Renal function and outcome of PTRA and stenting for atherosclerotic renal artery stenosis

BACKGROUND: Prior studies of percutaneous transluminal renal artery angioplasty and stenting (PTRAS) for atherosclerotic renal artery stenosis (RAS) have shown that renal function is improved in about 25%, stabilizes in about 40%, but worsens in about 25% of patients. The factors predicting benefit remain controversial. We tested the hypothesis that the baseline glomerular filtration rate (GFR) predicts the changes in GFR and blood pressure (BP) after PTRAS. METHODS: Treated hypertensive patients with positive renal color-coded duplex Doppler velocimetry and clinical criteria were screened by arteriography. Patients (N = 105) were included if they had an RAS >or=70%, a transluminal pressure gradient >or=30 mm Hg and, they had more than 100 days of follow-up. GFR was calculated from the serum creatinine concentration (SCr). Patients were divided by baseline GFR into subgroups with normal to mildly impaired (N = 52) or moderately to severely impaired (N = 53) initial GFR, according to a GFR >or=50 or <50 mL. min-1 respectively. All received PTRAS. RESULTS: For the entire group, after a mean follow-up period of 371 days, there were significant reductions in systolic and diastolic BP (before, 160 +/- 26/91 +/- 12 vs. after, 145 +/- 20/83 +/- 10 mm Hg, respectively; mean +/- SD; P < 0.0001), and a modest increase in the calculated GFR (before, 54 +/- 26 vs. after, 62 +/- 28 mL. min-1; mean +/- SD; P < 0.007). However, in the subgroup of patients with an initially lower GFR there was a significant increase in the calculated GFR (from 33.3 +/- 10 to 54 +/- 24 mL. min-1; mean +/- SD; P < 0.0001) despite no significant change in BP (161 +/- 27/90 +/- 12 vs. 151 +/- 21/86 +/- 12; P = NS). In contrast, in the subgroup with an initially higher GFR, there were significant (P < 0.0001) reductions in systolic BP (from 159 +/- 25 to 138 +/- 16 mm Hg) and diastolic BP (from 91 +/- 11 to 81 +/- 9 mm Hg), but no significant change in the calculated GFR (from 75 +/- 21 to 70.2 +/- 30 mL. min-1; P = NS). The significance of GFR variation in subgroups remained after correction of baseline data to exclude the influence of the expected regression to the mean. CONCLUSIONS: Patients with atherosclerotic RAS fulfilling strict criteria of severity may have significant improvements in BP one year after PTRAS but only modest in GFR. The initial GFR may anticipate whether the benefits in the outcome will be in renal function enhancement (those with an initially depressed GFR) or in hypertension control (those with an initially normal or mildly impaired GFR).