Long-term prognosis of idiopathic ventricular fibrillation: An eighteen-year experience from a tertiary center.

INTRODUCTION AND OBJECTIVES: Idiopathic ventricular fibrillation (IVF) is diagnosed in patients who survive sudden cardiac arrest (SCA), preferably with documented ventricular fibrillation (VF), without any identifiable structural or electrical abnormality. Current evidence provides limited guidance on the diagnosis and follow-up of these patients. Our aim was to assess the clinical outcomes of survivors of an aborted SCA attributed to IVF. METHODS: We retrospectively collected clinical data from all patients who survived SCA and implanted a cardiac defibrillator (ICD) between 2005 and 2023. RESULTS: A total of 38 patients, 36.8% female, with a mean age of 44±14 years old were included. Median follow-up time was 8.7 years (interquartile range (IQR) 4.7-14.7 years). All patients underwent a comprehensive diagnostic evaluation that excluded structural and coronary disease. During follow-up, underlying diagnoses were established in 34.2% of the whole cohort. Genetic testing, performed in 37.2%, revealed underlying diagnoses in 57.1% of those tested, compared to only 26.3% of patients who did not undergo genetic testing [p=0.035, OR=5.1 (95% confidence interval (CI) 1.2-21.5)]. Mortality was 10.5% (due to non-arrhythmic causes) and 36.8% patients received appropriate therapies with a median time to first ICD therapy of 39 [5.4-47.3] months. CONCLUSION(S): Etiological diagnosis and recurrence prediction in patients with IVF remains challenging, even with extensive diagnostic evaluation and long-term follow-up. In our study, genetic testing enhanced diagnostic yield. Consistent with previous findings, our cohort experienced a notable arrhythmic recurrence, with no cardiac deaths, underlining the pivotal role of ICD implantation in these patients.

Ressonância Magnética Cardíaca como Ferramenta Diagnóstica Etiológica em Pacientes Recuperados de Morte Súbita Cardíaca ou Arritmias Ventriculares Instáveis / Cardiac Magnetic Resonance as an Etiological Diagnosis Tool in Recovered Sudden Cardiac Death or Unstable Ventricular Arrhythmia Patients

Resumo Fundamento A ressonância magnética cardíaca (RMC) tem relevância diagnóstica crescente em sobreviventes de morte súbita cardíaca (MSC) ou arritmia ventricular instável (AVI) em países desenvolvidos. Objetivo Procuramos avaliar retrospectivamente o papel adicional da RMC em um país em desenvolvimento com poucos recursos disponíveis e que pode direcionar um uso mais eficaz desses recursos. Métodos Foram incluídos sobreviventes de MSC ou AVI admitidos entre 2009 e 2019 em uma instituição acadêmica terciária após a realização de RMC. Dados demográficos, clínicos e laboratoriais foram coletados dos prontuários. Imagens e laudos de RMC foram analisados e o impacto disso no diagnóstico etiológico final foi afirmado. Realizou-se análise descritiva e definiu-se p<0,05 como significativo. Resultados Sessenta e quatro pacientes, 54,9±15,4 anos, sendo 42 (71,9%) do sexo masculino. A maioria dos eventos (81,3%) foi extra-hospitalar e a taquicardia ventricular foi o ritmo mais comum. Medicamentos cardiovasculares foram utilizados anteriormente por 55 pacientes, sendo os betabloqueadores os medicamentos mais utilizados (37,5%). O eletrocardiograma apresentava áreas elétricas inativas em 21,9% e todos apresentavam fibrose na RMC. A média da fração de ejeção do ventrículo esquerdo (FEVE) foi de 44±14%, com 60,9% ≤50% e apenas 29,7% ≤35%. Identificou-se realce tardio com gadolínio em 71,9%, com padrão transmural em 43,8%. A miocardiopatia chagásica foi a etiologia mais comum (28,1%), seguida da miocardiopatia isquêmica (17,2%). Entre 26 sem etiologia previamente identificada, foi possível definir com RMC (15 pacientes - 57%). Conclusão De acordo com estudos anteriores em países desenvolvidos, a RMC foi capaz de aumentar o diagnóstico etiológico e identificar o substrato arritmogênico, permitindo melhor atendimento em metade dos pacientes subdiagnosticados.

Abstract Background Cardiac magnetic resonance (CMR) has an increasing diagnostic relevance in survivors of sudden cardiac death (SCD) or unstable ventricular arrhythmia (UVA) in developed countries. Objective To evaluate retrospectively the additional role of CMR in a developing country where few resources are available, and should be used more effectively. Methods The study included SCD or UVA survivors admitted between 2009 and 2019 at a tertiary academic institution referred to CMR. Demographic, clinical, and laboratory data were collected from the medical records. CMR images and reports were reviewed and their impact on the final etiological diagnosis was determined. A descriptive analysis was performed and p<0.05 established as significant. Results Sixty-four patients, 54.9±15.4 years old, and 42 (71.9%) males. Most events (81.3%) were out of the hospital and ventricular tachycardia was the most common rhythm. Cardiovascular medications were previously used by 55 patients, and beta-blockers were the most used medications (37.5%). Electrocardiogram had electrical inactive areas in 21.9% and all of them had fibrosis at CMR. Mean left ventricular ejection fraction (LVEF) was 44±14%, with 60.9% ≤50% and only 29.7% ≤35%. Late gadolinium enhancement was identified in 71.9%, with a transmural pattern in 43.8%. Chagas cardiomyopathy was the most common etiology (28.1%), followed by ischemic cardiomyopathy (17.2%). Among 26 without a previously identified etiology, CMR could define it (15 patients - 57%). Conclusion In accordance with previous studies in developed countries, CMR was capable of increasing etiological diagnosis and identifying the arrhythmogenic substrate, allowing better care in half of the underdiagnosed patients.

