Reduced hemoglobin after heart transplantation is no independent risk factor for survival but is associated closely with impaired renal function

Background. Reduced hemoglobin (Hb) levels after heart transplantation (HTX) are common; however, there are only limited data on the association of posttransplant anemia with survival. Methods. In the present study, the effect of Hb levels determined 7 to 12 months after HTX on survival was investigated in 156 heart transplant recipients (129 men and 27 women; age at transplantation, 51.3 +/- 10.45 years; follow-up, 6.77 +/- 3.6 years) by univariate and multivariate analyses including a broad range of clinical and demographic patient characteristics. Results. Anemia by standard definition was found in 141 of 156 (91.6%) patients. According to Hb levels above or below the gender-specific median (men, 12.07 g/dL; women, 11.69 g/dL), patients were separated into a high- or low-Hb group, respectively. Kaplan-Meier analysis demonstrated significantly worse survival in the low-Hb group (P=0.033). Those patients showed significantly lower body weight, higher serum creatinine levels, and lower calculated creatinine clearance; the association of creatinine clearance and Hb levels was highly significant (P < 0.0001). No differences were demonstrated between groups for age, preoperative cardiac diagnosis, diabetes, azathioprine, steroid or angiotensin-converting enzyme inhibitor medication, leukocyte and thrombocyte levels, rejection index, or cytomegalovirus (CMV) infection or serostatus. Multivariate Cox stepwise regression analysis demonstrated that CMV infection, diabetes, and female donor gender were significant risk factors for post-HTX survival. An Hb level below the median was, however, completely lost as a risk factor (P=0.44); instead, a strong trend for reduced creatinine clearance could be demonstrated (P=0.09). Subsequently, a significant association was demonstrated between low calculatedcreatinine clearance and impaired survival by separate Kaplan-Meier analysis (P=0.02). Conclusions. Low Hb levels after HTX do not represent an independent risk factor for reduced survival, but the demonstrated correlation appears to be primarily caused by concomitant functional renal impairment. Further studies will be required to investigate the role of post-HTX anemia as a sensitive indicator of functional renal impairment and the effects of anemia treatment on long-term survival.