Ablation of the epicardial substrate in patients with long-QT syndrome at risk of sudden death.

Sudden cardiac death remains a critical public health concern globally, affecting millions annually. Recent advances in cardiac arrhythmia mapping have demonstrated that the ventricular epicardial region has a critical arrhythmogenic role in some inherited cardiogenetic diseases. Among these, long-QT syndrome (LQTS) exposes patients to the risk of life-threatening arrhythmic events. Despite advancements, there is a need for more effective therapeutic strategies. A recent study has uncovered a noteworthy connection between LQTS and epicardial structural abnormalities, challenging the traditional view of LQTS as purely an electrical disorder. High-density mapping revealed electroanatomic abnormalities in the right ventricular epicardium, presenting a potential target for catheter ablation, to finally suppress ventricular fibrillation recurrences in high-risk LQTS patients.

Cardiac arrest as initial presentation of pheochromocytoma in a young.

We reported a case of pheochromocytoma with initial presentation of cardiac arrest. The patient underwent implantable cardioverter defibrillator for primary prevention but subsequently experienced repeated implantable cardioverter defibrillator shocks and syncopal episodes. A mass was found in the adrenal gland by CT, which was confirmed by anatomopathological analysis of the surgical specimen.

Right ventricular epicardial arrhythmogenic substrate in long-QT syndrome patients at risk of sudden death.

AIMS: The long-QT syndrome (LQTS) represents a leading cause of sudden cardiac death (SCD). The aim of this study was to assess the presence of an underlying electroanatomical arrhythmogenic substrate in high-risk LQTS patients. METHODS AND RESULTS: The present study enrolled 11 consecutive LQTS patients who had experienced frequent implantable cardioverter-defibrillator (ICD discharges triggered by ventricular fibrillation (VF). We acquired electroanatomical biventricular maps of both endo and epicardial regions for all patients and analyzed electrograms sampled from several myocardial regions. Abnormal electrical activities were targeted and eliminated by the means of radiofrequency catheter ablation. VF episodes caused a median of four ICD discharges in eleven patients (6 male, 54.5%; mean age 44.0 ± 7.8 years, range 22-53) prior to our mapping and ablation procedures. The average QTc interval was 500.0 ± 30.2 ms. Endo-epicardial biventricular maps displayed abnormally fragmented, low-voltage (0.9 ± 0.2 mV) and prolonged electrograms (89.9 ± 24.1 ms) exclusively localized in the right ventricular epicardium. We found electrical abnormalities extending over a mean epicardial area of 15.7 ± 3.1 cm2. Catheter ablation of the abnormal epicardial area completely suppressed malignant arrhythmias over a mean 12 months of follow-up (median VF episodes before vs. after ablation, 4 vs. 0; P = 0.003). After the procedure, the QTc interval measured in a 12-lead ECG analysis shortened to a mean of 461.8 ± 23.6 ms (P = 0.004). CONCLUSION: This study reveals that, among high-risk LQTS patients, regions localized in the epicardium of the right ventricle harbour structural electrophysiological abnormalities. Elimination of these abnormal electrical activities successfully prevented malignant ventricular arrhythmia recurrences.

Floppy mitral valve/mitral valve prolapse and sudden cardiac death.

It is well appreciated today that sudden cardiac death (SCD) occurs in patients with floppy mitral valve (FMV)/mitral valve prolapse (MVP) without significant mitral regurgitation . Data from studies most likely represent a heterogeneous population and probably underestimate the true incidence of SCD in this group of patients. SCD in patients with FMV/MVP occurs mostly in young individuals without comorbidities. Over the last decade, the phenotypic expression of patients with FMV/MVP at risk for SCD (bileaflet prolapse, redundant mitral leaflets, symptomatic young women) have been defined, possible pathophysiologic mechanisms leading to SCD have been proposed, and appropriate steps to prevent the catastrophic event, though in evolution, have been suggested. In this review, state-of-the-art knowledge related to SCD in patients with FMV/MVP is summarized.

Case Report: An Unusual Case of Pheochromocytoma.

Pheochromocytoma is a benign catecholamine secreting tumor, which is rare and originates from the adrenal gland. It has been known for a wide range of clinical manifestations and can mimic other difficult-to-diagnose diseases. Here, we report a female patient with acquired long QT syndrome, which is a rare complication of pheochromocytoma. Although relatively rare, the presence of pheochromocytoma should be considered in the case of malignant arrhythmias and electrocardiographic changes in patients.

Successful recovery of severe hypothermia with minimally invasive central catheter.