Long-term outcomes of non-contact multi-electrode balloon catheter mapping-guided ablation of ventricular arrhythmias originating from the outflow tract.

INTRODUCTION: The outflow tract (OT) regions of the ventricles are a common location of origin for idiopathic ventricular arrhythmias (VA). Non-contact mapping (NCM) with a multi-electrode balloon catheter Ensite-Array enables three-dimensional reconstruction of the geometry of the cardiac chambers and accurate mapping of the propagation map, based on a single beat analysis, facilitating the ablation and contributing procedure success. OBJECTIVE: Assessment of the feasibility and long-term outcomes following NCM-guided OT VA ablation. METHODS: Single center retrospective analysis of patients admitted for symptomatic OT VA ablation. Demographic and clinical characteristics of patients, procedure data and long-term outcomes were assessed. RESULTS: Fifty-eight patients (79.3% female, age 43.9±17.6 years) were considered, 89.7% without structural heart disease. In 85.7% of the cases left ventricle ejection fraction (LVEF) was preserved (LVEF≥50%), 8.6% had mild systolic dysfunction (LVEF 40%-49%) and 5.7% had moderate systolic dysfunction (LVEF 30%-39%). Twenty-four-hour Holter recording documented sustained VA episodes in 12.1% of the patients, non-sustained VA in 31.0%, and >10 000 premature ventricular complex (PVC)/24 h in 56.9%, with an ECG suggesting right ventricular OT origin in 84.5%. There was total elimination of PVC in 87.9% cases and a significant reduction in 3.4%. During a mean follow-up of 5.5 years, 87.9% patients remained asymptomatic without medication, 12.1% underwent re-ablation due to symptomatic PVC recurrence, and two cases underwent a third successful intervention. CONCLUSION: Non-contact mapping-guided multi-electrode balloon catheter VA ablation is a highly effective and safe procedure, with a low rate of long-term recurrence.

A new biomarker that predicts ventricular arrhythmia in patients with ischemic dilated cardiomyopathy: Galectin-3.

INTRODUCTION: Ventricular arrhythmias are caused by scar tissue in patients with ischemic dilated cardiomyopathy. The gold standard imaging technique for detecting scar tissue is magnetic resonance imaging (MRI). However, MRI is not feasible for use as a screening test, and also cannot be used in patients who have received an implantable cardioverter-defibrillator (ICD). In this study, we aimed to assess the association between levels of galectin-3 (Gal-3), which is known to be secreted by scar tissue, and the history of ventricular arrhythmias in patients with ischemic dilated cardiomyopathy who received an ICD. METHODS: Nineteen healthy controls and 32 patients who had previously undergone VVI-ICD implantation due to ischemic dilated cardiomyopathy were enrolled in the study. Patients were divided into three groups: the first group including patients who had received no ICD therapies, the second including patients with arrhythmia requiring therapies with no arrhythmia storm, and the third including patients who had arrhythmia storm. We assessed the association between Gal-3 levels and the history of ventricular arrhythmias in these patients. RESULTS: Gal-3 levels were significantly higher in the patient groups than in the control group (p<0.01). Gal-3 levels of patients with arrhythmias requiring ICD therapies were significantly higher than in patients with ICD not requiring therapies (p=0.02). They were also higher in patients with a history of arrhythmia storm than in patients without shocks (p=0.05). Receiver operating curve analysis showed with 84% sensitivity and 75% specificity that Gal-3 levels over 7 ng/ml indicated ventricular arrhythmia that required therapies. CONCLUSION: Gal-3 may be used to further improve risk stratification in patients with ischemic cardiomyopathy who are more prone to developing life-threatening arrhythmias.

Arritmia ventricular maligna asociada a un gossypiboma: reporte de un caso / Malignant ventricular arrhythmia associated to gossypiboma: clinical case report / Arritmia ventricular maligna vinculada a gossypiboma: reporte de um caso clínico

Un gossypiboma, oblitoma o textiloma se define como todo cuerpo extraño olvidado en el interior de un paciente durante una intervención quirúrgica. Representa una complicación posquirúrgica poco frecuente pero de consecuencias potencialmente graves. En general, se manifiesta con cuadros clínicos variables: una masa o pseudotumor, sangrados, fiebre, dolor, varios meses o años después de la cirugía original. También puede ser un hallazgo accidental. Describimos el caso clínico de una paciente con un gossypiboma vinculado a una cirugía cardíaca que se realizó 40 años antes al cuadro clínico actual, que se presenta con arritmia ventricular maligna.

A gossypiboma, oblitoma or textiloma is defined as a surgical object left in the interior of the body after surgery. It represents an uncommon but potentially life threatening post-surgery complication. Clinical manifestations are variable and depend on location, relations and size, from pseudo-tumoral masses, bleeding, fever, pain and other nonspecific presentations. The onset of symptoms is unpredictable, occurring from months or years after surgery. Patients may course asymptomatically and be diagnosed incidentally as an imaging finding. We describe a case of a patient with gossypiboma diagnosed 40 years after undergoing cardiac surgery, who presented with a malignant ventricular arrhythmia.

Um gossypiboma, oblitoma ou textiloma está definido como todo corpo estranho esquecido no interior de um paciente durante um procedimento cirúrgico, representando uma complicação pos cirúrgica pouco frequente, mas com consequências potencialmente graves. Geralmente, se manifesta com quadros clínicos variáveis: uma massa ou pseudotumor, sangramentos, febre, dor, varios meses ou anos após a cirurgia original ou ser um hachado acidental. Descrevemos o caso clínico de uma paciente com um gossypiboma vinculado a uma cirurgia cardíaca realizada 40 anos antes do quadro clínico atual, que se apresenta com arritmia ventricular maligna.

