Effect of A Reduction in glomerular filtration rate after NEphrectomy on arterial STiffness and central hemodynamics: Rationale and design of the EARNEST study

Abstract

BackgroundThere is strong evidence of an association between chronic kidney disease (CKD) and cardiovascular disease. To date, however, proof that a reduction in glomerular filtration rate (GFR) is a causative factor in cardiovascular disease is lacking. Kidney donors comprise a highly screened population without risk factors such as diabetes and inflammation, which invariably confound the association between CKD and cardiovascular disease. There is strong evidence that increased arterial stiffness and left ventricular hypertrophy and fibrosis, rather than atherosclerotic disease, mediate the adverse cardiovascular effects of CKD. The expanding practice of live kidney donation provides a unique opportunity to study the cardiovascular effects of an isolated reduction in GFR in a prospective fashion. At the same time, the proposed study will address ongoing safety concerns that persist because most longitudinal outcome studies have been undertaken at single centers and compared donor cohorts with an inappropriately selected control group.HypothesesThe reduction in GFR accompanying uninephrectomy causes (1) a pressure-independent increase in aortic stiffness (aortic pulse wave velocity) and (2) an increase in peripheral and central blood pressure.MethodsThis is a prospective, multicenter, longitudinal, parallel group study of 440 living kidney donors and 440 healthy controls. All controls will be eligible for living kidney donation using current UK transplant criteria. Investigations will be performed at baseline and repeated at 12 months in the first instance. These include measurement of arterial stiffness using applanation tonometry to determine pulse wave velocity and pulse wave analysis, office blood pressure, 24-hour ambulatory blood pressure monitoring, and a series of biomarkers for cardiovascular and bone mineral disease.ConclusionsThese data will prove valuable by characterizing the direction of causality between cardiovascular and renal disease. This should help inform whether targeting reduced GFR alongside more traditional cardiovascular risk factors is warranted. In addition, this study will contribute important safety data on living kidney donors by providing a longitudinal assessment of well-validated surrogate markers of cardiovascular disease, namely, blood pressure and arterial stiffness. If any adverse effects are detected, these may be potentially reversed with the early introduction of targeted therapy. This should ensure that kidney donors do not come to long-term harm and thereby preserve the ongoing expansion of the living donor transplant program (NCT01769924).

Diffuse left ventricular interstitial fibrosis is associated with sub-clinical myocardial dysfunction in Alström Syndrome: an observational study

“…Two other patients were seen at the National Centre during this time period but did not proceed with CMR due to contra-indications (one permanent pacemaker; one with a cochlear implant). Patients were compared to gender and age matched healthy controls with no history of cardiac disease recruited as part of an on-going clinical study [ 16 ].…”

Variability in cardiac MR measurement of left ventricular ejection fraction, volumes and mass in healthy adults: defining a significant change at 1 year

“…6 Briefly, subjects underwent CMR imaging (1.5 T Magnetom® Avanto; Siemens Healthcare, Erlangen, Germany) at baseline and 12 months. Serial contiguous short axis steadystate free precession (SSFP) cines were piloted from the vertical and horizontal long-axis images of the left and right ventricles [electrocardiogram R wave-gated, SSFP imaging (TrueFISP); temporal resolution, 40-50 ms; repetition time, 3.2 ms; echo time, 1.6 ms; flip angle, 60°; slice thickness, 7 mm with 3-mm gap] in accordance with previously validated methodologies.…”

Midterm echocardiographic follow-up of cardiac function after living kidney donation

“…In CRIB-DONOR (Chronic Renal Impairment in Birmingham-Kidney Donor; NCT01028703 -clinicaltrials.gov), a substudy of EARNEST, the investigators will additionally assess cardiac structure and function by cardiac magnetic resonance (CMR) imaging and echocardiography in 140 living kidney donors at 12 months after donation, similarly to our study [34].…”