Renal Denervation in Patients Taking Antihypertensive Drugs
- In patients taking antihypertension medications, renal denervation (RDN) showed no significant difference in mean 24-hour ambulatory BP when compared to sham treatment after 6 months of treatment.
- Importantly, RDN showed an improvement in office systolic BP of about 5 mm Hg (p = 0.0015) and a reduction in nocturnal BP.
- Antihypertensive medications were increased with higher frequency in the sham versus RDN groups, which would tend to blunt the ability to see the full benefit in the RDN group.
Does radiofrequency renal denervation (RDN) provide a benefit in patients with uncontrolled hypertension when compared to sham controls?
A total of 337 subjects were randomized to undergo radiofrequency RDN (n = 206) compared to a sham procedure (n = 131), which consisted of performing the renal arteriogram only and patients remaining on the angiographic table for ≥20 minutes. The patients and the subsequent BP assessors were blinded. Subjects were ages 20-80 years and had uncontrolled hypertension as defined by office systolic ≥150 and <180, diastolic BP ≥90, and 24-hour BP monitor mean ≥140 and <170 mm Hg. They were prescribed one, two, or three antihypertension medications.
RDN resulted in only a 1.9 mm Hg drop in 24-hour ambulatory BP monitoring (ABPM) after 6 months compared to sham, which was not statistically significant. However, a 4.9 mm Hg drop in office BP was noted that was significant, which is of unclear clinical significance considering a neutral effect on the 24-hour ABPM. Additionally, nighttime systolic BP was lower in the RDN group. There was greater increase in BP medication in the sham group, as more patients met “escape criteria,” and there may have also been protocol violations that were driven by patients’ and physicians’ awareness of the patients’ BP.
Radiofrequency RDN did not result in a statistically significant change in 24-hour BP in patients taking antihypertension medications when compared to sham controls. It did show a difference in office and nighttime BP that is of unclear clinical significance, given the lack of a 24-hour ABPM difference. Since patients in the sham group had their BP medications increased more frequently despite the investigator’s best efforts, the extent of a potential beneficial effect of RDN may have been obscured.
Lifestyle interventions and pharmacologic therapy for hypertension have been the mainstay for treatment for nearly 75 years. Despite earnest and diligent efforts by patients and physicians to implement these therapies, a large percentage of patients with hypertension remain inadequately treated and unable to enjoy the benefits from improved BP control. Patients are often unable to tolerate medications, unable to adhere to their lifestyle and medication regimens, or are simply worried, largely inappropriately but worried nonetheless, over the effects of long-term medication therapy. Innovative and new therapies are desperately needed and RDN provides one of those hopes.
This study shows some additional glimmers of hope in the utility of RDN in BP management of patients needing BP medications—a likely target group of newer therapies. Although office and nocturnal BP was improved, the results of the 24-hour ABPM were disappointing. This underscores the difficulty in performing studies on people with significantly elevated BP, as there is a natural tendency to increase BP medications in the control arm, as occurred in this study, because of genuine concerns of patients and their physicians who will be seeing more elevated BPs in a control arm when compared to an intervention that may yield an incremental benefit.
To further illustrate this conundrum, imagine if we were to test a novel lipid-lowering medication and found it to be minimally effective compared to placebo, but that subjects in the placebo arm often had their baseline statin dose increased more frequently and more intensively. Accepting such a study as null would have the potential of a chilling novel therapy that could benefit many.
So, what are we to do with this? First, we must recognize that present antihypertensive therapies are not meeting the present clinical needs both because of irremediable nonadherence a well as the fact that even the present therapies, when tolerated, cannot get everybody to goal. But we must also recognize that there may be subgroups of patients who might have benefit from RDN and continue our enthusiasm in development and testing of this and other novel therapies for the millions of patients for whom there are presently no pathways to optimal BP control.
Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Hypertension, Prevention
Keywords: Antihypertensive Agents, Blood Pressure, Denervation
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