Study Population
Before entry into the trial, all participating sites were required to qualify in a roll-in phase. Qualification involved approval of the expertise of the lead onsite interventionalist by the angiographic core laboratory. The details of this approval process are described in the Supplementary Appendix.
Trial enrollment began on May 16, 2005. All participating patients provided written informed consent. According to the original trial protocol, persons with severe renal-artery stenosis were eligible if they had hypertension with a systolic blood pressure of 155 mm Hg or higher while receiving two or more antihypertensive medications. Severe renal-artery stenosis was defined angiographically as stenosis of at least 80% but less than 100% of the diameter or stenosis of at least 60% but less than 80% of the diameter of an artery, with a systolic pressure gradient of at least 20 mm Hg. All angiograms were analyzed by the angiographic core laboratory at the University of Virginia with the use of a validated computerized quantitative vascular analysis program (Medis QVA 6.0).
A number of subsequent changes were made in the enrollment criteria during the course of the trial but before the trial concluded or the data were unblinded. The threshold of 155 mm Hg for defining systolic hypertension was no longer specified. Patients who did not have systolic hypertension but who had renal-artery stenosis could be enrolled if they had chronic kidney disease, which was defined as an estimated glomerular filtration rate (GFR) of less than 60 ml/min/1.73 m2 of body-surface area, as calculated with the use of the modified Modification of Diet in Renal Disease (MDRD) formula.18 Severe renal-artery stenosis could be identified with the use of duplex ultrasonography, magnetic resonance angiography, or computed tomographic angiography.
Exclusion criteria were renal-artery stenosis due to fibromuscular dysplasia, chronic kidney disease from a cause other than ischemic nephropathy or associated with a serum creatinine level higher than 4.0 mg per deciliter (354 μmol per liter), kidney length of less than 7 cm, and a lesion that could not be treated with the use of a single stent. Complete inclusion and exclusion criteria are listed in the Supplementary Appendix.