Four-year data from the LRT—Low Risk TAVR—trial show that transcatheter aortic valve implantation (TAVI) in low-risk patients with symptomatic severe aortic stenosis yields low adverse event rates and excellent haemodynamics, according to LRT principal investigator Ron Waksman (Medstar Washington Hospital Center, Washington DC, USA).
Waksman delivered these findings during a late-breaking trial session at CRT 2022 (27 February–1 March, Washington DC, USA), describing the results at four years as “excellent” in terms of their low rates of mortality, disability and stroke, and for haemodynamics maintained throughout the duration of the follow-up.
LRT was the first US Food and Drug Administration (FDA)-approved investigational device exemption (IDE) trial in the USA to evaluate the safety and feasibility of TAVI with either balloon-expandable or self-expanding valves in low-risk symptomatic patients with severe aortic stenosis. The investigator-initiated trial enrolled a total of 200 patients, and had a primary endpoint of VARC-II defined all-cause mortality at 30 days, with annual clinical follow-up carried out annually at one, two, three and four years.
The first data from the trial, delivered at the European Society of Cardiology (ESC) annual meeting in 2018, found no significant differences in the rate of all-cause mortality between low-risk patients undergoing TAVI and a historical control group of low-risk patients undergoing surgical aortic valve replacement.
Enrolment for the trial took place between January 2016 and February 2018, with the main inclusion criteria including severe symptomatic aortic stenosis, with low surgical risk defined as a Society of Thoracic Surgeons (STS) score of <3%. Patients were suitable for transfemoral access with a commercially-available TAVI device, and had a life-expectancy of more than one year, Waksman explained in his CRT presentation.
Importantly, Waksman noted that the centres involved in the study were not necessarily high-volume sites, and many were not included initially in any of the pivotal TAVI trials. “It was very important to see how real-world interventionalists—not the high-enrolling sites—perform in such a study,” Waksman commented.
His presentation sought to offer key details on the clinical outcomes and the haemodynamics of the transcatheter valves at four years after TAVI in the low-risk patient population, as well as the impact of hypo-attenuated leaflet thickening (HALT) on late clinical outcomes and structural valve deterioration.
The mean age of patients enrolled in the trial was 73, 61.5% of whom were male. The majority—88.2%—received balloon-expandable valves, while 11.7% received self-expanding valves.
Detailing the outcomes, Waksman ran through the rates of all-cause death through each phase of the follow-up, reporting that at 30 days there were zero deaths, six deaths (3%) at one-year, eight at two years (4.1%), 15 at three years (8.2%), and 21 at four years (12.1%). Most of the deaths were non-cardiovascular (8.6%), and cardiovascular deaths accounted for 3.4% of patients, Waksman reported.
Reflecting on the data relating to HALT, Waksman reflected that there was not much difference if the patient had HALT or not. In terms of structural valve deterioration, Waksman said that there was no severe structural valve deterioration, with respect to the presence of HALT.
“When we look at the haemodynamics they were satisfactory at four years with the mean gradient of the aortic valve area, and they were pretty much consistent without any deterioration through the four years of follow-up, done by the Echo core lab,” Waksman said.
Summarising the overall message from the findings, Waksman told the CRT audience: “We report today excellent outcomes at four years with low mortality, disability and stroke rates in these low-risk TAVI patients. There are excellent haemodynamics maintained for the four years.
“It was reassuring that despite an early signal in 30 days of decreased aortic valve area, in the measured indices in patients with HALT, these differences were no longer apparent through the four years. Furthermore, HALT was not associated with any higher rate of structural valve deterioration.”
The findings led Waksman to conclude that TAVI is safe and effective in low-risk patients with low adverse event rates and excellent valve haemodynamics, though he did point to the potential for lingering pacemaker rates through four years. Subclinical leaflet thrombosis at 30 days did not significantly affect transcatheter valve haemodynamics through the four years.
“The LRT four-year results substantiate TAVI as the first-line therapy for low-risk patients with severe aortic stenosis,” said Waksman.
