Novel, More Accurate Assessments of Renal Function in Heart Transplant Patients: Commentary on ‘Chronic kidney disease after heart transplantation: a single-centre retrospective study at Skåne University Hospital in Lund 1988-2010’

Abstract

Emerging improvements in heart transplantation have led to increased survival and a greater need to better understand the long-term complications of heart transplant. An emerging postsurgical issue of nonrenal solidorgan transplantation is development of chronic kidney disease (CKD), which has been related to significant morbidity and mortality in heart transplant patients that is related to factors that exist before, during and after surgeries. A better understanding of these factors is imperative to predicting and diagnosing CKD in patients with heart transplants.In this issue of Transplant International, Soderlund et al. [1]. describe a retrospective single-centre study of 134 heart transplantation (HT) patients from 1988 to 2010 with annual follow-ups to monitor renal function. Instead of using traditional creatinine-based calculations such as the CKD-EPI, Schwartz or MDRD formulae to estimate glomerular filtration rate (GFR) and incidence of CKD, the authors of this study instead use iohexol clearance measurements. Iohexol clearance has been shown to be a simple, exact and reliable method for such calculations [2].A series of interesting observations were made from their analysis. Particularly, a trend towards steepest GFR declines and CKD progression was observed during the first year post-transplant. Specifically, median GFR decreased from 67.0 during transplant assessment to 56.0 at year 1, 53.0 at year 5 and 44.5 at year 10. On average, GFR declined by 2.2 AE 14.6 ml/min/1.73 m [2] per year post-transplant; however, during the first year, the rate of decline was 11.9 AE 25.8 ml/min/1.73 m [2], much higher. Following in this trend, observations were made that increases in serum creatinine, serum urea, systolic blood pressure and diastolic blood pressure increased over the first year while only slightly increasing if at all after the first year. Taken together, this study suggests that although renal function declines slowly, the majority of the decline occurs early in the first year post-transplant, suggesting this time period is the most critical for monitoring. This time period encompasses the time when the highest doses of calcineurin inhibitors (CNIs) are used, as this is the period of time when rejection is most likely to occur. For this reason, more comprehensive monitoring is required and the use of iohexol to assess GFR provides a more accurate approach for monitoring renal function and preventing deterioration of renal function.In a regression model, proteinuria was the only predictor of steeper GFR decline (>30% in year 1) after ª 2015 Steunstichting ESOT 527