Multidisciplinary consensus on the use of hydroxychloroquine in patients with systemic lupus erythematosus.

BACKGROUND: Hydroxychloroquine (HCQ) is the first-line treatment for systemic lupus erythematosus (SLE); however, there is heterogeneity in its clinical use. This consensus aims to bridge the gap in SLE treatment by providing practical and valuable recommendations for health professionals. METHODS: The methodology used is based on a systematic literature review and a nominal group technique (NGT). A ten-member scientific committee formulated eight clinically relevant questions. First, a systematic review was conducted to identify the available evidence, which the scientific committee evaluated to developed recommendations based on their expertise, achieving consensus through NGT. RESULTS: 1673 titles and abstracts were screened, and 43 studies were included for meeting the inclusion criteria. The scientific committee established 11 recommendations for HCQ use in initiation, maintenance, and monitoring, considering benefits and potential adverse effects of HCQ. Unanimous agreement was achieved on all recommendations. CONCLUSIONS: The available evidence supports HCQ's effectiveness and safety for SLE. Individualized assessment of the initial HCQ dose is important, especially in situations requiring dose reduction or discontinuation. This risk-benefit assessment, specifically focusing on the balance between retinal toxicity and the risk of SLE relapse, should guide decisions regarding medication withdrawal, considering disease activity, risk factors, and HCQ potential benefits. Close monitoring is essential for optimal disease management and minimize potential risks, such as QT prolongation or retinal toxicity.

Atrial fibrillation and QT prolongation after a single dose of hydroxychloroquine / Fibrilación auricular y prolongación del QT después de una dosis única de hidroxicloroquina

Non-antiarrhythmic drugs may induce QT-prolongation and increase the risk of arrhythmias. Recent studies have determined that there is a risk of atrial fibrillation (AF) due to QT prolongation. We report a case of FA associated to QT prolongation secondary to a single dose of hydroxychloroquine (HCQ) in an 83-years-old polymedicated patient admitted to our hospital due to SARS-CoV-2 infection. Quetiapine was prescribed as regular medicine after admission and a 5-days oral HCQ regimen was started for COVID-19. Thirty minutes after HCQ loading dose, FA was reported on electrocardiogram (EKG). COVID-19 treatment is leading to use off-label drugs that may generate adverse effects. It should be considered that drugs that induce QT prolongation may be triggers for atrial arrhythmias. There is not any report of sudden onset of increased QT interval with associated arrythmia after a single dose of HCQ, even in a short course treatment. (AU)

Los fármacos no antiarrítmicos pueden inducir la prolongación del intervalo QT y aumentar el riesgo de arritmias. Estudios recientes han determinado que existe riesgo de desarrollar fibrilación auricular (FA) asociada a la prolongación del intervalo QT. Presentamos un caso de FA asociado a prolongación del QT secundario a una dosis única de hidroxicloroquina (HCQ) en una paciente polimedicada de 83 años ingresada en nuestro hospital por infección por SARS-CoV-2. A la paciente se le prescribió quetiapina como parte de su medicamento habitual al ingreso y se inició tratamiento frente a COVID-19 basado en HCQ oral. Treinta minutos tras la dosis de carga de HCQ, se informó FA en el electrocardiograma (ECG). El tratamiento de COVID-19 está llevando al uso de medicamentos no aprobados que pueden generar efectos adversos. Además, debe considerarse que los fármacos que inducen la prolongación del QT pueden desencadenar arritmias auriculares. No se han reportado casos de aparición repentina de aumento del intervalo QT con arritmia asociada después de una dosis única de HCQ. (AU)

Severe primary hypothyroidism presenting as polymorphic ventricular tachycardia / Hipotiroidismo primario grave que se presenta como taquicardia ventricular polimórfica

Abstract Introduction: Hypothyroidism may have various cardiovascular manifestations due to morphological, functional and electrical alterations in the heart. The usual electrocardiographic findings being sinus bradycardia, low voltage complexes, and slowed intraventricular conduction. Hypothyroidism manifesting as polymorphic ventricular tachycardia has only been reported in a few case reports. Clinical case. A 60-year-old lady presented to us in the emergency department in an unresponsive and unconscious state and electrocardiogram showed a polymorphic ventricular tachycardia. After initial resuscitation with direct current cardioversion and supportive care, she found to have severe hypothyroidism and responded well to thyroid replacement therapy. Conclusion. Polymorphic ventricular tachycardia is a life threatening emergency that can have various etiologies. Polymorphic ventricular tachycardia secondary to primary hypothyroidism is a rare presentation but it is treatable and reversible with thyroid replacement therapy. In patients presenting with QT interval prolongation and ventricular tachycardia, hypothyroidism should be one of the differential diagnosis.

