Study shows no advantage in revascularization over medical treatment for renal function.
CHICAGO—Revascularization provides no advantage over medical treatment for renal function in patients with renal artery stenosis (RAS), data suggest.
The findings come from one-year follow-up of the Angioplasty and Stent for Renal Artery Lesions (ASTRAL) trial, which enrolled patients with atherosclerotic renovascular disease (ARVD). Patients with significant RAS were randomized if the supervising clinicians were “un-certain” whether revascularization would be of benefit.
The study’s primary end point was rate of decline in renal function. At one-year follow-up, investigators observed an identical minor deterioration in renal function (increase of 18 µmol/L) in the two groups receiving medical therapy (including aspirin, statins, ACE inhibitors, angiotensin receptor blockers, and other anti-hypertensive agents) plus percutaneous renal revascularization or medical therapy alone, Philip A. Kalra, MD, of Hope Hospital in Salford, U.K., lead nephrologist for the trial, reported here at the American College of Cardiology annual meeting.
Pooled data analysis of all patients showed that systolic and diastolic pressure decreased by a similar degree in both groups (5/3 mm Hg) between baseline and 12 months.
Additionally, Dr. Kalra and his colleagues observed no differences between treatment arms in risk-adjusted mortality, MI, stroke, vascular death, hospitalization for angina, fluid overload, heart failure, or the need for coronary intervention four years after randomization.
The rates for revascularization and medical treatment four years after randomization were 22% and 30%, respectively, for MI, 19% and 18% for stroke, 30% and 33% for vascular death, 24% and 29% for angina-related hospitalization, 44% and 55% for fluid overload or heart failure, and 9% and 12% for the need for coronary intervention or bypass graft surgery.
At four years, 83% of the revascularization group was free of a first renal event (ARF, dialysis, renal transplant, nephrectomy, and renal death) compared with 77% of the medically treated group. The difference was not statistically significant, however.
Also, no significant differences were observed in several pre-specified subgroups which included analysis by severity of baseline renal function, degree of stenosis, renal length or whether renal function was deteriorating prior to intervention, but the subgroup analyses were not as statistically strong as the main trial end points because of smaller patient group sizes.
Fifty-six centers (52 in the United Kingdom and four in Australasia) enrolled 806 patients with renal failure, making the study the largest yet to evaluate the effectiveness of catheter-based interventions following percutaneous renal revascularization in ARVD. Recruitment was initiated in 2000 and ended in 2007.
At baseline, subjects had a mean age of 70 years (range, 42-88 years), and 63% were male. The mean serum creatinine level was 179 mmol/L, the mean estimated glomerular filtration rate (GFR) was 40 mL/min per 1.73 m2, and the mean BP was 151/76 mm Hg. Fifty-four percent of patients were ex-smokers, and 30% were diabetic.
Forty-nine percent of patients had a previous history of CAD, 40% had a history of peripheral vascular disease, and 19% had a history of stroke. The average degree of RAS was 76%, and 98% of patients were on antihypertensive medication. Only 13 (3.2%) patients randomized to receive medical therapy crossed over to receive revascularization later in the follow-up period.
Aside from offering no superior benefit, revascularization also was associated with complications. Twenty-four patients experienced an immediate complication: 23 in the revascularization group and one in the medical-treatment arm. Three percent of revascularized patients experienced a serious procedural complication, including poorly positioned stents, perforation, and injury to the renal artery.
Dr. Kalra pointed out that neither treatment arm provided comparative benefit for the secondary end points of BP and major events. He emphasized that a fuller understanding of the findings requires longer follow-up. Dr. Kalra also advised that certain patients with RAS should continue to receive revascularization if they have more definite indications for this treatment, such as acute renal failure or acute heart failure.