Fenotipo heterogéneo del síndrome de QT largo causado por la mutación KCNH2-H562R: importancia del estudio genético familiar / Heterogeneous phenotype of long QT Syndrome caused by the KCNH2-H562R Mutation: Importance of familial genetic testing

Introducción y objetivos: El síndrome de QT largo es una canalopatía hereditaria que se asocia a síncope y muerte súbita. La heterogeneidad fenotípica de esta enfermedad hace que el estudio genético sea fundamental para detectar a los sujetos con síndrome de QT largo oculto. En este trabajo se exponen las características de una familia con 13 portadores de la mutación missense KCNH2-H562R que afecta a la región del poro del canal HERG. Métodos: Se describió la mutación KCNH2-H562R en un varón de 65 años con intervalo QTc prolongado que presentó un episodio de torsade de pointes. Posteriormente, se identificaron 13 portadores de la mutación en la familia. Se realizó evaluación clínica, electrocardiograma y ecocardiograma a los portadores (edad, 48 ± 26 años; el 46% varones). Resultados: El QTc medio en los portadores fue de 493 ± 42 ms (3 [23%] mostraron QTc normal); 6 (46%) tuvieron síntomas (4, síncope; 1, muerte súbita; 1, muerte súbita resucitada [probando]). Durante el tratamiento con bloqueadores beta, 11 (92%) de los 12 portadores permanecieron asintomáticos a los 5 años de seguimiento (1 paciente requirió simpatectomía cardiaca izquierda). El acortamiento del QTc con bloqueadores beta fue de 50 ± 37 ms. Hubo 1 muerte súbita en un paciente que rechazó tratamiento con bloqueadores beta. Conclusiones: El estudio familiar es fundamental en la interpretación de los resultados de los tests genéticos en la actualidad. Este artículo describe el fenotipo variable y heterogéneo de una amplia familia portadora de la mutación KCNH2-H562R y destaca el papel del estudio genético en la identificación de los individuos en riesgo que se beneficiarían del tratamiento con bloqueadores beta (AU)

Introduction and objectives: Long QT syndrome is an inherited ion channelopathy that leads to syncope and sudden death. Because of the heterogeneous phenotype of this disease, genetic testing is fundamental to detect individuals with concealed long QT syndrome. In this study, we determined the features of a family with 13 carriers of the KCNH2-H562R missense mutation, which affects the pore region of the HERG channel. Methods: We identified the KCNH2-H562R mutation in a 65-year-old man with a prolonged QTc interval who had experienced an episode of torsade de pointes. Subsequently, a total of 13 mutation carriers were identified in the family. Carriers (age 48 [26] years; 46% males) underwent clinical evaluation, electrocardiography and echocardiography. Results: The mean (standard deviation) QTc in carriers was 493 (42) ms (3 [23%] showed normal QTc); 6 (46%) had symptoms (4, syncope; 1, sudden death; 1, aborted sudden death [proband]). While under treatment with beta-blockers, 11 of 12 carriers (92%) remained asymptomatic at 5 years of follow-up (1 patient required left cardiac sympathectomy). The QTc shortening with beta-blockers was 50 (37) ms. There was 1 sudden death in a patient who refused treatment. Conclusions: Family study is essential in the interpretation of a genetic testing result. This article describes the heterogeneous and variable phenotype of a large family with the KCNH2-H562R mutation and highlights the role of genetic study for the appropriate identification of at-risk individuals who would benefit from treatment (AU)

Heterogeneous Phenotype of Long QT Syndrome Caused by the KCNH2-H562R Mutation: Importance of Familial Genetic Testing.

INTRODUCTION AND OBJECTIVES: Long QT syndrome is an inherited ion channelopathy that leads to syncope and sudden death. Because of the heterogeneous phenotype of this disease, genetic testing is fundamental to detect individuals with concealed long QT syndrome. In this study, we determined the features of a family with 13 carriers of the KCNH2-H562R missense mutation, which affects the pore region of the HERG channel. METHODS: We identified the KCNH2-H562R mutation in a 65-year-old man with a prolonged QTc interval who had experienced an episode of torsade de pointes. Subsequently, a total of 13 mutation carriers were identified in the family. Carriers (age 48 [26] years; 46% males) underwent clinical evaluation, electrocardiography and echocardiography. RESULTS: The mean (standard deviation) QTc in carriers was 493 (42) ms (3 [23%] showed normal QTc); 6 (46%) had symptoms (4, syncope; 1, sudden death; 1, aborted sudden death [proband]). While under treatment with beta-blockers, 11 of 12 carriers (92%) remained asymptomatic at 5 years of follow-up (1 patient required left cardiac sympathectomy). The QTc shortening with beta-blockers was 50 (37) ms. There was 1 sudden death in a patient who refused treatment. CONCLUSIONS: Family study is essential in the interpretation of a genetic testing result. This article describes the heterogeneous and variable phenotype of a large family with the KCNH2-H562R mutation and highlights the role of genetic study for the appropriate identification of at-risk individuals who would benefit from treatment.

Utilidad de un catéter de ablación con sensor de fuerza en la evaluación de las áreas de cicatriz miocárdicas de pacientes con taquicardia ventricular / Usefulness of the contact force sensing catheter to assess the areas of myocardial scar in patients with ventricular tachycardia

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Multiple interatrial electrical connection after heart transplantation.

A 62-year-old woman who underwent heart transplantation 6 years later presented a regular atrial tachycardia. Electrophysiologic evaluation showed an atrial arrhythmia in the recipient atrium with 2:1 conduction to the donor atrium, with a confusing electroanatomical map. With the suspect of alternant conduction through two different breakthroughs, the map was split in two concordant maps, corresponding to two connections that were successfully ablated. Later on, a third connection was detected and therefore ablated.