic bleeding. More studies are needed to describe the pts profile who are more exposed to these complications and how to avoid them.

PO-05-150 A CASE OF QUINIDINE RESPONSIVE PURKINJE-MEDIATED POLYMORPHIC VENTRICULAR TACHYCARDIA

Polymorphic ventricular tachycardia (PMVT) has several different etiologies including ischemic ventricular fibrillation (VF), VF in coronary artery disease without active ischemia, idiopathic VF, and Torsades De Pointes (TdP). To review a case of quinidine responsive Purkinje mediated PMVT and the importance of considering alternative formulations of quinidine. N/A A 74-year-old female with no cardiac history presented with an inferior STEMI. An echocardiogram showed LV ejection fraction of 25% with multiple regional wall motion abnormalities. Left heart catheterization revealed multivessel disease for which she underwent CABG x 2 (LIMA to LAD, SVG to PDA) with intraoperative course complicated by VT requiring lidocaine drip. Ventricular arrhythmias initially seemed responsive to lidocaine; however, 4 days after CABG the patient was noted to have increased ectopic burden on telemetry and ultimately developed PMVT that required defibrillation (Fig 1A, 1B). Repeat catheterization revealed patent stents. Telemetry and ECGs were typical for Purkinje-mediated PMVT, so the patient was started on quinidine sulfate IR 400 mg every 8 hours with successful lidocaine wean and improvement in ectopic burden, with cessation of PMVT. Unfortunately, approximately 9 days after quinidine sulfate initiation the patient was noted to have rising LFTs with a normal abdominal ultrasound, platelet count, and white blood cell count, prompting discontinuation of quinidine. Without quinidine she had recurrence of PVCs that triggered bouts of PMVT (Fig 1C). PVC ablation was considered, targeting short-coupled PVCs in the border zone of scar that could be triggers for the patient’s PMVT. However, it was felt that the patient was too tenuous for ablation. Ultimately, she was trialed on quinidine gluconate ER formulation. This was started as once daily dosing and titrated up to 12-hour dosing with suppression of PVCs/PMVT and no further LFT derangements. The patient ultimately underwent ICD implant for secondary prevention and was discharged home. Purkinje mediated PMVT can occur in patients with coronary artery disease without acute ischemia. We describe a case of quinidine mediated hepatitis that was overcome by switching formulation from quinidine sulfate IR to quinidine gluconate ER. It is essential that hospitals, particularly arrhythmia referral centers, keep quinidine supplies in stock because this medication can be lifesaving during arrhythmic storms.

PO-04-054 FIRST REPORTED HUMAN CASE OF ELECTRICAL STORM TREATED WITH THE NEW HIGH-POWER-SHORT-DURATION TACTIFLEXTMABLATION CATHETER.

In the last decade, standard-power-long-duration radiofrequency delivery systems were the standard care to treat ventricular arrhythmias. Recently, high-power-short-duration radiofrequency delivery systems are available and TactiFlexTM Ablation Catheter is the most recent one. we present the first worldwide case of electrical storm catheter ablation using the new TactiFlexTM. N/A A 78 years old female was admitted to the emergency department because of arrhythmic storm. Thirty days earlier she had been hospitalized for acute coronary syndrome. On initial assessment, she appeared soporous, arterial blood pressure was 80/50 mmHg and ECG revealed sustained monomorphic ventricular tachycardia, regular cycle length, left bundle branch morphology, negative concordance in precordial lead. Patient therapy included metoprolol, mexiletine and cordarone; intravenous lidocaine and procainamide were added, with poor results in controlling arrhythmia; then, we decide to perform VT catheter ablation. Left ventricle mapping was performed with TactiFlexTM and AdvisorTM HDGrid Mapping Catether supported by the new EnsiteX V2 electro-anatomical mapping system and Omnipolar Technology. During voltage substrate mapping we found a central necrotic core area surrounded by a low voltage area in the mild-apical posterior-lateral wall. During late potential mapping the same area showed late and multi-fragmented potentials. Clinical tachycardia was easily induced during programmed ventricular pacing. VT activation map was performed and no meso-diastolic potentials or "early meets late" areas were found, probably signifying a possible epicardial regions involvement in the VT circuitry: it was not possible to reconstruct the entire arrhythmia circuit. Activation velocity map was performed and VT slowed in the same regions of low voltage and fragmented potentials. High-power radiofrequency energy (35W-25seconds or 40W-20seconds pulses) was delivered in the mid-basal posterior-septal wall obtaining VT termination. Subsequently, substrate homogenization, which include late and fragmented potentials elimination, was performed. No ventricle arrhythmias were inducible during programmed ventricular pacing. No procedure-related complications occurred. TactiFlexTM appears safe and effective to control left VT. Further reports and studies are needed to evaluate the most appropriate Watts and seconds to perform effective and safe human left ventricle injuries.