Resumen Introducción: El hipotiroidismo puede presentar diferentes manifestaciones cardiovasculares dadas por alteraciones morfológicas, funcionales y eléctricas en el corazón, siendo los hallazgos electrocardiográficos usuales son la bradicardia sinusal, los complejos de bajo voltaje y la conducción intraventricular lenta. El hipotiroidismo manifestado como taquicardia ventricular polimórfica solo se ha descrito en unos pocos reportes de caso. Caso clínico: Se trata de una mujer de 60 años que acudió que acurdió al servicio de urgencias en un estado inconsciente y sin respuesta a estímulos, y el electrocardiograma reveló taquicardia ventricular polimórfica. Luego de la reanimación inicial con cardioversión con corriente directa y tratamiento sintomático se le encontró un hipotiroidismo grave, el cual se trató con terapia de reemplazo con hormona tiroidea. y se obtuvo una buena respuesta Conclusión. La taquicardia ventricular polimórfica es una emergencia vital que puede tener varias etiologías. La taquicardia ventricular polimórfica secundaria a un hipotiroidismo primario es una presentación poco común, pero es tratable y reversible con la terapia de reemplazo con hormona tiroidea. En los pacientes que presentan una prolongación del intervalo QT y taquicardia ventricular, es pertinente incluir el hipotiroidismo en el diagnóstico diferencial.

Ventricular arrhythmias are associated with increased QT interval and QRS dispersion in patients with ST-elevation myocardial infarction.

INTRODUCTION AND OBJECTIVES: The electrocardiogram continues to be essential in the diagnosis of acute myocardial infarction, and a useful tool in arrhythmic risk stratification. We aimed to determine which electrocardiographic variables can successfully predict the occurrence of ventricular arrhythmias (VA) in patients following ST-segment elevation myocardial infarction (STEMI). METHODS: We performed an observational study including 667 patients with STEMI admitted to the University Hospital in Sancti Spíritus, Cuba. Demographic variables, cardiovascular risk factors, and clinical variables were recorded. Electrocardiographic variables included QT interval duration (measured and corrected) and QT dispersion, QRS duration and dispersion, JT interval duration and ST-segment elevation magnitude. We also determined left ventricular ejection fraction and glomerular filtration rate. A binary statistical regression model and a regression tree were used to determine the variables that successfully predicted VA. RESULTS: VA occurred in 92 (13.8%) patients, within the first 48 hours in 68 (73.9%) and after this period in 24 (26.1%) patients. The variables associated with VA were QT interval duration >529 ms and QT dispersion >66 ms, QRS dispersion >50 ms, and the presence of ST-segment elevation in six or more leads. CONCLUSIONS: The main predictor of VA occurring during the initial 48 hours was QT interval duration, while, after this period, it was QRS dispersion.

Androgen deprivation therapy mimicking acute coronary syndrome: A case report.

An 80-year-old man diagnosed with prostate cancer and under treatment with androgen deprivation therapy presented at the emergency room with chest pain, repolarization abnormalities and QT interval prolongation on electrocardiogram. An initial diagnosis of acute coronary syndrome was proposed, but biomarkers and coronary angiography were negative. Hydroelectrolyte balance and echocardiogram were also normal. Some weeks after drug withdrawal, repolarization changes reverted. A rare side effect of these drugs mimicking an acute coronary syndrome was the most probable diagnosis.

Riesgo de prolongación del intervalo QT asociado al tratamiento / The risk of treatment-induced QT interval prolongation

Objetivo: La prolongación del intervalo QT puede aumentar la estanciahospitalaria y la tasa de mortalidad de los pacientes. Esta investigacióndetermina la incidencia de prolongación del intervalo QT debido al usode medicamentos y evalúa el método más apropiado para realizar elmonitoreo electrocardiográfico.Método: Se realizó un estudio observacional retrospectivo en pacienteshospitalizados en el Hospital Clínica Bíblica durante el año 2018. Serevisaron los expedientes de los pacientes con hospitalización superiora 48 horas cuya historia clínica incluyera al menos tratamiento con unmedicamento que prolongara el intervalo QT y que las medidas manualesdel intervalo QT fueran corregidas con la fórmula Fridericia y Rautaharju,y las medidas automáticas con la fórmula Bazett. La valoración del riesgose realizó con la escala RISQ-PATH.Resultados: De los 141 pacientes analizados, 23 tenían una arritmia previaen su historia clínica y 14 de ellos sufrieron complicaciones durante la hospitalización.Un total de 113 (80%) pacientes tenían un valor alto RISQ‑PATHy sólo a 64 se les realizó un electrocardiograma al ingreso. En promedio,los pacientes recibieron tres medicamentos que aumentaban el intervalo QT.La mayoría de los QT obtenidos automáticamente fueron más cortos queaquellos obtenidos en forma manual. De todas las correcciones, los valoresdel intervalo QT más largos se obtuvieron con la fórmula de Bazett, y los máscortos con la fórmula Rautaharju. No ocurrieron eventos como taquicardiaventricular compleja o torsade de pointes durante el estudio.Conclusiones: Es necesario implementar estrategias que permitan una mejor monitorización del intervalo QT con el fin de prevenir las complicacionesderivadas en los pacientes ospitalizados

