Renal Denervation Results Promising
DALLAS—Data from a small pilot study reveal that renal denervation “slows or even halts the decline of renal function in treatment-resistant hypertensive patients” with stage 3 or 4 chronic kidney disease. The 15-patient study was presented at a poster session during the American Heart Association's Scientific Sessions 2013.
The study was conducted in patients with stage 3 or 4 CKD with a mean age of 66 years and an office blood pressure (BP) of 140/90 mm Hg or higher despite treatment with at least three antihypertensive agents and a 24-hour ambulatory BP of 130/80 mm Hg. All underwent renal denervation using the Medtronic Symplicity Flex catheter system. Renal function was evaluated up to three years prior to and up to one year after renal denervation.
Estimated glomerular filtration rate (eGFR), calculated using the Modification of Diet in Renal Disease (MDRD) formula, was 47.0 mL/min/1.73 m2 at baseline. Other baseline characteristics were a mean office BP of 157/78 mm Hg, a mean 24-hour ambulatory BP of 157/80 mm Hg, a mean aortic systolic BP of 150.0 mm Hg, and a mean heart rate of 66 bpm. Seventy-five percent had diabetes. Patients were on a mean of 5.8 antihypertensive agents at entry.
One year following renal denervation, office BP was reduced by a mean of 26/6 mm Hg and 24-hour ambulatory BP was reduced by 13/6 mm Hg, reported lead investigator Roland E. Schmieder, MD, from the department of nephrology, University Hospital of Erlangen, Germany. Aortic systolic BP declined by 24 mm Hg.
Before renal denervation, the mean decline in eGFR was 5.6 mL/min/1.73 m2. After renal denervation, eGFR remained stable (47.0 mL/min/1.73m2 at baseline vs. 49.2 mL/min/1.73m2 at one year). The difference in eGFR change per year pre- and post-renal denervation was significant.
None of the 15 patients experienced a doubling of serum creatinine or required dialysis after renal denervation at any point.
Researchers from the First Cardiology Clinic at the University of Athens, Greece, presented their own findings on renal denervation (using the EnligHTN) in 20 patients with drug-resistant hypertension who were followed for six months. Cardiac parameters were assessed using transthoracic echocardiography and blood measurement of N-terminal B-type natriuretic peptide (NT-proBNP). Mean age of the sample was 57 years; patients were on a mean of 4.5 antihypertensive drugs at baseline.
Both office BP and 24-hour ambulatory BP decreased significantly from baseline to month 6. The effects on blood pressure were accompanied by favorable cardiac remodeling and attenuation of neurohormal overdrive as reflected by decreased NT proBNP levels.
Significant improvements from baseline in left atrial diameter, left ventricular mass index, and diastolic function were observed six months after renal denervation. Intervernicular septum in diastole decreased significantly from 12.1 mm at baseline to 11.6 mm at six months, and the mitral valve E'/A' ratio increased significantly from 0.62 to 0.82. NT-pronBNP fell from 85.0 pg/mL at baseline to 58.6 pg/mL at month 6).