Renal denervation is slowly crawling out of its grave, but Vascular Dynamics is taking a slightly different approach to lowering blood pressure. The company makes a device called MobiusHD, which is implanted in the neck and gently stretches the carotid artery. This is interpreted by the body a signal of high blood pressure, causing peripheral vasodilation as a reaction.
The device is already on sale in Europe, but has not yet reached the US. It came a step closer today, though, with the release of interim data in US patients showing a significant reduction in ambulatory systolic blood pressure with the device.
Interim data from the European Calm-FIM trial were presented at the ESC meeting in August. Today’s data, presented at the Transcatheter Cardiovascular Therapeutics meeting in Denver, include patients in both the European and US Calm-FIM studies.
The combined cohort comprised 42 patients with resistant hypertension who were being treated with a minimum of three antihypertensive drugs. All were treated with MobiusHD, which is implanted via catheter in the carotid sinus.
The blood is the life
Vascular Dynamics says these patients saw an average reduction of ambulatory systolic blood pressure of more than 19mmHg from baseline at six months.
This is pretty remarkable: in the study of Medtronic’s Symplicity Spyral renal denervation system that reignited interest in this area back in August, that device could only muster a mean decline in 24-hour ambulatory systolic blood pressure, at three months, of 5.5mmHg (ESC 2017 – The corpse of renal denervation starts twitching, August 28, 2017).
Naturally, since these are different trials of entirely different technologies, the data on MobiusHD and Spyral are not directly comparable. And this is particularly true given that Medtronic’s study had a sham control group. Historically, trials of renal denervation with no sham control groups showed far more dramatic effects on blood pressure – decreases of around 15mmHg were common – than those that did have sham comparison. It seems plausible that something similar might occur with MobiusHD.
In the combined US and European Calm-FIM trials, 89% of MobiusHD recipients had a drop in office systolic blood pressure of greater than 10mmHg at six months, or a fall in 24-hour ambulatory systolic blood pressure of 5mmHg or more. If the mean drop on this last measure was 19mmHg there must have been a great deal of variation for at least 11% of patients to have had a drop of less than 5mmHg.
Vascular Dynamics has now kicked off the pivotal US study for the device. Calm-2 will enrol 300 patients and, crucially, will include a sham arm. The study will not report until summer 2020, though, so it will be some years before the company can hope for FDA approval.
And that will only occur if the blood pressure reductions remain impressive when the sham control is introduced. If MobiusHD really can cut blood pressure by nearly 20mmHg, and do so safely, it will find a ready market – and a takeout of Vascular Dynamics, by Medtronic, say, could become more likely.
If, however, the blood pressure decrease in Calm-2 turns out to be similar to the 5mmHg or so seen with Medtronic’s Spyral, US approval might still happen – but sales will probably not take off. Cardiologists have questioned whether an effect that small could justify the trauma and expense of the Spyral implantation procedure, and a similar calculation would apply to MobiusHD.
|Vascular Dynamics' clinical trials|
|Study||Description||N||Primary completion||Trial ID|
|Calm-FIM Eur||Open-label, European||30||August 2016||NCT01911897|
|Calm-FIM US||Open-label, US||20||December 2017||NCT01831895|
|Calm-Diem||Open-label, European||200||December 2017||NCT02827032|
|Calm-Start||Double-blind, sham-controlled, European||110||June 2018||NCT02804087|
|Calm-2||Randomised, double-blind, sham-controlled, US pivotal trial||300||May 2020||NCT03179800|