Following the positive results obtained by drug-coated balloon in the peripheral arterial disease, many operators have started to extend the indications of these devices and are beginning to use them in different conditions, outside of the instructions for use, with the common aim of preventing restenosis, writes Fabrizio Fanelli, Rome, Italy.
Drug-coated balloons are currently considered a valid tool in the treatment of peripheral vessels. Several studies have reported a marked improvement of the patency rate with these devices compared to that achieved with plain balloon angioplasty. This is due to the action of the drug that inhibits cell proliferation and reduce neointimal hyperplasia.
Following these good results, many operators have started to extend the indications of these devices and have started to use them in different conditions, outside of the instructions for use, with the common aim of preventing restenosis.
Renal artery stenosis is a frequent pathology that plays an important role in hypertension. However in the last few years, endovascular procedures (angioplasty and stenting) have become less popular because the results of randomised controlled trials such as ASTRAL and CORAL have demonstrated that intervention has little benefit when compared to best medical therapy.
Fibromuscular dysplasia is still considered a complex situation to be managed and this is confirmed by a very poor patency rate after interventional procedures. In the majority of such patients, angioplasty represents the treatment of choice, correlated with the patient’s young age and with the lesion location (especially when lesion is deep in the renal arteries). Sometimes, when the lesion is located in the proximal portion of the renal artery, stents can be implanted to improve the patency rate. At any rate, stenting is never performed as first line treatment and only after a failed angioplasty.
Considering this background, we can assume that drug-coated balloons might play a role in the treatment of renal in-stent restenosis and that paclitaxel can be highly effective in preventing restenosis in fibromuscular dysplasia.
However, some technical considerations regarding the size of the balloons available and their characteristics for these procedure cannot be overlooked. In fact, since drug-coated balloons are being used off-label, 0.035” balloon catheters, that are not designed for renal applications are being used, or coronary drug-coated balloons that in some cases are not large enough, are being used as well. The availability of dedicated devices will be able to reduce the technical difficulties of the procedures and potentially improve the results.
In our experience, we have treated 16 patients with renal artery disease: nine with in-stent restenosis and seven with fibromuscular dysplasia. All patients in the in-stent restenosis group were treated for reappearance of symptoms and increase of systolic blood pressure. Moreover, ultrasound demonstrated the presence of restenosis within the stent lumen with increase of the flow velocity. All patients were treated with the IN.PACT Admiral drug-coated balloon (Medtronic). From a technical point of view, after selective catheterisation of the targeted renal artery, a digital substraction angiography was performed to evaluate the lesion location. Lesions were pre-dilated with a conventional Rx 0.014” balloon catheter 1mm undersized followed by the insertion of the In.pact Admiral drug-coated balloon.
In the second group of fibromuscular dysplasia patients, two were treated for the first time and five were treated for recurrence of stenosis after previous angioplasty dilatation. One patient, a 37-year-old woman, underwent four revisions with balloon angioplasty during two years of follow-up. In the last reintervention, a stent was also deployed to try to improve the patency rate. Seven months later, she came back to the hospital for reappearance of hypertension. Ultrasound-colour-Doppler showed a severe in-stent restenosis. A reintervention was performed and after pre-dilatation of the in-stent restenosis with a 5mm conventional balloon, a 6mm In.Pact Admiral balloon was inflated for 60 seconds. The patient improved from the clinical point of view and no more reinterventions were required. After 36 months Ultrasound-colour-Doppler showed the patency of both the artery and the stent.
In the follow-up of all in-stent restenosis and fibromuscular patients treated with the drug-coated balloon (from six to 39 months) we noticed that no patients from both groups came back for reappearance of symptoms or restenosis. At follow-up ultrasound colour Doppler showed a patent vessel with regular blood flow in each patient.
While there are several limitations of this study, one of them being the small number of patients that have been treated, we can consider drug-coated balloons to be a valid tool in the management of renal artery pathologies. In our view, despite the fact that a larger number of patients and a longer follow-up needs to be evaluated, these initial results can be judged as positive and satisfactory. If further studies confirm our data, the use of drug-coated balloons, especially in patients with fibromuscular dysplasia will surely be a treatment turning point with significant improvement in quality of life.
Fabrizio Fanelli is a professor of Radiology, Vascular and Interventional Radiology Unit, “Sapienza” University of Rome, Italy