Background--Mulibrey nanism is a rare inherited disease characterized by growth failure and multiorgan manifestations, including constrictive pericarditis. Its long-term course, the results of pericardiectomy, and the details of myocardial involvement have not been reported previously.

Methods and Results--We studied 49 patients (26 men) born before 1985 and followed for up to 25 years. By 1999, 25 patients (51%) had developed congestive heart failure (CHF), 19 (39%) had undergone pericardiectomy for constrictive pericarditis, 10 (22%) had died of cardiac causes, and 5 (10%) had died of noncardiac causes. Of the 19 pericardiectomized patients, 12 derived lasting clinical benefit, whereas 1 patient suffered an early noncardiac death and 6 died later of unrelieved or recurrent CHF. At echocardiography in 34 living patients, left ventricular mass adjusted for body height and weight averaged (±SEM) 149±5 g in 21 unoperated patients, 144±8 g in 13 pericardiectomized patients, and 104±7 g in 16 healthy persons matched for age and sex (P=0.000). Autopsies of 11 patients showed fibrotic thickening of the pericardial leaves with myocardial hypertrophy and variable but mostly mild myocardial fibrosis. Endocardial thickening was seen in 3 patients.

Conclusions--Constrictive pericarditis, myocardial hypertrophy, and variable myocardial fibrosis constitute the main elements of Mulibrey heart disease. At least one half of patients ultimately develop CHF. Pericardiectomy generally provides clinical benefit, but in approximately one third of patients, CHF may recur because of coexisting myocardial involvement.