Ventricular Fibrillation Storm Research Articles

Electrocardiographic characteristics and catheter ablation of premature ventricular complex- mediated ventricular fibrillation

Abstract Background Premature ventricular contractions (PVCs) can trigger ventricular fibrillation (VF) in patients with/or without structural heart disease. There are limited data on coexisting electrocardiographic (ECG) features and catheter ablation outcomes in these patients which could suggest the concomitant presence of an abnormal electrical and structural substrate. Purpose We investigated ECG and electroanatomic characteristics and clinical outcomes in patents who underwent catheter ablation of PVCs triggering VF. Methods We analyzed data from a consecutive series of patients who underwent catheter ablation between 08/2019 and 04/2023 for PVCs triggering VF. On the 12-lead ECG, we assessed the following abnormalities: (a) Early repolarization (ER) pattern in either inferior or lateral leads (Figure 1), or (b) QRS Notching of either the native sinus beat or PVC (Figure 2). Post-ablation follow up outcomes were collected using a combination of ICD interrogation, remote transmission and clinical follow up. Results The cohort included 15 patients: age 52.1±16.8 years, 46.7% females, and 26.7% presenting with VF storm. On average, there were 3.8 HV shocks/per patient from an ICD prior to the index ablation procedure (range: 0-19 shocks). On the 12-lead ECG, the mean coupling interval of the PVC leading to VF was 204±82 ms, and an overall narrow PVC morphology with a mean QRS duration of 107±17 ms. We observed early repolarization (ER) in 6 (40%) of the cohort. In most patients (n=11; 73.3%), at least one of the 2 ECG abnormalities were present. An endocardial-only approach was adequate in all patients, and during catheter ablation, Purkinje potentials were targeted in 10 (66%) of the patients. Based on activation and pace-mapping, the PVCs were localized to the following sites: (a) left ventricular (LV) septum in 11 (73.3%), (b) papillary muscles in 2 (13.3%), and (c) other sites such as the Moderator band and right ventricular outflow tract in the remaining 2 (13.3%) patients. The ablation locations on the LV septum extended from basal to mid-septum. After an average of 1.7 ablation procedures targeting PVC-triggering VF, 12 (80%) patients remained free of sustained ventricular arrhythmias and ICD shocks, over a mean follow up of 479±395 days. Conclusion In most patients with PVCs-triggering VF, there was an evidence of an ECG abnormality either in the form of an ER pattern or notching of either the Sinus QRS or the PVC complex on pre-ablation ECG. During ablation, Purkinje potentials and PVCs were mapped to and ablated in the region of the LV interventricular septum and papillary muscles. Over long-term follow up, catheter ablation seemed durable and effective in reducing VF episodes and ICD shocks.Presence of Early Repolarization patternPresence of a notching pattern in the Si

High-risk Brugada syndrome: factors associated with arrhythmia recurrence and benefits of epicardial ablation in addition to implantable cardioverter defibrillator implantation.

This study aims to evaluate the prognostic impact of the arrhythmogenic substrate size in symptomatic Brugada syndrome (BrS) as well as to validate the long-term safety and effectiveness of epicardial radiofrequency ablation (RFA) compared with no-RFA group. In this prospective investigational long-term registry study, 257 selected symptomatic BrS patients with implantable cardioverter defibrillator (ICD) implantation were included. Among them, 206 patients underwent epicardial RFA and were monitored for over 5 years post-ablation (RFA group), while 51 patients received only ICD implantation declining RFA. Primary endpoints included risk factors for ventricular fibrillation (VF) events pre-ablation and freedom from VF events post-ablation. In the RFA group, BrS substrates were identified in the epicardial surface of the right ventricle. During the pre-RFA follow-up period (median 27 months), VF episodes and VF storms were experienced by 53 patients. Independent risk factors included substrate size [hazard ratio (HR), 1.13; 95% confidence interval (CI), 1.08-1.18; P < 0.001], aborted cardiac arrest (HR, 2.98; 95% CI, 1.68-5.28; P < 0.001), and SCN5A variants (HR, 2.22; 95% CI, 1.15-4.27; P = 0.017). In the post-RFA follow-up (median 40 months), the RFA group demonstrated superior outcomes compared with no-RFA (P < 0.001) without major procedure-related complications. Our study underscores the role of BrS substrate extent as a crucial prognostic factor for recurrent VF and validates the safety and efficacy of RFA when compared with a no-RFA group. Our findings highlight the importance of ajmaline in guiding epicardial mapping/ablation in symptomatic BrS patients, laying the groundwork for further exploration of non-invasive methods to guide informed clinical decision-making.

