Association of ostium secundum atrial septal defects with mitral valve prolapse.

Severe prolapse of the mitral valve leaflets was seen at left ventricular angiography in 16 of 92 patients with a secundum type atrial septal defect studied prospectively from 1970 to 1974. The patients were aged 15 to 69 years; angioplasty or mitral valve replacement was carried out in nine. In 9 of 122 patients aged 15 to 55 years who were operated on for closure of a secundum type atrial septal defect between 1956 and 1969, mitral regurgitation due to prolapse but with intact chordae tendineae was seen at operation. In three of these patients chordal rupture was seen at a second operation 2 to 6 years later. The outlook in the syndrome of mitral valve prolapse may be less benign than is usually believed.