Association Between Shock Etiology and 5-Year Outcomes After Venoarterial Extracorporeal Membrane Oxygenation

BackgroundOutcomes of patients requiring venoarterial extracorporeal membrane oxygenation (VA-ECMO) vary greatly by etiology, but large studies that incorporate the spectrum of shock supported with ECMO are rare. ObjectivesThe purpose of this study was to describe the etiology-related outcome of patients with shock supported with peripheral VA-ECMO. MethodsAll consecutive adults with peripheral VA-ECMO between January 2015 and August 2018 at Pitié-Salpêtrière Hospital (Paris, France) were included in this retrospective observational study. The indication for VA-ECMO was cardiogenic shock. Rates of hospital death and neurological, renal, and pulmonary complications were evaluated according to etiology. ResultsAmong 1,253 patients, hospital and 5-year survival rates were, respectively, 73.3% and 57.3% for primary graft failure, 58.6% and 54.0% for drug overdose, 53.2% and 45.3% for dilated cardiomyopathy, 51.6% and 50.0% for arrhythmic storm, 46.8% and 38.3% for massive pulmonary embolism, 44.4% and 42.4% for sepsis-induced cardiogenic shock, 37.9% and 32.9% for fulminant myocarditis, 37.3% and 31.5% for acute myocardial infarction, 34.6% and 33.3% for postcardiotomy excluding primary graft failure, 25.7% and 22.8% for other/unknown etiology, and 11.1% and 0.0% for refractory vasoplegia shock. Renal failure requiring hemodialysis developed in 50.0%, neurological complications in 16.0%, and hydrostatic pulmonary edema in 9.0%. ConclusionsAlthough the outcome differs depending on etiology, this difference is related more to the severity of the situation associated with the cause rather than the cause of the shock per se. Survival to 5 years varied by cause, which may reflect the natural course of the chronic disease and illustrates the need for long-term follow-up.

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.

