Renal arterial stenosis: long term clinical outcomes of percutaneous transluminal angioplasty and stent implantation for hypertension and renal function

Introduction: Despite conflicting literature reports, patients affected by renovascular hypertension with >0.8 renal resistive index (RI) have long been considered non-eligible for revascularization. Purpose: This study evaluates the long-term clinical outcome (blood pressure control, renal function) of renal artery stenosis (RAS) interventional treatment (PTA/stenting) among patients with renovascular hypertension diagnosed in our institution in the last 15 years using ultrasound. The referral for PTA/Stenting was made after positive US evaluation, by referring physicians irrespective of preprocedural renal RI. A second purpose of the investigation was to assess the prevalence of >60% RAS and to establish the diagnostic accuracy of the US diagnosis of RAS compared with Angio-MR (MRA), Angio-CT (CTA) and Digital Angiography (DA). Methods: 1502 patients with resistant hypertension underwent 1609 renal Duplex US examinations between June 2001 and November 2016. A >60% RAS was diagnosed in the presence of >200 cm/s peak systolic velocity (PSV), with a >3.5 renal aortic ratio (RAR=renal PSV/aortic PSV). Normal interlobular acceleration time was defined as <80 ms and normal renal parenchymal thickness (RPT) was defined as >10mm. Patients were interviewed by telephone on their clinical status, cardiovascular outcome, medication use, and renal function, two years after the vascular procedure. Results: 160 patients (10.6%) met US criteria for RAS: the most common finding was proximal unilateral RAS (99 patients-6.6%); 50/160 (31.2%) RAS patients underwent further investigation (DA, CTA and MRA). DA and US were consistent in 11 out of 12 patients (91.7%), MRA and US in 5 out of 6 patients (83.3%), CTA and US in 33 out of 38 patients (86.8%). A PSV >200 cm/s showed the strongest correlation with positive results of DA and CTA (present in 100% of positive DA and CTA). A >0.8 RI and a <10mm RPT were found in all patients who died within 2 years from the procedure. 22.5% of patients with >1.2 mg/dl and 10.7% of those with <1.2 mg/dl serum creatinine were stented. In the 104 medically treated patients serum creatinine increased from 1.22±0.06 to 1.45±0.09 mg/dl (p=0.001); serum creatinine dropped significantly in the stented group [1.77±0.26 to 1.26±0.13 mg/dl (p=0.041)]. The number of antihypertensive drugs in use dropped significantly after PTA/Stent procedure (1.84±0.54 to 1.11±0.45, p=0.001) implying an improvement in clinical blood pressure control. Conclusions: A 10.6% RAS prevalence was found in the 1502 patients with resistant hypertension evaluated with US. PSV was the most sensitive parameter to diagnose RAS with a good agreement with other diagnostic imaging techniques. Irrespective of preprocedural RI, the PTA/stenting led to an improvement in renal function (serum creatinine) and blood pressure control. A >0.80 RI and a <10mm RPT showed a stronger relation with cardiovascular deaths.