[Mitral valve prolapse associated with Basedow's disease and active hyperthyroidism. Preliminary report].

We performed 2 dimensional echocardiograms to investigate the presence of mitral valve prolapse (MVP) in 21 patients with Graves disease and active hyperthyroidism. 22 healthy subjects were used as a control group. The incidence of MVP was 24% (n = 5) in hyperthyroid patients compared to 5% (n = 1) in normals (NS by Fisher's exact test). Age, T3 and T4 levels were similar in hyperthyroid patients with and without MVP, but the clinical course was longer in the former. A study in a larger group of patients may help establish the increased incidence of MVP in hyperthyroidism.