TAVR shows ‘excellent safety’ at 30 days in low-risk patients
A new study published in the Journal of the American College of Cardiology provides reassurance that TAVR is a safe alternative to surgical aortic valve replacement (SAVR) in low-risk patients, as zero of the 200 people undergoing the transcatheter procedure died or experienced a disabling stroke within 30 days.
The nonrandomized trial was the first FDA-approved study to enroll patients deemed at low surgical risk for TAVR. All patients had severe symptomatic aortic stenosis and a Society of Thoracic Surgeons predicted risk of mortality (STS PROM) of 3 percent or lower.
Those patients were compared to 719 control individuals from the STS registry who underwent SAVR at the same 11 institutions performing the TAVRs.
Thirty-day mortality and in-hospital stroke rates were 1.7 percent and 0.6 percent, respectively, in the SAVR group compared to zero in the TAVR group. Permanent pacemaker implantation rates were 5 percent or lower in each group, and only two patients in the TAVR group (1 percent) had moderate or severe paravalvular regurgitation at hospital discharge. However, upon 30-day follow-up imaging, 14 percent of TAVR patients demonstrated subclinical leaflet thrombosis.
This finding wasn’t correlated with cerebrovascular events but warrants further attention in longer-term follow-up and additional studies, noted lead author Ron Waksman, MD, with MedStar Washington Hospital Center in Washington, D.C., and colleagues.
“The finding of zero mortality and zero disabling stroke at 30 days demonstrates the excellent safety of TAVR in low-risk patients,” Waksman et al. wrote. “It is important to highlight that except for the sponsor, enrolling centers in the LRT (Low Risk TAVR) trial were not high-volume centers or experienced centers in clinical trials. As such, these results truly represent contemporary real-world TAVR practice in the United States.”
The authors said there may not be a significant mortality benefit for TAVR over SAVR in low-risk patients, but other possible benefits of the less-invasive approach include shorter hospital stays and better prosthesis hemodynamics. The average length of stay for TAVR patients in this study was two days, more than four days shorter than SAVR patients from the STS database.
Even so, the mortality findings were interesting, the authors said, as they indicated the STS-PROM score may only be accurate for surgical patients.
“The expected mortality rate in the SAVR cohort according to STS-PROM score was 1.6%, and the observed 30-day mortality was 1.7%. Thus, STS-PROM appears to be an accurate predictor of mortality in low-risk patients undergoing SAVR,” they wrote. “By contrast, the expected mortality in the TAVR cohort was 1.8% and the observed 30-day mortality rate was 0%. Thus, STS-PROM appeared to overestimate mortality in TAVR patients, which is consistent with prior observations.”
In a related editorial, Michael J. Mack, MD, with Baylor Scott & White Health in Dallas, said there are some problems with comparing a prospectively selected TAVR cohort with retrospective SAVR data from the STS registry. For one, the SAVR procedures were performed from 2013 to 2017—compared to 2016 to 2018 for TAVR—and included some patients undergoing concomitant coronary artery bypass grafting. Also, Mack highlighted the issue of “double counting” some variables, as the propensity-score matching included variables that were already included in the STS PROM score, which itself was a variable contained in the propensity.
“Despite the concerns of the comparison to a historical SAVR cohort, the excellent early outcomes of TAVR do stand on their own without the need to be compared in a retrospective manner,” Mack wrote. “The results should not be totally unexpected or surprising in view of the progressively better outcomes achieved in the RCTs (randomized controlled trials) because the risk profiles have become lower, the third-generation device and delivery systems have improved, and with greater experience in patient selection and procedure performance.”
Mack noted two randomized trials of TAVR versus SAVR in low-risk patients are underway, and those results could shed additional light on the comparative effectiveness of the procedures in this patient population. One study is using Edwards Lifesciences’ Sapien 3 valve and the other is using Medtronic’s Corevalve Evolut R system, and both trials have planned follow-up periods of 10 years.
Mack said the study by Waksman et al. provides “an early peek” at what might be expected regarding the early safety of TAVR in these trials, but more important information will be gleaned during longer-term follow-up of the randomized trials.
“With only 200 nonrandomized patients with 30-day follow-up, the incremental information gained is relatively limited, but reassuring, while we await the outcomes of the 2 low-risk randomized trials,” Mack wrote. “What we can state confidently is that TAVR is safe in low-risk patients with no 30-day mortality and a low stroke rate. It is hoped that the investigators will expand their experience and provide longer-term follow-up so we can begin to understand efficacy and durability because these will be the key issues in low-risk patients.”
Daniel joined TriMed’s Chicago editorial team in 2017 as a Cardiovascular Business writer. He previously worked as a writer for daily newspapers in North Dakota and Indiana.