Atrial imaging and cardiac Rhythm In cryptogenic Embolic Stroke: the ARIES study
Authors: Castrejon Castrejon S , Rigual R R , Fernandez Gasso L F G , Martinez Cossiani M M C , Ruiz Ares G R A , Perez David E P D , Lopez Fernandez T L F , Rodriguez Pardo J R P , Garcia Castro J G C , De Celis E D C , Casado L C , Hervas C H , Fuentes B F , Merino J L M L 
Published: May 2024

Abstract

Background
One of the underlying causes of cryptogenic stroke is an unknown cardioembolic etiology, and the most frequent is atrial fibrillation (AF). It is not unusual to find non-sustained (&lt;30 s) "microfibrillatory" atrial tachycardias (nsAT) or frequent atrial ectopic beats (AE) during the work-up but its pathological significance remains uncertain.

Purpose
Our aim is to analyze the risk of developing AF or nsAT in patients with cryptogenic stroke and compare their atrial function using advanced echocardiography and their clinical outcome during the follow-up.

Methods
The ARIES study (Atrial imaging and cardiac Rhythm In cryptogenic Embolic Stroke) is an observational, prospective study in patients admitted for recent cryptogenic stroke in a comprehensive Stroke Unit. We analyze the frequency of detecting AF and nsAT in two 30-day ECG records with a wearable device and we compare echocardiographic signs of left atrial (LA) dysfunction according to rhythm classification: AF, high-burden nsAT/AE (&gt;2 nsAT/24 hours or &gt;3.000 AE/24 hours respectively) and normal sinus rhythm (NSR). Finally, we evaluate stroke recurrence and mortality at 12-months and report changes in classification of stroke etiology during the follow-up.

Results
In total prolonged rhythm study (1st and 2nd 1-month wearable EKG), AF was found in 35 (32.1%) patients, high-burden nsAT/AE in 27 patients (24.8%) and normal rhythm was found in 47 patients (43.1%). Patients with AF compared with patients with NSR presented higher values in LA volume (69.9±21.8 vs 49.4±26.5, p&lt;0.001) , LA index volume (38.8±11.2 vs 27.3±11.8 ml/m2, p&lt;0.001), 3D LA index volume (50.6±17.2 vs 34.0±15.4 ml/m2, p&lt;0.001), 3D-telediastolic LA volume (89.5±27.7 vs 66.8 ±31.9 ml/m2, p=0.002), 3D-telesistolic LA volume (43.6±15.3 vs 25.3±17.4 ml/m2, p &lt;0.001), lower rates of LA ejection fraction (50 ±14.6 vs 62.7±11.8, p=0.001) and LA strain in reservoir (22.0±8.6 vs 30.4±10.5, p&lt;0.001) and contraction (10.5±8.18 vs 17.1±7.5, p&lt;0.001). After multivariable regression analysis (age, HTA and CHASDS2VASC) all the differences remained significative. High-burden nsAT/AE and NSR patients presented significant differences in LA index volume (33.4±12.4 vs 27.3±11.8 ml/m2, p=0.043) and LA strain in reservoir (26.6±12.5) vs 31.0±10.1, p=0.034) that disappeared after multivariate regression analysis. There were no significant differences in ischemic recurrence or mortality between the three groups.

Conclusions
In patients with cryptogenic stroke, we registered a high rate of AF and high-burden nsAT/AE. AF patients showed notable alterations in LA volume, LA function and reservoir and contraction strain, while patients with high-burden nsAT/AE showed less structural alteration in echocardiography without difference in stroke recurrence among groups.