Objective: QT interval prolongation can increase patients’ hospitalstay and mortality rate. This study aims to determine the incidence ofdrug-induced QT interval prolongation and establish which QT intervalmeasurement method is the most appropriate for electrocardiographicmonitoring.Method: A retrospective observational study was conducted of patientsadmitted to the Clínica Bíblica Hospital during 2018. The electronic medicalrecords of patients hospitalized for longer than 48 hours and whosedrug regimen included at least one drug potentially able to prolong the QTinterval were reviewed. Manually-measured QT intervals were correctedusing Fridericia’s and Rautaharju’s formulae, while automatically-measuredQT intervals were corrected with Bazett’s formula. Risk was assessed usingthe RISQ-PATH scale.Results: Of the 141 patients analyzed, 23 had arrhythmia as per theirclinical history and 14 suffered a complication during their stay in hospital.A total of 113 (80%) had a high RISQ-PATH score and only 64 were subjectedto an electrocardiogram on admission. Patients received a meanof three potentially QT interval prolonging drugs. Most of the QT ntervalsmeasured automatically were shorter than those obtained manually. Of allcorrections, the longest QTc interval values were obtained with Bazett’sformula, and the shortest with Rautaharju’s formula. None of the patientsdeveloped TdP or complex ventricular tachycardia.Conclusions: Every effort should be made to implement strategies conducive to more effective monitoring of the QT interval to prevent QT intervalprolongation related complications in hospitalized patients

Arritmias ventriculares en el síndrome de takotsubo: cuestión de sexo / Sex-related risk of arrhythmia in takotsubo syndrome

Resumen El síndrome de takotsubo, también conocido como miocardiopatía de estrés, representa un difícil reto diagnóstico, pues en muchos casos su presentación es superponible al infarto de miocardio por ruptura de placa; el diagnóstico definitivo se basa en la ausencia de lesiones culpables en la coronariografía. La fisiopatología de la enfermedad no está por completo establecida, y tiene un pronóstico generalmente benigno. Sin embargo, existe un porcentaje no despreciable de pacientes que sufren complicaciones graves, entre las que destacan las arritmias malignas tipo taquicardia ventricular polimórfica por prolongación del intervalo QT. A pesar de que el síndrome de takotsubo afecta principalmente a las mujeres, quienes por otra parte también suelen tener intervalos QT más prolongados en condiciones basales, la muerte súbita de origen arrítmico aparece con mayor frecuencia en los hombres que sufren esta enfermedad. Se presentan dos casos de ensanchamiento extremo del intervalo QT corregido en pacientes con takotsubo que tuvieron desenlaces diferentes. El propósito de este trabajo es destacar y revisar las diferencias electrocardiográficas y pronósticas relacionadas con el sexo de los sujetos que desarrollan esta controvertida enfermedad.

Abstract Takotsubo syndrome, also known as stress cardiomyopathy, is a difficult diagnostic challenge as, in many cases, its presentation can overlap with that of myocardial infarction due to plaque rupture. The definitive diagnosis is based on the lack of culprit lesions on coronariography. The pathophysiology of the disease has not been completely ascertained, and it has a generally benign prognosis. However, a not inconsiderable percentage of patients experience serious complications, notably malignant arrhythmias like polymorphic ventricular tachycardia due to a prolonged QT interval. Despite takotsubo syndrome affecting mainly women who, furthermore, generally have longer basal QT intervals, sudden death due to arrhythmias is more common in men with this disease. Two cases are presented of extremely prolonged corrected QT intervals in patients with takotsubo, with different outcomes. The purpose of this paper is to highlight and review the electrocardiographic and prognostic differences related to the gender of the individuals who develop this controversial disease.