Successful percutaneous coronary intervention with extracorporeal membrane oxygenation in a patient with acute inferior wall myocardial infarction complicated by electrical storm, cardiogenic shock, and cardiac arrest: a case report

BackgroundHigh-risk patients with coronary heart disease who develop acute myocardial infarction (AMI) have severe coronary lesions. If severe complications occur, such as malignant ventricular arrhythmia, cardiogenic shock, and cardiac arrest, implementation of emergency percutaneous coronary intervention (PCI) may be hindered, leading to a higher perioperative mortality rate. Extracorporeal membrane oxygenation (ECMO) can pave the way for rapid myocardial reperfusion therapy. When cardiac arrest occurs, hemodynamic support with ECMO can facilitate revascularization with PCI, which can increase the time available for further salvage and treatment and reduce intraoperative risk during PCI.Case presentationHerein, we report a case of a 61-year-old man with AMI who suffered electrical storm of sustained malignant ventricular fibrillation, cardiogenic shock, and cardiac arrest and was successfully treated with PCI with ECMO support. During PCI, repeated aspiration and removal of the right coronary artery thrombus were performed, and blood flow was restored after right coronary artery balloon dilation. One episode of defibrillation was delivered to restore sinus rhythm. Then, stents were implanted in the distal and proximal right coronary artery lesions to achieve revascularization. After PCI with ECMO support, irreversible malignant arrhythmia returned to sinus rhythm through coronary perfusion, which prevented death following unsuccessful cardiopulmonary resuscitation. After applying active treatments, including anti-shock, mechanical ventilation, anti-inflammation, and organ support, the patient was discharged after his condition and vital signs stabilized. The patient was followed up once a week after hospital discharge, and his cardiopulmonary function recovered well.ConclusionsWith ECMO support, PCI should be performed immediately in patients with inferior wall AMI complicated by electrical storm of sustained ventricular fibrillation, cardiogenic shock, and cardiac arrest to facilitate stent placement, achieve complete revascularization, restore coronary perfusion, and avoid death

Fatal Ventricular Fibrillation Storm in a Young Patient with Marfan Syndrome.

Fatal Ventricular Fibrillation Storm in a Young Patient with Marfan Syndrome.

190 FATAL PEMBROLIZUMAB CARDIOTOXICITY REFRACTORY TO CORTICOSTEROID THERAPY: A CASE REPORT OF CLINICALLY SUSPECTED MYOCARDITIS.

Abstract We report the case of an 80 years old, fit, mildly hypertensive man receiving adjuvant immunotherapy with Pembrolizumab for stage IIIC (pT4a pN1b) cutaneous nodular melanoma, for which he had also undergone radical surgery. His preoperative ECG was unremarkable. Few days after his first Pembrolizumab dose, he started complaining of gradually worsening muscle aches and weakness and double vision, as well as of brief episodes of otherwise asymptomatic palpitations, so that he finally showed up at the Emergency Department (day 1). Clinical examination revealed mild hypertension, low-grade temperature, subtotal bilateral ophthalmoplegia, fatigable left palpebral ptosis, dysarthria, dysphagia, and neck and limb hyposthenia. Laboratory analyses indicated an inflammatory state with mild neutrophilia and elevated C reactive protein, associated to an increase in serum creatinine, creatine kinase and transaminases. Chest x-ray and brain CT demonstrated no alterations. The ECG showed sinus rhythm at 90 bpm and a previously unknown right bundle branch block (RBBB). The patient was admitted to the Internal Medicine ward in the suspect of Pembrolizumab toxicity leading to myositis and myasthenia and to hepatorenal dysfunction, and Methylprednisolone 1 mg/kg/day was administered intravenously ex adiuvantibus, together with Pyridostigmine and low flow oxygen. The next morning (day 2), dyspnea and palpitations ensued, atrial fibrillation at 130 bpm with RBBB was recorded, while the echocardiogram showed normal biventricular dimensions and systodiastolic function, mild aortic and mitral regurgitations, and the absence of pericardial effusion or inferior vena cava congestion. A single, oral, 60 mg dose of Diltiazem was administered, but suspended few hours later upon evidence of atrioventricular block (AVB) 2:1 (HR 40 bpm) quickly escalating to 3:1 (HR 40 bpm) and, later on, of atrial fibrillation with slow ventricular rate (HR 36 bpm). Given a CHA2DS2-VASc score equal to 3, anticoagulation was started. The patient was then moved to the intensive care unit for bradycardia and worsening tachydyspnea. Respiratory function as well as clinical and laboratory parameters of neuromuscular, renal and hepatic impairment began improving (day 3). However, rhythm monitoring showed progression of conduction anomalies with the appearance of sino-atrial block, left bundle branch block and alternance between Mobitz I AVB, AVB 2:1 and complete AVB. High-sensitivity cardiac troponin I remained stably highly elevated, around 25000 ng/L. Control echocardiography showed the onset of mild left ventricular systolic dysfunction with a mild pericardial effusion. A cardiac magnetic resonance was planned to corroborate the hypothesis of Pembrolizumab-induced myocarditis. However, on day 5 respiratory and hemodynamic worsening occurred, up to cardiocirculatory arrest due to an electrical storm of ventricular tachycardia and fibrillation, despite in-range electrolytes, with emergency echocardiogram revealing also a dysfunctioning right ventricle. Despite prolonged resuscitation attempts, including high-dose corticosteroid, death ensued. Widely used in cancer treatment, immune checkpoint inhibitors (ICI) bear the potential for immune-related adverse events, including cardiovascular ones: brady- and tachy- arrhythmias, acute myocardial infarction, pericarditis, myocarditis, pulmonary embolism, and vasculitis; in particular, ICI-related myocarditis, reportedly highly arrhythmogenic, often occurs together with myositis and myasthenia (“triple M rule”); despite immunosuppression, mortality still remains high.

