Abstract Body (Do not enter title and authors here): Background
Atrial fibrillation (AF) is increasingly recognized as a cause of secondary mitral regurgitation (SMR), exacerbating heart failure symptoms and complicating the management of AF.
Hypothesis
SMR quantified using cardiac magnetic resonance (CMR) 4D flow is associated with left atrial (LA) structural derangements in patients with AF.
Goals
To demonstrate an association between the atrial volume and fibrosis with mitral regurgitation severity
Methods
Patients were recruited from the University of Washington Medical Center AF clinics. CMR was used to quantify LA fibrosis through late gadolinium enhancement, LA emptying fraction (LAEF), left ventricular end-diastolic volume (LVEDV), left ventricular ejection fraction (LVEF) (Panel A). Total mitral valve flow, regurgitant fraction, and peak velocity were quantified using CMR-derived 4D flow and cine images (Panel B). Patients with valvular disease (rheumatic valvular disease and prosthetic valves) were excluded from the analysis.
Results
A total of 44 patients were included (71 years (64-76), 39% with persistent AF, BMI 28.8 kg/m² ± 6.2, 45% females, 43% hypertensive, and 20% with a history of heart failure). 4D flow quantified MR was at 14% (3.7-45) which represented the median percentage of mitral regurgitant flow (MR flow/Total Mitral Flow), total mitral flow 29.2 mL (14.2-60.8), and peak velocity 194.5 cm/s ± 72.6. Using CMR cine images, median LVEF was 62.4% (56.4-66), heart rate was 65 bpm (49.5-75), left atrial volume was 97.3±39.3 mL, LAEF was 42.4±18.5%, and LVEDV was 146±44.6 mL. Left atrial fibrosis was 14.0% ± 7.9. Using multivariable linear regression, there was a significant association between LA volume and MR fraction (β = 0.35, p=0.04) after adjusting for peak velocity, LAEF, fibrosis, LVEDV, LVEF, and HR. Moreover, there was an association between HR and MR fraction (β = -0.3; p=0.04) and between total mitral flow and MR fraction (β = -0.78; p<0.001).
Conclusion
In a cohort of AF patients without primary valvular abnormalities, secondary mitral regurgitation quantified using 4D flow CMR was associated with advanced atrial remodeling manifesting through LA volume increase.