Niña de 12 años con síncope durante el ejercicio / 12-year-old girl with syncope during exercise

Continuamos con la serie de casos clínicos en Cardiología Pediátrica revisando los motivos de consulta frecuentes en las consultas de Pediatría de Atención Primaria, presentados de forma breve y práctica y tratando de mostrar la utilidad del electrocardiograma, método diagnóstico del que disponemos en Atención Primaria. En este número se presenta el caso de una niña de 12 años con un episodio de síncope durante el ejercicio. Se discuten los hallazgos electrocardiográficos y la orientación en el manejo de este paciente (AU)

We continue reviewing the Pediatric Cardiology series of clinical cases, which display the reasons for frequent consultation in Primary Pediatric Care. We present them in a brief and practical way, trying to show the usefulness of the electrocardiogram, which proves to be the main diagnostic tool used in Primary Care. This issue describes the case of a 12-year-old girl who suffered an episode of syncope during exercise. Electrocardiographic findings and guidance in the management of this patient are discussed. (AU)

Variables electrocardiográficas asociadas a la aparición de eventos cardiovasculares adversos en el infarto agudo de miocardio sin elevación del segmento ST / Electrocardiographic variables associated to the occurrence of adverse cardiovascular events in non-ST elevation acute myocardial infarction

Introducción: La frecuencia de infarto agudo de miocardio sin elevación del segmento ST se está incrementando y, con ella, los resultados adversos en pacientes con enfermedad coronaria isquémica aguda. Objetivo: Identificar las variables electrocardiográficas asociadas a la aparición de eventos cardiovasculares adversos en el infarto agudo de miocardio sin elevación del segmento ST. Método: Se realizó un estudio transversal, de tipo correlacional, con 68 pacientes con infarto agudo de miocardio sin elevación del segmento ST atendidos en el Hospital Arnaldo Milián Castro, en la provincia de Villa Clara. Se estudiaron los hallazgos electrocardiográficos y eventos cardiacos adversos durante el ingreso. Se hicieron análisis bivariados para establecer la relación de ambas variables, utilizando el estadígrafo chi cuadrado y el riesgo relativo. Resultados: Los hallazgos electrocardiográficos más frecuentes fueron la inversión de la onda T (#8805; 2mm), depresión del segmento ST y el QT corregido largo mediante la fórmula de Bazzet. El 26,5 por ciento presentaron eventos cardiovasculares adversos. La depresión del segmento ST, el QT largo corregido y la elevación del segmento ST en aVR se asociaron significativamente con eventos adversos intrahospitalarios (p lt; 0,05). Conclusiones: La asociación de la depresión del segmento ST, la elevación del segmento ST en aVR y el QT largo corregido con la ocurrencia de eventos cardiovasculares adversos intrahospitalarios, sugiere que estos hallazgos se pueden tener en cuenta como posibles indicadores de evolución desfavorable en pacientes con infarto agudo de miocardio sin elevación del segmento ST(AU)

Introduction: The frequency of non-ST elevation acute myocardial infarction is on the increase, and so is the number of adverse results in patients with acute ischemic coronary disease. Objective: Identify the electrocardiographic variables associated to the occurrence of adverse cardiovascular events in non-ST elevation acute myocardial infarction. Method: A cross-sectional correlational study was conducted of 68 patients with non-ST elevation acute myocardial infarction cared for at Arnaldo Milián Castro Hospital in the province of Villa Clara. Attention was paid to electrocardiographic findings and adverse cardiac events occurring during the hospital stay. Bivariate analyses were performed to establish the relationship between the two variables, using the chi square statigram and relative risk estimation. Results: The most common electrocardiographic findings were T-wave inversion (#8805; 2 mm), ST depression and long corrected QT by Bazzet's formula. Of the total study subjects 26.5 percent had adverse cardiovascular events. ST depression, long corrected QT and ST elevation in aVR were significantly associated to in-hospital adverse events (p < 0.05). Conclusions: Association of ST depression, ST elevation in aVR and long corrected QT with the occurrence of adverse in-hospital cardiovascular events suggests that these findings may be taken into account as possible indicators of an unfavorable evolution in patients with non-ST elevation acute myocardial infarction(AU)

QT interval greater than 460 ms in multiple electrocardiograms during follow-up in patients with Brugada syndrome: What does it contribute?