B-PO03-206 TERMINATION OF VENTRICULAR FIBRILLATION DURING CATHETER ABLATION

Catheter ablation (CA) targeting Purkinje triggers is an established technique for treating ventricular fibrillation (VF). However, the mechanism of human VF maintenance is not well understood. While 2 previous cases of spontaneous termination of VF after CA have been reported, none have occurred during radiofrequency (RF) application. N/A N/A A 50 year-old man presented to an outside hospital with a STEMI and underwent PCI to the RCA. He developed VF refractory to IV amiodarone, lidocaine and over 10 defibrillation attempts. He was placed on full circulatory support and transferred to our institution. Procainamide and then PO quinidine were also ineffective with persistent VF storm. The VF appeared to be initiated by a PVC with indeterminate V1 morphology with superior axis and dominant S wave, suggestive of moderator band (MB) or left posterior fascicle PVC (Panel A). He was brought to the EP lab, where the same PVC initiated VF, requiring defibrillation. An ablation catheter was positioned at the MB (Panels B, C). 85 s into an episode of VF, RF energy was delivered and in 3.8 s terminated VF to monomorphic VT (MMVT) (Panel D). The MMVT was then mapped to an exit site lateral to the posteromedial papillary muscle. The signal was 65 ms pre-QRS at this site and ablation terminated VT to SR. VF and VT did not recur and circulatory support was weaned. To our knowledge, this case is the first reporting direct termination of VF during delivery of RF energy. Though it is well known that abnormal Purkinje potentials and resultant PVCs may serve as initiators of VF, this case presents direct evidence that the triggering focus may in fact be critical to VF maintenance.

Case reports of antegrade and retrograde iatrogenic coronary spiral dissection complicating percutaneous coronary intervention: Keep calm and carry on!

Iatrogenic dissection during PCI represents one of the most fearing complication of interventional cardiology, since abrupt hemodynamic instability and patient compromise may occur related to coronary occlusion. In this emergency situation, different hemodynamic support devices and interventional skills, are needed in order to promptly recover the patient from cardiogenic shock, especially when the left coronary three is involved by the dissection. We report herein two different iatrogenic retrograde, and antegrade dissections, one involving both left anterior descending artery, left circumflex and aortic bulb and the second characterized by abrupt closure of left main associated with severe hemodynamic compromise and ventricular fibrillation storm which required continuous DC shocks, Impella and ECMO devices support to stabilize the patient. Both cases were successfully managed percutaneously. Different techniques and tricks in order to re-open the vessels are described. In case of iatrogenic coronary dissection, a “keep calm and carry on” strategy should be adopted by the interventional cardiologist team in order to solve such dramatic complication.

Structurally Abnormal Myocardium Underlies Ventricular Fibrillation Storms in a Patient Diagnosed With the EarlyRepolarization Pattern.

