Altered left atrial metrics in patients with cryptogenic stroke: A systematic review and meta‐analysis

Abstract Background There is no defined cause for cryptogenic stroke/embolic stroke of undetermined source (CS‐ESUS). As atrial fibrillation (AF) develops in a significant proportion of these patients, it has been suggested that left atrial (LA) myopathy may predispose to CS‐ESUS. We investigated alterations in echocardiographic measures of LA size and function in patients with CS‐ESUS. Methods A systematic literature review and meta‐analysis was performed. PubMed, EMBASE, Cochrane Library, Web of Science and SCOPUS were searched for articles published between 1 January 1990 and 10 February 2023. All observational studies of adult CS‐ESUS patients with LA volume or function measurements performed by transthoracic echocardiogram were included. Individual random effects meta‐analyses were performed on LA measurements in the CS‐ESUS patients using subgroup analysis of comparator groups. Results We included 29 articles with 3927 CS‐ESUS patients. Analysis of weighted mean differences showed CS‐ESUS patients had altered LA structure and function parameters, with a larger maximum indexed LA volume, reduced LA emptying fraction and/or LA reservoir strain, compared to healthy controls and noncardioembolic stroke patients. Conversely, CS‐ESUS patients had a smaller left atrium with better function, compared to cardioembolic stroke patients and CS‐ESUS patients who subsequently developed atrial fibrillation. Conclusions LA volume and function are altered in CS‐ESUS patients compared to healthy controls and other stroke aetiologies. An underlying atrial myopathy in a subset of CS‐ESUS patients may be involved in both thrombogenesis and dysrhythmia (specifically AF). While LA functional assessment is not currently recommended following stroke, it may offer an opportunity for recurrent stroke risk stratification.