136 A SHOCKING CASE OF MYOCARDITIS?

Abstract Background Cardiac involvement is common in systemic sclerosis (SSc), being a poor prognostic factor and the leading cause of mortality. Cardiac involvement ranges from a serendipitous diagnosis to relevant cardiac manifestations such as arrhythmias, pericardial effusion, myocardial dysfunction, and valvular diseases. Case report A 39-year-old female without remarkable medical history, on estroprogestinic therapy was admitted to our hospital in June 2020 after an out-of-hospital cardiovascular arrest due to ventricular fibrillation (VF). A coronary angiography ruled out coronary artery disease. Magnetic resonance imaging (MRI) showed a picture of acute myopericarditis characterized by late linear and nodular intramyocardial and subepicardial gadolinium enhancement of the septal and inferior segments of the left ventricle, with trivial oedema in the same location in turbo inversion recovery magnitude (TIRM) sequences. A subcutaneous-implantable cardiac defibrillator (S-ICD) was positioned for secondary prevention. At the 5 months ICD interrogation, 3 episodes of VF detected and treated by the device were documented. In December 2020 two more appropriate device interventions on polymorphic VT/VF occurred. A septal myocardial biopsy was then performed showing diffused replacement fibrosis in the absence of signs of acute inflammation or virus on the molecular investigation. In March 2021 the patient was referred to our institution after experiencing several ventricular arrhythmia episodes successfully treated by the ICD. A myocardial positron emission tomography (PET) scan documented the uptake of 18-fluorodeoxyglucose at middle and basal septum. A 'targeted' myocardial biopsy showed a substitutive fibroadiposis with sporadic inflammatory cells, in absence of cardiotropic viruses on the molecular investigation. We then initiated Anakinra, an anti-IL1 agent with an anti-inflammatory effect to prevent further development of "inflammation-driven fibrosis". Given the Raynaud's phenomenon reported by the patient, a capillaroscopy was performed, confirming isolated megacapillaries and apical haemorrhages, compatible with early pattern scleroderma. Immunologic examinations found homogeneous ANA 1:320 and anti-RNA polymerase III, while other autoantibodies, viral serologies and tubercular analysis were negative. In October 2021, the patient was readmitted to our hospital for recurrence of arrhythmic storm. A radiofrequency catheter-based ablation was performed. After a new episode of VT properly treated by the S-ICD in May 2022, the device was explanted, and a cardiac resynchronization therapy defibrillator was implanted. The genetic analysis identified a heterozygous deletion (c1262_1263del) of Lamin A (LMNA) classified as probably pathogenic in left ventricular arrhythmogenic cardiomyopathy or dilated cardiomyopathy. Conclusion A diagnosis of borderline myocarditis in anti-RNA-polymerase III+ systemic sclerosis with heterozygous deletion of LMNA was finally formulated, after having excluded pulmonary (PET, forced vital capacity, and CO lung diffusion in normal range), cutaneous, musculoskeletal and gastro-oesophageal involvement as well as a paraneoplastic nature (by total body PET) given the positivity for antiRNA-polymerase III.

178 ARRHYTHMIC STORM IN ATTR WILD TYPE AMYLOIDOSIS: AN UNUSUAL COMBINATION

Abstract Cardiac amyloidosis (CA) is characterized by extracellular protein fibril deposition in the myocardium leading to restrictive heart failure. Both atrial and ventricular arrhythmias are common in CA. Study have shown up to one half of patients with CA die suddenly. However, the most common cause of sudden death has been historically through to be secondary electromechanical dissociation rather than a lethal ventricular arrhythmia. We present the case of a 84 years old man, with a history of hypertension, dyslipidaemia, and prior smoking. In June 2020 the patient was admitted to the emergency room of our hospital due to an episode of hemodynamically unstable sustained ventricular tachycardia (SVT). The patient underwent electrical cardioversion with restoration of sinus rhythm. An echocardiogram that showed a slightly reduced ejection fraction (FE = 45%), severe concentric hypertrophy, grade 3 diastolic dysfunction with high pressures in the left ventricular (LV) cavity, and a reduced GLS (-13.8%) with a typical apical-sparing aspect. A cardiac magnetic resonance (Fig.1). was performed showing a diffuse area of LGE with a subepicardial pattern involving left ventricular and atrial segments, compatible with myocardial storage disease. In order to complete the diagnostic workout, we performed a bone scintigraphy (Fig.2). (Positive for CA, with Perugini score grade 2), a genetic test (negative for hATTR-CA mutations) and free light chain in serum (negative for AL-CA). The patient was discharged at home after ICD implantation in secondary prevention and prescribed appropriate heart failure therapy. In May 2022 the patient was readmitted in emergency room for dyspnea during an arrhythmic storm characterized by several SVTs and ICD interventions, and atrial fibrillation (FA). After stabilization of clinical parameters, the patient was hospitalized in our ward. We optimized medical therapy with metaprololo 100 mg 1 cp BID, cordarone 600 mg ev and mexiletina 200 mg cp BID. During the hospitalization we succeeded in reducing SVT burden. However, ventricular PVCs and slow SVT remained. For this reason, we decided to perform an electrophysiological study (EPS) followed by catheter ablation. The EPS found two low voltage areas (Fig.3). The first were found under the aortic valve; the second was an area of dense scar and fragmented potentials along the basal-posterior wall. After ablation of the first area we succeeded in removing clinical PVCs. During the ablation of the second area the procedure was complicated by ventricular fibrillation that required advanced life support and many electrical shocks. The patient was discharged at home in absence of further episodes of SVTs with optimized therapy At a three moths follow up no arrhythmic events were recorded.

