FRACTURE AFTER CARDIAC TRANSPLANTATION - A PROSPECTIVE LONGITUDINAL-STUDY

Cardiac transplantation is associated with increased prevalence of ver tebral fractures, but the natural history of and risk factors for frac ture after this life-saving procedure are unclear. We evaluated 47 pat ients (34 men and 13 postmenopausal women) before transplantation with spinal radiographs, determination of bone density by dual energy x-ra y absorptiometry, and measurement of biochemical indexes of mineral me tabolism. During the first year after transplantation, incident fractu res were documented radiographically. Associations among demographic c haracteristics, bone density, biochemistries, and fracture risk were e valuated with logistic regression analysis. Despite supplementation wi th elemental calcium (1000 mg/day) and vitamin D (400 IU/day), 17 pati ents (7 women and 10 men) sustained a total of 34 fractures. Most frac tures involved the spine, and 85% of the patients who experienced frac ture did so within 6 months of transplantation. Fifty-four percent of the women and 29%, of the men experienced fracture. Femoral neck bone mineral density was significantly lower in women who experienced fract ure than in those who did not (0.604 +/- 0.11 vs. 0.760 +/- 0.12 g/cm( 2); P < 0.04), but did not differ in men according to fracture outcome . The amount of bone loss at the femoral neck by 6 months after transp lantation was significantly greater in men with fracture than in men w ithout fracture (12.0 +/- 6.4% vs. 6.8 +/- 5.3%;P < 0.04), but did not differ in women according to fracture outcome. Pretransplant 1,25-dih ydroxyvitamin D levels were significantly lower (25 +/- 9 vs. 39 +/- 1 7 pg/mL; P < 0.007) and intact PTH levels tended to be higher in men w ho did not experience fracture (37 +/- 15 vs. 69 +/- 46 pg/mL; P < 0.0 6). Individual pretransplant bone density measurements demonstrated su bstantial overlap between patients who did and did not experience frac ture, and normal bone density did not necessarily protect against frac ture after transplantation. We conclude that fractures are a common an d early complication of cardiac transplantation. No pretransplant meas urement has yet been identified that reliably predicts fracture after transplantation in the individual patient.