Correspondence
The Effect of Balloon Angioplasty on Hypertension in Atherosclerotic Renal-Artery Stenosis
N Engl J Med 2000; 343:438-439August 10, 2000
- Article
To the Editor:
The study by van Jaarsveld and colleagues (April 6 issue)1 compared angioplasty with antihypertensive-drug therapy in patients with renal-artery stenosis and inadequately controlled hypertension. We are concerned about several aspects of this study: the small sample, the use of angioplasty alone rather than with stenting, the treatment-crossover rate, and the authors' interpretation of the outcome with respect to blood pressure.
Of the 50 patients randomly assigned to receive drug therapy, 22 (49 percent) subsequently underwent angioplasty, resulting in a dilution of the difference in long-term outcomes. Nevertheless, the mean number of drugs required at 12 months was lower in the angioplasty group than in the drug-therapy group. In addition, the angioplasty group had greater improvements in other outcome measures, such as the number of defined daily drug doses and systolic and diastolic blood pressure, although some of the differences were not statistically significant. Had the sample been larger, the power to detect treatment differences would have been greater.
Further evidence of better outcomes with angioplasty includes the cure of hypertension in 7 percent of the patients in the angioplasty group, and a higher proportion of patients with improved blood-pressure control in the angioplasty group (68 percent, vs. 38 percent in the drug-therapy group). These improvements occurred despite a very high rate of restenosis, as compared with the rates reported in studies of renal-artery stenting. Aorto-ostial lesions are common, and stenting has been shown to be the most effective way to address this problem.2
Finally, given the demographic characteristics of the study subjects, hypertension could not be ruled out in most cases, and angioplasty cannot be expected to relieve nonrenovascular hypertension.
2 ReferencesWalter A. Tan, M.D.
Mark H. Wholey, M.D.
University of Pittsburgh Medical Center–Shadyside, Pittsburgh, PA 15232Jeffrey W. Olin, D.O.
Heart and Vascular Institute of New Jersey, Morristown, NJ 079601
van Jaarsveld BC ,Krijnen P ,Pieterman H , et al. The effect of balloon angioplasty on hypertension in atherosclerotic renal-artery stenosis. N Engl J Med 2000;342:1007-1014
Full Text | Web of Science | Medline2
Blum U ,Krumme B ,Flugel P , et al. Treatment of ostial renal-artery stenoses with vascular endoprostheses after unsuccessful balloon angioplasty. N Engl J Med 1997;336:459-465
Full Text | Web of Science | Medline
To the Editor:
Van Jaarsveld et al. conducted a difficult and badly needed randomized trial of renal-artery angioplasty as compared with medical treatment for renovascular hypertension. Renal-artery angioplasty is not a benign procedure and should not be used indiscriminately.
We are concerned, however, that the study assessed the effect of renal-artery angioplasty in patients with renal-artery stenosis rather than with physiologically documented renovascular hypertension. Renal-artery stenosis is often incidental, and renal-artery angioplasty is clearly not helpful in such patients. The study included some patients with as little as 50 percent stenosis of a renal artery; 35 percent of the patients had normal findings on renal scintigrams, and some patients probably had indeterminate findings (the percentage is not stated). Thus, at least 35 percent of the patients probably had renal-artery stenosis but not renovascular hypertension. The authors report that the outcome was unrelated to the imprecise radiographic measurement of stenosis, but they did not assess the relation between the blood-pressure response and other angiographic or scintigraphic indicators of renovascular hypertension, such as the pressure gradient and poststenotic dilatation.
Despite the authors' conclusions, the study actually attests to the value of renal-artery angioplasty. This finding is clouded by the use of an intention-to-treat analysis in a study in which more than 40 percent of the patients in the drug-therapy group underwent angioplasty, and many of them clearly benefited from the procedure. In addition, occlusion of the renal artery occurred in 9 percent of the patients in the drug-therapy group after only 12 months.
In summary, this study was a laudable attempt to document the benefit of renal-artery angioplasty in a controlled, randomized trial, but it fell short primarily because of the many patients enrolled who had renal-artery stenosis rather than renovascular hypertension.
Samuel J. Mann, M.D.
Mark S. Pecker, M.D.
Phyllis August, M.D.
Weill Medical College of Cornell University, New York, NY 10021Author/Editor Response
The authors reply:
To the Editor: We agree with Tan et al. and Mann et al. that early crossover to angioplasty may have influenced the outcome in the drug-therapy group in our study. However, our ethics committee objected to a design in which crossover was allowed only six months after randomization, because at the time our study was designed, many clinicians regarded angioplasty as a mandatory treatment.
Stenting probably improves the anatomical results of angioplasty, but it was not possible to perform stenting at all the participating centers at the time the study was designed. The finding that the greater patency achieved with stenting than with angioplasty is not correlated with improved blood pressure and renal function1 justifies skepticism about the additional benefit of stenting.
Tan et al. argue that our interpretation of the blood-pressure data was inappropriately negative. However, after three months, when no crossover had occurred, there was no significant difference in blood pressure between the two treatment groups. The difference in the mean number of drugs in the two groups — which also explains the difference in the number of patients with improvement — may be attributable in part to the protocol requirement to increase the number of drugs in the drug-therapy group and to discontinue them in the angioplasty group. The intention-to-treat analysis showed that the strategy of extending the drug therapy and switching to angioplasty only if the patient did not have a response was as effective as the strategy of performing angioplasty immediately.
Renovascular hypertension is a complicated and controversial matter. If it is defined as hypertension caused by renal hypoperfusion,2 it seems attractive to include patients with “physiologically documented renovascular hypertension.” However, including such patients reverses the burden of proof, because there are no reliable tests to identify them. Improvement in hypertension after the stenosis has been relieved is not a workable criterion because of the possible technical failure of angioplasty and the irreversible later phase of renal hypertension and because a diagnosis made in retrospect precludes the selection of patients before the intervention. In fact, we tried to identify indicators of the blood-pressure response but found that abnormal scintigraphic findings and the severity of stenosis — both assumed to be indicators of renovascular hypertension — did not predict the blood-pressure response.
2 ReferencesBrigit C. van Jaarsveld, M.D.
Pieta Krijnen, M.Sc.
Jaap Deinum, M.D.
Erasmus University, 3000 CA Rotterdam, the Netherlands1
Van de Ven PJ ,Kaatee R ,Beutler JJ , et al. Arterial stenting and balloon angioplasty in ostial atherosclerotic renovascular disease: a randomised trial. Lancet 1999;353:282-286
CrossRef | Web of Science | Medline2
Kaplan NM. Clinical hypertension. 7th ed. Baltimore: Williams & Wilkins, 1998:301.
- Citing Articles (3)
Citing Articles
1
Francesca Pizzolo, Giancarlo Mansueto, Salvatore Minniti, Mariangela Mazzi, Elisabetta Trabetti, Domenico Girelli, Roberto Corrocher, Oliviero Olivieri. (2004) Renovascular disease: effect of ACE gene deletion polymorphism and endovascular revascularization. Journal of Vascular Surgery 39:1, 140-147
CrossRef2
Chet R. Rees. (2003) PTRA and Stenting for Hypertension: An Analysis of Outcomes. Journal of Vascular and Interventional Radiology 14:2, P164-P170
CrossRef3
Brigit C. van Jaarsveld, Jaap Deinum. (2001) Evaluation and treatment of renal artery stenosis: impact on blood pressure and renal function. Current Opinion in Nephrology and Hypertension 10:3, 399-404
CrossRef