BACKGROUND: Severe hypothermia can result in malignant arrhythmias or cardiac arrest and require invasive central rewarming modalities due to a core body temperature < 28 °C. Difficult rescue missions can make continuous CPR challenging, but the decrease in oxygen consumption at these low temperatures allows for successful recovery despite the delay. Although other active warming techniques, such as peritoneal lavage, intravascular warming catheter, and renal replacement therapy can be beneficial, the consensus statements recommend extracorporeal life support as the preferred rewarming method. CASE PRESENTATION: A 42-year-old female was found in a pond after presumed exposure for 30-40 min with an outside temperature of 17 °F (-8 °C) and was found to be in ventricular fibrillation. ACLS protocol was then initiated. At the hospital, she was intubated and sedated with continuous CPR during multimodal rewarming, including active internal via the ZOLL Icy catheter. One hour after rewarming, with core temperature above 29 °C, she was defibrillated and achieved ROSC. As she continued to warm, she made purposeful movement and was warmed and maintained at euthermia. She was initiated on antibiotics due to aspiration concerns and titrated off vasopressors with extubation on day 2 of hospitalization. She had mild complaints of extremity numbness and chest pain from compressions prior to discharge on hospitalization day 4. CONCLUSIONS: This case has a successful resuscitation of severe hypothermia associated with cardiac arrest. The patient was warmed at greater than 4 °C/h with a less invasive, quicker and potentially more available approach to warming. With equipment improvements, the ability to provide prolonged CPR while rewarming may suggest that transferring to an extracorporeal life support center is not necessary.

Case Report: Venoarterial Extracorporeal Membrane Oxygenation Support for Caowu-Induced Cardiac Arrest.

Introduction: Caowu, the main root of the Aconitum plant, is widely used in China. Aconitine is the main toxic component of Aconitum, which can cause a variety of malignant arrhythmias and lead to death. Four patients who developed malignant arrhythmia after drinking medicinal wine containing Caowu were reported in this study. Cardiac arrest occurred soon after symptom onset. All patients received venoarterial extracorporeal membrane oxygenation (VA-ECMO) support after conservative medical treatment had failed. Patients who were directly transferred to our hospital received VA-ECMO support earlier than patients who were first treated at a local hospital. One patient received hemoperfusion in the emergency room before VA-ECMO support; the other three patients began hemoperfusion after VA-ECMO treatment. Surviving patients who received VA-ECMO earlier after symptom onset showed no obvious neurological complications. The patient who received a longer cardiopulmonary resuscitation time but received hemoperfusion before VA-ECMO had mild neurological complications. The mortality rate was 25% (1 of 4 patients). Two patients had thrombotic complications in venous vessels. Conclusions: Cardiogenic shock due to refractory ventricular tachycardia caused by aconitine is lethal. Conservative supportive treatment did not provide a short-term antiarrhythmic effect and the cardiogenic shock was not well controlled. VA-ECMO treatment combined with hemoperfusion is promising temporary support to successfully treat aconitine-induced cardiogenic shock caused by refractory ventricular tachycardia.

The Role of Acute Hyperglycemia on the Risk of Malignant Arrhythmia in Acute Myocardial Infarction Patients: A Study of Myocardial Damage, Ion Channel Changes and Inflammatory Factors.

BACKGROUND: acute myocardial infarction (AMI) is often followed by hyperglycemia. To date, there is no study that examine the role of myocardial damage, ion channel changes and increased inflammatory response as a pathomechanism of malignant arrhythmias due to hyperglycemia in AMI patients. The aim of this study is to determine the effect of acute hyperglycemia on the occurence of malignant arrhythmias, troponin I, VLP, echocardiographic strain, ion channel changes (CaMKII) and hsCRP. This study also aims to assess the effect of troponin I, VLP, GLS, CaMKII and hsCRP on the occurence of malignant arrhythmias in AMI patients with acute hyperglycemia. METHODS: a cross-sectional study followed by a cohort study was conducted on AMI patients treated at ICCU Cipto Mangunkusumo Hospital Jakarta during November 2018 to May 2019 period. Patients with severe infections and who had experienced malignant arrhythmias at admission were excluded from the study. The occurence of malignant arrhythmias as the main outcome of this study and CaMKII level were assessed on the fifth day of treatment. Patients who died before the fifth day of treatment due to causes other than malignant arrhythmias were excluded from analysis. The association between acute hyperglycemia with VLP and the occurence of malignant arrhythmias was analyzed through a chi-square test, whereas the differences between troponin I, GLS, CaMKII and hsCRP, based on the hyperglycemia status of the patient, were analyzed by Mann-Whitney U test. RESULTS: a total of 110 patients were included in the study. Two patients died on the third day of observation due to malignant arrhythmias. No significant relationship was found between acute hyperglycemia in AMI and malignant arrhythmias (RR = 1,38, 95%CI 0.50-3.77). There were differences of CaMKII level on day-1 and day-5 between those who were experienced malignant arrhytmia and those who were not (p-value for differences are 0,03 and 0,01, respectively. In the acute hyperglycemia group, there was difference of CaMKII day-5 levels between positive and negative VLP (p = 0.03). CONCLUSION: it was concluded that the inititial stage of AMI causes more dominant myocardial damage, as compared to metabolic factors. In the next stage of AMI, acute hyperglycemia increases ROS and the activation of ion channel changes described by CaMKII. This change results in electrophysiological remodeling of the heart, as seen in the VLP image on SA-ECG.