The Use of Cardiac Stereotactic Radiation Therapy (SBRT) to Manage Ventricular Tachycardia: A Case Report, Review of the Literature and Technical Notes

among cardiac arrhythmias, ventricular tachycardia (VT) is one that can lead to cardiac death, although significant progress has been made in its treatment, including the use of implantable cardioverter-defibrillators (ICD) and radiofrequency catheter ablation. Nevertheless, long-term recurrence rates remain in about half of patients and drastically impact the patient's quality of life. Moreover, recurrent ICD shocks are painful and are associated with higher mortality and worsening of heart failure. Recently, more and more experiences are demonstrating potential efficacy in the use of stereotactic body radiotherapy (SBRT) (also called cardiac radio-ablation) to treat this condition. In this paper, we report our experience in the use of cardiac radio-ablation for the treatment of refractory ventricular tachycardia with a focus on the technique used, along with a review of the literature and technical notes. an 81-year-old male patient with a long history of non-ischemic dilated cardiomyopathy and mechanical mitral prosthesis underwent a biventricular cardioverter defibrillator implant after atrial ventricular node ablation. At the end of 2021, the number of tachycardias increased significantly to about 10 episodes per day. After failure of medical treatment and conventional RT catheter ablation, the patient was treated with SBRT for a total dose of 25 Gy in a single session at the site of the ectopic focus. No acute toxicity was recorded. After SBRT (follow-up 7 months) no other VT episodes were recorded. SBRT appears to be safe and leads to a rapid reduction in arrhythmic storms as treatment for VT without acute toxicity, representing one of the most promising methods for treating VT storms.

Mechanical circulatory support in ventricular arrhythmias.

In atrial and ventricular tachyarrhythmias, reduced time for ventricular filling and loss of atrial contribution lead to a significant reduction in cardiac output, resulting in cardiogenic shock. This may also occur during catheter ablation in 11% of overall procedures and is associated with increased mortality. Managing cardiogenic shock and (supra) ventricular arrhythmias is particularly challenging. Inotropic support may exacerbate tachyarrhythmias or accelerate heart rate; antiarrhythmic drugs often come with negative inotropic effects, and electrical reconversions may risk worsening circulatory failure or even cardiac arrest. The drop in native cardiac output during an arrhythmic storm can be partly covered by the insertion of percutaneous mechanical circulatory support (MCS) devices guaranteeing end-organ perfusion. This provides physicians a time window of stability to investigate the underlying cause of arrhythmia and allow proper therapeutic interventions (e.g., percutaneous coronary intervention and catheter ablation). Temporary MCS can be used in the case of overt hemodynamic decompensation or as a “preemptive strategy” to avoid circulatory instability during interventional cardiology procedures in high-risk patients. Despite the increasing use of MCS in cardiogenic shock and during catheter ablation procedures, the recommendation level is still low, considering the lack of large observational studies and randomized clinical trials. Therefore, the evidence on the timing and the kinds of MCS devices has also scarcely been investigated. In the current review, we discuss the available evidence in the literature and gaps in knowledge on the use of MCS devices in the setting of ventricular arrhythmias and arrhythmic storms, including a specific focus on pathophysiology and related therapies.

Stellate ganglion blockade for treatment of ventricular arrhythmia storm: a meta-analysis

