Efecto de los fármacos en la prolongación del QT y la aparición de muerte súbita en la COVID-19 / Effect of Drugs on QT Prolongation and Sudden Death in COVID-19

Introducción: Las evidencias científicas han demostrado que durante el período pandémico por la COVID-19 ha existido un incremento de la incidencia de muerte súbita cardiovascular, proporcional al incremento de los casos y a la letalidad por la enfermedad. Objetivos: Compilar información sobre los fármacos empleados en el tratamiento de la COVID-19 y sus posibles efectos en la prolongación del intervalo QT y la aparición de muerte súbita. Métodos: Se realizó una búsqueda de información a partir de las bases de datos PubMed, Medline y SciELO, en los idiomas español e inglés en el período de enero de 2020 a enero de 2023. Resultados: Los hallazgos más recientes sugieren que los factores relacionados con el tratamiento médico del paciente para sus enfermedades cardiovasculares previas, el empleo concomitante de drogas para otras comorbilidades, el ensayo de nuevas drogas que se investigan en la actualidad para el tratamiento de la enfermedad y el uso inadecuado de fármacos en complicaciones graves por la COVID-19, pueden ocasionar prolongación del intervalo QT y arritmias ventriculares tipo torsades de pointes, lo que puede conllevar a la aparición de muerte súbita. Conclusiones: Ha sido demostrado el efecto deletéreo de los fármacos en el tratamiento de la COVID-19 y sus posibles asociaciones a la terapéutica del paciente, en la prolongación del tiempo de repolarización ventricular cardíaca, cuya traducción eléctrica es un intervalo QT prolongado y su contribución a la génesis de arritmias malignas potencialmente fatales capaces de desencadenar un paro cardíaco y evolucionar a la muerte súbita(AU)

Scientific evidence has shown an increase in the incidence of sudden cardiovascular death during the COVID-19 pandemic period. This has been proportional to the increase in cases and mortality from the disease. Direct and indirect injury to the myocardium and vascular system allow to partially explain the statistics. Among the factors related to the medical treatment of the patient for previous cardiovascular diseases, it is the concomitant use of drugs for other comorbidities. The trial of new drugs for the treatment of this condition and the inappropriate use of drugs in serious complications from COVID-19 are currently being investigated. These can cause QT prolongation and torsades de pointes ventricular arrhythmias, which can lead to sudden death. Monitoring the QT interval is recommended, before and during treatment, in patients who come to the emergency room with a clinical condition suggestive of COVID-19. Additionally, modifiable factors favoring its prolongation should be evaluated. Decision-making in the application of therapeutic protocols in patients with COVID-19 with prolonged QTc at baseline, or with increased QTc after starting treatment, must go through the analysis of the risk/benefit ratio defined by a multi- and interdisciplinary team(AU)

Arritmias ventriculares en el posoperatorio de cirugía cardíaca / Ventricular arrhythmias in the postoperative period of cardiac surgery / Arritmias ventriculares no pós-operatório de cirurgia cardíaca

Resumen: Las arritmias representan unas de las complicaciones más frecuentes en el posoperatorio de cirugía cardíaca (POCC). Pueden alterar la evolución del paciente, su tiempo de internación, la conducta terapéutica y aumentan los costos en salud. Su diagnóstico y manejo adecuados, mejoran el pronóstico de los pacientes a largo plazo. La fibrilación auricular (FA) es la arritmia más frecuente del POCC, siendo menos frecuentes otras arritmias supraventriculares. Las arritmias ventriculares son causa de aumento de morbi-mortalidad y sobre sus principales características se centrará esta revisión.

Summary: Arrhythmias represent one of the most frequent complications during the postoperative period of cardiac surgery. They may worsen patient evolution, increase the in-hospital length of stay, modify therapeutics and increase health costs. Its proper diagnosis and management improves the long-term prognosis of patients. Atrial fibrillation is the most common arrhythmia in the postoperative period of cardiac surgery, with other supraventricular arrhythmias being less common. Ventricular arrhythmias are cause of increases in morbidity and mortality. Their main characteristics will be discussed in this review.