INTRODUCTION: Corrected QT interval (QTc) >460 ms in the right precordial leads has been described as a predictor of malignant ventricular arrhythmias (MVA) in patients with Brugada syndrome (BrS). OBJECTIVE: To assess the presence of QTc>460 ms in multiple electrocardiograms (ECGs) during follow-up as a predictor of recurrence of MVA in patients with BrS. METHODS: The study group included 43 patients with BrS and an implantable cardioverter-defibrillator. ECGs were performed serially between June 2000 and January 2017. QT interval was measured and QTc was obtained by Bazett's formula. The sample was divided into three groups: Group 1 (patients with no ECGs with QTc>460 ms); Group 2 (patients with only one ECG with QTc>460 ms); and Group 3 (patients with two or more ECGs with QTc>460 ms). RESULTS: The following variables were more frequently observed in Group 3: family history of sudden death (p=0.023), previous history of cardiorespiratory arrest (p=0.032), syncope (p=0.039), documented MVA (p=0.002), and proportion of ECGs with coved-type ST interval during follow-up (p=0.002). In Group 3, 67% of BrS patients had events during follow-up, as opposed to only 22% of Group 1 and 14% of Group 2 (Group 1 vs. Group 2, p=0.33015; Group 1 vs. Group 3, p=0.04295; and Group 2 vs. Group 3, p=0.04155). CONCLUSIONS: QTc>460 ms in more than one ECG during follow-up increases the risk of MVA events in patients with BrS.

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.

Repolarización ventricular en la terapia oncológica / Ventricular repolarization in cancer therapy

RESUMEN Se discuten los procesos de despolarización y repolarización ventriculares, con su falta de uniformidad y su heterogeneidad, tanto en pacientes con corazón sano como en aquellos enfermos, cuestión de rangos. Se analizan las mediciones que expresan las características de la repolarización ventricular: el intervalo QT y otras mediciones incluso más fidedignas como el intervalo TPICO-TFINAL, su dispersión y otras. Se precisa la existencia del signo y del síndrome de QT largo, así como los tres procesos básicos de la arritmogenia: la heterogeneidad, la alternancia y la dispersión, con las diferencias de los potenciales de acción en las tres zonas del miocardio ventricular. Se precisan los factores de riesgo del QT largo (común con esta terapia), de las arritmias ventriculares (en especial la torsión de puntas, extremadamente rara en estos casos) y se discute la necesidad de valorar datos clínicos, eléctricos, comorbilidades, conflictos agregados y las medidas a tomar en estos pacientes.

ABSTRACT Ventricular depolarization and repolarization processes are discussed, including their differences and heterogeneity both in patients with a healthy/sick heart, a matter of ranges. Measurements expressing the characteristics of ventricular repolarization are analyzed: the QT interval and other even more reliable measurements such as the TPEAK-TEND interval, its dispersion and others. We emphasize on the existence of the long QT syndrome (and sign) and the three basic processes of arrhythmogenesis: heterogeneity, alternation and dispersion, with differences in action potentials in the three zones of the ventricular myocardium. The risk factors of long QT (common in this therapy) and ventricular arrhythmias (especially torsades de pointes, extremely rare in these cases) are highlighted. The need to assess clinical and electrical features, comorbidities, aggregate conflicts, and management of these patients is also discussed.

Non-invasive ECG recording and QT interval correction assessment in anesthetized rats and mice / Eletrocardiograma não invasivo e avaliação da correção do intervalo QT em roedores anestesiados

Rats and mice are the most common species used in experimental cardiac electrophysiology studies. Electrocardiogram (ECG) recording shows paramount importance for monitoring arrhythmias and cardiac function in several disease models, including QT syndrome. However, the lack of standardized reference values and QT correction formula for different animal species and lineages represent a challenge for ECG interpretation. The aim of this study is to provide an improved method for ECG recording, establishing reference range values and determine the QT formulas with higher correlation to heart rate (HR). A total of 10 Wistar rats, 10 Swiss mice, 10 C57BL/6 mice and 10 FVB/NJ mice were used in the study. Animals were submitted to anesthesia with isoflurane and ECG recording was performed using a six-channel non-invasive electrocardiograph. QT was corrected using the following formulas: Bazzett, Fridericia, Mitchell, Hodges, Van der Water and Framingham. Normal range values for ECG parameters were established in all animals studied. Pearsons' correlation defined Hodges formula as the most suitable for QT correction. This study demonstrated an improved method of ECG recording with reference values for Swiss, FVB/NJ, C57BL/6 mice, and Wistar rats. Hodges' formula was the most effective formula for QT correction in rodents, whereas Bazett's and Friderica formulas were ineffective for such animals. The present work contributes to arrhythmias investigation in experimental cardiology and may reduce misinterpretations in rodents' ECG.(AU)