Abstract Background Autonomic neuromodulation and particularly stellate ganglion blockade (SGB) has been tested in ventricular arrhythmia (VA) storm, but there is so far no robust evidence to inform clinical practice and its use remains limited. Purpose We aimed to summarize the efficacy and safety of SGB in patients with VA storm. Methods We searched PubMed, the Cochrane Library and Scopus from inception to 15th March 2022, for studies performing either pharmacological or electrical SGB in the context of drug-refractory VA storm. Case series with less than 10 patients were excluded. We performed a single-arm random effects meta-analysis of studies to calculate the pooled proportion estimate of freedom from VA recurrence after SBG and the overall mean change of VA burden from baseline. Results Of 409 articles identified and screened, we considered eligible six studies comprising a total of 106 patients. The mean age was 61.6±13.9 years, 79.2% were male, the mean left ventricular ejection fraction was 28.8±12.7%, and 47.1% had underlying ischemic cardiomyopathy. In five trials the patients received pharmacological SGB with bupivacaine, ropivacaine, or/and lidocaine (left-sided or bilateral), while in one study transcutaneous magnetic stimulation of the left stellate ganglion was used. The pooled proportion of patients free of VA recurrences was 65% (95% CI 51–78%, I2=46%) at the first 24 hours post-SGB (Figure 1A), and 54% (95% CI 43–64%, I2=0%) at 72 hours (Figure 1B). The number of VA episodes was significantly reduced from a mean baseline of 7.01±8.34 episodes/24h before SGB to 0.93±1.64 episodes/24h after SGB. The mean absolute reduction of VA episodes was 5.44 (95% CI 2.83–8.05, I2=88%) (Figure 1C) while the mean absolute reduction of external or internal defibrillation events was 3.36 (95% CI 0.62–6.09, I2=84%) (Figure 1D). No serious procedure-related complications were reported. The overall in-hospital mortality was 28.4%. Conclusions SGB appears an effective and safe treatment in patients with VA storm with approximately 1 in 2 patients exhibiting complete suppression of VA for 72 hours and an approximately 80% mean relative reduction in VA burden. Funding Acknowledgement Type of funding sources: None.

Short-Coupled Idiopathic Ventricular Fibrillation: A Literature Review With ExtendedFollow-Up.

Idiopathic ventricular fibrillation is responsible for approximately 5%-7% of cases of aborted cardiac arrest. Recent studies have shown that short-coupled ventricular premature complexes are present at the onset of idiopathic ventricular fibrillation in 6.6%-17% of patients. The present review provided information on 86 patients with short-coupled malignant ventricular arrhythmias that were reported as case reports or small patient series during the last 70 years. In 75% of the 81 cases published during the last 40 years, extended information and follow-up (from 2.63 ± 4.5 years to 10.67±7.8 years; P< 0.001, between the original publication to the latest update) could be obtained from the authors. The review shows that short-coupled malignant ventricular arrhythmias occurred almost equally in males and females, at the mean age of 40 years. A tendency for later occurrence of the arrhythmia by 4 years was observed in females. A prior history of syncope was noted in 45.3% of the patients, whereas arrhythmic storm occurred in 42% at presentation. The most common mode of revelation of short-coupled malignant ventricular arrhythmias was syncope (53.5%), followed by aborted cardiac arrest (26.7%) and recurrent arrhythmic event after prior implantable-cardioverter defibrillator implantation for idiopathic ventricular fibrillation (17.4%). For the first time, short-coupled malignant arrhythmias exhibiting "not-so-short" coupling intervals (≥350milliseconds) were found in a significant proportion of patients (17.4%). Duringlong-term follow-up, quinidine yielded a slightly higher success rate in arrhythmia control than ablation. Largerstudies are necessary to assess the best strategy for the management of this potentially lethal arrhythmia.

Early Left Ventricular Thrombus Following Ventricular Fibrillation/Ventricular Tachycardia Electrical Storm.

Left ventricular thrombus (LVT) formation is a serious clinical complication of low-flow states that may be seen in an ischaemic, arrhythmic heart. While LVT formation has a poor prognosis, in the setting of myocardial infarction it is usually a result of post-infarct sequelae such as left ventricle aneurysms, and inflammatory changes from damaged tissue, with the LVT taking several days to form. Arrythmias such as ventricular tachycardia (VT) or ventricular fibrillation (VF) may also lead to thrombus formation, as they contribute to stasis due to decreased cardiac output. Large anterolateral myocardial infarctions can cause electrical or arrhythmic storm, characterized by more than three episodes of VT or VF in a 24-hour period. This prolonged state of dyskinesis further increases the risk of thrombosis, creating a compounding effect. Here, we report the case of a patient who had a VF cardiac arrest with electrical storm secondary to anterolateral myocardial infarction complicated with LVT formation found on echocardiogram after the cardiac arrest, which was absent on presentation. This thrombus formation occurred particularly early during the course of the patient’s arrest, possibly due to the compounding factors increasing the risk of thrombosis. Herein, we discuss in detail the risk factors for LVT formation, its mechanism and management options. A review of the literature also shows that LVT formation in the acute phase of arrest, as seen in our patient, is rare.LEARNING POINTSLeft ventricular thrombus (LVT) formation occurs 3–14 days after myocardial infarction, but in the setting of concomitant ventricular fibrillation arrest, may occur within the first 24 hours.Risk factors for LVT formation include a large infarct, anterior/anterior apical infarction, decreased ejection fraction (particularly <30–35%), left ventricular aneurysm, and delayed time to revascularization.Although diagnosis is generally made on transthoracic echocardiography with intravenous contrast, cardiac MRI with contrast has better sensitivity and specificity.Treatment consists of anticoagulation with a vitamin K antagonist or heparin for 3–6 months with a repeat echocardiogram to confirm the thrombus has organized or resolved. Further trials are needed to assess the efficacy of direct oral anticoagulants.

