Renal Frame Count and Renal Blush Grade. Quantitative Measures That Predict the Success of Renal Stenting in Hypertensive Patients With Renal Artery Stenosis

Objectives: This study sought to identify angiographic parameters of favorable clinical response to renal artery stenting. Background: Stenting improves blood pressure (BP) control in patients with renal artery stenosis (RAS), but markers predicting a favorable clinical response are limited. Methods: Renal perfusion was quantified in hypertensive patients (BP ≥140/90 mm Hg) without RAS by determining renal frame count (RFC) (angiographic frames [30 frames/s] for contrast to reach distal renal parenchyma after initial renal artery opacification) and renal blush grade (RBG) (0: none, 1: minimal, 2: normal, 3: hyperemic parenchymal blush). It was hypothesized that stenting unilateral RAS in hypertensive patients would result in decreased RFC and increased RBG, which might predict BP reduction. Results: The RFC in 17 consecutive hypertensive patients without RAS (control group) (64.4 ± 14.2 years, 12 male, 22 kidneys) was 20.1 ± 5.4, whereas RBG was 2.33 ± 0.66. In 24 consecutive hypertensive patients with unilateral RAS (study group) (72.7 ± 11.3 years, 8 male), reduced RFC (26.6 ± 9.1 to 21.4 ± 6.7, p < 0.001) and increased RBG (1.63 ± 0.71 to 2.13 ± 0.85, p = 0.03) were observed after renal stenting. At 6 months, reduced BP (systolic BP 150.6 ± 15.6 mm Hg to 128.6 ± 15.5 mm Hg, p < 0.001; diastolic BP 77.2 ± 15.6 mm Hg to 68.3 ± 10.4 mm Hg, p = 0.022) without change in number of hypertensive medications was observed. Clinical responders (systolic BP reduction >15 mm Hg) had a greater decrease in RFC (7.7 ± 4.6 vs. 1.7 ± 5.1, p = 0.009) and 78.6% of patients with >4 RFC decrease were responders (p = 0.024). Conclusions: This study shows that quantitative indices of renal perfusion (RFC and RBG) are impaired in patients with RAS and improve after stenting, and that RFC reduction is associated with BP reduction.