Impact of aggressive blood pressure reduction on kidney function after renal denervation: long-term outcome
Objective. To investigate the dynamics of renal function in patients with resistant arterial hypertension after renal denervation depending on the degree of central and peripheral blood pressure (BP) reduction and the baseline state of the kidneys.Design and methods. A total of 22 patients (mean age 56,1 ± 10,2 years, 9 males) with treated resistant hypertension undergoing bilateral renal denervation (RDN) (Symplicity RDN System, Medtronic, USA) were included. Office BP measuring, 24-hour ambulatory BP monitoring (ABPM) (SpaceLabs 90207, USA), applanation tonometry (SphygmoCor, AtCor Medical, Australia) with the calculation of central aortic blood pressure (CAP), Doppler ultrasonography (Vivid 7 dimension) were obtained at baseline and at 1, 3, 6, 12, 18 and 24 months after RDN. Urine levels of NGAL (neutrophil gelatinase-associated lipocalin), KIM-1 (kidney injury molecule 1), L-FABP (Liver-type fatty acid binding protein), albuminuria and serum levels of сystatin C (sCysC) and creatinine (sCr) were measured by quantitative enzyme immunoassay at baseline and at 1, 3, 6, 12, 18 and 24 months after RDN. Glomerular filtration rate was estimated by the level of sCr and sCysC by CKD-EPI formula.Results. All patients were divided into 3 groups according BP reduction: 1 - BP increase above 0 mm Hg; 2 - BP reduction from 0 to -30 mm Hg; 3 - BP reduction by > 31 mm Hg. An increased sCysС was registered in a group with decreased 24-hour systolic BP (1,06 ± 0,41; 0,93 ± 0,18 and 1,22 ± 0,23 ng/mL; F = 2,882; р = 0,04) and increased urine KIM-1 level - in a group with decreased office diastolic BP (2,18 ± 1,94; 1,53 ± 1,02 and 4,41 ± 0,97 pg/mL; F = 3,663; р = 0,03) at 3-month follow-up. An increased sCr level was registered in a group with decreased 24-hour systolic BP (78,3 ± 3,7; 88,2 ± 6,8 and 142,00 ± 8,8 μmol/L; F = 61,987; p = 0,004) and diastolic CAP (83,4 ± 8,2; 82,0 ± 8,0 and 142,0 ± 9,4 μmol/L; F = 23,476; p = 0,01), also an increased urine L-FABP level - in a group with decreased office diastolic BP (3531,3 ± 1795,0; 997,5 ± 1096,8 and 7351,7 ± 3297,0 pg/mL; F = 12,103; p = 0,002) at 6-month follow up.Conclusions. Renal function worsening in patients during the period of maximum BP lowering may be associated with an excessive BP reduction. Therefore, we can suggest the occurrence of the J-curve phenomenon in relation to the kidneys.