Mapping of mitral regurgitant defects by cardiovascular magnetic resonance in moderate or severe mitral regurgitation secondary to mitral valve prolapse

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Abstract

Abstract Purpose
In mitral valve prolapse, determining whether the valve is suitable for surgical repair depends on the location and mechanism of regurgitation. We assessed whether cardiovascular magnetic resonance (CMR) could accurately identify prolapsing or flail mitral valve leaflets and regurgitant jet direction in patients with known moderate or severe mitral regurgitation.

Citation
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Methods
CMR of the mitral valve was compared with trans-thoracic echocardiography (TTE) in 27 patients with chronic moderate to severe mitral regurgitation due to mitral valve prolapse. Contiguous long-axis high temporal resolution CMR cines perpendicular to the valve commissures were obtained across the mitral valve from the medial to lateral annulus. This technique allowed systematic valve inspection and mapping of leaflet prolapse using a 6 segment model. CMR mapping was compared with trans-oesophageal echocardiography (TOE) or surgical inspection in 10 patients.

Results
CMR and TTE agreed on the presence/absence of leaflet abnormality in 53 of 54 (98%) leaflets. Prolapse or flail was seen in 36 of 54 mitral valve leaflets examined on TTE. CMR and TTE agreed on the discrimination of prolapse from flail in 33 of 36 (92%) leaflets and on the predominant regurgitant jet direction in 26 of the 27 (96%) patients. In the 10 patients with TOE or surgical operative findings available, CMR correctly classified presence/absence of segmental abnormality in 49 of 60 (82%) leaflet segments.

Conclusion
Systematic mitral valve assessment using a simple protocol is feasible and could easily be incorporated into CMR studies in patients with mitral regurgitation due to mitral valve prolapse.

Introduction
Mitral valve repair is preferred over prosthetic valve replacement for patients with mitral valve prolapse and symptomatic severe mitral regurgitation as it avoids the need for chronic anti-coagulation, has lower surgical mortality and results in better survival and long-term left ventricular function [1,2]. Mitral valve repair but not valve replacement, may also be reasonable for asymptomatic patients with severe mitral regurgitation and preserved left ventricular function if the probability of successful repair is greater than 90% [3]. Deciding if successful mitral valve repair is likely depends on accurately determining the location of leaflet abnormality, mechanism of regurgitation and the presence of a flail leaflet. Currently, 2-dimensional TTE is the first line investigation for assessing the mechanism of mitral regurgitation and identifying which leaflet is involved. However, when uncertainty is present, systematic mapping of the leaflets with TOE may be required [4,5].

CMR using cine images with optimised spatial and temporal resolution can also resolve mitral valve leaflet structure and motion, and can identify regurgitant jet direction. However, systematic mapping of mitral regurgitation in patients with mitral valve prolapse using CMR has not been described. In this study, we assess the feasibility of a simple CMR mapping protocol to provide an accurate anatomic map of leaflet abnormalities and identify mitral regurgitant jet direction.

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References
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