Ratos e camundongos são as espécies mais comumente utilizadas em estudos experimentais de eletrofisiologia cardíaca. O registro do eletrocardiograma (ECG) é de suma importância para o monitoramento de arritmias e função cardíaca em vários modelos de patologias. No entanto, a falta de valores de referência padronizados e a fórmula de correção do QT para diferentes espécies e linhagens animais representam um desafio para a interpretação do ECG. O objetivo deste estudo é fornecer um método melhorado para o registro de ECG, estabelecendo valores de referência e determinar as fórmulas QT com maior correlação com a freqüência cardíaca (FC). Um total de 10 ratos Wistar, 10 camundongos Swiss, 10 camundongos C57BL/6 e 10 camundongos FVB/NJ foram utilizados no estudo. Os animais foram submetidos à anestesia com isoflurano e o registro de ECG foi realizado com eletrocardiógrafo não invasivo de seis canais. O QT foi corrigido usando as seguintes fórmulas: Bazzett, Fridericia, Mitchell, Hodges, Van der Water e Framingham. Os valores da normalidade para os parâmetros do ECG foram estabelecidos em todos os animais estudados. A correlação de Pearson definiu a fórmula de Hodges como a mais adequada para a correção do QT. Este estudo demonstra um método melhorado de registro de ECG com valores de referência para camundongos Swiss, FVB/NJ, C57BL/6 e Wistar. A fórmula de Hodges foi a mais eficaz para correção de QT em roedores, enquanto as fórmulas de Bazett e Friderica apresentaram valores mais baixos de correlação. O presente trabalho contribui para a investigação de arritmias em cardiologia experimental e pode reduzir interpretações erradas no ECG de roedores.(AU)

Comparación de cuatro fórmulas para ajustar el intervalo QT a la frecuencia cardiaca en pacientes cardiópatas / Comparison of four formulas to adjust the QT interval to the heart rate in a cardiac patient / Comparação de quatro fórmulas para ajustar o intervalo QT à freqüência cardíaca em pacientes com doença cardíaca

Resumen. Introducción: La prolongación del intervalo QT en el electrocardiograma es un conocido factor de riesgo para desarrollar eventos cardiovasculares. En Latinoamérica existe poca evidencia acerca de la epidemiología de este tipo de alteraciones electrocardiográficas. El objetivo de este estudio fue evaluar la prevalencia del intervalo QT corregido largo según cuatro fórmulas. Metodología: Estudio descriptivo retrospectivo. Se realizó una revisión de 156 registros electrocardiográficos de 12 derivaciones realizados a pacientes mayores a 40 años. Las medidas se realizaron manualmente y posteriormente los valores se ajustaron a la frecuencia cardiaca mediante cuatro fórmulas validadas existentes. Se consideró intervalo QT largo cuando la duración sobrepasaba los 470 ms. Resultados: De los 156 registros analizados, 55.7% de los registros pertenecieron a pacientes de sexo femenino y la edad media fue 70.3 ± 9.7 años. 9.6% de los registros fueron considerados como largos mediante la fórmula de Bazzet, 4.4% mediante la fórmula de Hodges, 3.8% mediante la fórmula de Fridericia y 3.2% mediante la fórmula deFramingham. La fórmula de Fridericia fue hallada como la más consistente para ajustar el intervalo QT a la frecuencia cardiaca. Conclusión: Dependiendo de la fórmula utilizada la prevalencia del intervalo QT largo varió significativamente. La fórmula de Fridericia fue la que demostró mejor consistencia.

Abstract. Introduction: The prolongation of the QT interval in the electrocardiogram is a well-known risk factor for developing cardiovascular events. In Latin America there is no much evidence about the epidemiology of electrocardiographic alterations. The objective of this study was to evaluate the prevalence of long corrected QT interval according to four formulas. Methodology: Retrospective descriptive study. A total of 156 electrocardiographic records of 12 referrals made to patients older than 40 years were review. The measurements were made manually and later the values ​​were adjusted to the heart rate by means of four existing validated formulas. The long QT interval was considered when the duration exceeded 470ms. Results: Of the 156 records analyzed, 55.7% of the records belonged to female patients and the mean age was 70.3 ± 9.7 years. 9.6% of the records were considered long using the Bazzet formula, 4.4% according to the Hodges formula, 3.8% according to the Fridericia formula and 3.2% according to the Framingham formula. The formula of Fridericia was found to be the most consistent to adjust the QT interval to the heart rate. Conclusion: Depending on the formula used, the prevalence of the long QT interval varied significantly. The formula of Fridericia was the one that showed the best consistency.