Parada cardíaca súbita por arritmia ventricular en pacientes con infarto agudo de miocardio / Sudden cardiac arrest due to ventricular arrhythmia in patients with acute myocardial infarction

RESUMEN Introducción: La muerte súbita cardíaca no ha disminuido de igual manera que la mortalidad por enfermedad coronaria, por la elevada incidencia de las paradas cardíacas súbitas (PCS). Objetivos: Determinar factores predictivos de PCS por arritmia ventricular en pacientes con infarto agudo de miocardio. Método: Se realizó un estudio analítico en el Servicio de Cardiología de Las Tunas entre 2011 y 2017. La población de estudio estuvo conformada por los 917 pacientes ingresados con infarto agudo de miocardio. Los 90 pacientes con PCS en arritmia ventricular constituyeron el «grupo de casos¼; el resto fue el «grupo control¼. Se utilizó estadística descriptiva y un modelo de regresión logística múltiple, y se calculó el índice de probabilidad (odds ratio [OR]), con un 95% de confiabilidad para determinar los factores predictivos. Resultados: En los pacientes del grupo de casos predominó el sexo masculino (73%), el infarto biventricular (24,7%), la fracción de eyección ventricular izquierda (FEVI) <35% (18,9%) y los fallecidos (41,1%) en relación al grupo control. Al 10,0% se le administró betabloqueadores en la primera asistencia médica. El shock cardiogénico (OR=15,3), la FEVI <35% (OR=8,51), la creatina quinasa > 1200 UI (OR=2,77), la obesidad (OR=3,16), el hábito de fumar (OR=2,28), el supra/infradesnivel del ST en el electrocardiograma >15 mm (OR=2,23) y el infarto anterior (OR=2,39) se asociaron a la PCS en arritmia ventricular. Conclusiones: El shock cardiogénico, la FEVI <35%, la creatina quinasa >1200 UI, la obesidad, el hábito de fumar, el supra/infradesnivel del ST en el electrocardiograma >15 mm y el infarto anterior fueron factores predictivos de PCS en arritmia ventricular.

ABSTRACT Introduction: Sudden cardiac death has not decreased in the same way as mortality due to coronary heart disease, because of the high incidence of sudden cardiac arrest (SCA). Objectives: To determine predictive factors of SCA due to ventricular arrhythmia in patients with acute myocardial infarction. Method: An analytical study was carried out in the Cardiology Department of Las Tunas between 2011 and 2017. The population of study was 917 patients admitted with acute myocardial infarction. All 90 patients with SCA in ventricular arrhythmia represented the "case group"; the rest were the "control group". Descriptive statistics were used, as well as a multiple logistic regression model; the odds ratios (OR) was calculated, with 95% reliability to determine the predictive factors. Results: In the patients of the case group predominated: male sex (73%), biventricular infarction (24.7%), left ventricular ejection fraction (LVEF) <35% (18.9%) and deceased (41.1%); all these results compared to the control group. A 10.0% was given beta-blockers on their first medical assistance. Cardiogenic shock (OR 15.3), LVEF <35% (OR 8.51), creatine kinase >1200 IU (OR 2.77), obesity (OR 3.16), smoking (OR 2.28), ST-segment elevation/depression on the electrocardiogram >15 mm (OR 2.23) and anterior wall infarction (OR 2.39) were associated with SCA due to ventricular arrhythmia. Conclusions: Cardiogenic shock, LVEF <35%, creatine kinase > 1200 IU, obesity, smoking, ST-segment elevation/depression on the electrocardiogram >15 mm and anterior wall infarction were predictive factors of SCA due to ventricular arrhythmia.

Bloqueo atrioventricular completo, taquicardia ventricular y muerte súbita en una paciente gestante a término / Complete atrioventricular block, ventricular tachycardia and sudden death in a pregnant woman at term

Resumen Se presenta un caso clínico de una mujer gestante que presentó bloqueo atrioventricular completo en labor de parto, bradicardia severa, intervalo QT prolongado secundario, torsión de puntas y paro cardiorrespiratorio, del cual fue recuperada. Se discuten los mecanismos potenciales que pueden desencadenar este escenario.

Abstract A clinical case of a pregnant woman who presented with complete atrioventricular block in labor, severe bradycardia, secondary prolonged QT interval, Torsades de pointes and aborted cardiorespiratory arrest is presented. Potential mechanisms that can trigger this scenario are discussed.

Taquicardia ventricular como manifestación de sarcoidosis cardíaca. Reporte de un caso / Ventricular tachycardia as a manifestation of cardiac sarcoidosis. Case report

La sarcoidosis es una enfermedad inflamatoria crónica que posee una amplia variabilidad de presentaciones clínicas. El compromiso cardíaco de esta patología oscila en el orden del 5%, pudiendo variar desde anormalidades en la conducción hasta la falla cardíaca. Existe poco conocimiento sobre los beneficios de su tratamiento y no hay datos que evalúen la reducción de la mortalidad a largo plazo, por lo que genera este tipo de pacientes un gran desafío para el profesional. A continuación presentamos el caso de un masculino de 37 años con taquicardia ventricular como debut cardiológico de una sarcoidosis.

