Left atrial structure and function among different subtypes of atrial fibrillation: an echocardiographic substudy of the AMIO-CAT trial

Abstract

Abstract Aims  Little is known about cardiac structure and function among atrial fibrillation (AF) subtypes; paroxysmal AF vs. persistent AF (PxAF), and across AF burden. We sought to assess differences in left atrial (LA) measures by AF subtype and burden. Methods and results  This was a cross-sectional echocardiographic substudy of a randomized trial of AF patients scheduled for catheter ablation. Patients had an echocardiogram performed 0–90 days prior to study inclusion. We performed conventional echocardiographic measures, left ventricular (LV) and LA speckle tracking. Measures were compared between AF subtype and burden (0%, 0–99%, and 99–100%) determined by 72-h Holter monitoring. Of 212 patients, 107 had paroxysmal AF and 105 had PxAF. Those with PxAF had significantly reduced systolic function (LV ejection fraction: 48% vs. 53%; P < 0.001), larger end-systolic and end-diastolic LA volumes (LAVi and LAEDVi), reduced LA emptying fraction (LAEF: 29% vs. 36%, P < 0.001), and reduced LA strain (LAs) (LAs: 20% vs. 26%, P < 0.001). LA measures remained significantly lower in PxAF after multivariable adjustments. All LA measures and measures of systolic function were significantly impaired in patients with 99–100% AF burden, whereas all measures were similar between the other groups (LAVi: 40mL/m2 vs. 33mL/m2 vs. 34mL/m2; LAEDVi: 31mL/m2 vs. 21mL/m2 vs. 22mL/m2, LA emptying fraction: 23% vs. 35% vs. 36%, LAs: 16% vs. 25% vs. 25%, for 99–100%, 0–99%, and 0% AF, respectively, P < 0.001 for all). These differences were consistent after multivariable adjustments. Conclusion  LA mechanics differ between AF subtype and burden and these characteristics influence the clinical interpretation of these measures.