Resumo: As arritmias representam uma das complicações mais frequentes no pós-operatório de cirurgia cardíaca. Eles podem modificar a evolução do paciente, o tempo de internação, o comportamento terapêutico e aumentam os gastos de saúde. Seu diagnóstico e manejo adequados melhoram o prognóstico dos pacientes a longo prazo. A fibrilação atrial é a arritmia mais comum no pós-operatório de cirurgia cardíaca, com outras arritmias supraventriculares sendo menos comuns. As arritmias ventriculares são causa do aumento de morbimortalidade. Suas principais características serão analisadas nesta revisão.

Taquicardia incesante del tracto de salida del ventrículo derecho - ¿Taquimiocardiopatía?: El enigma / Incessant right ventricular outflow tract tachycardia - Tachycardiomyopathy? The enigma

RESUMEN Las taquicardias ventriculares de larga duración o incesantes pueden causar insuficiencia cardíaca, disfunción del ventrículo izquierdo y cardiomiopatía, cuadros que revierten una vez resueltas las arritmias. Se trata de un diagnóstico de exclusión: puede existir una cardiopatía de base que empeora con la taquicardia y debe precisarse si la arritmia lleva a la cardiomiopatía (puede existir un subregistro) o viceversa. Se presenta un paciente con taquicardia incesante del tracto de salida del ventrículo derecho, de larga evolución, con repercusión hemodinámica, cardiomiopatía dilatada y disfunción grave del ventrículo izquierdo, rebelde a fármacos antiarrítmicos y con dos ablaciones fallidas, pendiente de biopsia endomiocárdica y nueva ablación de su taquicardia. Se discuten algunas pistas para diferenciar las arritmias del tracto de salida del ventrículo derecho, en sus variantes benignas (las más frecuentes) y malignas. Algunas pistas para diferenciarlas son: la duración del complejo QRS, el intervalo de acoplamiento de la extrasístole y la frecuencia de la taquicardia.

ABSTRACT Long-lasting or incessant ventricular tachycardias may cause heart failure, left ventricular dysfunction, and cardiomyopathy; conditions that reverse once the arrhythmias have been solved. This is a diagnosis of exclusion: there may be a basic heart disease that worsens with the tachycardia and it must be clarified whether the arrhythmia leads to cardiomyopathy (there may be an underregistration) or vice versa. A patient with incessant right ventricular outflow tract tachycardia, with long evolution, hemodynamic repercussion, dilated cardiomyopathy and severe dysfunction of the left ventricle, refractory to antiarrhythmic drugs and with two failed ablations, pending endomyocardial biopsy and new ablation of his tachycardia is presented. Some clues to differentiate right ventricular outflow tract arrhythmias, in their benign (most frequent) and malignant variants, are discussed. Some clues to differentiate them are: the duration of the QRS complex, the coupling interval of premature contractions and the heart rate of the tachycardia.

Papel del sistema Purkinje y del tracto de salida del ventrículo derecho en las arritmias ventriculares malignas y la muerte súbita / Role of the Purkinje system and right ventricular outflow tract in malignant ventricular arrhythmias and sudden death

RESUMEN El sistema Purkinje y el tracto de salida del ventrículo derecho tienen un papel trascendente en relación con las arritmias ventriculares malignas (taquicardia y fibrilación ventriculares, torsión de puntas) y con la muerte súbita cardíaca. Se discuten su fisiopatología, participación en el origen (extrasístoles desencadenantes) y mantenimiento de estas arritmias, y las posibilidades ablativas para disminuir las recurrencias y los episodios de tormenta eléctrica. Se expone el diagnóstico diferencial entre variantes benignas y malignas de la taquicardia ventricular relacionada con el tracto de salida del ventrículo derecho y la relación entre factores genéticos, estructurales, electroanatómicos y funcionales (inflamación, fibrosis), con los eventos clínicos y la vulnerabilidad a las arritmias. Se necesita reclasificar algunas de estas enfermedades, vistas ahora en su carácter orgánico-funcional (síndrome de Brugada, por ejemplo), lo cual implica cambios revolucionarios en algunos conceptos clásicos y una nueva visión en cuanto a la estratificación de riesgo y la conducta terapéutica.

