Blog entry by Arif Khwaja
An interesting pilot, proof of concept study is published in JASN online today looking at the role of renal dennervation in patients with resistatnt hypertension and CKD. In the last couple of years a number of studies have suggested that renal dennervation maybe useful in the management of resistant hypertension and larger scale clinical trials are currently underway to test this hypothesis. As yet however there have been no studies in the CKD population. The rationale is that there is increased renal sympathetic activation in CKD and further that activation of the renal afferent sympathetic system in response to CKD also increases central sympathetic activation. Renal denervation involves placing a radiofrequency catheter in the renal artery ( accessed by femoral artery) to allow ablation of renal sympathetic chain.
In this study by Hering and colleagues from Melbourne, 15 patients with CKD 3/4, a mean office BP of around 174/9, taking an average of 5.6 drugs underwent the procedure. At follow up that is between 3-12 months there was no difference in creatine-based eGFR or cystatin C suggesting that the procedure has no adverse effects on kidney function. Mean changes in office systolic and diastolic BP at 1, 3, 6, and 12 months were −34/−14, −25/−11, −32/−15, and −33/−19 mmHg, respectively. Interestingly and perhaps disappointingly the mean 24 hour BP and daytime BP didnt change. However there was a significant reduction in nightime systolic BP on 24 hour monitoring falling from a mean of 154 to 144mmHg at 6 months. i.e. there was a restoration of nightime dipping of BP - lack of nightime dipping is a stronger predictor of CV events than daytime BP. Interestingly there was no significant change in the number of medications being taken at the end of the study. The lack of effect on daytime BP is not easily explainable but the numbers are of course small and there is substantial intrpatient variability. Peripheral arterial stiffness as assessed by augmentation index was significantly reduced at 3 months suggesting that the effect on blood pressure was real. There were reductions in proteinuria, BNP and increases in hamegloblin at 3 months but these did not reach statistical significance.
Theres clearly a long way to go before we know whether this technique will impact on meaningful outcomes but in CKD but as the authors say this preliminary study provides guidance for the design of further cinical trials to evaluate the short and long term effects of the technique in CKD.