Use of Doppler ultrasonography to predict the outcome of therapy for renal-artery stenosis

Background: Prospectively identifying patients whose renal function or bloo d pressure will improve after the correction of renal-artery stenosis has n ot been possible. We evaluated whether a high level of resistance to flow i n the segmental arteries of both kidneys (indicated by resistance-index val ues of at least 80) can be used prospectively to select appropriate patient s for treatment. Methods: We evaluated 5950 patients with hypertension for renal-artery sten osis using color Doppler ultrasonography, and we measured the resistance in dex as follows: [1-(end-diastolic velocity (divided by) maximal systolic ve ocity)] x 100. Among 138 patients who had unilateral or bilateral renal-art ery stenosis of more than 50 percent of the luminal diameter and who underw ent renal angioplasty or surgery, the procedure was technically successful in 131 (95 percent). Creatinine clearance and 24-hour ambulatory blood pres sure were measured before renal-artery stenosis was corrected; 3, 6, and 12 months after the procedure; and yearly thereafter. The mean (+/-SD) durati on of follow-up was 32+/-21 months. Results: Among the 35 patients (27 percent) who had resistance-index values of at least 80 before revascularization, the mean arterial pressure did no t decrease by 10 mm Hg or more after revascularization in 34 (97 percent). Renal function declined (defined by a decrease in the creatinine clearance of at least 10 percent) in 28 (80 percent); 16 (46 percent) became dependen t on dialysis; and 10 (29 percent) died during follow-up. Among the 96 pati ents (73 percent) with a resistance-index value of less than 80, the mean a rterial pressure decreased by at least 10 percent in all but 6 patients (6 percent) after revascularization; renal function worsened in only 3 (3 perc ent), all of whom became dependent on dialysis; and 3 (3 percent) died (P<0 .001 for the comparison with patients with a resistance-index value of at l east 80). Conclusions: A renal resistance-index value of at least 80 reliably identif ies patients with renal-artery stenosis in whom angioplasty or surgery will not improve renal function, blood pressure, or kidney survival. (N Engl J Med 2001;344:410-7.) Copyright (C) 2001 Massachusetts Medical Society.