Functional significance of elevated mitral gradients after repair for degenerative mitral regurgitation

Background: We have observed that elevated mitral gradients can develop in some patients after mitral valve repair for degenerative mitral regurgitation.

Methods and results: We screened 275 patients who had mitral valve repair involving >1 leaflet scallop between October 2001 and July 2010. Mitral valve hemodynamics were assessed at rest and at peak exercise using the cycle ergometer. B-type natriuretic peptide levels were measured at rest and after exercise. The patients also performed a 6-minute walk test and short-form 36-Item Health Survey questionnaire. We enrolled 110 patients, with resting mean mitral diastolic gradient of ≤3 mm Hg in 35 patients (group 1) and >3 mm Hg indicative of elevated mitral gradients in 75 patients (group 2). Posterior mitral leaflet plication (P=0.04) and the use of a complete mitral annuloplasty ring (P<0.0001) were associated with elevated mitral gradients. Group 2 patients had larger left atrial volume (P=0.02), higher mitral gradients at peak exercise and higher pulmonary artery systolic pressure at rest and at peak exercise, and lower exercise capacity (101±40 versus 122±51 W; P=0.02). Group 2 patients also had higher B-type natriuretic peptide levels and lower scores in 3 short-form 36-Item Health Survey health concepts. Multivariate regression analyses showed that mitral valve area was an independent predictor of maximum exercise capacity (P=0.003).

Conclusions: After mitral valve repair for degenerative mitral regurgitation, elevated mitral gradients is not uncommon and is associated with worse intracardiac hemodynamics, higher B-type natriuretic peptide levels, lower exercise capacity, and poorer quality of life. Further refinement in the surgical technique may reduce the incidence of this complication.