1 A trial fibrillation (AF) is associated with extensive abnormalities in atrial structure and function. 1–3 It is well-established that structural atrial changes precede the development of AF and progress with increased duration of sustained AF 4 . The changes in atrial function impair not only the booster pump function but also the atrial reservoir and conduit functions during ventricular systole and early diastole. 5,6 Progressive atrial remodeling includes fibrotic changes that promote AF maintenance. 7 This idea is sup- ported by observations of increased left atrial (LA) fibrosis in patients with long-standing persistent AF. 4 LA structural and functional remodeling is associated with increased inci- dence of AF, as well as AF recurrence after cardioversion or ablation. 8–11 See Clinical Perspective Late gadolinium enhanced (LGE) cardiac magnetic reso- nance (CMR) can noninvasively quantify the extent of LA fibrosis. 12,13 Atrial function is commonly evaluated by speckle- tracking echocardiography; however, the technique is limited for resolution of the thin and asymmetrical LA myocardium and for the analysis of the posterior LA, where most of the fibrosis are located. 7 In contrast, myocardial motion can be accurately tracked with CMR because of its ability to accu- rately define endocardial and epicardial borders. 14 CMR fea- ture-tracking, a novel post–processing technique which tracks myocardial motion using cine CMR images, has recently been developed. 15–19 In this study, we sought to examine the Background—Atrial fibrillation (AF) is associated with left atrial (LA) structural and functional changes. Cardiac magnetic resonance late gadolinium enhancement (LGE) and feature-tracking are capable of noninvasive quantification of LA fibrosis and myocardial motion, respectively. We sought to examine the association of phasic LA function with LA enhancement in patients with AF. Methods and Results—LA structure and function was measured in 90 patients with AF (age 61±10 years; 76% men) referred for ablation and 14 healthy volunteers. Peak global longitudinal LA strain, LA systolic strain rate, and early and late diastolic strain rates were measured using cine–cardiac magnetic resonance images acquired during sinus rhythm. The degree of LGE was quantified. Compared with patients with paroxysmal AF (60% of cohort), those with persistent AF had larger maximum LA volume index (56±17 versus 49±13 mL/m 2 ; P=0.036), and increased LGE (27.1±11.7% versus 36.8±14.8%; P<0.001). Aside from LA active emptying fraction, all LA parameters (passive emptying fraction, peak global longitudinal LA strain, systolic strain rate, early diastolic strain rate, and late diastolic strain rate) were lower in patients with persistent AF (P<0.05 for all). Healthy volunteers had less LGE and higher LA functional parameters compared with patients with AF (P<0.05 for all). In multivariable analysis, increased LGE was associated with lower LA passive emptying fraction, peak global longitudinal LA strain, systolic strain rate, early diastolic strain rate, and late diastolic strain rate (P<0.05 for all). Conclusions—Increased LA enhancement is associated with decreased LA reservoir, conduit, and booster pump functions. Phasic measurement of LA function using feature-tracking cardiac magnetic resonance may add important information about the physiological importance of LA fibrosis. (Circ Cardiovasc Imaging. 2015;8:e002769. DOI: 10.1161/ CIRCIMAGING.114.002769.) Key Words: atrial fibrillation ◼ atrial function, left ◼ gadolinium ◼ magnetic resonance imaging © 2015 American Heart Association, Inc. Circ Cardiovasc Imaging is available at http://circimaging.ahajournals.org DOI: 10.1161/CIRCIMAGING.114.002769 Received April 18, 2014; accepted December 19, 2014. From the Department of Cardiology (M.H., J.A.C.L., I.M.K., K.F., D.S., H.A., J.R., J.E.M., H.C., S.N.), Department of Radiology (S.L.Z.), The Johns Hopkins University School of Medicine, Baltimore, MD; and Department of Biostatistics (V.Z.), Department of Epidemiology (S.N.), The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD. The Data Supplement is available at http://circimaging.ahajournals.org/lookup/suppl/doi:10.1161/CIRCIMAGING.114.002769/-/DC1. Correspondence to Mohammadali Habibi, MD, 600 N Wolfe St, Carnegie 546, Baltimore, MD 21287. E-mail mhabibi3@jhmi.edu Association of Left Atrial Function and Left Atrial Enhancement in Patients With Atrial Fibrillation Cardiac Magnetic Resonance Study Mohammadali Habibi, MD; Joao A.C. Lima, MD; Irfan M. Khurram, MD; Stefan L. Zimmerman, MD; Vadim Zipunnikov, PhD; Kotaro Fukumoto, MD, PhD; David Spragg, MD; Hiroshi Ashikaga, MD, PhD; John Rickard, MD; Joseph E. Marine, MD; Hugh Calkins, MD; Saman Nazarian, MD, PhD Atrial Structure and Function by guest on April 12, 2016 http://circimaging.ahajournals.org/ Downloaded from by guest on April 12, 2016 http://circimaging.ahajournals.org/ Downloaded from by guest on April 12, 2016 http://circimaging.ahajournals.org/ Downloaded from