Mechanical Dispersion Assessed by Strain Echocardiography Is Associated with Malignant Arrhythmias in Chagas Cardiomyopathy.

BACKGROUND: Sudden death is one of the characteristics of Chagas disease (ChD). With the development of strategies for the prevention of malignant arrhythmias, especially with implantable cardioverter-defibrillators (ICDs), there is interest in developing strategies to predict sudden cardiac death. The aim of this study was to test the hypothesis that global longitudinal strain (GLS) and mechanical dispersion (MD) may be associated with malignant ventricular arrhythmias in patients with ChD. METHODS: A cross-sectional study was conducted including 62 patients with ChD who were separated into two groups according to ICD implantation status. Group 0 consisted of 34 patients with ChD without ICDs, and group 1 comprised 28 patients with ICDs. Complete echocardiographic studies, including GLS and MD measurements, were performed in all patients. RESULTS: Chamber dimensions, ejection fraction, and diastolic function showed no significant differences between patients with and those without ICDs. GLS was reduced in patients with ChD with ICDs compared with those without (P = .02). By receiver operating characteristic curve analyses, GLS identified patients with ChD with ICDs with sensitivity of 67% and specificity of 69%. MD was more pronounced in patients with ChD with ICDs compared with those without (P < .001), with a C statistic of 0.83 (95% CI, 0.71-0.91). MD > 57 msec detected ICD presence with sensitivity of 79% and specificity of 71% and was superior to GLS and ejection fraction (P < .05). In multivariate analysis, New York Heart Association functional class (odds ratio, 3.02; 95% CI, 1.09-8.39; P = .03), MD (odds ratio, 1.11; 95% CI, 1.04-1.19; P = .001), and GLS (odds ratio, 0.72; 95% CI, 0.54-0.96; P = .026) were significant and independently associated with malignant arrhythmic events. CONCLUSIONS: GLS and MD may add important information in the risk stratification of patients with ChD. The use of MD by strain echocardiography could be an attractive tool in the decision making for ICD placement as primary prevention for sudden cardiac death in patients with ChD.

Can we protect from malignant arrhythmias by modulation of cardiac cell-to-cell coupling?

Defects in intercellular coupling in the heart play a key role in the initiation and persistence of malignant arrhythmias. Such disorders result from abnormal expression and distribution of connexins, the major constituents of cardiac gap junction channels. The alterations of myocardial connexin are well established as a consistent feature of both human and animal heart disease and aging. Following these facts, the modulation of connexin mediated intercellular coupling is suggested as a new antiarrhythmic approach. This review provides recent data supporting this concept. It can be challenging for the development of new antiarrhythmic drugs. Moreover, findings point out the implication of some endogenous compounds in protection from life-threatening arrhythmias via preservation of myocardial connexin.

Heart rate variability density analysis (Dyx) for identification of appropriate implantable cardioverter defibrillator recipients among elderly patients with acute myocardial infarction and left ventricular systolic dysfunction.

AIMS: Dyx is a new heart rate variability (HRV) density analysis specifically designed to identify patients at high risk for malignant ventricular arrhythmias. The aim of this study was to test if Dyx can improve risk stratification for malignant ventricular tachyarrhythmias and to test if the previously identified cut-off can be reproduced. METHODS AND RESULTS: This study included 248 patients from the CARISMA study with ejection fraction ≤40% after an acute myocardial infarction and an analysable 24 h Holter recording. All patients received an implantable cardiac monitor, which was used to diagnose the primary endpoint of near-fatal or fatal ventricular tachyarrhythmias likely preventable by an implantable cardioverter defibrillator (ICD), during a period of 2 years. A Dyx ≤ 1.96 was considered abnormal. The secondary endpoint was cardiovascular death. At enrolment 59 patients (24%) had a Dyx ≤ 1.96 and 20 experienced a primary endpoint. A Dyx ≤ 1.96 was associated with a significantly increased risk for malignant arrhythmias [hazards ratio (HR) = 4.36 (1.81-10.52), P = 0.001] and cardiovascular death [HR = 3.47 (1.38-8.74), P = 0.008]. Compared with important clinical risk parameters (age >70 years and QRS > 120 ms), Dyx ≤ 1.96 significantly added predictive value (P = 0.0066). CONCLUSIONS: Dyx was a better predictor of ventricular tachyarrhythmias than the traditional measures of HRV and heart rate turbulence, particularly in the elderly. Dyx might be a useful tool for better selection of ICD candidates in the elderly population, since a normal Dyx in this group was associated with a very low risk for malignant ventricular arrhythmias.ClinicalTrials.gov Identifier NCT00145119.

