Introduction:
Atrial fibrillation (AF) is associated with left atrial (LA) electrical, structural, and contractile remodeling. Cardiac magnetic resonance (CMR), late gadolinium enhancement (LGE) and feature tracking are capable of noninvasive quantification of LA fibrosis and myocardial motion, respectively.
Hypothesis:
Increased LA fibrosis measured with LGE is associated with worsening of the phasic LA function measured with feature tracking CMR.
Methods:
The cohort included 90 patients (age 61 ± 10 years, 76% male) with symptomatic drug-resistant AF referred for ablation. Peak global longitudinal LA strain (PLAS), LA systolic strain rate (SR-s), and early (SR-ed) and late diastolic (SR-ld) strain rates were measured using cine-CMR images acquired during sinus rhythm. The degree of LGE was quantified using normalized image intensity.
Results:
Compared to patients with paroxysmal AF (60% of cohort), those with persistent AF had larger maximum LA volume index (LAVImax, 56 ± 17ml/m2 versus 49 ± 13ml/m2 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, PLAS, SR-s, SR-ed and SR-ld) were lower in patients with persistent AF (p< 0.05 for all). Increased LA fibrosis was associated with lower LA passive emptying fraction, PLAS, SR-s, SR-ed, and SR-ld after adjusting for age, sex, hypertension, heart failure, left ventricular ejection fraction, type of AF, and LA volume (p<0.05 for all).
Conclusions:
Increased LA fibrosis is associated with decreased LA reservoir, conduit, and booster pump functions. Phasic measurement of LA function using feature-tracking CMR is feasible and may add important information regarding the physiological importance of LA fibrosis.
Left Ventricular Filling Pressure Assessment Using Left Atrial Transit Time by Cardiac Magnetic Resonance Imaging