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Renal Denervation Lowered BP in Patients with Moderate Treatment-Resistant Hypertension
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Renal denervation reduced BP obtained in office and through ambulatory BP monitoring in patients with moderate and true treatment-resistant hypertension at 6 months, according to results of an investigator-initiated, open-label, prospective study recently published in the Journal of the American College of Cardiology.
The multicenter trial consisted of 54 patients with an office BP of ≥140/90 mm Hg and <160/100 mm Hg who were on antihypertensive medication consistently for 2 months. Initial 24-hour ambulatory BP monitoring (ABPM) confirmed true-resistant hypertension (≥130/80 mm Hg) in each patient. Patients with renal artery anatomy and secondary causes of hypertension were excluded.
Three months after the catheter-based renal denervation, systolic BP was not reduced to a statistically significant extent (from 151 ± 6 mm Hg to 146 ± 23 mm Hg; P=.164); however, diastolic BP was (from 82 ± 11 mm Hg to 79 ± 12 mm Hg; P=.011). In 36 patients with ABPM after renal denervation, systolic office BP dropped from 151 ± 5 mm Hg to 142 ± 20 mm Hg (P=.012) and diastolic from 84 ± 10 mm Hg to 79 ± 11 mm Hg (P=.003).
At 6-month follow-up, an office systolic BP reduction of ≥10 mm Hg was seen in 61.1% of patients and controlled BP of <140/90 mm Hg was achieved in 51%. Overall, the 151 ± 6 mm Hg baseline BP dropped a mean of 13/7 mm Hg in all patients and 24-hour ABPM a mean of 14/7 mm Hg in 34 patients.
Researchers noted that heart rate was lowered from 67 ± 11 beats per minute (BPM) to 63 ± 10 BPM (P=.006). “The change of heart rate did not correlate with the reduction of [systolic BP] at 3 months (r=–0.042; P=.768) and at 6 months (r=–0.095; P=.538), indicating that [renal denervation] resulted in a reduction of [heart rate] independently of its BP lowering effects,” researchers wrote.
Responding to the results, Krishna J. Rocha-Singh, MD, FACC, director of the Prairie Vascular Institute, and Richard E. Katholi, MD, FACC, partner at Prairie Cardiovascular Consultants, both in Springfield, Ill., wrote that including non-responsive results is necessary to accurately interpreting data. In this trial, researchers noted an increase of 7 ± 13 mm Hg in systolic BP after 6 months in non-responders.
Krishna J. Rocha-Singh
“Understanding whether ‘non-response’ actually means ‘no-response’ or ‘worst-response’ post-[renal denervation] may assist in identifying patient-related pre-procedure predictors of clinical BP response or the lack thereof,” Rocha-Singh and Katholi wrote.
Furthermore, they suggest that longer-term follow-up is needed in order to accommodate for “slower-responders.”
With a 12 month follow-up, “The reported six-month BP ... may turn out to be more beneficial than reported and the maximal BP reduction in this moderate-treatment resistant hypertension cohort may yet be fully realized,” they wrote.
For more information:
Ott C. J Am Coll Cardiol. 2013;doi:10.1016/j.jacc.2013.06.023.
Rocha-Singh K. J Am Coll Cardiol. 2013;doi:10.1016/j.jacc.2013.06.020.
Disclosures: Katholi, Ott and Rocha-Singh report no relevant financial disclosures.
Perspective
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Paul D. Williams, MD
Ott and colleagues describe a small pilot study of 54 patients treated with renal sympathetic denervation using the Symplicity catheter (Medtronic) for moderate treatment refractory hypertension, defined as office BP ≥140/90 and <160/100 mm Hg. All patients received 24-hour ABPM to rule out white-coat hypertension. Six months following therapy there were significant reductions in both office BP (by 13/7mmHg) and average ABPM (by 14/7mmHg), despite an overall reduction in the number of antihypertensive agents taken.
Catheter-based renal denervation has been best studied to date in severe refractory hypertension (office BP >160 mm Hg or >150 mm Hg for diabetics). The findings of the current study are interesting as they have the potential to substantially expand the indications for this therapy to include those with less severe hypertension. However, this is a small uncontrolled pilot study and further confirmatory large randomized trials are required (Symplicity HTN-4 is planned). It is also important to remember that, despite the widespread use and enthusiasm for renal denervation, only one relatively small unblinded randomized controlled trial has been published to date (Symplicity HTN-2). The results of the pivotal Symplicity HTN-3 trial, which includes a sham procedure placebo arm and has finished recruiting, are therefore eagerly awaited and vital for the future development of this technology.
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