Download this article's Factoid (PDF & PPT for Gold Subscribers)

Only 40% of patients with so-called treatment-resistant hypertension referred for renal denervation in Europe are actually eligible for the procedure, primarily because even “impossible” blood pressure can be controlled with medication in an experienced center, according to a study published in the June 2014 issue of Hypertension. The findings suggest that tertiary referral centers should act as gatekeepers prior to considering denervation.

Jan A. Staessen, MD, PhD, of University Hospitals Leuven (Leuven, Belgium), and colleagues collected data on 731 patients referred to 11 centers participating in the European Network Coordinating Research on renal Denervation in treatment-resistant hypertension (ENCOReD) registry. Eligibility was determined according to both SYMPLICITY HTN-2 criteria and the centers’ judgment.

Patients were referred by both specialists (75.6%) and general practitioners (24.4%). The average age was 61.6 years, office blood pressure at screening was 177/96 mm Hg, and number of blood pressure-lowing drugs taken was 4.1. Despite being deemed worthy for referral, at the time of presentation to the tertiary center, many patients:

• Had no drug inhibiting the renin-angiotensin system (14.9%)
• Had no calcium antagonist (27.2%)
• Had no diuretic (18.0%)
• Were prescribed ≥ 2 drugs inhibiting the renin-angiotensin system (21.5%)
• Were not receiving spironolactone (74%)

Based on SYMPLICITY criteria, 42.5% of patients referred were ineligible, and 39.7% were deemed ineligible by individual centers’ standards, though there was notable variability between centers.

The most common reasons for ineligibility were:

• Controlled or substantially improved blood pressure after treatment adjustment (46.9%)
• Anatomic reasons (renal artery stenosis, history of renal stenting, or other; 17.0%)
• Secondary hypertension (11.1%)

In half of the cases, treatment adjustment involved prescription of low-dose spironolactone (25-50 mg/d).

Eligible patients tended to be younger, had higher office and ambulatory blood pressure, were taking more drug classes, and had a higher eGFR.

True Proportion of Eligible Patients Probably Even Smaller

The study authors point out that most patients in the study were referred because “blood pressure control was considered impossible to achieve, often after years of unsuccessful attempts.” As a result, they say, “hypertension centers with a record in clinical experience and research should remain the gatekeepers before renal denervation is considered.”

Dr. Staessen and colleagues add that the proportion of patients with true resistant hypertension in whom  renal denervation seems both feasible and justified “is probably still an order of magnitude lower and might further decrease if all patients would be assessed for drug adherence or would have received maximal and optimized drug treatment, including low-dose spironolactone whenever possible.”

Registry, Longitudinal Follow Up Still Needed

In an email with TCTMD, Deepak L. Bhatt, MD, MPH, of Brigham and Women’s Hospital (Boston, MA), confirmed that this result echoes “what hypertension experts have been saying all along and what we observed in SYMPLICITY HTN-3– that a large percentage of patients deemed as having treatment-resistant hypertension can have their blood pressure controlled in experienced referral centers.”

“Still,” Dr. Bhatt posited, “there are a sizeable number of patients who could benefit from novel drugs or procedures for hypertension that is truly resistant to current medical therapy.”

Moving forward, Dr. Bhatt called for a registry and longitudinal follow-up. Furthermore, he wrote, “What will really move the field forward, however, are randomized, blinded trials using catheter systems in which we can confirm that actual denervation is likely to have occurred.”

Related Stories:

• Renal Denervation Shows Promise in Patients Refractory to Stenting
• Renal Denervation Fails to Meet Efficacy Endpoints Compared with Placebo Procedure
• Long-term Outcomes with Renal Denervation Show Sustained Benefit