Fernando Arribas-Ynsaurriaga

Flutter auricular 1:1 tras la administración de vernakalant para cardioversión de fibrilación auricular

Vernakalant is a novel antiarrhythmic drug that has proved its efficacy at restoring sinus rhythm in recent-onset atrial fibrillation (AF). Its mechanism of action is based on selective partial blocking of potassium currents in the atrial myocardium, prolonging the atrial refractory period without significantly affecting ventricular refractoriness. This makes it potentially beneficial as a low-effect ventricular proarrhythmogenic, even in patients with structural heart disease. Class IC drugs–used to restore sinus rhythm and prevent AF recurrence–favor the appearance of flutter, often with 1:1 ventricular conduction. Vernakalant also appears to favor the development of flutter, although 1:1 atrioventricular conduction has not been reported to date. We present the case of a 77-year-old man with coronary disease without infarction, with hypertensive cardiopathy, normal ventricular function, and 1 previous episode of persistent AF requiring electrical cardioversion. Treatment was with acenocoumarol, enalapril, and simvastatin. The patient was referred for electrophysiologic study for typical paroxystic atrial flutter with 240 ms cycle length in the electrocardiogram. Initially in sinus rhythm, during placement of the circular multipolar catheter used to record electrocardiograms and for stimulation he developed sustained AF after a 10-min observation period. We decided to use intravenous vernakalant for cardioversion. After a first 3 mg/kg infusion, the AF organized into flutter with 320 ms cycle length, descending atrial activation sequence in the anterior right atrium, and exact return cycle in the cavotricuspid isthmus, compatible with typical flutter (Fig. 1). Atrioventricular conduction was initially variable, later stabilizing to 1:1 with right bundle branch block (Fig. 2). Given good tolerance despite rapid ventricular frequency, we decided to interrupt the drug infusion and perform radiofrequency ablation of the cavotricuspid isthmus. The Class IC antiarrhythmic drugs flecainide and propafenone slow atrial conduction by blocking voltage-dependent rapid sodium channels, favoring the stability of macro re-entry circuits in anatomic regions with predisposed structures (IC flutter). In the right atrium, they condition the slowing of atrial conduction and limit transversal conduction through the crista terminalis, facilitating the appearance of flutter circuits around the tricuspid annulus. Due to atrial conduction slowing, IC flutter is usually slow and can be led 1:1 to the ventricles. This greatly accelerates ventricular frequency that is often accompanied by aberrant conduction, which can condition poor hemodynamic tolerance of the arrhythmia. Although experience in the clinical use of vernakalant is very limited, data on its efficacy and safety in 4 controlled clinical trials has been published. Vernakalant has demonstrated efficacy superior to a placebo plus amiodarone in cardioversion of recent-onset AF (52% vs 4%-5% at 90-min observation) with 8% post-dose incidence of atrial flutter–which is far superior to amiodarone (0.9%), above all in patients receiving antiarrhythmic drugs.

Delayed positive response to a flecainide test in a patient with suspected Brugada syndrome: a worrisome finding.

Servei de Cardiologia, Hospital Universitari de la Vall d’Hebron, Vall d’Hebron Institute of Research (VHIR), Barcelona, Spain Servei de Cardiologia, Hospital Universitari de la Vall d’Hebron, Barcelona, Spain Unitat de Cardiopaties Congènites de l’Adolescent i de l’Adult (UCCAA), Hospital Universitari de la Vall d’Hebron, Barcelona, Spain Unitat de Cardiopaties Congènites de l’Adolescent i de l’Adult (UCCAA), Hospital Universitari de la Santa Creu i Sant Pau, Barcelona, Spain

Association Between Mutations in the NKX2.5 Homeobox, Atrial Septal Defects, Ventricular Noncompaction and Sudden Cardiac Death

