Balloon angioplasty versus medical therapy for hypertensive patients with renal artery obstruction.
BACKGROUND: Atherosclerotic renal artery stenosis is the most common cause of secondary hypertension. Balloon angioplasty is widely used for the treatment of hypertensive patients with renal artery stenosis. OBJECTIVES: The objective of this systematic review was to compare the effectiveness of balloon angioplasty (with and without stenting) with medical therapy on blood pressure control, renal function, frequency of renovascular complications, and side effects in hypertensive patients with atherosclerotic renal artery stenosis. SEARCH STRATEGY: The reviewers performed a search of MEDLINE from 1966 to December 2002, EMBASE from 1980 to 2002, Science Citation Index from 1990 to 2002, the Cochrane Central Register of Controlled Trials and personal files to identify randomised controlled trials comparing balloon angioplasty with medical therapy in hypertensive patients with renal artery stenosis. In addition, reference lists of papers resulting from this search were hand-searched, and authors of published trials were contacted to enquire if they were aware of any eligible unpublished trials. SELECTION CRITERIA: Randomised and quasi-randomised controlled trials comparing balloon angioplasty with medical therapy in hypertensive patients with haemodynamically significant renal artery stenosis (greater than 50 per cent reduction in luminal diameter and minimal follow-up of six months). DATA COLLECTION AND ANALYSIS: Two investigators independently extracted data on trial design, characteristics of trial participants, types of interventions, and outcome measures. The quality of the available data precluded a formal meta-analysis to assess the effect on blood pressure, renal function, and number and defined daily doses of antihypertensive drugs. Peto's odds ratios and corresponding 95% confidence intervals (CI) were calculated for dichotomous outcomes such as the presence or absence of patent vessels and renovascular complications. MAIN RESULTS: Three randomised controlled trials involving 210 patients met the inclusion criteria. In unselected patients there was a consistent, but statistically non significant trend towards lower blood pressure in the balloon angioplasty group. Patients treated with balloon angioplasty required less antihypertensive drugs in two of three trials, and were more likely to have patent renal arteries after 12 months (OR 4.2, 95% CI 1.8 to 9.8). There were no differences in renal function. There were significantly fewer cardiovascular and renovascular complications in patients treated with angioplasty (OR 0.32, 95% CI 0.15 to 0.70, test for heterogeneity p > 0.1). REVIEWER'S CONCLUSIONS: Available data are insufficient to conclude that balloon angioplasty is superior to medical therapy in lowering blood pressure of patients with renal artery stenosis in whom blood pressure can be controlled with medical therapy. In patients with hypertension refractory to medical therapy, there is some weak evidence that balloon angioplasty lowers blood pressure more effectively than medical therapy. Balloon angioplasty appears to be safe and leads to fewer cardiovascular and renovascular complications. There is a need for randomised controlled trials comparing the effect of balloon angioplasty and medical therapy on the preservation of renal function in the long term.