La repolarización auricular y sus implicaciones clínicas / Atrial repolarisation and its clinical implications

Resumen La onda P en el electrocardiograma representa exclusivamente la despolarización de las aurículas puesto que la repolarización auricular queda oculta en el QRS. Sin embargo, cuando la repolarizacón auricular se hace evidente en el electrocardiograma se convierte en un elemento clave para el diagnóstico de algunas enfermedades. Diferente sucede en la repolarización ventricular; la repolarización auricular adopta el mismo sentido de la despolarización ya que sigue un sentido cráneo-caudal y se da desde el epicardio hacia el endocardio.

Abstract The P wave on the electrocardiogram exclusively represents atrial depolarisation, since atrial repolarisation is hidden in the QRS complex. However, when atrial repolarisation becomes evident in the electrocardiogram, it is a key element for the diagnosis of some diseases. Unlike what happens in ventricular repolarisation, atrial repolarisation adopts the same direction as depolarisation since it follows a craniocaudal course and it goes from the epicardium towards the endocardium.

Advanced interatrial block: A predictor of covert atrial fibrillation in embolic stroke of undetermined source.

AIMS: One third of ischemic strokes are of unknown etiology. Interatrial block (IAB) is a marker of atrial electromechanical dysfunction that may predispose to the development of atrial fibrillation (AF). We hypothesized that IAB, especially in its advanced form, could be a marker of covert AF in patients with embolic stroke of undetermined source (ESUS). METHODS: We reviewed a single center cohort of ESUS patients with no prior history of AF. According to P-wave analysis of baseline ECG we distinguished 3 groups: normal P-wave duration (P-wave < 120 ms), partial IAB (P-IAB, P-wave ≥ 120 ms) and A-IAB (A-IAB, P-wave ≥ 120 ms with biphasic morphology in inferior leads). Follow-up was done 1, 6 and 12 months after discharge; then every 6 months. AF episodes, frequent premature atrial contractions (PACs) (>1%) and atrial tachyarrhythmias (runs of >3 consecutive PACs) were detected on 24 h Holter. The primary endpoint was new-onset AF detection on follow-up by any means. RESULTS: A high prevalence of both P-IAB (n = 30, 40%) and A-IAB (n = 23, 31%) was found in 75 ESUS patients. After a 521 day mean follow-up, 14 patients (19%) were diagnosed of AF. A-IAB independently predicted AF diagnosis (p =0.042) on follow-up. 24 h Holter analysis showed greater frequency of PACs and atrial tachyarrhythmia episodes in patients with IAB (p = 0.0275). CONCLUSIONS: In this hypothesis-generating study, A-IAB in the setting of ESUS is an independent risk predictor of covert AF. Although additional randomized clinical trials are warranted, A-IAB identifies ESUS patients with advanced atrial disease that could potentially benefit from early oral anticoagulation in secondary prevention.

Acute myocardial infarction due to coronary embolism in atrial fibrillation: case presentation and systematic review / Infarto agudo de miocardio debido a embolia coronaria en fibrilación auricular: presentación de caso y revisión sistemática

Abstract: Atrial fibrillation is the most common sustained arrhythmia in the general population, responsible for significant morbidity and mortality due to an increased risk of systemic embolism. The anatomic and hemodynamic characteristics of the cardiovascular system direct most emboli towards the central nervous system or the peripheral circulation, being coronary embolism an uncommon event. This has led to a paucity in the available medical literature regarding the importance of atrial fibrillation as a cause of acute myocardial infarction and the treatment these patients should be offered, with most of the evidence arising from case reports and small case series. A case of acute myocardial infarction associated with coronary embolism in a patient with new onset atrial fibrillation who was successfully treated with thrombus aspiration is presented, followed by a systematic review of the topic. The objective of this review is to establish the clinical characteristics of patients with coronary embolism due to atrial fibrillation and determine the best treatment options based on the available evidence.

Resumen: La fibrilación auricular es la arritmia sostenida más común en la población general, responsable de una gran morbilidad y mortalidad debido a un mayor riesgo de embolia sistémica. Las características hemodinámicas y anatómicas del sistema cardiovascular conducen directamente la mayoría de los émbolos hacia el sistema nervioso central o a la circulación periférica, siendo la embolia coronaria infrecuente. Esto ha llevado a una escasez en la literatura médica sobre la importancia de la fibrilación auricular como causa de infarto agudo de miocardio y del tratamiento que debe ser ofrecido a estos pacientes, con la mayoría de las pruebas derivadas de informes de casos y series de casos pequeñas. Un caso de infarto agudo de miocardio asociado con embolia coronaria en un paciente con fibrilación auricular de nueva aparición que fue tratada exitosamente con tromboaspiración es presentado, seguido de una revisión sistemática del tema. El objetivo de esta revisión es determinar las características clínicas de los pacientes con embolia coronaria debido a fibrilación auricular y determinar las mejores opciones de tratamiento basadas en la evidencia disponible.