Calidad de vida relacionada con la salud en pacientes con arritmia ventricular una medición con el ASTA, en dos momentos / Health-related quality of life in patients with ventricular arrhythmia a measurement with the ASTA, at two moments

Objetivo: Establecer una comparación en las mediciones de calidad de vida relacionada con la salud y carga de los síntomas con el ASTA en pacientes con arritmia ventricular, antes y después de implante de cardiodesfibrilador. Método: observacional analítico, con diseño de serie de casos y de abordaje cuantitativo. Participaron 83 pacientes, con diagnóstico de arritmia ventricular de dos instituciones de la ciudad de Bucaramanga, con dos mediciones, antes y después de implante de cardiodesfibrilador. Instrumento: Arrhythmia-Specific questionnaire in Tachycardia and Arrhythmia (ASTA), versión validada al español. Análisis: se utilizó estadística descriptiva y para determinar el cambio en los puntajes de las mediciones iniciales y finales, se utilizó, la prueba pareada de T Student. Resultados: los pacientes con arritmia ventricular que recibieron implante de cardiodesfibrilador, son en su mayoría hombres con una media de edad de 60,97 años, de estratos socioeconómicos bajos, ocupación hogar y labores agrícolas, el puntaje en la escala de calidad de vida inicial fue de 10.97 y de 9.52 para la medición final post-implante, con un valor de p: 0.001, para la comparación entre los dos puntajes, lo que muestra una diferencia estadísticamente significativa. Conclusión: la evaluación de la calidad de vida del paciente con arritmia ventricular medida por un instrumento especifico, muestra una afectación de la calidad de vida, con una leve mejoría en la medición a un mes posterior al implante del cardiodesfibrilador y visualiza la importancia de intervenciones de Enfermería en etapas tempranas del pre-implante en diferentes aspectos.

Objective: To establish a comparison in health-related quality of life measurements and symptoms burden with ASTA in patients with ventricular arrhythmia, before and after implantation of a cardiodefibrillator. Method: observational analytical, with case series design, with a quantitative approach. A total of 83 patients participated, with a diagnosis of ventricular arrhythmia from two institutions in the city of Bucaramanga, with two measurements, before and after implantation of a cardiodefibrillator. Instrument, Arrhythmia-Specific questionnaire in Tachycardia and Arrhythmia (ASTA), version validated in Spanish. Analysis: descriptive statistics were used and, to determine the change in the scores of the initial and final measurements, the paired test of T -Student was used. Results: patients with ventricular arrhythmia, and who received a cardio-defibrillator implant, are mostly men, with a mean age of 60.97 years, from low socioeconomic strata, household occupation and agricultural work, the score in the quality scale of initial life was of 10.97 and of 9.52 for the final measurement after implant, with a value of p: 0.001, for the comparison between the two scores, which shows a statistically significant difference. Conclusion: the evaluation of the quality of life of the patient with ventricular arrhythmia, measured by a specific instrument, shows an affectation of the quality of life, with a slight improvement in the measurement one month after the implantation of the cardiodefibrillator. And the importance of nursing interventions in the early stages of pre-implantation in different aspects is visualized.

Autonomic cardiovascular control and cardiac arrhythmia in two pregnant women with hypertrophic cardiomyopathy: Insights from ICD monitoring.

In women with hypertrophic cardiomyopathy (HCM), pregnancy prompts major changes in hemodynamic and cardiac autonomic function that may precipitate heart failure (HF) or increase the risk of cardiac arrhythmia. We report the clinical follow-up of two patients with non-obstructive HCM implanted with a cardioverter defibrillator (ICD) allowing for continuous analysis of heart rate (HR), heart rate variability (HRV) and cardiac arrhythmia throughout the entire course of pregnancy. Both patients experienced increased HR and decreased HRV from the early stages of pregnancy, which persisted until delivery. Premature ventricular contractions (PVCs) and runs of non-sustained ventricular tachycardia (NSVT) reached a peak in the second and third trimesters, concurrent with sympathetic hyperactivity. In one patient with baseline NYHA class II HF symptoms, increased PVCs and NSVT were consistent with the deterioration of HF, supporting the decision to bring the delivery forward. While both patients experienced a persistent increase in sympathetic tone and ventricular ectopic activity, no life-threatening arrhythmias were documented. During pregnancy, patients with hypertrophic cardiomyopathy develop progressive neuroautonomic imbalance, prompting an increase in non-sustained ventricular arrhythmia. This enhanced arrhythmia burden warrants close follow-up and rhythm assessment during the third trimester, especially in women who have heart failure symptoms before pregnancy. Implantable cardioverter defibrillators provide a continuous analysis of heart rate variability and arrhythmia burden that supports therapeutic decision-making during follow-up.

Flecainide Reduces Ventricular Arrhythmias in Patients With Genotype RyR2-positive Catecholaminergic Polymorphic Ventricular Tachycardia.

INTRODUCTION AND OBJECTIVES: Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited disease characterized by polymorphic or bidirectional ventricular arrhythmias (VA) triggered by physical or emotional stress in young people with a structurally normal heart. Beta-blockers are the cornerstone of treatment, while flecainide has recently been incorporated into the therapeutic arsenal. The aim of this study was to report our experience with this drug. METHODS: The cohort included 174 genotype-positive CPVT-patients from 7 families. We collected data from patients who were receiving flecainide and analyzed the indications, adverse effects and dosage, clinical events, VA and arrhythmic window during exercise testing, and implantable cardioverter-defibrillator (ICD) shocks during follow-up. RESULTS: Eighteen patients (10.4%) received flecainide; 17 patients in combination with beta-blockers, and 1 patient as monotherapy due to beta-blocker intolerance. None of the patients presented side effects. In 13 patients (72.2%) the indication was the persistence of exercise-induced VA and in 5 patients (27.7%) persistent ICD-shocks, despite on beta-blockers. After flecainide initiation, the exercise-induced VA quantitative score was reduced by more than 50% in 66.7% of the members of family 1 (32.76 ± 84.06 vs 74.38 ± 153.86; P = .018). The arrhythmic window was reduced (5.8 ± 11.9 bpm vs 19.69 ± 21.27 bpm; P = .007), and 4 of 5 patients with appropriate ICD shocks experienced no further shocks in the follow-up. CONCLUSIONS: In CPVT-patients flecainide reduces clinical events, exercise-induced VA, the arrhythmic window, and ICD shocks, with good tolerance.