1. Ramos-Casals M, Brito-Zerón P, López-Guillermo A, Khamashta MA, Bosch X. Adult haemophagocytic syndrome. Lancet. 2014;383:1503–1516. 2. Bergman MM, Gagnon D, Doern GV. Pichia ohmeri fungemia. Diagn Microbiol Infect Dis. 1998;30:229–231. 3. Reina JP, Larone DH, Sabetta JR, Krieger KK, Hartman BJ. Pichia ohmeri prosthetic valve endocarditis and review of the literature. Scand J Infect Dis. 2002;34:140–141. 4. João I, Duarte J, Cotrim C, et al. Native valve endocarditis due to Pichia ohmeri. Heart Vessels. 2002;16:260–263. 5. Yanghua Q, Weiwei W, Yang L, Jian X, Qian S. Isolation, identification, and antifungal susceptibility test for Kodamaea ohmeri: a case report on endocarditis. Journal of Medical Colleges of PLA. 2010;25:252–256. 6. Sundaram PS, Bijulal S, Tharakan JA, Antony M. Kodamaea ohmeri tricuspid valve endocarditis with right ventricular inflow obstruction in a neonate with structurally normal heart. Ann Pediatr Cardiol. 2011;4:77–80.

Letter to the EditorAppropriate Use Criteria for Cardiopulmonary Exercise Testing in Patients With Cardiac Resynchronization Devices. ResponseCriterios de uso apropiado para la ergoespirometría en el paciente portador de dispositivos de resincronización cardiaca. Respuesta

We wish to thank Dr. Dominguez-Rodriguez and Dr. Abreu-Gonzalez for their interest and comments regarding our publication. Cardiopulmonary exercise testing is a functional test of indisputable value in patients with cardiac resynchronization therapy (CRT) devices since, in addition to enabling objective evaluation of the functional response to treatment, it also provides prognostic information, an input that eventually could have therapeutic implications. Treadmill exercise testing is far more limited in the functional and prognostic assessment of patients with CRT devices and, in this respect, we are in complete agreement. However, the objective of our study was not to carry out a strictly functional assessment, much less a prognostic evaluation, of patients receiving CRT. This study was prospectively designed to determine the number of patients who experienced a loss of pacing capture during exercise, analyze the causes, and attempt to correct them, because nearly constant pacing is considered to be essential for achieving a response to therapy. The results obtained indicate that pacing capture was lost during exercise in 24% of the patients, which led to a process of clinical decision making to correct it. Thus, we concluded that treadmill exercise testing is a simple, accessible, and useful tool for follow-up of patients with CRT, and helps to guide clinical decisions related to drug therapy, device programing, and indications for atrioventricular node ablation. Given the small sample size, it is not possible to conclude from our report that exercise testing should be systematically employed in all the patients receiving CRT. However, we firmly believe that it can be highly useful in the assessment of certain patients, such as nonresponders or those who have atrial arrhythmias as the baseline rhythm.

Usefulness of Exercise Test in Cardiac Resynchronization Therapy Follow-up

de pacientes portadores de dispositivos de resincronización cardiaca Usefulness of Exercise Test in Cardiac Resynchronization Therapy Follow-up Sra. Editora: Se ha demostrado que la terapia de resincronización cardiaca (TRC) mejora el pronóstico, los sı́ntomas y la capacidad de ejercicio de los pacientes con insuficiencia cardiaca, disfunción grave del ventrı́culo izquierdo y trastornos de la conducción intraventricular. Sin embargo, a pesar de los esfuerzos realizados en mejorar la selección de candidatos, el lugar de estimulación y la programación del dispositivo, sigue habiendo un 30-35% de pacientes que no responden a este tratamiento. Diferentes estudios señalan que el mayor grado de beneficio con la TRC se obtiene con el mantenimiento de una estimulación biventricular casi constante. Sin embargo, el logro de este objetivo se puede ver limitado por conducción auriculoventricular (AV) intrı́nseca y fibrilación auricular con conducción rápida a los ventrı́culos. El objetivo de nuestro estudio es describir el comportamiento de la TRC durante el ejercicio y valorar la utilidad de la ergometrı́a convencional en el seguimiento tras el implante. Se incluyó a 33 pacientes con miocardiopatı́a dilatada e indicación de TRC; 21 (64%) eran respondedores a la terapia (definida como disminución del volumen telesistólico del ventrı́culo izquierdo al menos un 15% respecto del basal a los 6 meses del implante). Las caracterı́sticas clı́nicas de los pacientes del estudio se resumen en la tabla. Se realizó ergometrı́a en cinta sin fin con protocolo adaptado a la situación funcional basal del paciente. El tiempo medio