ABSTRACT The Purkinje system and the right ventricular outflow tract play a pivotal role in relation to malignant ventricular arrhythmias (ventricular tachycardia and fibrillation, torsades de pointes) and sudden cardiac death. Details such as their pathophysiology, origin involvement (triggering extrasystoles) maintenance of such arrhythmias, and ablative possibilities to reduce recurrences and electrical storm events are discussed herein. The differential diagnosis between benign and malignant ventricular tachycardia related to the right ventricular outflow tract, and the relationship between genetic, structural, electroanatomical and functional factors (inflammation, fibrosis) with clinical events and vulnerability to arrhythmias are presented. Some of these diseases need to be reclassified as they are now seen in their organic-functional character (Brugada syndrome, for example), and this implies radical changes in some classical concepts as well as a new perspective on risk stratification and therapeutic management.

Arritmias y muerte súbita en la falla cardíaca: estratificación eléctrica de grupos de riesgo / Arrhythmias and sudden death in heart failure: electrical stratification of risk groups

RESUMEN Se presenta una panorámica de la falla cardíaca ligada a las arritmias y a la muerte súbita, que pueden coexistir, agravarse, o ser causa o consecuencia una de otra. Se discuten los signos eléctricos premonitorios que permiten estratificar riesgo en pacientes con eventos previos, con posible acercamiento a la realidad, y en quienes no los han presentado (la mayoría, los no protegidos), y resulta muy difícil o imposible establecer un pronóstico. Estos signos son numerosos, esquivos, de baja especificidad y sensibilidad, ninguno es absoluto ni despreciable, para interpretarlos se requiere una visión integral. Se discuten las extrasístoles ventriculares como predictoras y desencadenantes de arritmias, de muerte súbita y de miocardiopatía, y la utilidad de los procedimientos ablativos frente a los medicamentosos. Los signos eléctricos son buenos para identificar grandes grupos de riesgo pero no lo son tanto para, dentro del gran grupo de bajo riesgo (la mayoría), identificar los individuos de alto riesgo.

ABSTRACT In this research is presented an overview of heart failure related to arrhythmias and sudden death, which can coexist, worsen, or be cause or consequence of one another. Here are discussed the premonitory electrical signs that allow to stratify risk in patients with previous events, with a possible approach to reality, and in those who have not presented them (most of them, the unprotected ones) and where a prognosis is very difficult, or impossible, to be established. These signs are numerous, elusive, with low specificity and sensitivity, none is absolute or negligible, in order to interpret them, a comprehensive vision is required. Premature ventricular contractions are discussed as predictors and triggers of arrhythmias, sudden death and cardiomyopathy, as well as the usefulness of ablative procedures versus medications. Electrical signs are good for identifying large risk groups but not for identifying high risk individuals inside the large low risk group (the majority).

Canalopatías iónicas: generalidades y panorámica actual / Ion channelopathies: Overview and current status

Se presenta un panorama actual sobre las enfermedades de los canales iónicos cardíacos, con sus características comunes y algunas particularidades. Son síndromes arritmogénicos hereditarios por disfunciones en el tráfico de los canales iónicos al nivel de la membrana (mutaciones en los genes que codifican proteínas, con ganancia o pérdida de función), arritmias peligrosas para la vida, síncopes y muerte súbita, sin anormalidades estructurales gruesas detectables por los métodos convencionales. Estas enfermedades han experimentado un vertiginoso desarrollo en su entendimiento, diagnóstico y terapéutica en las últimas 2 décadas y se vislumbra un futuro promisorio con la genética molecular. Son diagnósticos de exclusión, se eliminan las cardiopatías estructurales, los trastornos electrolíticos y metabólicos, otras causas eléctricas y el empleo de fármacos antiarrítmicos. Se presentan en jóvenes aparentemente sanos, cuyo debut puede ser una arritmia ventricular maligna o un evento de muerte súbita, del cual solo es reanimado el 5 porciento. Comprenden un espectro clínico muy amplio, desde los asintomáticos (signos eléctricos, no síndromes), hasta los que fallecen. Su frecuencia real no se conoce debido a: muerte, diagnóstico erróneo, signos mínimos, intermitentes u ocultos. Se incorporan nuevas entidades, algunas se superponen y es muy difícil estratificar riesgo antes del debut. Se han creado registros internacionales. Se presentan los datos de nuestro Registro Nacional cubano de canalopatías en pacientes reanimados de eventos de muerte súbita seguidos durante 10 años

