Left Atrial Dysfunction in the Pathogenesis of Cryptogenic Stroke: Novel Insights from Speckle-Tracking Echocardiography

Utility of left atrial strain for predicting atrial fibrillation following ischemic stroke

Twenty-five percent of ischemic strokes (IS) are cryptogenic, but it is estimated that paroxysmal atrial fibrillation (PAF) is the underlying cause in up to a third of cases. We aimed to investigate the predictive value of speckle tracking of the left atrium (LA) in diagnosing PAF in IS patients. We retrospectively studied 186 IS patients with a clinical echocardiographic examination during sinus rhythm. Outcome was PAF defined by at least one reported episode of AF following their IS. Conventional echocardiographic measures were performed. Global longitudinal strain (GLS), LA reservoir-(ε_s), conduit-(ε_e), contraction-strain (ε_a) and LA dyssynchrony (standard deviation of time-to-peak ε_s; LA SD-T2P) were obtained by left ventricular and LA speckle tracking. Of 186 patients, 28 (15%) were diagnosed with PAF. PAF-patients did not differ from non-PAF patients with regards to GLS nor SD-TPS, but atrial strain measures were significantly impaired at baseline (ε_s 27 vs. 35%, ε_e 12 vs. 16%, ε_a 15 vs. 18%, p < 0.02 for all, for PAF and non-PAF, respectively). However, only ε_s remained independently associated with PAF after adjustment for clinical and echocardiographic parameters (OR 1.13 [1.04; 1.22], p = 0.003, per 1% decrease). ε_s also provided the highest area under the receiver operating characteristic curve among all variables (AUC = 0.74). With a cutoff of 29%, ε_s had a specificity of 76% and a negative predictive value of 93%. Atrial reservoir strain is independently associated with PAF and may be used to improve the diagnosis of PAF following IS.

Multimodality Imaging for Best Dealing With Patients in Atrial Arrhythmias

The management of atrial fibrillation (AF) is not only a clinical challenge but also an imaging challenge. The role of different imaging modalities to estimate the thromboembolic risk in AF is a key clinical question. The present review summarizes the advances of myocardial imaging in the stratification of thromboembolic risk, diagnosis, and management of left atrial thrombosis in patients with AF. These imaging techniques are also important for understanding arrhythmias and their consequences. It is becoming fundamental for guiding therapy. Still, large studies are required, but be sure that left atrial imaging will become more and more clinically fundamental.

Atrial Cardiopathy and Sympatho-Vagal Imbalance in Cryptogenic Stroke: Pathogenic Mechanisms and Effects on Electrocardiographic Markers

Recently, atrial cardiopathy has emerged as possible pathogenic mechanism in cryptogenic stroke and many electrocardiographic (ECG) markers have been proposed in order to detect an altered atrial substrate at an early stage. The autonomic nervous system (ANS) plays a well-known role in determining significant and heterogeneous electrophysiological changes of atrial cardiomyocytes, that promote atrial fibrillation episodes in cardioembolic stroke. Conversely, the role of ANS in atrial cardiopathy and cryptogenic stroke is less known, as well as ANS effects on ECG markers of atrial dysfunction. In this paper, we review the evidence linking ANS dysfunction and atrial cardiopathy as a possible pathogenic factor in cryptogenic stroke.