Any Renal Function Decline in Living Kidney Donors a Cardiac Risk

Increased left ventricular mass found in donors with even mild decreases in renal function.
Increased left ventricular mass found in donors with even mild decreases in renal function.

Living kidney donors with mild kidney function decline experience adverse effects on the heart's structure and function, independent of blood pressure, a new study finds.

“Even in very healthy people, a small reduction in kidney function from normal to just a bit below normal was associated with an increase in the mass of the left ventricle, a change that makes the heart stiffer and impairs its ability to contract,” explained senior author Jonathan Townend, MD, in a press release.

For the Chronic Renal Impairment in Birmingham (CRIB)-Donor study, Dr. Townend, professor of cardiology at the Queen Elizabeth Hospital Birmingham in Edgabaston, UK, and colleagues looked for a direct link between decreases in kidney function after donation and heart and blood vessel changes. They compared 68 kidney donors (average age 47) with 56 healthy controls fit for donation and who did not have nephrectomy (average age 44).

At 12 months, the average decline in isotopic glomerular filtration rate (GFR) in donors was -30 mL/min/1.73m2, according to results published online in Hypertension. Few donors reached an estimated GFR less than 45 mL/min/1.72m2.

Compared with controls, donors experienced significant increases in left ventricular mass (7 vs. -3 g, measured with magnetic resonance imaging by a blinded reviewer) and mass to volume ratio (0.06 vs. 0.09 g/mL) that were graded with decreases in GFR. In addition, aortic distensibility and global circumferential strain decreased.

Donors also had greater risks of developing detectable troponin T, a predictor of cardiovascular events and mortality, and microalbuminuria. Serum uric acid, parathyroid hormone, fibroblast growth factor-23, and C-reactive protein increased significantly and require future investigation as mediators, according to the researchers.

Dr. Townend and colleagues observed no change in ambulatory blood pressure, which was less than 140/90 mmHg mg for all participants. “This is evidence that reduction in kidney function itself leads directly to measurable adverse effects on the heart and blood vessels, even without other risk factors. More research is needed to know just what aspects of reduced kidney function are responsible for the effects.”

The investigators could not exclude the possibility that factors related to nephrectomy may exert adverse effects on the heart.

In the meantime, Dr. Townend reassured donors: “Even if there is a small increase in your long-term risk of heart disease after donation, it is still likely that you will be at lower than average risk.” Clinicians should discuss heart disease prevention steps with potential donors. 

Sources

  1. Moody WE, Ferro CJ, Edwards NC, et al. Cardiovascular Effects of Unilateral Nephrectomy in Living Kidney Donors. Hypertension 2016;67:368-377; doi: 10.1161/hypertensionaha.115.06608.
  2. Even small reductions in Kidney Function May Damage Heart, Blood Vesssels [press release]. American Heart Association; January 11, 2016.
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