Induced Brugada syndrome: Possible sources of arrhythmogenesis.

Brugada syndrome is an inherited cardiac condition with the potential for development of life-threatening arrhythmias in relatively young individuals without significant structural cardiac abnormalities. The condition is characterized by a distinct coved-type ST segment elevation in the right precordial leads (V1-V3). This hallmark pattern (type 1) is often dynamic and sometimes concealed, and may be unmasked in certain conditions or under the effect of certain agents, which include variation of sympathovagal balance, hormones, metabolic factors and drugs. These factors may not only modulate electrocardiographic morphology and induce the characteristic type 1 pattern, but also predispose to ventricular arrhythmias. The risk of malignant arrhythmias in acute events with induced type 1 pattern may be imminent, particularly if the patient in fact has Brugada syndrome. The physician should be aware of the modulating factors that may underlie a Brugada pattern, and be able to recognize, identify and promptly correct them. The mechanisms responsible for the type 1 pattern and possible associated ventricular arrhythmias induced by these modulating factors have attracted growing attention and interest. Furthermore, not all induced Brugada ECG patterns are observed in patients with Brugada syndrome, existing the possibility for acquired Brugada patterns/syndrome and Brugada phenocopies. This paper reviews the modulating factors associated with induced type 1 pattern as possible causes of arrhythmogenesis, particularly in Brugada syndrome patients, describes some of the probable underlying mechanisms, and discusses the concepts of acquired Brugada syndrome and Brugada phenocopies.

Síndrome de Brugada como causa de muerte súbita de origen cardíaco / Brugada syndrome as a cause of sudden cardiac death

ResumenMuerte súbita se define como un evento fatal e inesperado que ocurre en un individuo aparentemente sano. Una de las principales causas son las de origen cardiovascular, entre las cuales se encuentran las anormalidades electrofisiológicas primarias como lo es el síndrome de Brugada. Este se define como una canalopatía que afecta canales de sodio, producto de una variante genética, principalmente de herencia autosómica dominante.Se ha determinado que la mutación del gen SCN5A es la más asociada con el síndrome. El diagnóstico se realiza mediante historia clínica y patrones electrocardiográficos específicos y generalmente se presenta como síncope o como muerte súbita resucitada debida a taquicardia ventricular polimórfica o fibrilación ventricular. El desfibrilador automático implantable es la principal herramienta para la prevención de muerte súbita, sin embargo, previo a su uso debe hacerse una adecuada estratificación de los pacientes, tanto para prevenir muerte súbita, como para evitar el uso innecesario del dispositivo.

AbstractSudden death is defined as an unexpected fatal event occurring in an apparently healthy subject. Sudden cardiac death is a leading cause, among which are primary electrical abnormalities such as Brugada Syndrome. Brugada Syndrome is an autosomal dominant channelopathy affecting the sodium channel. SCN5A has emerged as the most common gene associated with Brugada syndrome. The diagnosis is suggested by the clinical history in a patient with specific electrocardiographic pattern. The most typical presentation is syncope or resuscitated sudden death due to polymorphic ventricular tachycardia or ventricular fibrillation. An implantable cardioverter defibrillator is the main tool for preventing sudden death, and correct risk stratification in these patients is important both to prevent sudden death and to avoid unnecessary implantable cardioverter defibrillator use.

Time domain heart rate variability in Boxer dogs with arrhythmogenic right ventricular cardiomyopathy / Variabilidade da frequência cardíaca no domínio do tempo em cães da raça Boxer com cardiomiopatia arritmogênica do ventrículo direito

ABSTRACT: The aim of the present study was to assess heart rate variability (HRV) in Boxer dogs affected by arrhythmogenic right ventricular cardiomyopathy (ARVC). Fourteen Boxer dogs classified as affected and 28 classified as unaffected were included in a prospective case-control study. Dogs underwent 24-hour ambulatory ECG and were classified as affected (>1,000 VPCs/24 hours) or unaffected (<20 VPCs/24 hours) by ARVC based on the number of ventricular arrhythmias. HRV was assessed using 24-h Holter ECG monitoring; the studied parameters were SDNN, SDANN, SDNNIDX, rMSSD and pNN50. Data were submitted to logarithmic transformation and HRV parameters were compared between groups and correlated according to the disease status, number and severity of ventricular arrhythmias using Student’s t test, linear regression and Spearman’s test. There was no interaction between the HRV parameters and the number and severity of ventricular arrhythmias. SDNNlog (2.35±0.14 vs. 2.46±0.12, P=0.01), SDNNIDXlog (2.18±0.14 vs. 2.24±0.10, P=0.002) and pNN50log (1.47±0.19 vs. 1.64±0.13, P=0.002) were significantly lower in the affected group compared with the unaffected. According to this study, HRV are different in a population of Boxers dogs affected by ARVC compared to a population of unaffected dogs, and these differences are not consequences of low cardiac output caused by ventricular arrhythmias since animals that had higher number and complexity of arrhythmias were not those who had lower values of HRV.

