A Case of Renal Artery Brachytherapy for In-Stent Restenosis: Four-Year Follow-up

ABSTRACT: Renal artery stent implantation is associated with high rates of restenosis, particularly in vessels less than 4.5 mm in diameter. We describe 4-year follow-up results in the first patient to receive renal artery brachytherapy for this indication. A 68-year-old man who presented with “flash” pulmonary edema, hypertension and renal impairment was found to have severe bilateral renal artery stenosis and was treated with bilateral stent implantation. Following clinical deterioration due to severe in-stent restenosis, he underwent repeat angioplasty followed by intra-stent brachytherapy. To our knowledge, this is the first use of such therapy and hence the 4-year follow-up demonstrating excellent bilateral patency is the longest to date. J INVAS CARDIOL 2004;16:287–288 Key words: brachytherapy, pulmonary edema, renal artery stenosis, restenosis “Flash” pulmonary edema is a recognized presentation in patients with renal artery stenosis (RAS). Treatment can be difficult, but renal revascularization by angioplasty is the treatment of choice.¹ Endovascular stents offer advantages over angioplasty alone, i.e., higher initial success rates and a lower incidence of restenosis.² Yet restenosis remains a significant problem, particularly in smaller vessels, occurring in up to 39%.³ Although brachytherapy, employing local radiation, has been successfully used in coronary arteries to treat in-stent restenosis, its efficacy in other arteries is unclear. We report the use of brachytherapy in a case of renal artery in-stent restenosis in a patient with high cardiovascular risk. Case Report. A 68-year-old man with multiple cardiovascular risk factors (type II diabetes mellitus, mixed hyperlipidemia, gout, cigarette smoking) was admitted with hypertensive nephropathy following several episodes of unexplained pulmonary edema. He had poorly controlled hypertension despite 4 antihypertensive medications and history of a previous inferior myocardial infarction. Renal and coronary angiography demonstrated good left ventricular systolic function with an occluded, well-collateralized right coronary artery, and severe, bilateral, ostial RAS (Figures 1a and 1b). Bilateral percutaneous renal artery angioplasty and stent implantation (4 x 9 mm Palmaz Schatz stents for the right and left renal arteries) was performed with a good angiographic result (Figures 1c and 1d). The patient responded well, with an improvement in renal function and improved control of the hypertension on only 2 antihypertensives. Six months later, angiography prompted by a deterioration in renal function and deterioration in hypertension control revealed severe, bilateral, in-stent restenosis (Figures 1e and 1f). Renal angioplasty and placement of a further stent in the right renal artery were performed with a good angiographic result (Figure 1g and 1h). This was followed by intra-stent beta-irradiation using a 4 mm centering balloon with dosages of 24 Gy in the right renal artery and 22 Gy in the left. Again, the patient responded well, with hypertension controlled on 3 medications and a reduction and subsequent stabilization in serum creatinine. Four years later (following a readmission with chest pain requiring coronary angiography), opportunistic renal angiography revealed no evidence of renal artery in-stent restenosis (Figures 1i and 1j). Discussion. RAS is a common, progressive cause of hypertension and renal impairment. “Flash” pulmonary edema can occur in these patients, possibly resulting from a hyper-renic state due to renal artery insufficiency, culminating in sudden increases of blood pressure and causing left ventricular dysfunction and pulmonary edema.⁴ The goals of treating these patients with RAS are to prevent further incidence of pulmonary edema and to preserve renal function. Renal angioplasty with stenting has an initial success rate approaching 100%.^5,6 Given the correct selection of patients, this procedure is well tolerated and can provide lasting clinical benefits (50% of patients have improved blood pressure control and 25% have improved or maintained serum creatinine).³ Furthermore, in this quoted experience, only 50% of the patients received stents, the greater use of which may further improve the long-term results. Compared to angioplasty alone, stent deployment offers better initial results and improved long-term patency.⁷ Despite this, restenosis rates can remain as high as 39%,^3,8 particularly with vessels smaller than 4.5 mm, as in this case. The most common form of treatment for RAS is repeat balloon angioplasty and stent deployment. Brachytherapy with either gamma- or beta-radiation is well established for the treatment of restenosis in the coronary arteries.^9,10 We therefore decided to use brachytherapy in this aggressive case of restenosis. To our knowledge, this is the earliest reported use of intra-renal brachytherapy and hence the patient with the longest follow-up. Good 1-year results from this treatment have been recently reported.^11,12 It should also be noted that the rate of recurring restenosis following repeat balloon angioplasty is less. It is therefore theoretically possible, although less likely, that the excellent long-term result obtained could be a result of the balloon angioplasty alone. The good long-term patency of the present case may illustrate a template for the use of renal artery brachytherapy in high cardiovascular risk patients. Given the high rate of restenosis and the wish to avoid repeat invasive procedures, it can be suggested that all subjects receive brachytherapy following stent insertion. The emergence of drug-eluting stents demonstrating high clinical efficacy in the treatment of intra-coronary in-stent restenosis¹³ may further complicate this area; therefore, this question might best be answered with a randomized, controlled trial.