Severe mitral regurgitation: a common occurrence in the aging patient with secundum atrial septal defect.

Severe mitral valve regurgitation (MR) which necessitated mitral valve replacement was identified in 19 (3.9%) of 498 consecutive patients (age range 1-83 years) with secundum atrial septal defects (ASD). The incidence of severe MR was significantly higher in patients older than age 50 years, 15 of 98 (15%), than in patients either below 21 years, 1 of 213 (0.4%), or between ages 21 to 49 years, 3 of 187 (2%). The higher frequency and severity of MR in the older ASD patient has not previously been appreciated. The morphology of severe MR in the older ASD patient consists of fibrous thickening and deformity of the mitral leaflets with shortening and thickening of the chordae tendineae. Because of the rarity of severe MR in the young patient with ASD, the mitral valve pathology is still poorly defined.