PARTNER 3 and EVOLUT Trials

sAVR (transcatheter aortic valve replacement), also called TAVI (transcatheter aortic valve implantation), is a less invasive alternative to surgical aortic valve replacement (sAVR), i.e. open-heart surgery in patients with severe symptomatic aortic stenosis.

Surgical aortic valve replacement is an established, time-proven technique with excellent results, but it is obviously an open heart surgery and, as such, a major undertaking. As a new procedure with unknown long-term results, TAVI was initially used only in the most high-risk patients who were too sick to undergo surgery. Over time, with increasing good experience, the indication criteria have been gradually expanded to lower-risk patients. PARTNER 3 and EVOLUT trials, which have been recently reported, shed some light on the choice between surgical and catheter procedure.

PARTNER 3 trial was a trial with 950 patients with severe aortic stenosis who were considered low-risk. They were randomised to sAVR versus TAVI with a balloon-expandable SAPIEN 3 valve. The primary endpoint was death, stroke, or all-cause hospitalisation, and secondary endpoints were death, stroke and new atrial fibrillation at 30 days.

The primary endpoint occurred in 15.1% in the sAVR group and 8.5% in the TAVI group; this was statistically significant and transcatheter procedure was superior to surgery. Regarding the length of stay, TAVI was understandably much shorter. Major bleeding complications were less common in TAVI. However, pacemaker implantation and paravalvular leak were more frequent in the TAVI group.

Evolut trial randomised 1468 patients with severe aortic stenosis between TAVI with a self-expanding Medtronic valve (CoreValve, Evolut R, or the Evolut PRO) and sAVR. The primary endpoint was death or disabling stroke. The mean follow-up of this study was 12.2 months. The primary endpoint was met in 5.3% of patients in the TAVI arm and 6.7% of patients in the surgical arm. The new-onset AF at 30 days was 7.7% in the TAVI arm and 35.4% in the surgery arm.

Both trials therefore showed either equivalence or superiority of TAVI compared to sAVR. The main shortcoming was a short follow-up: only one year in the PARTNER 3 trial and two years in the EVOLUT trial. The results so far are very encouraging, but there are no long-term data about the efficacy and safety of the transcatheter approach. An important consideration is the patient's age, which will impact decision-making whether to prioritise good short-term results in less invasive procedure or solid long-term results in the more invasive undertaking. The average age of patients in the trials above was 75 years, and in this age category, TAVI is probably the preferred option. For younger patients in their ’60 and below, surgical treatment – at least for now – remains the default choice. Both trials will have a follow-up for ten years. It will be a worthwhile wait.