Is there an alternative explanation to post-myocardial infarction emergence of mitral regurgitation? A CMR-LGE observational study.

BACKGROUND AND AIM OF THE STUDY: Post-myocardial infarction (MI) mitral regurgitation (MR) is thought to be due to a passive, rather than active, remodeling of the mitral valve apparatus and its relationship with other cardiac structures that contribute to MR. Standard contrast-enhanced magnetic resonance (CMR) late gadolinium enhancement (LGE) may be sensitive to non-myocardial pathology involving the mitral valve leaflets. It was hypothesized that the presence of mitral valve enhancement (MVE) on LGE imaging in post-MI patients would be associated with an increased incidence of MR. METHODS: The presence or absence of MVE was noted in patients presenting for CMR with MI and non-MI indications requiring LGE. A chi-square analysis was performed for non-contiguous variables; SPSS (Chicago) software was utilized for the statistical analysis. RESULTS: Eighty-seven patients (54 males, 33 females) underwent LGE-CMR studies utilizing a 1.5 T GE scanner with MultiHance gadolinium contrast administration. LGE+ (present) was noted in 68 patients, and LGE- (absent) in 19 patients. Post-MI patterns of LGE+ were noted in 51 patients and LGE-in 36 patients; MVE+ was noted in 39 patients and MVE- in 48; and MR+ was present in 67 patients and absent (MR-) in 20 patients. MVE was observed chiefly in post-MI patients (33/51; 65%) and infrequently in non-post-MI patients (6/36; 17%; chi2 = 17.8, p < 0.001, power = 0.995). Further, MR was present more frequently in patients with MVE (36/39; 92%) compared to patients without MVE (31/48; 65%; chi2 = 7.8, p = 0.005, power = 0.814). CONCLUSION: MVE is present in a large number of post-MI patients but rarely in non-post-MI patients. Post-MI patients with, rather than without, MVE are far more likely to have MR. These observations suggest a specific but as-yet unknown reactive process that may contribute to mitral leaflet remodeling in post-MI patients, potentially contributing to an increased incidence of MR in post-MI patients.