An overview is presented of the current status of cardiac ion channel diseases, their common characteristics and some distinguishing features. Ion channelopathies are inherited arrhythmogenic syndromes caused by ion channel traffic dysfunctions at membrane level (mutations in protein-encoding genes with gain or loss of function), life-threatening arrhythmias, syncope and sudden death, without any gross structural abnormality detectable by conventional methods. The past two decades have witnessed speedy progress in the understanding, diagnosis and treatment of these diseases, a situation which will continue to be as promising in the future with the application of molecular genetics. They are exclusion diagnoses. Structural heart diseases, electrolyte and metabolic disorders, other electrical causes and the use of antiarrhythmic drugs are all discarded. They appear in seemingly healthy young persons, whose debut may be a malignant ventricular arrhythmia or a sudden death event, from which only 5 percent are reanimated. They have a very broad clinical spectrum, ranging from asymptomatic cases (electrical signs, no syndromes) to fatal cases. Their actual frequency is unknown, due to: death, erroneous diagnosis, and minimal, intermittent or hidden signs. New diseases are incorporated, some overlap and it is very difficult to stratify risk before the debut. International registries have been developed. The paper presents the data contained in the Cuban National Channelopathy Register for patients reanimated from sudden death events and followed up for 10 years

Complicaciones del cardioversor-desfibrilador automático implantable: Tormenta eléctrica arrítmica / Complications of the automated and implantable cardioverter-defibrillator: arrhythmic electrical storm

El servicio de arritmias y estimulación eléctrica programada del corazón es centro nacional de referencia de los pacientes con cardiopatía estructural o sin ella y arritmias ventriculares malignas, para precisar diagnósticos y tomar las medidas terapéuticas adecuadas, principalmente la implantación del cardioversor-desfibrilador automático. Desde hace 24 años se implantan estos dispositivos y se observó lo frecuente de sus complicaciones (con inclusión de la tormenta eléctrica), en coincidencia con la literatura. Se elaboró una serie propia, cuyos datos se han publicado y presentado. Ahora se intenta una panorámica del problema. El dispositivo salva la vida y tiene indicaciones precisas, se requiere una adecuada primera decisión porque de lo contrario resultan mayores los riesgos que los beneficios. No debe dejar de implantarse en quien sea necesario, pero tampoco se debe colocar sin una indicación precisa, en alguien que no va a utilizarlo pero sí a enfrentarse con todos sus problemas de por vida pues una vez implantado nadie ya se atreverá a retirarlo

The service of heart programmed electric stimulation and arrhythmias is national center of reference of patients with or without structural heart disease and malignant ventricular arrhythmias to specify exactly the diagnoses and to take the appropriate therapeutical measures, mainly the implantation of the implantable cardioverter-defibrillator. From 24 years ago these devices are implanted observing the frequent of its complications (included the electrical storm), coinciding with literature. An own series was designed whose data have been published and presented. Now, a panorama of the problem is tried. The device save the life and has precise indications, requiring an appropriate first decision because otherwise the risks are greater than the benefits. This device must to be implanted in who is necessary, but neither must to be placed without a precise indication, in someone who not goes used it but yes to face with all the problems thoroughout the life since once implanted nobody will be bold enough for to remove it

Intervalo QT corto intermitente en un paciente con muerte súbita cardiaca / Intermittent short QT interval in a patient with sudden cardiac death

Se presenta el caso de un hombre de 21 años de edad, sin cardiopatía estructural demostrable por los métodos convencionales, reanimado de un episodio de muerte súbita cardiaca. Su historia familiar incluye dos hermanos muertos súbitamente en el primer año de vida. El paciente tuvo diez episodios de taquicardia ventricular (varios de ellos registrados), uno de ellos lo llevó al evento de muerte del cual fue reanimado. Las anormalidades electrocardiográficas fueron un intervalo QT corto intermitente (280 ms), un QT corregido de 320 ms y un segmento ST corto. Con posterioridad el intervalo QT retornó a cifras normales (360 ms o más); ocasionalmente midió 335 ms (no tan corto como el inicial). El estudio electrofisiológico fue normal (intervalos AH y HV, períodos refractarios, no inducibilidad de la arritmia). El paciente rechazó la opción de cardioversor desfibrilador automático implantable y recibe amiodarona hasta la actualidad (200 mg/día), no ha repetido la arritmia en cuatro años. Los electrocardiogramas seriados son muy importantes para identificar pacientes con intervalo QT corto intermitente. El acortamiento del intervalo onda J-T pico es relevante. La arritmia puede ser fibrilación o taquicardia ventriculares.