The aim of this study was to investigate the mechanism underlying QRS-slurring in a patient with the early repolarization pattern in the electrocardiogram (ECG) and ventricular fibrillation (VF) storms. The early repolarization pattern refers to abnormal ending of the QRS complex in subjects with structurally normal hearts and has been associated with VF. We studied a patient with slurring of the QRS complex in leads II, III, and aVF of the ECG and recurrent episodes of VF. Echocardiographic and imaging studies did not reveal any abnormalities. Endocardial mapping was normal but subxyphoidal epicardial access was not possible. Open chest epicardial mapping was performed. Mapping showed that the inferior right ventricular free wall activated the latest with local J-waves in unipolar electrograms. The last moment of epicardial activation concurred with QRS-slurring in the ECG whereas the J-waves in the local unipolar electrograms occurred in the ST-segment of the ECG. Myocardial biopsies obtained from the late activated tissue showed severe fibrofatty alterations in the inferior right ventricular wall where fractionation and local J-waves were present. After ablation, the early repolarization pattern in the ECG disappeared and arrhythmias have been absent since (follow-up 18months). In this patient, the electrocardiographic early repolarization pattern was caused by late activation dueto structurally abnormal myocardium. The late activated areas were marked by J-waves in local electrograms. Ablation of these regions prevented arrhythmia recurrence and normalized the ECG.

Refractoriness to subcutaneous implantable cardioverter defibrillator after frequent therapies for ventricular fibrillation storms in a Brugada syndrome case

BackgroundThe subcutaneous implantable cardioverter defibrillator (S-ICD) is an alternative to the transvenous implantable cardioverter defibrillator for the prevention of sudden cardiac death. Here, we report a rare case of refractoriness to an S-ICD after frequent therapies for ventricular fibrillation (VF) storms.Case presentationA 24-year-old man underwent a bout of syncope with vomiting and incontinence at home. He was brought to the emergency room and was witnessed to spontaneously go into VF successfully converted by external defibrillation. Previously, he was diagnosed with a type I Brugada electrocardiogram pattern by a pilsicainide administration test in another hospital. Although he had a family history of sudden cardiac death in 3 relatives, including his brother, he was followed closely without any therapies because he had never had an episode of syncope. He was implanted with an S-ICD without any trouble. Seven months later, frequent S-ICD shocks for VF storms occurred. His VF was controlled by using intravenous amiodarone, which was converted to an oral preparation. However, his VF recurred after another 2 months. The analysis of his S-ICD data revealed that 4 consecutive shock deliveries could not terminate his VF and the final shock delivered could fortunately terminate it because of a high defibrillation threshold test (DFT) due to an increasing shock impedance (64 to 90 Ω). First, we performed an epicardial Brugada syndrome ablation and subsequently replaced and repositioned the S-ICD lead from a left to a right parasternal site. After the re-implantation of the S-ICD, the DFT test improved to within normal range. According to the pathological analysis, infiltration of inflammatory cells and extensive fibrosis were confirmed in the subcutaneous tissue around the shock lead and S-ICD body.ConclusionFrequent S-ICD shocks for VF storms might cause various pathological changes around the device and lead to a high DFT.

P3827Low dose of quinidine is effective to normalize the slow inactivation in mutant Kv4.3 channel identified in an early repolarization syndrome patient

Abstract Background Early repolarization syndrome (ERS) is characterized by J-point elevation in the ECG and ventricular fibrillation (VF). Several mutations in genes encoding cardiac ion channels have been reported as the causes for ERS. For the treatment of ERS, clinical studies have shown that quinidine is effective for the suppression of electrical storm. However, the mechanism or the optimal concentration for quinidine to suppress the electrical storm has not been elucidated yet. Purpose The aim of the present study is to clarify pharmacological effect of quinidine on mutant Kv4.3 channel by electrophysiological analysis and to establish theoretically effective treatment for ERS. Methods A KCND3 mutation, p.G306A, identified heterozygously in a 12-year-old boy was examined by whole-cell patch-clamp methods using CHO cells. We performed functional analysis of the Kv4.3 channels encoded by KCND3 of wild-type (WT), heterozygous (WT/G306A), or homozygous (G306A) mutants. Pharmacological normalizing effects of quinidine to the WT and mutant channels were investigated by loading test in various concentration. The sensitivity of quinidine was evaluated in terms of the concentration of the clinical course and the loading test. Results The patient suffered VF while sleeping or under sedation. Significant J-point elevations in multiple leads were recorded and he was diagnosed as ERS. Quinidine administration in the serum concentration of 1.2 to 3.1 μM was effective to stop his VF storm. Mutant Kv4.3 currents showed significantly slow inactivation time course (Fig 1), which meant that the mutation caused the gain-of-function channel. Quinidine loading to the mutant Kv4.3 normalized the inactivation time course in concentration-dependent manner (Fig 2, 3). In the loading concentration of 1 μM, the peak currents were not changed regardless of the voltage (Fig 4). The optimal serum concentration of quinidine in clinical use as multi-ion-channels blocker is 6 to 15 μM and the concentration was higher than that of the patient to stop the VF storm. The electrophysiological analysis showed that the low dose loading of quinidine was effective to prevent the gain-of function change of mutant Kv4.3 channels. Electrophysiological analysis Conclusions We showed the pharmacological mechanism of quinidine against the mutant Kv4.3 channels identified in an ERS patient. Even the low concentration of quinidine was effective to normalize the slow inactivation, gain-of-function, in mutant Kv4.3 channels. Our data would be helpful to confirm the optimal concentration of quinidine for ERS patients to avoid adverse effect.

