A meta-analysis conducted by Sardar et al. evaluated the change in blood pressure in response to catheter-based renal sympathetic denervation (RSD). The data, published in the Journal of the American College of Cardiology (JACC), suggested that RSD reduces ambulatory systolic blood pressure (ASBP) in patients with hypertension as compared with sham controls.
Previous studies have explored the effect of catheter-based RSD and hypertension; however, the data remains inconclusive. The six trials included used radiofrequency ablation using different catheters (Symplicity Flex Catheter, unipolar Medtronic Flex catheter, Symplicity Spyral multi-electrode catheter, Symplicity G3 (Medtronic) generator, Symplicity Spyral multi-electrode catheter, radiofrequency energy delivered by the Symplicity renal-denervation catheter and Endovascular ultrasound renal denervation with Paradise endovascular ultrasound renal denervation system as their methods for renal sympathetic denervation.
[perfectpullquote align=”full” bordertop=”false” cite=”” link=”” color=”” class=”” size=””]“Altogether, the present study affirms the safety and efficacy of renal denervation for blood pressure reduction, and highlights the importance of incorporating the previously described modifications in trial design. Also, based on our analysis, future large trials should include longer follow-up, be powered for efficacy endpoints including clinical outcomes, and incorporate objective measurement of medication adherence.”– Dr. Partha Sardar, M.D.[/perfectpullquote]
The authors conducted a random-effects meta-analysis comparing weighted mean differences (WMDs) in BP in order to assess the impact of RSD in patients with hypertension. The investigators included six sham-controlled trials (starting June 2018) including three second-generation RSD trials where 582 out of a total of 977 patients received RSD, while 395 of them had a sham procedure. The follow-up period of these patients varied from 2 to 6 months. The results showed a statistically significant reduction in 24 hours ambulatory systolic blood pressure (ASBP), which was the primary outcome of the study, and office SBP in all trials in patients who had RSD as compared to sham (WMD -3.65 mm Hg, 95% confidence interval, -5.33 to -1.98; p < 0.001). Moreover, other outcomes of the study which included a reduction in office SBP, daytime ASBP, 24-hour ambulatory diastolic BP (DBP), daytime ambulatory DBP, and office DBP were found to be statistically significant in patients with first generation RSD when compared with SBP for patients with 2nd generation RSD. This comparison did not show a significant difference in 24 hours ambulatory SBP. Lastly, the adverse effects were rare.
[perfectpullquote align=”full” bordertop=”false” cite=”” link=”” color=”” class=”” size=””] “After including all available randomized, sham-controlled trial data, our study demonstrated that renal denervation afforded a significant reduction in blood pressure. The observed blood pressure reduction was even more prominent in more recent, so-called ‘second generation trials.’ While these more recent trials are smaller, pilot studies, we believe they provide proof-of-concept and should address concerns over lack of efficacy raised after publication of earlier 1st generation trials. Outside of the United States, I suspect that our findings will support the continued use of renal denervation for patients with uncontrolled hypertension. In the United States, renal denervation remains investigational and will have to await completion of ongoing pivotal trials and FDA consideration before it could become widely available.”- Dr. Herbert D Aronow, M.D.[/perfectpullquote]
A previous study, published on March 2019 in JACC titled “Renal denervation for resistant hypertension in the contemporary era: A systematic review and meta-analysis,” showed that renal denervation has no significant benefits in patients with resistant hypertension. However, both antihypertensive drugs and RDN showed more pronounced reductions in blood pressure in single-arm studies. Experts claimed that with consistent data on benefits of renal denervation in larger studies, there could be a significant effect on guidelines. Renal denervation could serve to be superior as compared to antihypertensive medications as it did not have limitations including drug intolerance, non-compliance, and changes in BP.
According to the authors, “The present study affirms the safety and efficacy of renal denervation for blood pressure reduction and highlights the importance of incorporating the previously described modifications in trial design. A large pivotal trial should be designed in a manner consistent with the second-generation trials included in this analysis. These include minimization of participants with isolated systolic hypertension, the performance of procedures by highly experienced operators, employment of more complete techniques of radiofrequency ablation, and use of other novel approaches such as endovascular ultrasound renal denervation. Also, based on our analysis, future large trials should include longer follow-up, be powered for efficacy endpoints including clinical outcomes, and incorporate objective measurement of medication adherence.” However, they acknowledged the fact that the results were subject to some limitations including different study protocols and patient characteristics in different trials. The results of this meta-analysis certainly contributed significant conclusions and called for the designing and conduction of larger clinical trials to assess the long term efficacy and safety of RSD in hypertensive patients.