This paper presents a 21 years-old-male without structural heart disease who was reanimated from a sudden cardiac death event. His familial history included two siblings suddenly dead in their first year of life. The patient had 10 episodes of ventricular tachycardia (some of them were registered). Electrocardiographically abnormalities were an intermittent short QT interval (280 ms), short QTc (320 ms) and a short ST segment. QT interval subsequently returned to a normal range (360 ms or more), while occasionally a length of 335 ms was recorded. The electrophysiological study findings (AH and HV intervals, refractory periods) were normal. The patient refused the implantable cardioverter defibrillator and he is receiving oral amiodarone (200 mg/day). The evolution has been satisfactory along four years. Sequential electrocardiograms are very important to identify patients with an intermittent short QT interval. Shortening of the interval J wave-Tpeak is also relevant. Related arrhythmias could be ventricular tachycardia or fibrillation.

Alterações contráteis segmentares e sua associação com arritmias ventriculares complexas, em pacientes chagásicos com eletrocardiograma normal ou borderline / Regional left ventricular dysfunction and its association with complex ventricular arrhythmia, in chagasic patients with normal or borderline electrocardiogram

INTRODUÇÃO: Morte súbita representa a principal causa de óbito em chagásicos. Eventos fatais em pacientes saudáveis, com anormalidades contráteis, foram documentados. O objetivo deste trabalho é determinar a associação entre alteração contrátil e arritmias ventriculares complexas em pacientes chagásicos, classe funcional I, eletrocardiograma normal ou borderline e função ventricular preservada. MÉTODOS: Quarenta e nove pacientes com doença de Chagas e eletrocardiograma normal ou borderline realizaram ecocardiograma, teste ergométrico e Holter. Avaliou-se a contratilidade global e segmentar dos ventrículos e a presença de arritmias ventriculares complexas induzidas no esforço e espontâneas, respectivamente. A análise estatística foi feita pelo modelo Log-Linear geral. RESULTADOS: Idade média de 56 anos; 55 por cento mulheres. Alterações contráteis segmentares em 24,5 por cento dos pacientes; 12 por cento dos Holter e 18 por cento dos testes ergométricos positivos. Houve associação entre arritmia e alteração segmentar condicionada à presença da disfunção sistólica leve do ventrículo esquerdo. CONCLUSÕES: Alterações contráteis, na presença de disfunção global leve, indicam pacientes sob maior risco de arritmias complexas.

INTRODUCTION: Sudden death is the major cause of death among chagasic patients. A significant number of fatal events in patients without apparent heart disease and borderline electrocardiogram, but with contractile ventricular dysfunction, have been documented. This work aimed to determine the association between regional dysfunction and the presence of ventricular arrhythmia in chagasic patients without apparent heart disease. METHODS: Forty-nine patients with normal or borderline electrocardiogram were submitted to echocardiogram, exercise stress test and Holter. The presence of cardiac contractile alterations and complex ventricular arrhythmia was analyzed. Statistic analysis used the general Log-Linear model. RESULTS: Mean age 56 years-old; 55 percent women. Regional ventricular dysfunction was verified in 24.5 percent of patients; positive Holter in 12 percent and exercise stress test in 18 percent. An association between complex ventricular arrhythmia and contractile abnormalities in the presence of mild left ventricle dysfunction was verified. CONCLUSIONS: Regional contractile abnormalities with mild left ventricle dysfunction in Chagasic patients indicate a group with higher risk of complex ventricular arrhythmias, who require specific follow-up.

