Stent Placement in Ostial and Nonostial Atherosclerotic Renal Arterial Stenoses: A Prospective Follow-up Study
Stent Placement in Ostial and Nonostial Atherosclerotic Renal Arterial Stenoses: A Prospective Follow-up Study
Abstract & Commentary
Synopsis: Renal arterial stent placement considerably improved patency in ostial stenoses, but compared with the technically successful percutaneous transluminal renal angioplasty, it does not significantly improve primary patency in proximal and isolated truncal renal arterial stenoses.
Source: Baumgartner I, et al. Stent placement in ostial and nonostial atherosclerotic renal arterial stenosis: A prospective follow-up study. Radiology 2000;216(2):498-505.
The most common etiology of renal artery stenosis is atherosclerosis, and the usual clinical manifestation is hypertension, or in more severe bilateral disease, renal failure. Percutaneous transluminal renal angioplasty (PTRA) has been the standard of percutaneous intervention. However, the anatomic configuration of the lesion has presented a group of patients in which stenting may result in better outcome compared to angioplasty alone. The aim of the study was to compare the patency results of PTRA and stent-assisted PTRA in atherosclerotic ostial, proximal, and isolated truncal renal arterial stenoses. Over a period of approximately four years, 163 patients underwent 200 primary catheter treatments with PTRA, or primary stent insertion for symptomatic renal arterial stenosis. Ostial lesions were defined as stenoses located within 5 mm of the aortic lumen and caused by atherosclerotic disease of the aorta. Transstenotic pressure measurements were used to estimate the success of the intervention. Stent placement was done when a transstenotic pressure gradient greater than 10 mm Hg and/or an angiographic residual stenosis of more than 60% in diameter remained after PTRA. The stent of choice was the balloon expandable Palmaz stent (Johnson & Johnson Interventional Systems, Warren, NJ). Technical success after percutaneous intervention was defined as an estimated residual stenosis of less than 50% according to angiographic results and a transstenotic pressure gradient lower than 10 mm Hg. The patients were followed clinically and with regular Duplex ultrasound. The lesions analyzed were considered to have an ostial (n = 54), proximal (n = 94), or isolated truncal (n = 39) location within the main renal artery, or to be located in an accessory artery that had a diameter of less than 80% of the diameter of the main renal artery (n = 10). Renal artery occlusion was present in three patients. The mean follow-up time was 9 ± 4 months. The primary 12-month PTRA patency rates were 34% for ostial stenoses, 65% for proximal stenoses and 83% for truncal stenoses. The corresponding stent patency rates were 80%, 72%, and 66%, respectively. The stent-related reduction in relative risk of developing restenosis within 12 months was 70% in the ostial stenoses (P = 0.002) and 20% in the proximal stenoses (not significant). The isolated truncal renal arterial lesions showed a more favorable result with PTRA alone. There were three (1.6%) deaths within 30 days. None of these deaths was related to the interventional procedure. The rate of complications directly related to PTRA was 3.1% and the rate of complications associated with stent placement was 8.6%. Baumgartner and colleagues concluded that renal arterial stent placement was primarily indicated in ostial stenoses, but not in proximal and isolated truncal renal arterial stenoses.
Comment by Moni Stein, MD
In the late 1970s, PTRA was introduced by Grüntzig as an alternative to surgical reconstruction for renal arterial stenosis.1 The most promising result of PTRA occurs in patients with fibromuscular dysplasia with cure rates of approximately 80%. In patients treated for atherosclerotic renal arterial stenosis, the effects of PTRA on blood pressure have been less encouraging.2 Renal artery stents have emerged in the last decade as a new treatment that might overcome poor angioplasty results, immediate postangioplasty complications, and restenosis for atherosclerotic renal arterial lesions.3 The study reviewed in this issue shows clearly that ostial renal atherosclerotic lesions are better treated with stents rather than angioplasty alone. This finding is not surprising since ostial lesions are caused by aortic atherosclerotic plaques rather than isolated renal artery plaques. A balloon expandable stent provides structural rigidity and support at the origin of the renal artery, pushing the aortic plaque away from the renal artery origin. In a recent meta-analysis looking at 14 articles concerning patients with hypertension, renal failure, or both, it was shown that renal arterial stent placement is a successful treatment with a high initial success rate (98%) and a mean restenosis rate of 17% at a mean follow-up of 17 months.3 The clinical success is not as impressive, showing that at a follow-up of 6-48 months, hypertension was cured in 20% of the patients and improved in 49%. Renal function in the patients with impaired renal function was improved in 30% and stabilized in 38%. van de Ven and colleagues performed a randomized, prospective study to compare PTRA with renal artery stenting in patients with ostial atherosclerotic renal-artery stenosis.4 Forty-two patients were assigned PTRA and 43 were assigned to stenting. Primary technical success rate of PTA was 57% compared to 88% for stenting. Complications were similar in both groups. At six months, the primary patency rate was 29% for PTRA and 75% for stenting. This review concludes that renal artery stenting gives a more durable result than angioplasty alone for ostial renal artery lesions. The full clinical effect of these treatment modalities is still under investigation.
References
1. Grüntzig A, et al. Treatment of renovascular hypertension with percutaneous transluminal dilatation of a renal-artery stenosis. Lancet 1978;1:801-802.
2. Martin EC, et al. Renal angioplasty for hypertension: Predictive factors for long-term success. AJR Am J Roentgenol 1981;137:921-924.
3. Leertouwer TC, et al. Stent placement for renal arterial stenosis: Where do we stand? A meta-analysis. Radiology 2000;216:78-85.
4. van de Ven PJ, et al. Arterial stenting and balloon angioplasty in ostial atherosclerotic renovascular disease: a randomized trial. Lancet 1999;353:282-286.
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