Spontaneous pneumothorax and mitral valve prolapse.

We searched for mitral valve prolapse in patients with spontaneous pneumothorax to test the hypothesis that both may be part of a common disorder of connective tissue. Echocardiographic mitral valve prolapse was found in 11 (50 percent) of 22 patients who had suffered spontaneous pneumothorax compared to four (10 percent) of 40 age-matched control subjects (p less than 0.01). The body mass index (BMI) (weight/height2) was lower (p less than 0.001) in the group with pneumothorax; in five patients who were the thinnest in the study (BMI less than 2 standard deviations lower than mean normal value), mitral valve prolapse was present in four. The finding of a strong association of spontaneous pneumothorax with mitral valve prolapse, especially in subjects with an abnormal body build, suggests that in many patients, spontaneous pneumothorax may be a manifestation of a systemic abnormality of connective tissue.