Abstract 17119: Renal Sympathetic Denervation Using an “Off-the-Shelf” Irrigated Radiofrequency Ablation Catheter for the Management of Drug-Resistant Hypertension

Introduction: Catheter-based renal sympathetic denervation using a specialized radiofrequency (RF) ablation catheter has recently been demonstrated to achieve sustained BP lowering in drug-refractory hypertension (HTN) pts. In theory, this non-irrigated RF ablation catheter has the potential to cause char formation at the point of catheter-tissue contact. We studied whether the same saline-irrigated RF ablation catheters used for ablation at other cardiovascular sites, which in theory would minimize the thromboembolic risk related to ablation itself, can safely provide similar BP reduction in refractory HTN pts. Methods: Ten pts with drug-resistant HTN (7±1 anti-hypertensive drugs/pt) underwent bilateral renal denervation with a standard saline-irrigated RF ablation catheter. Ambulatory BP recordings (24-hr) were obtained at baseline, and 1, 3, and 6 months post-procedure. In 5 pts, pre- and post-procedural measures of renal sympathetic activity were assessed, including plasma aldosterone, metanephrine, normetanephrine and plasma renin activity. All pts underwent follow-up renal angiography (at 1-5 months) to assess for renal artery (RA) stenosis. Results: Over a 6 month period, 1) the mean change in systolic/diastolic BP was -28/-20 mmHg; 2) all patients experienced a decrease in systolic BP of at least 10 mm Hg (range: 10-32 mm Hg); 3) there was no evidence of RA stenosis or aneurysm at repeat angiography; and 4) there was a significant decrease in renal sympathetic activity at 3 months: including metanephrine (-12±4, p=0.003) and normetanephrine (-17±4, p=0.0008) levels. There was also a significant decrease in aldosterone levels (-60±33 ng/l, p=0.02). Changes in the remaining variables were not significant: plasma renin activity (0.2 mg/l/hod, p=0.4), serum creatinine (-1 mmol/L, p=0.4); renin (0.3 mg/l/hod, p=0.4). Conclusions: Renal sympathetic denervation can be performed safely and effectively in pts with resistant hypertension using a standard saline-irrigated ablation catheter. Randomized placebo-controlled trials remain necessary to rule out a biofeedback-mediated placebo effect.