A new study, results of which were presented at the weekend’s European Society of Hypertension(ESH) meeting in Milan, has cast doubt on the claims of Renal Denervation to be a “miracle” panacaea blood pressure treatment. Researchers suggest that in a real world setting the results are not as spectacular as those derived from office-based studies, and even point to placebo effects.
It’s a fact that most of the bigger studies we’ve seen on the effects of Renal Denervation have been performed under the blanket of company sponsored trials, none bigger than Medtronic’s Symplicity series. At the weekend, Belgian researchers presented their findings at the ESH meeting and came to some rather different conclusions, as reported on Heartwire.
So what’s changed?
Well, the main difference between the Belgian work and its comparator studies, is that blood pressure in its series was based on Ambulatory, rather than office-based assessment. The researchers say their study is the largest collection of ambulatory blood-pressure measurements (ABPM) , and say the results on ABPM are not impressive. The obvious question is why, and the researchers remain as quizzical as the audience. It seems that in drug tests, ABPM normally shows a BP lowering effect in ABPM to be some 70% of that measured in office-cuff tests. yet in this series the results were only 30% of those achieved in the office.
The other surprising complication for the renal denervation lobby was that the results were highly patient-specific, “a substantial proportion of patients treated with renal denervation having no change in blood pressure at all or even showed increased systolic blood pressure after the procedure”.
Lead investigator Prof Alexandre Persu (Cliniques Universitaires Saint-Luc, Brussels, Belgium) told heartwire. “There might be true responders, and we have observed important reductions in blood pressure in a limited number of patients, but we can’t predict who these patients are going to be, and, in fact, we do not know what really happened in these specific cases. If this technique is going to make it in clinical practice, we definitely need to identify factors that are predictive of treatment success.”
The results are certain to pour at least some cold water on the excitement generated by this wonder therapy over the past couple of years. Indeed the new guidelines on blood pressure treatment presented at the ESH meeting state that the procedure needs more data from long-term comparison trials to establish safety and efficacy against the best possible drug regimens.
As for the researchers themselves, they’re advocating randomized, controlled clinical trials that should include a primary end point using ABPM. In addition, drug therapy needs to be optimized and patients need to be screened appropriately for secondary and so-called white-coat resistant hypertension, including only those with truly resistant hypertension. In other words, Renal Denervation is so shrouded in uncertainty that it should be reserved for use as a last resort in patients for whom all other treatments have been explored and for whom the diagnosis of resistant hypertension is a fully secure one.
Physicians currently advocating the therapy will no doubt have something to say, as will an industry that has been building up a full head of steam. The idea that it should be reserved for research use will not go down at all well.
Full Heartwire piece here.