Histopathology of renal failure after heart transplantation: A diverse spectrum

Background: Chronic kidney disease occurs frequently after heart transplantation and is associated with significant morbidity and mortality. Herein we describe the histopathology associated with renal failure in a cohort of heart transplant recipients. Methods: Over a 4-year period all patients with an estimated GFR <30 ml/min/1.73 m ² or significant proteinuria were referred to the kidney transplant clinic for clinical evaluation. A percutaneous renal biopsy was performed as part of a standardized evaluation. Results: Eighteen patients underwent renal biopsy 5.8 ± 4.1 years after transplantation. Hypertension (88.9%), Type 2 diabetes (55.6%) and allograft vasculopathy (38.9%) were prevalent. All patients were receiving calcineurin inhibitors. Mean creatinine was 2.9 ± 1.2 mg/dl with an estimated GFR 27.9 ± 9.1 ml/min/1.73 m ². Eight patients (44%) had proteinuria >1 g per 24 hours. The major histologic findings were nephrosclerosis plus diabetic glomerulopathy (50%), nephrosclerosis and focal segmental glomerulosclerosis (22.2%) and nephrosclerosis alone (22.2%). One patient had direct CNI toxicity consisting of nodular sub-adventitial hyalinosis. Eleven patients (61.1%) had glomerular disease and 11 patients (61.1%) had moderate or severe tubular atrophy. During follow-up, 5 patients (27.8%) started hemodialysis, 4 (22.2%) died, and 2 (11.1%) received a renal transplant. Conclusions: We observed diverse histologic patterns in this series of renal biopsies suggesting that chronic kidney disease after heart transplantation has a complex and varied pathologic basis. Further defining the renal injuries that precede heart transplantation and predispose to the progression of kidney disease after transplant may assist in treating this population.