Clinical characteristics, therapy and long-term outcome of short-coupled idiopathic ventricular fibrillation. A systematic review of published case reports with new extended long-term follow-up

Abstract Funding Acknowledgements Type of funding sources: None. Background Short-coupled idiopathic ventricular fibrillation (SC-IVF) is a rare, potentially lethal arrhythmia, initiated by SC-PVCs. Only small series have been published. Purpose To assess the clinical characteristics, therapies and long-term outcomes of patients (pts) with SC-IVF. Methods Data from all published case reports on SC-IVF/Polymorphic VT were collected. Inclusion criteria were normal cardiac work-up including during follow-up (FU), and documented SC-PVC-VF available for our analysis and ruling out early repolarization syndromes and CPVT at VF onset. Updated information was provided by 82% of authors contacted, with 22 additional ECG tracings provided. Results A total of 100 pts’ cases were identified, including 82 who met inclusion criteria. Mean FU increased from 2.75+3.6 years in the original publications to 10.5+7.9 years (p&amp;lt;0.0001). There were 42 (51%) males, aged 39.6+13.5 years at the time of SC-IVF diagnosis. Pts presented with syncope (40%), aborted cardiac arrest (ACA) (16%), ACA + arrhythmic storm (13%), arrhythmic storm (10%), ICD shocks (8%) or palpitations (1%). Prior history included syncope in 32 (39%) pts. Mean coupling interval of the SC-PVC was 293.6+50.7ms. Presumed sites of PVC origin were the RV, LV and RVOT in 54%, 21% and 5% of pts, respectively. A total of 69 (84%) pts had an ICD implanted before or after SC-IVF documentation. During long-term treatment with quinidine (n=11) or verapamil (n=32), SC-IVF did not recur in 82% and 50% of pts, respectively (p=0.08). Ablation was performed in 43 (92%) of the 47 pts in whom it was attempted. Ablation sites were the Purkinje RV (43%) or LV (23%), and the non-Purkinje RV (19%) or LV (2%). Acute and late success rates after a first ablation were 83% and 61.7%, respectively. A second ablation in 7 pts yielded a 74.5% total success rate. No difference was found in the success rate of quinidine compared with ablation procedures (p=0.6). During FU, 4 pts died including 2 from sudden cardiac death; both pts were treated with verapamil and refused ICD implantation or replacement. Conclusion SC-IVF mainly presents following syncope. Quinidine and ablation procedures have comparable long-term high efficacy in arrhythmia control. The commonest sites of successful ablation are the RV and LV Purkinje fibers.

Epicardial mapping as first intention approach for structural ventricular tachycardia ablation

