Abstract
Background: Global extracellular volume fraction (ECV) assessed with cardiac magnetic resonance (CMR) has been shown to be elevated in patients with chronic mitral regurgitation compared with healthy controls. Limited work has been published on ECV changes following reduction in chronic volume overload with mitral valve intervention. We examined changes in ECV in patients with chronic mitral valve regurgitation after surgical mitral valve repair (SMVR). Methods: All patients underwent CMR studies before and after SMVR. CMR studies were performed with cine, phase contrast, T1 maps, and late gadolinium enhancement (LGE) imaging. Mid, short axis T1 maps were divided into 6 cardiac segments, each classified as LGE absent or present. ECV was derived from T1 maps using area-weighted averages of only segments where LGE was absent, by a reader blinded to study date, clinical history and valve status. Results: Fifteen patients underwent SMVR a median of 1.4 (interquartile range [IQR] 0.8, 2.3) months after an initial CMR study (Table). Repeat CMR was performed a median 12.4 (IQR 7.2, 19.2) months after SMVR. None were on calcium channel blockers, nitrates, or direct arterial vasodilators. Following SMVR, significant reverse remodeling was seen with reductions in indexed left atrial volume and left ventricular parameters except end systolic volume (Table). ECV decreased from a mean 28.3% to 26.0% (p=0.01) (Table). No significant correlation was seen between changes in left sided CMR parameters and ECV (p=NS). Conclusion: In this pilot study of patients with significant chronic mitral regurgitation undergoing valve repair, a reduction in extracellular volume fraction was seen after 6 months or more, suggesting a decrease in myocardial fibrosis alongside reverse structural remodeling. Larger studies are needed to substantiate these findings and evaluate the clinical significance of ECV changes beyond cardiac reverse remodeling in patients undergoing mitral valve repair.
Published Version
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