A de novo gain-of-function KCND3 mutation in early repolarization syndrome

Early repolarization syndrome (ERS) is characterized by J-point elevation on electrocardiograms and ventricular fibrillation (VF). Early repolarization arises from augmentation of the transmural electrical gradient in the cardiac action potential; therefore, the transient outward potassium current (Ito) has been regarded as a key candidate current for elucidating the mechanism of ERS. KCND3 encoding Kv4.3, an α-subunit of the Ito channel, is considered as one of target genes. The purpose of this study was to search for novel KCND3 mutations associated with ERS and to clarify the pathogenesis. We performed genetic screening for 11 unrelated probands with ERS and analyzed the electrophysiological properties of detected mutations by patch-clamp methods. A novel de novo KCND3 heterozygous mutation, Gly306Ala (c.917g>c), was found in 1 proband. The proband was a 12-year-old boy, who suffered VF storm and showed significant J-point elevation in multiple leads. Intravenous isoproterenol and subsequent administration of quinidine were effective in preventing VF recurrence and restored the J-point elevation. In electrophysiological analysis, cultured cells expressing mutant Kv4.3 showed significantly increased current densities, slow inactivation, and slow recovery from inactivation compared to wild type. Extracellular application of quinidine significantly restored the inactivation time course in mutant Kv4.3. A simulation study confirmed the relationship between the novel KCND3 mutation and early repolarization on electrocardiograms. A novel KCND3 heterozygous mutation was found to be associated with ERS. The pathogenesis can be explained by the increased Ito. Genetic screening for KCND3 could be useful for understanding the pathogenesis and selecting effective treatment.

Catheter Ablation of Refractory Ventricular Fibrillation Storm After Myocardial Infarction.

Ventricular fibrillation (VF) storm after myocardial infarction (MI) is a life-threatening condition that necessitates multiple defibrillations. Catheter ablation is a potentially effective treatment strategy for VF storm refractory to optimal medical treatment. However, its impact on patient survival has not been verified in a large population. We conducted a multicenter, retrospective observational study involving consecutive patients who underwent catheter ablation of post-MI refractory VF storm without preceding monomorphic ventricular tachycardia. The target of ablation was the Purkinje-related ventricular extrasystoles triggering VF. The primary outcome was in-hospital and long-term mortalities. Univariate logistic regression and Cox proportional-hazards analysis were used to evaluate clinical characteristics associated with in-hospital and long-term mortalities, respectively. One hundred ten patients were enrolled (age, 65±11years; 92 men; left ventricular ejection fraction, 31±10%). VF storm occurred at the acute phase of MI (4.5±2.5 days after the onset of MI during the index hospitalization for MI) in 43 patients (39%), the subacute phase (>1 week) in 48 (44%), and the remote phase (>6 months) in 19 (17%). The focal triggers were found to originate from the scar border zone in 88 patients (80%). During in-hospital stay after ablation, VF storm subsided in 92 patients (84%). Overall, 30 (27%) in-hospital deaths occurred. The duration from the VF occurrence to the ablation procedure was associated with in-hospital mortality (odds ratio for each 1-day increase, 1.11 [95% CI, 1.03-1.20]; P=0.008). During follow-up after discharge from hospital, only 1 patient developed recurrent VF storm. However, 29 patients (36%) died, with a median survival time of 2.2 years (interquartile range, 1.2-5.5 years). Long-term mortality was associated with left ventricular ejection fraction <30% (hazard ratio, 2.54 [95% CI, 1.21-5.32]; P=0.014), New York Heart Association class ≥III (hazard ratio, 2.68 [95% CI, 1.16-6.19]; P=0.021), a history of atrial fibrillation (hazard ratio, 3.89 [95% CI, 1.42-10.67]; P=0.008), and chronic kidney disease (hazard ratio, 2.74 [95% CI, 1.15-6.49]; P=0.023). In patients with MI presenting with focally triggered VF storm, catheter ablation of culprit triggers is lifesaving and appears to be associated with short- and long-term freedom from recurrent VF storm. Mortality over the long-term follow-up is associated with the severity of underlying cardiovascular disease and comorbidities in this specific patient population.

