Effects of renal volume and single-kidney glomerular filtration rate on renal functional outcome in atherosclerotic renal artery stenosis.

BACKGROUND Renal functional outcome is unpredictable after revascularization of high-grade atherosclerotic renal artery stenosis (RAS). 'Hibernating' parenchyma describes acute parenchymal injury where renal dysfunction is potentially reversible with treatment of the stenosis. We analysed renal parenchymal volume (PV) and single-kidney glomerular filtration rate (SK-GFR) characteristics to identify kidneys with hibernating parenchyma and hence determine renal functional outcome after revascularization. METHODS Fifty patients with > or =50% RAS underwent baseline analyses: (i) PV using magnetic resonance imaging; (ii) radioisotopic SK-GFR. Twenty-one patients (27 kidneys) underwent renal revascularization and 29 medical therapy alone. RESULTS Patients with revascularized kidneys manifesting high PV:SK-GFR showed improvement in global estimated GFR compared to conservatively managed counterparts at 6 months and 1 year (6 months: 6.2 +/- 2.9 versus -3.7 +/- 6.8, P = 0.038; 1 year: 3.5 +/- 3.0 versus -5.1 +/- 5.1 ml/min/1.73 m(2), P = 0.021). Twelve revascularized patients (16 kidneys) underwent repeat SK-GFR 4 months post-revascularization. Six of 16 revascularized kidneys had high baseline PV:SK-GFR and showed improved SK-GFR compared to kidneys with low or normal PV:SK-GFR (6.3 +/- 2.0 versus -0.9 +/- 4.2 ml/min, P = 0.002). CONCLUSIONS Our data suggest that, after revascularization, GFR improvement is likely if there is a disproportionately higher baseline PV:SK-GFR in the RAS kidney. Analysing these parameters can potentially identify these 'hibernating' kidneys and aid determination of renal functional outcome in RAS.