Summit, the pivotal trial of Abbott Laboratories’ Tendyne transcatheter mitral valve, will not read out until 2022, but early data from a small feasibility trial of the device give a hint of how it might perform in one of Summit’s patient cohorts: those with mitral annular calcification (MAC).
One-year data on the first nine patients in Abbott’s 30-patient feasibility study, all of whom had severe MAC, suggest that the device allows mitral regurgitation relief and symptom improvement. But further data will be necessary for approval, and that will not arrive for some time.
Small companies with catheter-mounted mitral valve prostheses have been the subject of furious deal-making by the big medtech players in cardiology – Abbott itself came by the Tendyne valve by acquiring its maker in 2015 (Deals galore for a new generation of transcatheter mitral valves, January 28, 2019). But no such device is yet approved, and trial data on these technologies has been fairly thin on the ground.
The data on the Tendyne valve, published today in the Journal of the American College of Cardiology, are the first of a dedicated transcatheter mitral valve in patients with severe MAC. MAC occurs when deposition of calcium causes the mitral valve annulus to become less flexible and thicker. In many patients, MAC can be severe and invade the myocardium, posing challenges for open surgical correction, potentially including atrioventricular groove disruption, a surgical complication that is nearly always fatal.
Moreover, MAC frequently is accompanied by severe morbidities that significantly increase surgical risk, such as coronary atherosclerosis, inflammatory disorders, and renal failure.
No extant therapies
Previous attempts at treating these patients have involved the off-label use of transcatheter aortic valves, and indeed an investigator-initiated feasibility study of this technique, using Edwards Lifesciences’ aortic valves, is ongoing. But use of aortic valves in this population has been associated with high rates of residual mitral regurgitation – in which the valve closes imperfectly, allowing blood to leak back into the left atrium – and conversion to open heart surgery, and a mortality rate of around 25%.
Fortunately the Tendyne device acquitted itself reasonably well. It was successfully implanted, and resulted in relief of mitral regurgitation in all nine patients.
None of the patients died during the implantation procedure, though during a median follow-up of 12 months there was one cardiac death and one noncardiac death.
There was no dysfunction of the implant, and mitral regurgitation remained absent in all treated patients. Two patients were readmitted to hospital for heart failure; neither died. Clinical improvement with mild or no symptoms occurred in all patients alive at the end of follow-up.
In an editorial accompanying the data, Josep Rodés-Cabau of the Quebec Heart & Lung Institute wrote that the study was “a major step forward in the field”, and said that the data open the door to a novel therapeutic option for patients with MAC.
All this will have to be confirmed in the other ongoing trials of Abbott’s prosthesis. The open-label European study is set to report early next year, but this will not include MAC patients, so Tendyne’s approval prospects in this population probably rest on the Summit data, two or three years hence.
|Trials of Abbott's Tendyne mitral valve|
|MAC feasibility trial||30||Jan 2020*||NCT03539458|
|Open-label US, European and Australian trial in patients with symptomatic mitral regurgitation||110||Dec 2019||NCT02321514|
|Summit – US pivotal trial in patients with mitral regurgitation or MAC, compared with use of Abbott's MitraClip valve repair device||1,010||Jun 2022||NCT03433274|
|*Full data. MAC = mitral annular calcification. Source: Clinicaltrials.gov.|