Transcatheter aortic valve implantation (TAVI) is safe in the short term in low-risk patients with symptomatic, severe bicuspid aortic stenosis (AS). Researchers also noted that subclinical leaflet thrombosis was present in a minority of patients at 30 days, but did not appear to be associated with clinical events, and that bicuspid AS patients are younger than patients with tricuspid AS.
Ron Waksman (Georgetown University and MedStar Heart & Vascular Institute, Washington DC, USA) presented the interim findings at a late breaking session at the Cardiac Resynchronisation Therapy meeting (CRT 2020; 23–25 February, Washington DC, USA) on behalf of his fellow investigators.
The LRT (Low-risk TAVI) trial is the first US Food and Drug Administration (FDA) approved investigational device exemption (IDE) to study low-risk bicuspid patients with AS undergoing TAVI. Waksman explained that TAVI was approved by the FDA in 2019 for low-risk patients with symptomatic severe AS regardless of aortic valve morphology, but that industry-sponsored low-risk pivotal trials excluded patients with bicuspid valves. The LRT bicuspid cohort study is a prospective multicentre registry to assess the feasibility of TAVI with commercially available valves in these patients.
The primary outcome was all-cause mortality at 30 days (VARC-II defined); secondary outcomes are safety and efficacy (New York Heart Association, NYHA), clinical outcomes (VARC II), valve hemodynamics by echocardiography, and subclinical leaflet thrombosis evaluation by computed tomography (CT) at 30 days.
Enrollment is ongoing to include 100 bicuspid patients; the interim analysis reported at CRT 2020 is of the first 61 consecutive patients. Inclusion criteria are symptomatic severe AS of a bicuspid aortic valve, low risk according to the multidisciplinary heart team, with an STS PROM ≤3%, suitable for transfemoral access with a commercial TAVI device, and with a life expectancy ≥one year. They were compared against contemporary bicuspid surgical aortic valve replacement (SAVR) patients, selected to match LRT inclusion/exclusion criteria, whose outcomes were extracted from STS for mortality through 30 days.
In the prospective bicuspid TAVI cohort, 30-day follow-up was available for 61 patients, and 30 day CT for 60 patients. Of the 216 participants who underwent low-risk isolated SAVR in the historical control cohort, 30-day follow up was available for 211.
Waksman outlined that the low-risk bicuspid AS TAVI patients had a short length of stay in hospital, with zero mortality at 30 days, zero disabling stroke at 30 days, and low rates of major adverse events at 30 days.
New onset atrial fibrillation occurred in 3.3% (2/61) and new permanent pacemaker implantation was required in 13.1% (8/61). At 30 days, the number of patients in NYHA class I had increased to 78.3% from 4.9%, and those in NYHA class II had reduced from 70.5% to 21.7%; no patients remained in NYHA class III and IV from a baseline of 23% and 1.6%, respectively.
Waksman described valve haemodynamics as “excellent”; from baseline to 30 days, the mean aortic valve gradient reduced from 55±15 to 13.1±4.1mmHg, and the aortic valve area increased from 0.7±0.2 to 1.7±0.4cm2.
An analysis of subclinical leaflet thrombosis found hypo-attenuated leaflet thickening (HALT) in 10.2% (6/59), reduced leaflet motion (RELM) in 6.9% (4/58), and hypoattenuation affecting motion (HAM) in 6.9% (4/58).
Waksman said: “Subclinical leaflet thrombosis was present in low-risk bicuspid patients at a similar rate to a previously published LRT tricuspid cohort [14%], and was not associated with clinical events at 30 days.”
The study has also been published in JACC: Cardiovascular Interventions.