General Medicine Nephrology

SPYRAL HTN-ON MED Trial: Renal Denervation in Uncontrolled Hypertension

The SPYRAL HTN-ON MED trial was a large multicenter global scale trial that compared the effect of renal denervation + antihypertensive medications with antihypertensive medications alone. The results were significantly in favor of renal denervation in patients who had uncontrolled hypertension noticed in the clinic settings. Check out the visual abstract and following text for the trial summary.

SPYRAL HTN-ON MED trial Summary

The role of the sympathetic nervous system in the pathogenesis of hypertension (HTN) is well known. Activation of afferent sympathetic fibers results in renin release, retention of sodium, and reduction in renal blood flow that lead to the increase in blood pressure (BP) values. Hypertension usually requires life-long medication regimen; however, many studies have highlighted the averseness of many patients to maintain the stable regimen.


Recently, surgical renal denervation (RDN) has emerged as an efficient way of diminishing the renal sympathetic stimulation, decreasing the release of renin, while maintaining the normal glomerular filtration rate and renal blood flow.


SPYRAL HTN-ON MED trial is a randomized, single-blind, sham-controlled proof-of-concept trial carried out by Kandazi DE, et al. to assess the safety and efficacy of renal denervation on BP in patients with uncontrolled HTN who were on antihypertensive medication. The RDN of the main renal artery and accessory branches was performed with a Spyral multi-electrode radiofrequency ablation device. The primary results of the first 80 patients in the SPYRAL HTN-ON MED trial were published in 2018, which demonstrated a significant decrease in office and 24-hour ambulatory BP from baseline to 6 months in RDN group compared to sham-control, with a mean drug adherence of 60%.


The previous SPYRAL HTN-OFF MED trial of the SPYRAL series by Townsend RR, et al. was published in 2017. This trial used the similar ablation device as in HTN-ON MED trial but was conducted in the absence of antihypertensive medications. This trial also demonstrated a significant reduction in 24-hour ambulatory BP from baseline at 3 months follow-up.


Furthermore, the reduction in systolic BP of approximately 5.5 to 9 mmHg in these SPYRAL trials corresponds to the effect of one antihypertensive drug. It is also important to note that the short-term safety profile of this new intervention is favorable with no major adverse effects recorded. These results have shown a promising future of RDN in the treatment of HTN, especially in patients with medication noncompliance or those with adverse effects of medication.


However, before RDN becomes a mainstream management option for the treatment of HTN, further research needs to show the improvements in cardiovascular morbidity and mortality with the use of RDN. Additionally, further research is also needed to establish a long-term safety beyond the initial 6 months post-procedure.


Summarized by / Author: Muhammad Uzair Lodhi, MD (1)

Summary Reviewer: Mustafa Rahim, MD, FACP, FASPC (1)


Authors Affiliation:

1. Department of Medicine, West Virginia University Robert C. Byrd Health Sciences Center, WV