Hemocromatosis primaria: Detección precoz de compromiso miocárdico a través de la resonancia magnética cardíaca / Primary Hemochromatosis Early Detection of Myocardial Involvement through Cardiac MRI

La hemocromatosis primaria es la enfermedad genética más común de Occidente (1 de cada 300 a 400 personas). El compromiso cardíaco durante sus estadios iniciales no se detecta por las técnicas de diagnóstico por imágenes y es durante este período cuando sobrevienen arritmias potencialmente letales. A través de la resonancia magnética cardíaca (RMC) con su secuencia de T2 estrella es posible detectar precozmente la afectación cardíaca y permite estratificar el riesgo y monitorizar la evolución del tratamiento de los pacientes afectados.

The primary hemochromatosis is the most common genetic disease in Western regions (1 out of 300/400 individuals). The cardiac involvement during its early stages is not detected with the diagnostic imaging techniques, and it is during these stages when potentially life-threatening arrhythmias occur. Through the CMRI, with its T2 star sequence, it is possible to early detect the cardiac involvement and to stratify the risk and monitor the evolution of treatment in affected patients.

Muerte súbita por causa eléctrica en sujetos sin enfermedad cardíaca estructural demostrable: Experiencia cubana / Sudden death due to electrical causes in individuals without demonstrable structural cardiac disease: Experience in Cuba

La muerte súbita cardíaca de causa eléctrica en sujetos con corazón "sano", constituye un problema clínico y de salud pública, aún no resuelto. Los objetivos del trabajo fueron: caracterizar pacientes reanimados de un evento de muerte súbita de causa eléctrica y conocer su evolución intervenida en tres años; y estudiar los signos eléctricos premonitorios de muerte súbita. Se estudiaron 42 sujetos, 30 hombres y 12 mujeres, edad promedio 37.7 años, con corazón "sano", por métodos clínicos y paraclínicos. Se consideraron 9 subpoblaciones, en mayor número los síndromes de Brugada y de QT largo y la fibrilación ventricular idiopática. Las arritmias responsables del evento fueron, en primer lugar, la fibrilación ventricular y la torsión de puntas. Existieron signos premonitorios en el 92.8% de los pacientes. Fueron frecuentes las recidivas de las arritmias malignas (71.4%) aunque en la estimulación eléctrica programada, sólo se logró reproducirlas en 4 de 18 pacientes. La fibrilación auricular predominó como arritmia coexistente (19%). En resumen, son frecuentes los signos premonitorios (en especial la fibrilación auricular) y las recidivas de las arritmias malignas aunque su inducibilidad en el laboratorio es pobre. La estratificación de riesgo es muy difícil, por el bajo valor predictivo de los métodos diagnósticos.

Sudden cardiac death due to electrical causes in individuals with no evidence of structural heart disease is an important clinical and public health problem, and it is not yet solved. The objectives of this study were: to characterize patients reanimated from a sudden death event of electrical cause; to know the mediated evolution during a period of three years and to study premonitory electrical signs. 42 individuals were studied, 30 were male and 12 female, mean age 37.7 years, healthy heart, by clinic and paraclinic methods. Nine subpopulations were studied, being Brugada syndrome, long QT syndrome and idiopathic ventricular fibrillation the most frequent. Ventricular fibrillation and twisting of the points were the arrhythmias responsible for most death events. There were premonitory signs in 92.8% and clinical recurrences of life-threatening events in 71.4% but they were induced during programmed electrical stimulation only in 4 of 18 patients. Atrial fibrillation was the most frequent coexistent arrhythmia (19%). In summary, there are frequent premonitory signs (particularly atrial fibrillation), and also malignant arrhythmic recurrences but a poor inducibility at the electrophysiology laboratory. It is very difficult to stratify the risk because of the low predictive value of diagnostic methods.