A prospective controlled study of the effects of renal transplantation on uraemic cardiomyopathy using cardiac magnetic resonance imaging

Background Uraemic cardiomyopathy is characterised by the development of left ventricular hypertrophy and fibrosis causing diastolic and systolic dysfunction. This disease process affects at least 70% of patients with end stage kidney disease. At present, the effects of renal transplantation on this myocardial disease remain unclear. Purpose To determine the effects of kidney transplantation on the structural and functional features of uraemic cardiomyopathy. Methods This employed a longitudinal, prospective, parallel-group, blinded end-point design. 50 transplant recipients recruited from our institutional transplant waiting list prior to transplant, and 20 transplant-listed control participants who did not receive a transplant were included. Cardiac magnetic resonance imaging was performed at recruitment and repeated at 12-24 months in both transplant recipients and controls. Measures of left ventricular mass, volume, systolic and diastolic function, myocardial fibrosis, and biochemical parameters were all recorded at baseline and follow-up. Biochemical parameters and blood pressure were also studied. Results There were significant reductions in left ventricular mass indexed to body surface area in the transplant group compared to controls (between group mean difference -11.37g/m2 95%CI [-18.49 - -4.25] P=0.002). There were no significant differences observed in measures of either systolic or diastolic function. There was a significant reduction in T1 times, a surrogate of cardiac fibrosis, measured in all segments in the mid ventricular slice in transplant recipients (between group difference -34.37ms 95%CI [-61.01 - -7.74] P=0.01. There was no significant difference in the change in T2 times between groups in any segment suggesting the reduction in T1 times is not due to a reduction in water content. There were significant between group differences in multiple biochemical and haematological parameters including NTproBNP, haemoglobin, and markers of chronic kidney disease – mineral bone disorder; parathyroid hormone (x0.40 95%CI[0.17 – 0.93]P0.035, phosphate (-0.28 mmol/L [-0.41 - -0.16]P<0.001) and Vitamin D (31.54 nmol/L 95%CI(16.03 -47.05)P<0.001). Conclusions This is the first study using cardiac MRI to demonstrate that LV mass reduces following renal transplantation, associated with a fall in T1 that may reflect reduction in fibrosis. This work enhances the current understanding of uraemic cardiomyopathy and provides a rationale for the development of targeted therapies aimed at preventing or reversing cardiovascular remodelling in patients with end stage kidney disease.