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Catheter-based renal sympathetic denervation reduces blood pressure (BP) in patients with resistant hypertension not only when measured in the office but also when ascertained through 24-hour ambulatory monitoring, reports a paper published online June 18, 2013, ahead of print in Circulation. But in patients with pseudo-resistant hypertension, who only show elevations in office BP to begin with—possibly ‘white coat hypertension’—the treatment fails to lower ambulatory BP.

Researchers led by Felix Mahfoud, MD, of the Saarland University Hospital (Homburg, Germany), enrolled 346 patients who underwent renal denervation for uncontrolled hypertension at 10 centers and, based on daytime ambulatory BP monitoring, divided them into 2 categories: 303 patients with true resistant hypertension and 43 with pseudo-resistant hypertension. Pseudo-resistance was defined as mean ambulatory 24-hour systolic BP < 130 mm Hg despite elevated office SBP readings.

True resistant patients had office systolic BP of 172.2 ± 22 mm Hg, and ambulatory BP of 154 ± 16.2 mm Hg. For the pseudo-resistant patients, those measurements were 161.2 ± 20.3 mm Hg and 121.1 ± 19.6 mm Hg, respectively.

Overall, renal denervation reduced office-based BP, both systolic and diastolic, as well as pulse pressure at 3, 6, and 12 months (P < 0.001). Changes in office BP more pronounced than those in ambulatory BP at each time point (P < 0.0001 for both systolic and diastolic).

However, looking separately at the 2 groups of patients, only in the true resistant patients were ambulatory BP measurements significantly reduced at various time points after renal denervation (tables 1 and 2).

Table 1. True Resistant Patients: Changes in 24-Hour Ambulatory BP, mm Hg^a

^a P < 0.001 for all comparisons.

Table 2. Pseudo-Resistant Patients: Changes in 24-Hour Ambulatory BP, mm Hg^a

^a P = NS for all comparisons.

True resistant patients had similar reductions in daytime and nighttime ambulatory BP. Renal denervation also reduced BP, both office and ambulatory, among patients who were treated with an aldosterone antagonist.

After adjustment for age, sex, body mass index, diabetes, and glomerular filtration rate, only office-based systolic BP at baseline predicted 6-month response to renal denervation (defined as systolic BP reduction of ≥ 10 mm Hg in office-based measurements and ≥ 5 mm Hg in ambulatory BP average). The relationship existed both as a continuous variable (OR 1.026; 95% CI 1.005-1.048; P = 0.017 per 1 mm Hg) and at a threshold of more than 170 mm Hg (OR 2.32; 95% CI 1.09-4.85; P = 0.029).

Outside Sources Say Study Limited

The study, while providing support for the use of renal denervation in true resistant patients, is severely limited, according to an accompanying editorial by Gianfranco Parati, MD, Juan Eugenio Ochoa, MD, and Grzegorz Bilo, MD, PhD, all of S. Luca Hospital (Milan, Italy).

In particular, Dr. Parati and colleagues highlight the high loss to follow-up. At 3 months, ambulatory BP data were available for only 245 of the 346 patients, a proportion that dropped to 236 at 6 months and 90 patients at 12 months. “This inevitably raises questions on possible biases due to the exclusion of a large subgroup of patients from the analyses,” they write, noting that the study also was not randomized.

Still, the results “nicely quantify the effect on ambulatory blood pressure,” said Deepak Bhatt, MD, MPH, of Harvard University Medical School (Boston, MA) in an e-mail communication with TCTMD, noting that, “as expected though not widely appreciated” the drop was greater in office BP than ambulatory measurements. Dr. Bhatt is co-principal investigator of the ongoing Symplicity HTN-3 trial.

George Bakris, MD, of the University of Chicago Medical Center (Chicago, IL), and a co-investigator on that trial, stressed to TCTMD in an e-mail communication that renal denervation is “not a panacea.”

He pointed out that the treatment would also be expected to improve glucose intolerance and restore nocturnal dipping on ambulatory BP because of its effects on sympathetic tone. But “since [ambulatory BP monitoring] is still a diagnostic tool and not well-reimbursed, the clinical utility of this finding is moot as it will only apply to those in research studies or those who can afford the [test],” Dr. Bakris said.

2. Parati G, Ochoa JE, Bilo G. Renal sympathetic denervation and daily life blood pressure in resistant hypertension: Simplicity or complexity [editorial]? Circulation. 2013;Epub ahead of print.

• Dr. Bakris reports serving as co-principal investigator of Symplicity HTN-3 and as a consultant for several pharmaceutical companies including Abbott, Boehringer Ingelheim, Daiichi-Sankyo, Janssen, and Takeda
• Dr. Bhatt reports receiving research grants from Amarin, AstraZeneca, Bristol-Myers Squibb, Eisai, Ethicon, Medtronic, Sanofi-Aventis, and The Medicines Company and serving as co-principal investigator for the Symplicity HTN-3 trial

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