ニフェカラント静注後に心室細動のelectrical stormが抑制された，急性冠症候群の2例

ニフェカラント静注後に心室細動のelectrical stormが抑制された，急性冠症候群の2例

Successful treatment of ventricular fibrillation storm triggered by short-long-short sequence; time to avoid managed ventricular pacing

Sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) is caused by ventricular tachyarrhythmia that can be effectively treated by implantable cardioverter defibrillator (ICD) therapy.We report of a 28-year-old man with HCM and a dual chamber ICD, originally implanted for primary prevention of SCD, (programmed to AAI(R)-DDD(R); managed ventricular pacing (MVP) mode, Medtronic Inc. St Paul, MN USA). He presented with recurrent ICD shocks due to ventricular fibrillation (VF) despite antiarrhythmic therapy. Careful assessment of the stored electrograms demonstrated a repetitive pattern of VF initiation following short-long-short sequences. Initially, activation of ventricular rate stabilization (VRS) algorithm failed to prevent recurrent VF. Ultimately, deactivation of MVP and reprogramming the device to DDD mode with VRS on, resulted in arrhythmia suppression and avoidance of ICD shocks. Physicians should be aware that although VRS function is available in MVP mode, it does not function in the AAI mode during MVP; in order to effectively treat short-long-short sequence induced ventricular arrhythmia by device programming.

Sites of Successful Ventricular Fibrillation Ablation in Bileaflet Mitral Valve Prolapse Syndrome.

Although the vast majority of mitral valve prolapse (MVP) is benign, a small subset of patients, predominantly women, with bileaflet prolapse, complex ventricular ectopy (VE), and abnormal T waves comprise the recently described bileaflet MVP syndrome. We compared findings on electrophysiological study in bileaflet MVP syndrome patients with and without cardiac arrest to identify factors that may predispose to malignant ventricular arrhythmia. Fourteen consecutive bileaflet MVP syndrome patients (n=13 women; median [limits], age at index ablation, 33.8 [21.0-58.7] years; ejection fraction, 60% [45%-67%]; all ≤ moderate mitral regurgitation; n=6 with previous cardiac arrest and implantable cardioverter defibrillator shocks for ventricular fibrillation; and n=8 without implantable cardioverter defibrillator although with symptomatic complex VE) were included. The 2 groups had similar baseline echocardiographic and electrocardiographic characteristics. All patients had at least 1 left ventricular papillary or fascicular VE focus. Purkinje origin VE was identified as the ventricular fibrillation trigger in 6 of 6 cardiac arrest patients (4 from papillary muscle) and Purkinje origin of dominant VE was seen in 5 of 8 (3 from papillary muscle) nonarrest patients. Acute success was seen in 17 of 19 procedures, and a ventricular fibrillation storm occurred within 24 hours of ablation in a single patient. Repeat ablation for recurrent symptomatic arrhythmia was performed in 6 patients. At 478 (39-2099) days of follow-up, 2 cardiac arrest patients received appropriate shocks. Symptoms from VE were reduced in 12 of 14. Bileaflet MVP syndrome is characterized by fascicular and papillary muscle VE that triggers ventricular fibrillation. Ablation of clinically dominant VE foci improves symptoms and reduces appropriate implantable cardioverter defibrillator shocks.