RESUMO: O objetivo do presente estudo foi avaliar a variabilidade da frequência cardíaca (VFC) em cães da raça Boxer acometidos pela cardiomiopatia arritmogênica do ventrículo direito (CAVD). Para isso, foram incluídos, em estudo prospectivo caso-controle, 14 cães classificados como acometidos pela CAVD e 28 classificados como não acometidos. Os cães foram submetidos à eletrocardiografia ambulatorial de 24 horas e então classificados como acometidos (quando apresentaram mais de 1.000 complexos ventriculares prematuros em 24 horas) ou não acometidos (quando apresentaram menos de 20 complexos ventriculares prematuros em 24 horas) pela CAVD, com base no número de arritmias ventriculares. A VFC foi avaliada mediante monitoramento Holter de 24 horas. Os parâmetros estudados foram SDNN, SDANN, SDNNIDX, rMSSD e pNN50. Os dados foram submetidos à transformação logarítmica e os parâmetros da VFC foram comparados e correlacionados de acordo com a presença ou não da doença, número e severidade das arritmias pelo teste t de Student, regressão linear e teste de Spearman. Não houve interação entre as variáveis da VFC e o número e a severidade das arritmias ventriculares. Porém, as variáveis SDNNlog (2,35±0,14 vs. 2,46±0,12, P=0,01), SDNNIDXlog (2,18±0,14 vs. 2,24±0,10, P=0.002) e pNN50log (1,47±0,19 vs. 1,64±0,13, P=0,002) foram significativamente menores no grupo de animais acometidos pela doença. De acordo com os resultados do presente estudo, a VFC é menor nos Boxers acometidos pela CAVD em relação aos cães não acometidos, e essa diferença não pode ser atribuída ao baixo débito cardíaco, supostamente causado pelas arritmias ventriculares, uma vez que os animais que apresentaram maior número e complexidade das arritmias não foram os que apresentaram os menores valores da VFC.

Short QT syndrome presenting as syncope: how short is too short?

We report the case of a 52-year-old man who presented to our emergency department (ED) after three episodes of syncope in the seven hours before admission. During his stay in the ED he had recurrent ventricular tachycardia (VT) requiring external electrical cardioversion. A 12-lead electrocardiogram (ECG) showed a short QT (SQT) interval (270 ms, QTc 327 ms), with frequent R-on-T extrasystoles triggering sustained polymorphic VT. After exclusion of other precipitating causes, the patient was diagnosed as having SQT syndrome (SQTS) according to the Gollob criteria. To our knowledge, this is the first known documentation of an SQT-caused arrhythmic episode on a 12-lead ECG, as well as the first reported case of SQTS in Portugal. The patient received an implantable cardioverter-defibrillator and was discharged. At a follow-up assessment 14 months later he was symptom-free, interrogation of the device showed no arrhythmic events, and the ECG showed a QT interval of 320 ms (QTc 347 ms).

Differences of ventricular late potential between acute STEMI and NSTEMI patients / Diferencias del potencial tardío ventricular entre pacientes con infartos agudos STEMI y NSTEMI

OBJECTIVE: To discuss the positive rate of ventricular late potential (VLP) between patients with acute ST-segment elevation myocardial infarction (STEMI) and patients with acute non NSTEMI. METHODS: One hundred and sixty-three cases of acute myocardial infarction (90 patients with STEMI and 73 with NSTEMI), admitted to the first hospital of China Medical University between June 2011 and August 2011, underwent VLP examination. RESULTS: The VLP positive rate of the STEMI group was 54.4%, while that of the NSTEMI group was 38.4%, and the differences have statistical meaning (χ2 = 4.186, p < 0.05). The occurrence rate of ventricular arrhythmia in VLP positive patients was 11.7%, while in VLP negative patients it was 3.5% (χ2 = 4.005, p < 0.05). CONCLUSION: The VLP positive rate of the STEMI group is higher than that of the NSTEMI group.

OBJETIVO: Analizar la tasa positiva del potencial tardío ventricular (PTV) entre pacientes con infarto agudo del miocardio sin elevación del segmento ST (NSTEMI por sus siglas en inglés) y el infarto agudo del miocardio con elevación del segmento ST (STEMI por sus siglas en inglés). MÉTODOS: Ciento sesenta y tres casos de infarto agudo de miocardio (90pacientes con STEMI) y 73 con NSTEMI, ingresados en la Universidad primer hospital de Medicina China entre junio y agosto de 2011, fueron sometidos a examen de PTV. RESULTADOS: La tasa positiva PVT del grupo STEMI fue 54.4%, mientras que la del grupo NSTEMI fue 38.4%, y las diferencias tienen significado estadístico (χ² = 4.186, p < 0.05). La tasa de ocurrencia de arritmia ventricular en pacientes PVTpositivos fue 11.7%, mientras que en los pacientes PVT negativos fue 3.5% (χ² = 4.005, p < 0.05). CONCLUSIÓN: La tasa PTV positiva del grupo STEMI es mayor que la del grupo NSTEMI.

Substrate mapping strategies for successful ablation of ventricular tachycardia: A review / Técnicas de mapeo y ablación del sustrato arrítmico en pacientes con taquicardia ventricular

Catheter ablation of ventricular tachycardia (VT) currently has an important role in the treatment of incessant ventricular tachycardia and reduction of the number of episodes of recurrent ventricular tachycardia. Conventional mapping techniques require ongoing tachycardia and haemodynamic stability during the procedure. However, in many patients with scar-related ventricular tachycardia, non-inducibility of clinical tachycardia, poor induction reproducibility, haemodynamic instability, and multiple ventricular tachycardias with frequent spontaneous changes of morphology, preclude tachycardia mapping. To overcome these limitations, new strategies for mapping and ablation in sinus rhythm (SR) - substrate mapping strategies - have been developed and are currently used by many centres. This review summarizes the progresses recently achieved in the ablative treatment of ventricular tachycardia using a substrate mapping approach in patients with structural heart disease.

La ablación de la taquicardia ventricular está adquiriendo gran importancia en el tratamiento de la taquicardia ventricular incesante así como en la reducción y prevención de episodios en pacientes con taquicardia ventricular monomorfa sostenida. El abordaje convencional requiere la inducción de la taquicardia ventricular y la tolerancia de la misma durante el procedimento. Sin embargo, en muchos pacientes con taquicardia ventricular, en contexto de un infarto previo, no es factible la inducción de la taquicardia clínica, la inducción presenta baja reproducibilidad, la taquicardia se acompaña de inestabilidad hemodinámica o se presentan múltiples morfologías con variaciones espontáneas de una morfología a otra que dificultan el mapeo durante la taquicardia. Para superar a estas limitaciones, se han desarrollado las técnicas de mapeo y ablación de sustrato en ritmo sinusal, que actualmente se llevan a cabo en muchos centros. Esta revisión se centra en los avances realizados en los últimos años en el campo de la ablación de sustrato de la taquicardia ventricular en el paciente con cardiopatía estructural.