Abstract Funding Acknowledgements Type of funding sources: None. Introduction In several structural arrhythmogenic diseases that comprise intricate endocardial, intramural and epicardial substrates, endocardial ablation of ventricular tachycardia (VT) is not sufficient and epicardial ablation has lately become a complementary and necessary tool. Purpose To evaluate the clinical characteristics of patients (pts) most suitable for first intention epicardial VT ablation. Methods Single-center prospective study of consecutive pts with structural heart disease undergoing first intention epicardial VT mapping between August 2015 and June 2021. Decision for epicardial approach was based on the etiology, VT electrocardiogram (ECG) and cardiac magnetic resonance (CMR) results. Under general anesthesia, subxiphoid access using a Tuhoy needle was done using fluoroscopic guidance and with high-density epicardial mapping was performed. Epicardial ablation was performed if relevant arrhythmogenic findings were locally confirmed. Results First intention epicardial VT ablation was attempted in 18 pts (mean age 59.8±12 years,94% male) of whom 16 had non-ischemic dilated cardiomyopathy (NICM,idiopathic:11; post-myocardis:4; hereditary:1) and 2 had right ventricular arrhythmogenic cardiomyopathy. Mean LVEF was 33% and 79% had a previous ICD (53% in primary prevenon). 69% were referred for ablation due to arrhythmic storm (1pt in cardiogenic shock). Epicardial access was achieved in 17 pts (94%), without acute complications. In 35% pts with NICM the decision for epicardial approach was based on the detection of subepicardial CMR delayed-hyperenhancement and relevant epicardial arrhythmic substrate was confirmed by mapping in all cases. In 3 pts radiofrequency (RF) applicaons were not performed at epicardium, as no abnormal electrograms were locally detected, and an addional endocardial approach was prosecuted. The mean overall procedure and fluoroscopic time were 123 and 28min, respectively, with a mean RF application me of 51min. After the procedure 1pt required pericardial drainage due to inflammatory pericardial effusion. No other acute complications occurred. During a mean follow-up of 2.8±1.8 years, only 3pts (17%) had VT recurrence; 5pts (28%) died due to end-stage heart failure and 2pts (11%) underwent heart transplantation. Conclusion In NICM a first intention epicardial VT ablation performed by experienced operators/centers is efficient, particularly if guided by CMR findings,and presents a safety profile.

P31 PERCUTANEOUS LEFT STELLATE GANGLION BLOCK AS PRE–TREATMENT STRATEGY FOR HIGH–RISK PATIENTS WHO ARE CANDIDATES FOR INVASIVE PROCEDURES POTENTIALLY ASSOCIATED WITH ADRENERGIC STIMULATION: AN HYPOTHESIS–GENERATING CASE REPORT

Abstract Introduction Percutaneous left stellate ganglion block (PLSGB) has been reported as a safety and effective procedure for the management of refractory arrhythmic storm (AS). In this report we present a case of a man with refractory AS effectively treated with PLSGB, subsequently candidate for an invasive procedure potentially associated with adrenergic stimulation and propose the use of this technique as pre–treatment strategy in this clinical setting. Case presentation A 57–year–old man was admitted to our hospital for AS. Past medical history revealed that two years earlier he had been treated with primary percutaneous coronary intervention for ST–segment elevation myocardial infarction. Four months before admission he underwent coronary artery bypass graft surgery with concomitant mechanical mitral valve replacement, closure of an interventricular defect and, considering the severe left ventricular disfunction, he was implanted with an automatic defibrillator in primary prevention. At the time of admission, he was treated with lidocaine infusion with remission of arrhythmic events. Comprehensive diagnostic workup revealed no overt triggers for AS. Five days after admission, the patient experienced recurrence of ventricular arrhythmias (VA), refractory to amiodarone, lidocaine, and magnesium infusion, increased pacing rate, and sedation with dexmedetomidine. PLSGB was then attempted with the injection of lidocaine and ropivacaine using an anatomical approach with complete remission of arrhythmic events. After a week free from VAs, a new AS was observed and PLSGB was repeated using the same modality with complete arrhythmic resolution. Considering the advanced heart failure, the patient was candidate to heart transplantation (HT) and, before undergoing gastro– and colonoscopy required for inclusion in the HT program, with the aim to reduce the risk of VA recurrences triggered by potential adrenergic stimulation, we pre–treated the patient with PLSGB using only ropivacaine, with successful induction of temporary Horner syndrome (Fig. A). The endoscopy procedures were performed successfully with no VA events and the patient was then discharged waiting for HT. Conclusion We propose the use of PLSGB as a pre–treatment strategy for patients at high–risk of VAs who are candidates for invasive procedures potentially associated with adrenergic stimulation. This report could be hypotheses–generating for further studies on this topic.