Conceptos actuales sobre la muerte súbita / Current concepts on sudden death

La muerte súbita se define como aquella que ocurre antes de una hora de la aparición de los síntomas. Es una condición grave que en diversos países supone un problema de salud pública y que en México implica entre 33 y 53 mil muertes anuales, en su mayoría ligadas a enfermedad isquémica del corazón. La causa primordial de la muerte súbita son las arritmias ventriculares graves, sin embargo determinar qué sujetos son susceptibles de tener un episodio arrítmico es complejo y por ello la relación costo efectividad de las medidas de estratificación de riesgo suele ser mala. En el presente trabajo se revisan las diferentes estrategias para determinar el riesgo de muerte súbita. Las estrategias para el tratamiento oportuno de la muerte súbita relativas a la población general utilizadas en diversos países tienen impactos variables en la supervivencia, sin embargo, en las poblaciones seleccionadas con alto riesgo de padecer un evento arrítmico ventricular, la mejor terapia disponible actualmente es el desfibrilador automático implantable, aunque en el trabajo se discuten otras opciones de tratamiento. En nuestro país es necesario hacer un importante esfuerzo de detección prevención y tratamiento oportuno para limitar las consecuencia de este problema.

Sudden death is defined as the death occurring less than one hour before the onset of the patient's symptoms. It is a severe condition considered a public health issue in several countries and in ours, it accounts for 33 000 to 53 000 annual deaths mainly related to ischemic heart disease. The main cause of sudden death are severe ventricular arrhythmias, but determining what patients are at risk for such an episode is complex, that is why risk stratification is usually a low cost-effective intervention. In the present study, we describe different sudden death risk stratification strategies. Different sudden death treatment strategies regarding general population have different success rates in different countries, nevertheless, among select high risk populations; the best therapy currently available is the automatic implantable cardioverter defibrillator. We also discuss other treatment options. In Mexico it is deemed necessary to do an important effort for the early detection, prevention and treatment of sudden death in order to limit the consequences of this problem.

Associação entre prolapso valvar mitral e doença ventricular direita arritmogênica / Association between Mitral Valve Prolapse and Arrhythmogenic Right Ventricular Disease

PURPOSE: To evaluate some features of ventricular arrhythmias in patients with mitral valve prolapse. METHODS: We studied 25 patients (female: 19; mean age: 37 +/- 13 years) with ventricular arrhythmias, mitral valve prolapse and normal ventricular function. All patients underwent a 24h Holter and high resolution ECG (HRECG). The Qtc intervals were measured in lead II (normal < 0.44 s). In order to define the possible origin of the ventricular focus, the morphology of the ectopic beats were analysed in leads I, II, aVF, V1 using the following criteria: 1) LBBB morphology with left axis deviation in the frontal plane (FP): origin at the inflow tract of the right ventricle (RV); 2) LBBB morphology with right axis deviation in the FP: origin at the outflow tract of the RV; 3) RBBB morphology with left axis deviation in the FP: origin at the posterior region of the left ventricle (LV). RBBB morphology with right axis deviation in the FP: origin at the anterior region of the LV. RESULTS: Twenty three (92) patients showed > 720 isolated ventricular ectopic beats/24 h. Paired ventricular response was detected in 18 (72) patients and non-sustained VT in 15 (60). HRECG was positive in six (24) patients and Qtc interval was prolonged in 13 (52). RV was the site of origin of the ventricular ectopic beats in 85 of the patients (outflow: 85; inflow: 15). Only five (20) patients had arrhythmias from the LV. CONCLUSION: There was a high incidence of ventricular arrhythmias with a low incidence of positive HRECG tests, suggesting that the mechanisms of the arrhythmias do not correlate with slow intramyocardial conduction. It was noted a strong association between mitral valve prolapse, arrhythmogenic right ventricular disease and Qtc prolongation. It is possible that in some of this patients the finding could represent a global myocardial disease.

Efficácia das drogas antiarrítmicas. Proposta para uma nova forma de avaliação baseada nos efeitos farmacológicos horários / Antiarrhythmic drug effectiveness. Proposal for a new approach based on pharmacological hourly effects