Resumo. Introdução: O prolongamento do intervalo QT no eletrocardiograma é um fator de risco conhecido para o desenvolvimento de eventos cardiovasculares. Na América Latina, há poucas evidências sobre a epidemiologia desse tipo de alteração eletrocardiográfica. O objetivo deste estudo foi avaliar a prevalência do intervalo QT longo corrigido de acordo com quatro fórmulas. Metodologia: Estudo descritivo retrospectivo. Uma revisão de 156 registros eletrocardiográficos de 12 derivações realizadas em pacientes com mais de 40 anos foi realizada. As medidas foram feitas manualmente e posteriormente os valores foram ajustados à freqüência cardíaca por meio de quatro fórmulas validadas existentes. O intervalo QT longo foi considerado quando a duração ultrapassou 470 ms. Resultados: Dos 156 prontuários analisados, 55,7% dos prontuários pertenciam a pacientes do sexo feminino e a média de idade foi de 70,3 ± 9,7 anos. 9,6% dos registros foram considerados longos usando a fórmula de Bazzet, 4,4% usando a fórmula de Hodges, 3,8% usando a fórmula de Fridericia e 3,2% usando a fórmula de Fraingham. A fórmula de Fridericia foi considerada a mais consistente para ajustar o intervalo QT à frequência cardíaca. Conclusão: Dependendo da fórmula utilizada, a prevalência do intervalo QT longo variou significativamente. A fórmula da Fridericia foi a que apresentou a melhor consistência.

Dispersión del intervalo QT corregido como predictor de arritmias ventriculares en el infarto agudo del miocardio / Dispersion of the corrected QT interval as a predictor of ventricular arrhythmias in acute myocardial infarction

RESUMEN Fundamento: La dispersión del intervalo QT es un marcador electrocardiográfico que puede resultar útil en la estratificación de riesgo arrítmicos en pacientes con infarto agudo del miocardio. Objetivo: Describir la influencia de la dispersión del intervalo QT corregido en asociación a otros factores de riesgo como predictores de arritmias ventriculares en el infarto agudo del miocardio con elevación del segmento ST. Metodología: Se estudiaron de menera prospectiva 209 pacientes que ingresaron de forma consecutiva con diagnóstico de infarto agudo de miocardio con elevación del segmento ST de enero de 2013 a junio de 2014 en el Hospital Provincial General Camilo Cienfuegos de Sancti Spíritus. Se recogieron datos clínicos, de laboratorio electrocardiográficos y ecocardiográficos; se determinó la implicación pronóstica de la dispersión del intervalo QT corregido en la aparición de arritmias ventriculares a través de la regresión logística binaria y las curvas de operador-receptor. Resultados: Las arritmias ventriculares se presentaron en 39 (18.7 %) pacientes. La dispersión del QT corregido mostró una adecuada capacidad de discriminación en la predicción de cualquier episodio arrítmico ventricular grave (c=0.768, p=0.0001). En el análisis multivariado la dispersión del QT resultó un predictor independiente de arritmias ventriculares (OR= 7.075; IC 95%= 1.6- 32.9; p=0.009). Conclusiones: La probabilidad de presentar arritmias ventriculares durante el infarto agudo del miocardio es mayor cuando se incrementan la dispersión del intervalo QT, por lo que se sugiere debe ser una variable a evaluar en la estratificación pronostica del infarto agudo del miocardio.

ABSTRACT Background: Dispersion of the QT interval is an electrocardiographic marker that can be useful in the stratification of arrhythmic risk in patients with acute myocardial infarction. Objective: To describe the influence of corrected QT interval dispersion in association with other risk factors as predictors of ventricular arrhythmias in acute myocardial infarction with ST-segment elevation. Methodology: 209 patients who entered consecutively with diagnosis of acute myocardial infarction with elevation of the ST segment from January 2013 to June 2014 at Camilo Cienfuegos General Provincial Hospital of Sancti Spíritus were studied prospectively. Clinical, electrocardiographic and echocardiographic laboratory data were collected; the prognostic implication of the corrected QT interval dispersion in the appearance of ventricular arrhythmias through binary logistic regression and operator-receiver curves was determined. Results: Ventricular arrhythmias occurred in 39 (18.7%) patients. The dispersion of the corrected QT showed an adequate discrimination capacity in the prediction of any serious ventricular arrhythmic episode (c = 0.768, p = 0.0001). In the multivariate analysis, QT dispersion was an independent predictor of ventricular arrhythmias (OR = 7.075, 95% CI = 1.6-32.9, p = 0.009). Conclusions: The probability of presenting ventricular arrhythmias during acute myocardial infarction is greater when the dispersion of the QT interval is increased, so it is suggested that it should be a variable to be evaluated in the prognostic stratification of acute myocardial infarction.