C2 STEREOTACTIC ABLATIVE RADIOTHERAPY (STAR) IN PATIENTS WITH ICD AND ARRHYTHMIC STORMS

Abstract Background The current therapy of recurrent ventricular tachycardia (VT) and arrhythmic storms is the radiofrequency catheter ablation (RFCA). The first experiences of stereotaxic radioablation of arrhythmia (STAR) as an alternative in patients (pts) with defibrillator (ICD) and Arrhythmic Storms are emerging. However, a standardized method for STAR is not yet available and many issues are still under discussion. We present the preliminary results of STAR in the pts of our Center. Material and method Pts with ICDs and Arrhythmic Storms, excluded from RFCA, were referred to STAR. Diagnostics performed were Electrophysiological study (EPS) using 3D electroanatomical mapping (3DEAM) using CardioInsightTM vest (Medtronic, Minneapolis, MN), cardio–CT scan and 18F–fluorine–2–deoxy–D–glucose positron emission tomography (18FDG – PET scan) in order to identify the target area of the ventricle. In all pts a sustained monomorphic VT was induced during EPS, and 3DEAM was used to identify the exit point of the VT (Fig. 1). In all cases, a 3 mm thick 4D CT scan was used (Fig. 2) with the aid of an abdominal thermoplastic mask. Each patient was treated with a TrueBeam Linac (Varian Medical Systems, Palo Alto, CA). The prescription of the dose from 21 to 25 Gy in a single delivery. Ethics committee approval was obtained prior to each treatment. Results From January 2020 to March 2021, 6 patients (5 M, 1 F), mean age 78 years (58–80) were treated with STAR. The median delivered dose was 25 Gy (range 21–25 Gy). In follow–up (FU) one patient died from end–stage heart failure after 30 days. At a median FU of 13 months, STAR treatment efficacy was observed in 3/5 patients, in whom no defibrillator activation was recorded. 2/5 patients had recurrence of TV, 2 and 6 months after STAR. No severe acute toxicity was recorded after radiotherapy. Conclusions Arrhythmic stereotaxic radioablation appears to be a safe and effective therapy in PTS with ICDs and arrhythmic storms. Completely non–invasive diagnostics and therapy make it very interesting and ambitious. Additional data is needed to improve the definition of the target zone and to standardize it in patients not eligible for RFCA.

P384 SUDDEN CARDIAC ARREST: LET’S LOOK BEYOND CORONAROPATHY

Abstract Introduction Sudden cardiac arrest (SCA) is a high mortality event. Up to 70% of SCAs are caused by an acute coronary syndrome; nevertheless, it is essential to consider also non–ischemic causes while evaluating a post–SCA patient. Clinical Case A 68–year–old male patient with history of hypertension and dyslipidemia, presenting to the emergency room (ER) for syncope. While waiting in the ER, another sincopal episode happened and ventricular fibrillation was detected, therefore he was treated with a DC shock. At the ECG record after SCA, any acute alteration was seen. At the blood tests, an early rise of myocardial injury markers was found. At bedside echocardiography, a slight apical hypokinesia with hypertrabeculation was reported. Hence, coronarography was performed and a multivasal ateromasic coronaropathy was treated with angioplasty and drug–eluting stenting of left main artery, left anterior descending artery and left circumflex artery. In the following days, other ventricular tachyarrhythmias episodes happened and were treated with DC shocks. Due to ventricular arrhythmias relapses and echocardiographic findings, a cardiac MRI was performed, showing subepicardial fatty infiltration in the mid–apical lateral wall with parietal bulging suggesting left ventricle arrhythmogenic cardiomyopathy. So, a cardiac defibrillator was implanted in secondary prevention. Genetic analysis was run and reported a VUS mutation on RYR2 gene, still under evaluation as a possible cause for the clinical events. Conclusions The present clinical case shows that many causes may lead to SCA. Our patient experienced syncopal episodes related to ventricular arrhythmias and an arrhythmic storm which were most likely caused by an ischemic event on the base of an undiagnosed left ventricle arrhythmogenic cardiomyopathy.