Mitral valve prolapse and pre-excitation.

Two out of 118 patients with mitral valve prolapse were found to have pre-excitation. The presence of mitral valve prolapse in one patient with Lown-Ganong-Levine syndrome and the persistence of prolapse in the presence and absence of pre-excitation in another patient with intermittent type B Wolff-Parkinson-White syndrome suggest that mitral valve prolapse in pre-excitation syndrome may not be secondary to the abnormal activation pattern of the left ventricle, which has been suggested as a possible mechanism by some investigators.