Dispersión del intervalo QT corregido como predictor de arritmias ventriculares en el infarto agudo del miocardio / Dispersion of the corrected QT interval as a predictor of ventricular arrhythmias in acute myocardial infarction

RESUMEN Fundamento: La dispersión del intervalo QT es un marcador electrocardiográfico que puede resultar útil en la estratificación de riesgo arrítmicos en pacientes con infarto agudo del miocardio. Objetivo: Describir la influencia de la dispersión del intervalo QT corregido en asociación a otros factores de riesgo como predictores de arritmias ventriculares en el infarto agudo del miocardio con elevación del segmento ST. Metodología: Se estudiaron de menera prospectiva 209 pacientes que ingresaron de forma consecutiva con diagnóstico de infarto agudo de miocardio con elevación del segmento ST de enero de 2013 a junio de 2014 en el Hospital Provincial General Camilo Cienfuegos de Sancti Spíritus. Se recogieron datos clínicos, de laboratorio electrocardiográficos y ecocardiográficos; se determinó la implicación pronóstica de la dispersión del intervalo QT corregido en la aparición de arritmias ventriculares a través de la regresión logística binaria y las curvas de operador-receptor. Resultados: Las arritmias ventriculares se presentaron en 39 (18.7 %) pacientes. La dispersión del QT corregido mostró una adecuada capacidad de discriminación en la predicción de cualquier episodio arrítmico ventricular grave (c=0.768, p=0.0001). En el análisis multivariado la dispersión del QT resultó un predictor independiente de arritmias ventriculares (OR= 7.075; IC 95%= 1.6- 32.9; p=0.009). Conclusiones: La probabilidad de presentar arritmias ventriculares durante el infarto agudo del miocardio es mayor cuando se incrementan la dispersión del intervalo QT, por lo que se sugiere debe ser una variable a evaluar en la estratificación pronostica del infarto agudo del miocardio.(AU)

ABSTRACT Background: Dispersion of the QT interval is an electrocardiographic marker that can be useful in the stratification of arrhythmic risk in patients with acute myocardial infarction. Objective: To describe the influence of corrected QT interval dispersion in association with other risk factors as predictors of ventricular arrhythmias in acute myocardial infarction with ST-segment elevation. Methodology: 209 patients who entered consecutively with diagnosis of acute myocardial infarction with elevation of the ST segment from January 2013 to June 2014 at Camilo Cienfuegos General Provincial Hospital of Sancti Spíritus were studied prospectively. Clinical, electrocardiographic and echocardiographic laboratory data were collected; the prognostic implication of the corrected QT interval dispersion in the appearance of ventricular arrhythmias through binary logistic regression and operator-receiver curves was determined. Results: Ventricular arrhythmias occurred in 39 (18.7%) patients. The dispersion of the corrected QT showed an adequate discrimination capacity in the prediction of any serious ventricular arrhythmic episode (c = 0.768, p = 0.0001). In the multivariate analysis, QT dispersion was an independent predictor of ventricular arrhythmias (OR = 7.075, 95% CI = 1.6-32.9, p = 0.009). Conclusions: The probability of presenting ventricular arrhythmias during acute myocardial infarction is greater when the dispersion of the QT interval is increased, so it is suggested that it should be a variable to be evaluated in the prognostic stratification of acute myocardial infarction.(AU)

Efectos de claritromicina sobre el Intervalo QT corregido, en pacientes añosos hospitalizados / Comparative Pharmacodynamic analysis of QT interval prolongation. Induced by Clarithromycin in elderly hospitalized patients

Se estableció los efectos de la claritromicina sobre el intervalo QT corregido (iQTc) en pacientes gerontes, que requirieron hospitalización por infección respiratoria, mediante registro electrocardiográfico al inicio y al final del tratamiento. Se observó en 61% de los casos un aumento del iQTC (0,04 seg en promedio). No obstante las comorbilidades asociadas, ningún caso evolucionó a taquicardia ventricular polimórfica

The effects of clarithromycin on the corrected QT interval (iQTc) in elderly patients, who required hospitalization due to respiratory infection, were established by electrocardiographic recording at the beginning and at the end of the treatment. An increase in iQTC was observed in all cases (0.04 sec on average). Despite the associated comorbidities, no case evolved to polymorphic ventricular tachycardia