Deep phenotyping of left atrial characteristics: sphericity and stiffness stratify patients with atrial fibrillation and cardioembolic stroke.

PURPOSE

Cardioembolic stroke (CES) comprises a high proportion of ischaemic stroke, and atrial fibrillation (AF) is a major risk factor. Novel left atrial (LA) parameters of stiffness and sphericity, have been posited as markers of atrial cardiomyopathy, that often manifests as stroke and AF. We sought to comprehensively evaluate LA parameters in patients with different grades of AF who suffered CES compared to AF patients without history of stroke.

METHODS

Consecutive CES patients who presented to our tertiary institute were prospectively recruited; 155 CES patients were classified by rhythm: sinus rhythm (n = 30), paroxysmal AF (PAF, n = 88), and permanent AF (perAF, n = 37). Patients with AF and no prior stroke (AF-NS) were simultaneously recruited (PAF n = 77, perAF n = 39). All recruited patients underwent transthoracic echocardiogram with detailed evaluation of LA parameters including volume, function, stiffness, mechanical dispersion, and sphericity.

RESULTS

Increased LA volume, stiffness, sphericity, mechanical dispersion and reduced LA function were observed in both patient groups; parameters worsened as AF grade progressed from PAF to perAF (p < 0.05 for all). Additionally, LA function was reduced, while mechanical dispersion, stiffness, and sphericity were increased in CES patients compared to rhythm matched AF-NS patients. Differentiation between AF groups and CES versus AF-NS was achieved through Principle Component Analysis (PCA); the latent factors comprised of LA parameters including LA minimum volume, LA emptying fraction, LA stiffness and circularity (measure of sphericity). We performed receiver operating curves of the parameters identified by PCA analysis; circularity, a measure of LA sphericity, had the highest AUC (0.701, p < 0.001) to discriminate CE stroke from AF-NS.

CONCLUSION

In addition to LA volume and function, novel measures of LA stiffness and sphericity are altered in patients with CES and between grades of AF. Our pilot study has identified that a composite of LA parameters may be important for discriminating increased stroke likelihood in CES patients, and between AF grades. Thus, detailed evaluation of LA parameters may have clinical utility in cardioembolic stroke and AF.