Compared to extensive studies in echocardiography, cardiac magnetic resonance (CMR) predictors of mitral regurgitation (MR) in mitral valve prolapse (MVP) have yet to be defined. Characterization of the mitral valve may be important for prognosis of progression of MVP-related MR and facilitating surgical decision making. In addition, papillary muscle (PM) fibrosis has been observed in pathological studies of MVP and in vivo by late gadolinium enhancement (LGE) and attributed to PM "stretch" by displaced mitral valve leaflets.

We aimed at evaluating the correlation between mitral valve characteristics and MVP-related MR, and in a subgroup of patients with LGE imaging, PM fibrosis.

By multivariate analysis, MR volume was correlated with posterior displacement (p = 0.002), anterior length (p < 0.001), and PM distance to coaptation point (p < 0.001), with a model adjusted R² = 0.53. PM LGE (Figure 1D) was present in 30 patients (44%) and was associated with posterior leaflet thickness (p = 0.04) by simple linear regression, but not leaflet displacement or any other parameter.

Posterior leaflet displacement, anterior leaflet length, and PM distance to coaptation point are the best CMR valve determinants of MVP-related MR. PM fibrosis by LGE is related to posterior leaflet thickness, but not to leaflet displacement. These findings suggest that PM "stretch" may not always translate into PM fibrosis.