A case of brugada syndrome presenting with ventricular fibrillation storm and prominent early repolarization

A 21-year-old man developed ventricular fibrillation (VF) while drinking alcohol and was admitted to our hospital. An electrocardiogram (ECG) on admission revealed remarkably prominent slurs on the terminal part of QRS complexes in the left precordial leads and a coved type ST elevation at higher intercostal spaces. After hypothermia therapy, he underwent implantation of an implantable cardioverter-defibrillator (ICD). Standard twelve-lead follow-up ECGs revealed early repolarization pattern and an intermittent coved type ST elevation. When the coved type ST elevation appeared, the early repolarization pattern in the inferior and left precordial leads was attenuated. Prominent early repolarization pattern was the most likely trigger of the VF storm in this Brugada patient.

Abstract 19422: Origin of Ventricular Fibrillation in Bileaflet Mitral Valve Prolapse Syndrome

Introduction: Although most patients with mitral valve prolapse (MVP) have a benign prognosis, there is a subgroup with bileaflet MVP syndrome (biMVPS) at increased risk of idiopathic ventricular fibrillation (VF). The phenotypic features of this syndrome include myxomatous bileaflet prolapse, complex ventricular ectopy (VE), T-wave inversion in inferolateral ECG leads, and female predominance. The mechanism of ventricular arrhythmia in these patients is unknown. Methods: We reviewed our center’s ablation experience of 14 consecutive patients with biMVPS patients between February 2007 and October 2013 (n=13 female, median [range] age at index ablation 33.8 [21.0 - 58.7] years, left ventricular ejection fraction [EF] 60 [45-67] %, all ≤ moderate mitral regurgitation [MR]). We compared findings from 6 with prior sudden cardiac arrest (SCA) and recurrent ICD shocks for drug refractory VF with 8 who had symptomatic drug-refractory complex VE but without prior SCA. Results: All patients with prior SCA had a predominant VE trigger for the VF. There was no difference between the two groups in EF, MR severity, VE burden, and number of different VE morphologies or foci ablated. Sites of successful VE ablation at index procedure were the LV papillary muscles (PM, n=6 anterior, 6 posterior), fascicular system (n=5 anterior, 4 posterior), mitral annulus (n=2), outflow tracts (3 RVOT, 1 LVOT), and coronary sinus (n=1). All patients had at least one LV papillary or fascicular VE focus. Purkinje origin VE was identified as the VF trigger in 6/6 SCA patients (3 from PM, 3 from LV fascicles) and only 4/8 (none from PM) non-SCA patients (p=0.04). Acute success was seen in 17/19 procedures with no complications. VF storm occurred within 24 hours of ablation in a single patient. At 310 (39 - 2099) days follow-up, 1 SCA patient received a single shock (p=0.031 compared to pre-ablation), and symptoms from VE were reduced in 12/14. Conclusions: BiMVPS is characterized by VE from the LV fascicles and papillary muscles that trigger VF. The VE is invariably multifocal and may also involve the outflow tracts and mitral annulus. Ablation of clinically dominant VE foci alleviates symptoms and reduces the number of VF-terminating ICD shocks.

Management of ventricular arrhythmias in suspected channelopathies.

Although structural heart disease remains the predominant substrate for ventricular arrhythmia, channelopathies including long QT syndrome (LQTS), short QT syndrome (SQTS), Brugada syndrome (BrS), catecholaminergic polymorphic ventricular tachycardia (CPVT), and early repolarization syndrome (ERS) are less common but important contributing entities. These etiologies require specific therapies potentially contrary to empirical management of arrhythmias associated with structural heart disease. Conventional therapy including antiarrhythmic drug therapy may not only fail to resolve unstable arrhythmias but worsen them. Additionally, channelopathy patients with implantable cardioverter defibrillators (ICD) and arrhythmic storms represent a major challenge, and the acute care team needs to be cognizant of unique circumstances that require specific acute therapies beyond empirical advanced life support algorithm recommendations.1 Successful and considered acute management of ventricular arrhythmias is contingent on a number of variables, including knowledge of the cardiac substrate or potential substrate; form, mechanism, and precipitants of ventricular arrhythmias; and acute effect of potential therapies. In the longer term, an understanding of the natural history of the channelopathy along with the efficacy of long-term therapy will lead to superior outcomes. This review will present the risk of ventricular arrhythmias associated with these uncommon entities, the evolving understanding of the mechanism of arrhythmia, and the mechanistic basis of therapies along with a clinical approach to summarize the evidence pertaining to acute and long-term management. Patients with a prolonged QT interval are at risk of sudden cardiac death (SCD) due to Torsade de Pointes (TdP; Figure 1). Most patients with congenital LQTS are asymptomatic and diagnosed incidentally on electrocardiogram screening or following family screening. However, syncope, aborted SCD, or SCD may be the first presentation. Most arrhythmic events in congenital LQT1 occur during physical or emotional stress, at rest or in association with sudden auditory stimulation in LQT2, and during sleep or rest in LQT3 …

