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 (10140 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.