PURPOSE--To use a new approach in order to assess the antiarrhythmic drugs, based in the hourly autonomic effects and antiarrhythmic efficacy of sotalol. METHODS--Sixteen patients were evaluated in a randomized double-blind placebo-controlled study. Patients were classified in group 1 (anti-arrhythmic efficacy) and group 2 (no antiarrhythmic efficacy). The following parameters were analyzed: 1) clinical variables as age, gender, cardiac disease and ventricular ectopies density; 2) drug effects on pNN50 in 24-hour and on mean hourly cardiac cycle length; 3) percentage of hourly ventricular ectopies distribution and its correlation with pNN50 and with mean hourly cardiac cycle length in all patients; 4) drug effects on mean hourly cardiac cycle length in groups 1 and 2; 5) correlation between hourly pNN50 and ventricular ectopies density after sotalol administration in groups 1 and 2; 6) hourly drug efficacy in groups 1 and 2 and correlation with pNN50. RESULTS--Efficacy of the drug was present in 8 (50) patients. Sotalol significantly increased 24-hour pNN50 (placebo 5.01 +/- 2.02; after drug, 11.70 +/- 5.59-p < 0.001), also increasing mean hourly cardiac cycle length during the day and night, in all patients (placebo 758.25 +/- 75.68 ms; after drug 967.71 +/- 80.17 ms-p < 0.000). It was noted that patients under placebo had different autonomic tonus; group 1 showed higher sympathetic activity as compared to group 2. Hourly drug efficacy was seen in 23 of 24-hour recordings in group 1 while it was not seen at any time in group 2. CONCLUSION--Sotalol significantly increased parasympathetic cardiac activity. The anti-arrhythmic response was related to the autonomic tonus seen before and after drug administration.

Eficácia do sotalol nas arritmias ventriculares idiopáticas com origem em trato de saída de ventrículo direito / Efficacy of Sotalol in Patients With Idiophatic Right Ventricular Arrhythmias

PURPOSE--To evaluate the effects of sotalol in patients (pts) with idiophatic ventricular arrhythmias (VT) from right ventricular outflow tract. METHODS--Eighteen pts with VT were enrolled (five with monomorphic repetitive ventricular tachycardia - MRVT). Pts were submitted to a double-blind crossover randomized study (placebo vs. 320 mg/po/d/sotalol; four weeks each), after a wash-out control period. Holter recording were recorded in control and placebo and drug periods. Eligible pts have > 50/h isolated ventricular premature beats (VPB) in control, with or without paired VPB or nonsustained VT (NSVT- > 3 beats, > 100bpm). Drug efficacy criteria was: > 75//reduction in isolated VPB and > 90//of paired VPB or NSVT. The effects of the drug on uncorrected QT interval was evaluated and also on circadian rhythm of VT through the hourly pNN50/VPB ratios. Values are given as mean +/- SD. Three recordings were compared by using paired Student's ®t® test. Statistical significance was assumed for p < 0.05. RESULTS--Differences between control and placebo were NS. Drug was effective in 61//of pts, reducing the 3 types of ET (VPB: placebo = 23.508 +/- 34.537; drug: 975 +/- 1357; paired placebo = 443 +/- 587; drug = 9 +/- 20). The drug was evaluated in 4 pts with MRVT, reducing all ectopic events, with efficacy of 60//over VPB and paired and 80//over NSVT (VPB: placebo = 52.639 +/- 42.207; drug: 1631 +/- 2062; paired: placebo = 796 +/- 754; drug: 20 +/- 30; NSVT: placebo = 4287 +/- 6343; drug: 9 +/- 11). Mean QT interval was 0.40 +/- 0.01s in control and 0.50 +/- 0.04s in the drug period, with no correlation between duration and efficacy. Sotalol modified the circardian rhythm of VPB in the non-responders group, mainly during the morning. CONCLUSION--Sotalol was effective in control of VT, mainly the MRVT. Its effect on VPB circadian rhythm may independently contribute to the overall efficacy profile and myocardial protective effect of this drug

Análise de potenciais tardios em pacientes com arritmias ventriculares malignas / Late potentials analysis in patients with malignant ventricular arrhythmia

PURPOSE--To assess the relationship between late potentials and spontaneous ventricular arrhythmias, organic heart disease, inducibility of arrhythmias at electrophysiological study and ejection fraction. METHODS--The population is comprised by 52 patients (41 men, 11 women with mean age 50 +/- 16 years) with spontaneous clinically documented ventricular tachycardia or ventricular fibrillation. An electrophysiological study was performed with conventional programmed stimulation. Within a week of the test a study of late potentials was also performed. RESULTS--Late potentials were documented in 73 per cent of the patients with ventricular tachycardia and only in 17 per cent of the patients with ventricular fibrillation. Sixty-eight percent of the patients with ischemic cardiopathy presented late potentials and in these, ventricular tachycardia was inducible in 93 per cent . Only one from a group of 7 patients with ventricular arrhythmias and no organic heart disease, presented late potentials. In patients with late potentials, 84 per cent have inducible ventricular tachycardia, but only 26 per cent of patients without late potentials have inducible ventricular tachycardia. The incidence of late potentials was inversely correlated with left ventricular ejection fraction. CONCLUSION--The presence of late potentials was more frequent in patients with ventricular tachycardia than in patients with ventricular fibrillation. The presence of late potentials has a sensibility of 81.5 per cent and a specificity of 78 per cent to detect patients with inducible ventricular tachycardia