High-resolution electrocardiography in the diagnosis of arrhythmogenic right ventricular cardiomyopathy in Boxer dogs / Eletrocardiografia de alta resolução no diagnóstico da cardiomiopatia arritmogênica do ventrículo direito em cães da raça Boxer

To evaluate the reliability of high-resolution electrocardiography in the diagnosis of arrhythmogenic right ventricular cardiomyopathy in Boxers, 20 dogs with no structural cardiac alterations at echocardiographic examination were grouped on the basis of frequency of ventricular arrhythmias, evaluated by 24-hour ambulatory ECG, and undergoing a high-resolution electrocardiography. High frequency QRS duration, duration of terminal QRS complex less than 40µV (LAS40) and root mean square voltage of the terminal 40 milliseconds of the QRS complex (RMS40) were measured. Differences in high-resolution ECG variables were not observed between groups. Therefore, the results of this investigation suggest that high-resolution electrocardiography is not a useful method for the diagnosis of arrhythmogenic right ventricular cardiomyopathy in Boxers without detectable myocardial alterations or systolic dysfunction.

Com o objetivo de avaliar a importância da eletrocardiografia de alta resolução no diagnóstico da cardiomiopatia arritmogênica do ventrículo direito do Boxer, 20 cães sem evidências de doença cardíaca estrutural à avaliação ecodopplercardiográfica foram agrupados de acordo com a frequência de arritmias ventriculares, avaliadas pela eletrocardiografia ambulatorial de 24 horas, e submetidos ao exame eletrocardiográfico de alta resolução. Duração do complexo QRS filtrado, duração dos sinais de baixa amplitude (menor que 40µV) dos últimos 40 milissegundos do complexo QRS e raiz quadrada média da voltagem ao quadrado dos últimos 40 milissegundos do complexo QRS (RMS40) foram as variáveis avaliadas. Não foram observadas diferenças significativas entre os grupos em relação às variáveis estudadas. Sendo assim, os resultados do presente estudo sugerem que a eletrocardiografia de alta resolução não é uma ferramenta útil no auxílio diagnóstico da cardiomiopatia arritmogênica do ventrículo direito dos cães da raça Boxer que não apresentam alterações miocárdicas evidentes ou disfunção sistólica.

Arritmia como única forma de presentación de la miocarditis / Arrhythmia as the only presentation form of myocarditis / Arritmia como a única forma de apresentação de miocardite

Introducción. Las arritmias ventriculares se presentan, en algunos pacientes, como único signo clínico de miocarditis, siendo ésta no incluida como probabilidad etiológica. La dificultad de la caracterización clínica de esta forma de presentación en esta patología no permite iniciar el tratamiento oportuno. Objetivo. Analizar la evolución clínica y el tratamiento de pacientes con arritmias, como única manifestación clínica de miocarditis. Materiales y método. Estudio descriptivo, observacional, transversal, retrospectivo de diecinueve pacientes con diagnóstico de miocarditis, asistidos en nuestra institución, entre los años 2000 y 2009. Se seleccionaron siete pacientes (35%), que presentaron arritmias ventriculares como única forma de manifestación clínica. La edad media de estos pacientes fue de 18 ± 7 años, cinco hombres y dos mujeres. Todos tuvieron biopsia endomiocárdica positiva para miocarditis. Se examinaron las historias clínicas a fin de observar el tipo de arritmia, la función ventricular, la respuesta al tratamiento recibido y la evolución clínica a corto y largo plazo. Para el análisis estadístico, se empleó el programa estadístico InfoStat/Profesional versión 2009p. Resultados. Todos los pacientes presentaron extrasístoles ventriculares frecuentes, 3 (43%) taquicardia ventricular no sostenida y 4 (57%) taquicardia ventricular sostenida, de éstos, 1 paciente padeció además fibrilación ventricular. La función ventricular fue normal en todos los pacientes (fracción de eyección: 62 ± 8,08%). Seis pacientes (86%) fueron tratados con inmunosupresores (corticoides y azatioprina), de los cuales 5 (72%) evolucionaron con extrasístoles ventriculares aisladas. Sólo un paciente continuó con taquicardia ventricular sostenida, que requirió implante de cardiodesfibrilador y ablación por radiofrecuencia. No hubo óbitos, en un seguimiento de 6 ± 3 años. Conclusiones. De los pacientes tratados con inmunosupresores se logró reducir la inflamación y controlar las arritmias. Se evidenció una buena evolución de los pacientes a corto y largo plazo.

Background. Ventricular arrhythmias occur in some patients as the only clinical sign of myocarditis; still it is not included as an etiological probability. The complexity of its clinical characterization does not allow an appropriate treatment. Aim.To analyze clinical evolution and treatment in those patients with arrhythmia as the only clinical manifestation of myocarditis. Materials and method. Descriptive, observational, transversal, retrospective study, enrolling nineteen patients diagnosed with myocarditis, attended in our institution within the period 2000-2009. Seven patients (35%) who presented ventricular arrhythmia as the only clinical manifestation were selected. Their mean age was 18 ± 7 years old, five men and two women. All of them underwent endomyocardial biopsy, resulting positive for myocarditis. Clinical histories were analyzed in order to examine arrhythmia type, ventricular function, response to received treatment, and clinical long and short-term evolution. Statistical analysis was performed with statistical program InfoStat/Profesional version 2009p. Results. All patients presented frequent ventricular extrasystoles; 3 (43%) non sustained ventricular tachycardia; 4 (57%) sustained ventricular tachycardia, and 1 of these patients had ventricular fibrillation. Ventricular function was normal in all patients (ejection fraction 62 ± 8,08%). Six patients (86%) received immunosupressors (corticoids y azatioprin), of which 5 (72%) evolved with isolated ventricular extrasystoles. Only one patient continued with sustained ventricular tachycardia, requiring defibrillator implantation and radiofrequency ablation. There were no deaths in a follow up of 6 ± 3 years. Conclusions. Immunosuppressive therapy allowed reducing inflammation and controlling arrhythmias. Patients showed a good short and long term evolution.

