Impaired bone geometry after heart and heart-lung transplantation in childhood

Impaired bone health has been advocated after solid organ transplantation in adult and pediatric patients. Osteoporosis accompanied by fractures have been found also in heart transplantation recipients.

Parameters of bone mineral density (BMD) and bone geometry were measured in 34 patients (15 females, mean age: 14.6 ± 5.5 years) 5.28 ± 5.16 years after heart transplantation (n=30) and heart-lung transplantation (n=4) using peripheral quantitative computed tomography. Transplantation had been performed because of dilated cardiomyopathy in 25, congenital heart disease in five, idiopathic pulmonary hypertension in three patients, and arrhythmogenic right ventricular dysplasia in one patient at a mean age of 9.4 ± 6.1 years.

Trabecular BMD (z scores -0.82 ± 0.50, P<0.01) was reduced and cortical BMD (0.62 ± 1.17, P<0.05) increased in patients (n=11) on steroids, whereas patients on immunosuppression with tacrolimus showed normal trabecular BMD (-0.19 ± 1.03). All patients had normal total cross-sectional area (CSA; -0.22 ± 1.50) and relatively enlarged medullary CSA (0.44 ± 1.37) resulting in smaller cortical CSA (-0.91 ± 1.20, P<0.01). Mean muscle CSA was significantly reduced (-2.02 ± 0.99, P<0.001) irrespective of glucocorticoid treatment and correlated significantly with cortical CSA (r=0.43, P=0.001).

After heart transplantation and heart-lung transplantation in childhood, all our patients showed altered bone geometry and low muscle CSA. Patients on glucocorticoid treatment had additionally lower trabecular BMD. The clinical impact of these findings on increased risk for fractures has to be determined.