MUNICH, Germany—Renal denervation, an innovative catheter-based procedure, displayed breadth of application as well as long-term efficacy in 2 reports presented August 27, 2012, at the European Society of Cardiology Congress.

Both involved the Symplicity catheter system (Medtronic, Minneapolis, MN), with one looking at its use in heart failure and the other updating a randomized trial on hypertension. 

Safety, Hints of Efficacy in Heart Failure Patients

In a pilot study reported by Milos Taborsky, MD, of University Hospital Olomouc and Palacký University School of Medicine (Olomouc, Czech Republic), renal denervation improved or stabilized several key parameters of heart failure. Dr. Taborsky said the established association between heart failure and neurohormonal activation as well as the positive effects of renal denervation in several animal studies prompted investigators to undertake this small human study. 

For the single-center trial, 51 patients with advanced heart failure who were not candidates for cardiac resynchronization therapy, ventricular assist devices, or heart transplantation were randomized to standard medical therapy with or without renal denervation. Overall, however, only about 25% were receiving medications within the target dose.

Patients received a mean 4.2 ± 1.3 radiofrequency applications on the right renal artery and 5.4 ± 2.0 on the left renal artery with the Symplicity system. Echocardiographic follow-up was performed at 6 and 12 months. 

At 1 year, renal denervation patients experienced significant improvements over baseline in LVEF, LV end diastolic and systolic volumes, and NT-proBNP. On the other hand, medical therapy patients saw no changes in these metrics, producing a significant difference favoring denervation between the groups for all (P < 0.01; table 1).

Table 1. Change in Heart Failure Parameters Over 1 Year After Renal Denervation

In addition, heart rate declined in the renal denervation group, while it was unchanged in the medical therapy group.

From a clinical standpoint, at 12 months 42% of renal denervation patients improved in New York Heart Association class compared with 22% of medical therapy patients. Moreover, about 8% of patients in the renal denervation group had been hospitalized due to heart failure vs. 18% in the standard therapy group (P < 0.001).

Because the primary goal of the study was to evaluate the procedure’s safety, the fact that renal denervation appeared to have no adverse effect on kidney function is very important, Dr. Taborsky said. Moreover, although 1 arteriovenous fistula requiring surgical revision, 1 thrombus, 1 TIA, and 1 case of hypotension were recorded in the renal denervation arm, complication rates between the groups were similar. No deaths occurred in the renal denervation group.

Among the questions this study raises, said Dr. Taborsky, are whether use of the heart rate drug ivabradine would have had an impact on the outcomes and if renal denervation will have differential effects on patients with ischemic vs. nonischemic heart failure. In addition, the role of other denervation technologies should be investigated, he urged.

“Renal denervation is particularly suited to patients without an extensive scar after [MI] and whose heart rate increases when they are treated with the maximum tolerated dose of beta blockers,” Dr. Taborsky said in a press statement. He added that the long-term effects of renal denervation in heart failure must be confirmed in a large randomized trial.

Good News from Symplicity Continues

Meanwhile, renal denervation showed long-term efficacy in its original application, reduction of hypertension, in 18-month data from the Symplicity HTN-2 trial reported by Murray D. Esler, MD, PhD, of the Baker IDI Heart and Diabetes Institute (Melbourne, Australia).

In this international, multicenter study, 106 patients with treatment-resistant hypertension were randomized to receive renal denervation using the Symplicity system plus their antihypertensive regimen (n = 49) or simply remain on their usual medications (n = 43). At baseline, blood pressure was similarly high in the treatment and control groups despite patients being on an average of 5 antihypertensive medications.  

At 18 months, blood pressure continued to decrease from the significant 12-month reductions reported earlier (table 1). 

Table 1. Change in Blood Pressure Over 18 Months After Renal Denervation

^a For difference from preprocedure blood pressure.               

In addition, 31 control patients who underwent renal denervation following the 6-month primary endpoint of change in systolic pressure experienced a reduction of 28 mm Hg systolic and 11 mm Hg diastolic pressure at 18 months (P < 0.01).

“This study provides reassurance that the sympathetic nerves haven’t regenerated,” Dr. Esler said in a press statement, adding that “safety results were sustained at 18 months as well, with no significant decline in kidney function.” 

2. Eisler MD. Catheter-based renal sympathetic denervation in patients with resistant hypertension: 18-month follow-up of the Symplicity HTN-2 trial. Presented at: European Society of Cardiology Congress; August 27, 2012; Munich, Germany.

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