Introdução. As arritmias ventriculares ocorrem em alguns pacientes, como o único sinal clínico de miocardite, ainda não incluída como de probabilidade de diagnóstico. A dificuldade da caracterização clínica da doença não permite o tratamento adequado para controlá-lo. Objetivo. Analisar a evolução clínica e tratamento de pacientes com arritmias, como a única manifestação clínica da miocardite. Materiais e métodos. Estúdio descritivo, observacional, transversal, retrospectivo, com dezenove pacientes com diagnóstico de miocardite, atendidos em nossa instituição entre os anos 2000 e 2009. Foram selecionados sete pacientes (35%) com arritmia ventricular como única forma de manifestação clínica. A idade média desses pacientes foi de 18± 7 anos, cinco homens e duas mulheres. Todos foram submetidos à biópsia endomiocárdica, resultando positivo para miocardite. As histórias clínicas foram analisadas a fim de avaliar o tipo de arritmia, função ventricular, a resposta ao tratamento recebido e evolução clínica a longo e curto prazo. A análise estatística foi realizada com o programa estatístico InfoStat/Profesional versão 2009p. Resultados. Todos os pacientes apresentaram extra-sístoles ventriculares freqüentes, 3 (43%) taquicardia ventricular não sustentada; 4 (57%) taquicardia ventricular sustentada, e um destes pacientes também sofreu fibrilação ventricular. A função ventricular era normal em todos os pacientes (fração de ejeção de 62 ± 8,08%). Seis pacientes (86%) receberam imunossupressores (corticóides e azatioprina), dos quais 5 (72%) evoluíram com extra-sístoles ventriculares isoladas. Apenas um paciente continuou com taquicardia ventricular sustentada, necessitando de implante de desfibrilador e ablação por radiofreqüência. Não houve mortes em um seguimento de 6 ± 3 anos. Conclusões. A terapia imunossupressora permitiu reduzir a inflamação e controlar arritmias. Os pacientes apresentaram boa evolução a curto e longo prazo.

Associação entre dissinergia miocárdica e arritmia ventricular na forma indeterminada da doença de Chagas / Association between left ventricular wall motion abnormalities and ventricular arrhythmia in the indeterminate form of Chagas disease

INTRODUÇÃO: Pacientes na forma indeterminada da doença de Chagas (FIDC) podem apresentar anormalidades contráteis segmentares, com evidências de pior prognóstico comparativamente a pacientes com estudo ecocardiográfico normal. O objetivo deste estudo foi de avaliar a associação entre a presença de anormalidade contrátil segmentar e a presença de distúrbios do ritmo cardíaco na FIDC. MÉTODOS: Foram estudados 38 pacientes na FIDC, sendo 26 pacientes sem anormalidade contrátil e 12 com presença de distúrbio contrátil ao estudo ecocardiográfico. Todos os pacientes foram submetidos a um estudo ecocardiográfico completo, incluindo o Doppler tecidual, bem como à monitorização eletrocardiográfica de 24h (Holter). RESULTADOS: Entre as diversas variáveis estudadas, foram encontradas diferenças significativas entre os dois grupos em relação à fração de ejeção (p < 0,001), dimensão sistólica do ventrículo esquerdo (p = 0,029) e tempo de contração isovolumétrica (p < 0,05) medidos pela ecocardiografia e Doppler tecidual, bem como extrassistolia ventricular isolada (p = 0,016) e em pares (p = 0,003) pela avaliação pelo Holter. CONCLUSÕES: Pacientes na FIDC que apresentam anormalidades contráteis quando avaliados pela ecocardiografia apresentam episódios mais frequentes de extrassistolia ventricular, traduzindo um maior dano morfofuncional e elétrico do coração, quando comparados a pacientes que apresentem estudo ecocardiográfico normal.

INTRODUCTION: Chagas' disease can lead to severe and potentially lethal damage of cardiac function. Thus, the identification of cardiac abnormalities in patients presenting the indeterminate form (IF) can be important for risk stratification. This paper aimed to demonstrate whether IF chagasic patients who presented wall motion abnormalities showed functional and electric disturbances compared to patients with normal echocardiogram and Doppler studies. METHODS: Thirty eight patients with the IF were studied, including 26 chagasic patients with normal electrocardiographic, radiological and echocardiographic exams and 12 chagasic patients showing segmental wall motion abnormalities in the echocardiographic exam. All the patients were submitted to complete echocardiogram and Doppler study, including tissue Doppler imaging (TDI) and Holter 24h monitoring. RESULTS: Among the variables evaluated, significant differences among the two groups were verified in relation to: the ejection fraction (p < 0.001); left ventricular systolic dimension (p = 0.029); isovolumic contraction time, measured by TDI in the basal segments of the left ventricle (p < 0.05); and the presence of isolated (p = 0.0005) and paired ventricular extrasystoles (p = 0.003), in the Holter monitoring. CONCLUSIONS: The indeterminate form of Chagas' disease can present cardiac wall motion abnormality, demonstrating functional and electric damage compared to chagasic patients with normal echocardiogram.