Mitral valve prolapse in myotonic dystrophy.

Forty-three patients with myotonic dystrophy (MyD) and 43 age- and sex-matched controls were prospectively evaluated for mitral valve prolapse (MVP) using both cardiac auscultation and echocardiography (ECHO). Prevalence of MVP was significantly increased in MyD patients when using either abnormal auscultation plus abnormal ECHO (23.3%, P less than 0.02) or abnormal ECHO alone (30%, P less than 0.01) as diagnostic criteria for MVP. Frequency of MVP was even more increased in patients with a thin, flat chest compared with patients with normal physical appearance (P less than 0.007). These findings are in support of the concept that the increased frequency of MVP in neuromuscular disorders is likely due to geometrical changes of the heart caused by thorax deformities, rather than structural changes of the mitral valve. For this reason, MVP in MyD probably belongs to the entity of so-called benign, secondary MVP. This is further supported by the absence of symptoms of "systemic" complications of MVP in our patient population.