Primary (spontaneous) chordal rupture: relation to myxomatous valve disease and mitral valve prolapse.

The excised valves of 152 consecutive patients who underwent isolated primary mitral valve replacement between May 1979 and July 1983 were studied to determine the cause of primary (spontaneous) rupture of the chordae tendineae and estimate the prevalence of floppy mitral valve with underlying myxomatous disease. Of these 152 patients, 72 had nonrheumatic disease; 42 (28% of the total group) had a floppy valve, and 39 of these valves had microscopic changes of myxomatous disease. Primary chordal rupture had occurred in 31 patients, including 29 with myxomatous disease. Seven of these patients had prior documentation of mitral valve prolapse and an additional 20 patients had a long-standing murmur. Ischemic mitral regurgitation (22 patients) accounted for the majority of the remaining 30 patients with nonrheumatic disease. Therefore, approximately half of all isolated mitral valve replacements in this institution are now performed for nonrheumatic disease, the majority for a floppy valve in which myxomatous disease was the underlying abnormality. Primary chordal rupture almost invariably occurs as a complication of myxomatous disease, and mitral valve prolapse may be a common precursor.