Taquicardia ventricular monomórfica repetitiva / Repetitive Monomorphic Ventricular Tachycardia

PURPOSE--To evaluate retrospectively clinical features of repetitive monomorphic ventricular tachycardia (RMVT). METHODS--Files of 11 patients with RMVT were analyzed (9 females, mean-age 37 +/- 17 years). All patients were submitted to clinical evaluation, ECG, Holter monitoring stress test, high-resolution ECG and echocardiogram; they were treated with antiarrhythmic drugs. RESULTS--Patients were in NYHA class I or II, 9 asymptomatics and 2 with palpitations. The ECG was normal in all of them. Cardiac memory was observed in 3. A left bundle branch block with inferior axis deviation in the frontal plane was present during RMVT in all patients (right ventricular outflow tract focus). Holter monitoring revealed mean of 12031 +/- 8345 isolated PVC/24h; 2892 +/- 234 ventricular couplets/24h and 1367 +/- 890 VTs/24h (mainly nonsustained). In 6 patients RMVT was suppressed during maximal exercise treadmill. High-resolution ECG was negative in all group. Five patients had a normal echocardiogram while 5 showed mitral valve prolapse. One patient developed tachycardiomyopathy. The arrhythmia was controlled with 320mg of oral sotalol in 3 of 4 that used this drug and with 120mg oral propranolol in one of 6 that used this drug. Drug resistance was present in the others. The mean follow-up period was 38 +/- 16 months. CONCLUSION--The results demonstrate that RMVT is a benign form of VT with no detectable anatomic substract by the currently used methods. It is probably induced by nonreentrant mechanism and frequently drug resistance is observed. Among the antiarrhythmic drugs commonly used, sotalol showed to be the most effective

Objetivo - Avaliar, retrospectivamente, os dados clínicos mais relevantes da taquiarritmia ventricular monomórfica repetitiva (TVMR). Métodos - Foram analisados os registros de 11 pacientes, 9 femininos, idade média de 37±17 anos, portadores de TVMR, todos submetidos à avaliação clínica seqüencial, ECG, Holter, prova de esforço em esteira, ECG de alta resolução (ECGAR) e ecocardiograma, sendo tratados com drogas antiarrítmicas. Resultados - Os pacientes encontravam-se em classe funcional I/II da NYHA, sendo 9 assintomáticos e 2 com queixas de palpitações. O ECG, em ritmo sinusal, foi normal nos 11 pacientes, havendo em 3 o fenômeno de memória cardíaca. O ECG durante a taquicardia mostrou QRS com BRE e eixo inferior no plano frontal (foco em via de saída de VD) em todo o grupo. O Holter mostrou no total dos pacientes, média de 12031±8345 extra-sístoles nas 24h; pareadas de 2892±234 e surtos de TV de 1367±890, a maioria não-sustentados. A prova de esforço aboliu a taquiarritmia no esforço máximo em 6 pacientes. O ECGAR foi negativo em todo o grupo. Cinco pacientes apresentavam ecocardiogramas normais, havendo em 5, sinais de prolapso da válvula mitral. Um paciente evoluiu com sinais de taquicardiomiopatia. A arritmia foi controlada em 3 pacientes com 320mg de sotalol VO (4 fizeram uso desta droga) e em 1 com 120mg de propranolol VO (usado em 6 pacientes), havendo nos restantes resistência medicamentosa. O tempo de seguimento médio foi de 38±16 meses. Conclusão - Os resultados indicaram ser a TVMR arritmia de evolução benigna, sem um substrato anatômico detectável pelos meios diagnósticos de rotina, desencadeada muito provavelmente por mecanismo eletrofisiológico não reentrante e com freqüente resistência medicamentosa. Dos antiarrítmicos utilizados de rotina, este estudo sugere ser o sotalol o mais efetivo