Monday, March 31, 2014


The journey of  Renal Denervation RDN ) begins with a small company called Ardian. Medtronic International acquired the "Ardian company". With that the catheter and the technic of ablating renal artery sympathetic nervous plexuses. This technique was innovated to treat the condition of resistant hypertension.
Initially when the results of Simplicity 1 and 2 were announced, we all felt that this was a promising technique There was hope for our patients with resistant hypertension.
The Europeans were quick to approve this technique, and it was CE mark approved. BUT the US FDA with held approval until the results of Simplicity HTN 3. They felt that Simplicity HTN 1,2 had no controlled arm.
For the same reason I also did not quickly embark on this Renal Denervation ( RDN ) program. I was also troubled that not only was there no controlled arm, there was also noway to know if your ablation was effective. BP response to RDN could lack up till 8-9 mths after the procedure and that 20%  were non responders. So I also waited for Simplicity 3.
Well, Simplicity 3 results were announced by the PIs Dr Deepak Bhatt, at the ongoing Annual Scientific Meeting of the American College of Cardiology, on the 29th March, at Washington. Simplicity HTN 3 involved 535 patients with resistant hypertension and half of them received a sham procedure and the rest of the 50% received the RDN..
Actually, in January 2014, the Medtronic International had already announced that Simplicity HTN 3 had failed to achieved its primary endpoint. This was carried in the Asian Wall Street. Well the full results were announced on 29th March. It showed that Those who received RDN had a 14.13 mmHg reduction in office BP and the controlled arm had a 11.74 mmHg reduction. The difference of 2.39 mmHg was NOT statistically significant. Using 24hrs BP monitoring, those who received RDN had a 6.75 mmHg reduction and the control arm had a 4.79 mmHg reduction. Again, the difference of 1.69 mmHg was NOT significant. So Simplicity HTN 3 did not meet its primary endpoint and so was a negative trial. But all agree that the RDN procedure is safe.
What lessons did we learn from Simplicity HTN 3. Well the most obvious for the scientific community is that we now see negative trials reported and that is good. Secondary, although we call it resistant hypertension, good medical therapy, including intensive monitoring and also life style modification can still reduce BP. Thirdly, that maybe the Simplicity HTN 3 investigators were in too much of a hurry to get results. 6 months maybe too short, in my opinion. Perhaps they should have waited for 9 months or 12 months, to see results. Fourthly, we need procedures that we can know the success of denervation immediately. Others, it is essentially no better than a sham procedure. Moving forward, maybe we may find a use for RDN is patients who have "white coat" hypertension, as these patients are usually very nervous with an over active SNS.
In my discussions with foreign faculties, maybe Medtronic will try and re-promote RDN as a procedure to modulate the sympathetic nervous system of the body for many other nervous disorders.
RDN certainly is not dead and buried. It may have to re-invent itself, and perhaps find other uses.
After the good results with Simplicity HTN 1,2, many other companies ( I counte 6-7 ) have also introduced their own cathers to ablate renal artery nerves. There are also on going trials. I hear that ENLIGHHTN using the St Judes catheter is still ongoing.
A for me, no RDN yet, until with get better results and also preferably, if there is a way of knowing success of procedure immediately, like in angioplasty.

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