Andersen-Tawil Syndrome with High Risk of Sudden Cardiac Death in Four Mexican Patients. Cardiac and Extra-Cardiac Phenotypes

ABSTRACT Background: Andersen-Tawil syndrome (ATS) is a cardiac channelopathy that is inherited in an autosomal dominant way, and it is characterized by a triad of periodic paralysis, ventricular arrhythmias, and includes some dysmorphic features with incomplete penetrance and variable expression that result in a challenging diagnosis. Objective: The objective of the study was to describe the cardiac and extra-cardiac phenotype in a cohort of patients with ATS at risk of sudden cardiac death (SCD) to improve its early clinical identification. Methods: In an observational, transversal study, with a deviant case sampling, four female patients with ATS at high risk of SCD were included in the study. They carried the heterozygous pathogenic variants c.407C>T [p.Ser136Phe], c.652C>T [p.Arg218Trp] (n=2), and c.431G>C [p.Gly144Ala] in the KCNJ2 gene. Patients were evaluated by a cardiologist, a clinical geneticist, and a physiatrist. Results: One patient had the classical facial phenotype and the other three had subtle manifestations. The group of patients presented a diverse set of clinical data such as: triangular face, broad forehead, broadening of medial eyebrows, auricular pits, low-set ears, eyelid ptosis, thin lips, mandibular hypoplasia, and diverse types of dental alterations, single transverse palmar crease, camptodactyly, and syndactyly. Long-exercise test showed a decrement in the percentage amplitude up to 44%, classifying patients in IV or V types according to Fournier’s scale. Conclusions: Extra-cardiac manifestations were a common finding in this series of ATS type1 at high risk of SCD. Its recognition could help the clinician in the early identification of patients with ATS, especially for the cardiologist since they are commonly referred only for evaluation of ventricular arrhythmias.

Manejo de la insuficiencia cardiaca con estimulación hisiana en bloqueo de rama derecha: reporte de caso / Management of heart failure with His bundle pacing in right bundle branch block: case report

Resumen La terapia de resincronización cardiaca mediante estimulación hisiana ha demostrado ser efectiva en pacientes con bloqueo de rama izquierda del haz de His e insuficiencia cardiaca. Paciente masculino, con 47 años de edad, con insuficiencia cardiaca, fracción de expulsión del 17% y miocardio dilatada idiopática, electrocardiograma en ritmo sinusal, bloqueo auriculoventricular de 1.er grado, intervalo PR 400 ms, bloqueo completo de rama derecha del haz de His, bloqueo del fascículo anterior de la rama izquierda del haz de His, duración del QRS 200 ms. Se decidió realizar estimulación selectiva del haz de His. La resincronización cardiaca biventricular convencional en pacientes con presencia de bloqueo completo de la rama derecha del haz de His no está indicada debido a la pobre respuesta al tratamiento. La estimulación hisiana permite reclutar la rama bloqueada y reestablecer la conducción a través de ella, de tal forma que, en ausencia de necrosis, se logre sincronía biventricular. En el caso presentado el reclutamiento de la rama derecha mediante estimulación hisiana se reflejó en el restablecimiento de la sincronía biventricular, medida por rastreo de marcas (speckle tracking) e incremento significativo de la fracción de expulsión del ventrículo izquierdo del 17 al 36.6%, con un incremento absoluto del 19.6%.

Abstract Cardiac resynchronization therapy has proven to be an effective therapy in patients with left bundle branch block and heart failure. Male, 47 years old, heart failure with a left ventricle ejection fraction of 17%, idiopathic heart failure. ECG with sinus rhythm, 1st degree AV block, PR 400 ms, complete right bundle branch block, anterior hemi-fascicle of the left bundle of His, and QRS duration 200 ms. We decided to perform a selective His bundle pacing. In patients with right bundle branch block the biventricular cardiac resynchronization is not indicated due to low treatment response. His bundle pacing allows recruiting the blocked branch and restoring conduction throughout it, therefore, in the absence of necrosis the biventricular synchrony is achieved. We presented a case of His bundle pacing with recruitment of the right bundle branch, which reestablish biventricular synchrony measured by speckle tracking, and with a significant increase of the left ventricle ejection fraction from 17 to 36.6%, with an absolute increase of 19.6%.