Role of Electrophysiological Studies in Predicting Risk of Ventricular Arrhythmia in Early Repolarization Syndrome

BackgroundThe early repolarization (ER) pattern is associated with an increased risk of arrhythmogenic sudden death. However, strategies for risk stratification of patients with the ER pattern are not fully defined. ObjectivesThis study sought to determine the role of electrophysiology studies (EPS) in risk stratification of patients with ER syndrome. MethodsIn a multicenter study, 81 patients with ER syndrome (age 36 ± 13 years, 60 males) and aborted sudden death due to ventricular fibrillation (VF) were included. EPS were performed following the index VF episode using a standard protocol. Inducibility was defined by the provocation of sustained VF. Patients were followed up by serial implantable cardioverter-defibrillator interrogations. ResultsDespite a recent history of aborted sudden death, VF was inducible in only 18 of 81 (22%) patients. During follow-up of 7.0 ± 4.9 years, 6 of 18 (33%) patients with inducible VF during EPS experienced VF recurrences, whereas 21 of 63 (33%) patients who were noninducible experienced recurrent VF (p = 0.93). VF storm occurred in 3 patients from the inducible VF group and in 4 patients in the noninducible group. VF inducibility was not associated with maximum J-wave amplitude (VF inducible vs. VF noninducible; 0.23 ± 0.11 mV vs. 0.21 ± 0.11 mV; p = 0.42) or J-wave distribution (inferior, odds ratio [OR]: 0.96 [95% confidence interval (CI): 0.33 to 2.81]; p = 0.95; lateral, OR: 1.57 [95% CI: 0.35 to 7.04]; p = 0.56; inferior and lateral, OR: 0.83 [95% CI: 0.27 to 2.55]; p = 0.74), which have previously been demonstrated to predict outcome in patients with an ER pattern. ConclusionsOur findings indicate that current programmed stimulation protocols do not enhance risk stratification in ER syndrome.

Abstract 20364: Successful Ablation of Ventricular Fibrillation in Malignant Bileaflet Mitral Valve Prolapse Syndrome

Introduction: Although the vast majority of mitral valve prolapse (MVP) is benign, women with bileaflet MVP (biMVP), complex ventricular ectopy (VE), and abnormal T waves may comprise the recently described malignant biMVP syndrome. The mechanism of ventricular arrhythmia is unknown. To further characterize the arrhythmic substrate, we reviewed our center’s ablation experience in 6 biMVP patients with prior cardiac arrest and recurrent ICD shocks for drug refractory ventricular fibrillation (VF). Methods and Results: Six women with biMVP (median age 31.5 [range 24.2 - 58.7] years, EF 65 [45 - 67]%, all ≤moderate mitral regurgitation) experienced 6 (3 - 25) appropriate ICD shocks over 4.8 (2.8 - 10.7) years and underwent index ablation between 2/2007 - 10/2013. All had multiple VE morphologies (median 7 [3 - 24]) with variable coupling intervals but with a predominant VE trigger for the VF. A median 2 (1 - 4) VE foci were ablated. Sites of successful ablation of VF-triggering and other dominant VE were left ventricular papillary muscles [PM] (1 anterior, 1 posterior, 1 both), fascicles (1 anterior, 1 posterior), or both (1 both PM and posterior fascicle). Outflow tract VE was also present and targeted (1 left, 1 right)i. Two underwent repeat ablation (288 and 312 days) for recurrent complex VE without shocks, with different foci to the index ablation (1 posterior fascicle, 1 both fascicles). The VF-triggering VE in all patients was confirmed as originating from within the left fascicular system, which in 3/6 was at a papillary muscle. Acute procedural success was seen in all with no complications to date. A VF storm occurred within 24 hours of ablation in a single patient. At follow-up of a mean 662 (47 - 2099) days, 1 patient received a single shock (p=0.03 vs. preablation). Symptomatic VE was reduced in all; while 3/6 continue Class 1c antiarrhythmics and 5/6 have beta blockade. Conclusion: Malignant biMVP syndrome is characterized by fascicular and papillary muscle PVCs that trigger ventricular fibrillation, yet in all patients, the VE is multifocal. Ablation of at least one focus appears to improve symptoms and reduce shocks.