Mitral regurgitation (MR) after percutaneous mitral balloon valvotomy (PMV)
is commonly an end point and may be a significant complication. Some incre
ase irt MR occurs in more than half of patients undergoing PMV. An increase
> 2 grades occurs in 3%-15% of patients, and < 5% have severe MR as a comp
lication. MR is a significant predictor for late cardiac events and preexis
ting MR before PMV is also associated with poor late outcome. Mild increase
s in MR are due to stretching of the annulus, excess commissural tearing, o
r papillary muscle trauma. Mild MR frequently disappears at follow-up and r
arely increases, Risk factors for development of MR have varied among multi
ple studies. Balloon oversizing and entrapment/tearing of chordae by the ba
lloon(s) are mechanical factors. Most predictors are related to the patholo
gic anatomy of the mitral valve. Older age, a larger end-systolic volume in
dex, and lower ejection fraction may be independent predictors of progressi
on of MR. Subvalvular disease and valve thickening have also been identifie
d as predictors. A recently described "scoring" system for predicting MR co
nsiders the distribution of anterior and posterior leaflet thickening, exte
nt of commissural calcification/fibrosis, and degree of subvalvular disease
. "Even" calcification/thickening produces a "lower" or "better" score than
"uneven" distribution. Bicommissural calcification and thickening and shor
tening of chordae all predict bad outcome. Thus careful echocardiographic e
valuation of mitral valve pathoanatomy pre-PMV can identify most predictors
of the development of MR.