Discussions with patients that balance unanswered questions over transcatheter aortic valve replacement (TAVR) in low-risk populations – particularly those of younger age – with patients’ “clear preference” for less invasive treatment will become more common, cardiology experts predict.
This prediction was published in a new state-of-the-art review published online Monday ahead of the June 14. issue of JACC: Cardiovascular Interventions. The authors were led by MedStar Washington Hospital Center’s Charan Yerasi, MD, and Toby Rogers, MD, PhD, (also with the National Institutes of Health).
Once limited to only inoperable or high-risk patients, TAVR is now approved for all patient risk profiles irrespective of age. This is despite the fact that evidence for approvals was in patients in their 70s for low- and intermediate-risk trials, and on those in their 80s for high-risk trials, the authors said.
Evidence in general for low-risk patients is based on three randomized clinical trials - NOTION (Nordic Aortic Valve Intervention Trial), PARTNER 3 (Placement of Aortic Transcatheter Valve) and Evolut Low Risk – and three non-randomized prospective studies – LRT (Low Risk TAVR), LRT Bicuspid and Evolut Low Risk Bicuspid. Mean age across these studies was between 68 and 79 years, and it was consistently demonstrated that TAVR procedures had numerically lower mortality rates than SAVR at 30 days, 1 year and 2 years.
However, “TAVR has never been systematically tested in young (<65 years), low-risk patients,” the authors stressed.
Therefore, despite overwhelming evidence of acceptable clinical outcomes in older low-risk patients, unanswered questions remain for their younger counterparts, and the choice between TAVR and SAVR for these patients is an ongoing debate.
The main concerns are over future coronary access following TAVR, which are deemed to carry the highest risk (theoretical risk score: 9); the risk of coronary obstruction with TAVR-in-TAVR and surgical TAVR explantation, both also carrying higher risk (6); the use of bicuspid aortic valves, which has a low risk (1) for paravalvular leak and medium risk for stroke (4); and over durability of transcatheter heart valves (THVs), again deemed a low risk (1).
The authors also noted concerns for these patients with the management of concomitant conditions such as aortopathy, mitral valve disease, and coronary artery disease.
Current guidelines for young low-risk severe aortic stenosis patients recommend shared decision-making that accounts for the patient preference. Many of these patients have active lifestyles, the authors said, noting they generally prefer to avoid surgery – despite better outcomes for surgical aortic valve replacement (SAVR) in younger patients.
These patients also tend to prefer to avoid bleeding risks associated with lifelong anticoagulation which – while more durable – is necessary with mechanical valves. Bioprosthetic valves do not come with the same need for anticoagulation but are less durable, so reintervention is a future risk.
The authors went on to analyze data linked to each of the key risk areas, with summaries including for bicuspid aortic valves, coronary access after TAVR, valve durability and risk of coronary obstruction with TAVR-in-TAVR.
Bicuspid Aortic Valves
The data for TAVR in patients with bicuspid aortic valve stenosis show “satisfactory clinical outcomes” and that significant paravalvular leak (PVL) is rarely seen with new generation THVs, and “hemodynamic status by echocardiography is excellent”.
Still, the authors stressed that higher stroke rates remain a “genuine concern,” so studies are needed to determine whether cerebral embolic protection devices could mitigate the risk.
“It is very important to consider excess leaflet calcification and raphe calcification in the risk stratification of young patients with bicuspid aortic valve stenosis, and this should be considered during clinical decision making in heart team meetings,” the authors wrote.
Coronary Access After TAVR
The prevalence of significant coronary artery disease will “probably be lower in young, low risk patients with aortic stenosis.” However, coronary access for future intervention remains “a genuine concern.”
“It is important to remember that coronary access after SAVR is typically easy because of anatomically correct commissural alignment, resection of the native leaflets, and low threshold for concomitant coronary artery bypass graft surgery in patients with severe coronary artery disease,” they said.
Commissural alignment also remains an important feature that can facilitate coronary access, they added.
Durability of THVs
“Although the data on TAVR durability are not as extensive as for SAVR, there does not appear to be any signal to date for early degeneration,” the authors said, adding that the true frequency of degeneration may, in any case, be significantly underestimated in early SAVR research, since it mostly reports reoperation.
The authors go on to suggest that, based on the data so far in high-risk long-term follow-up studies such as NOTION and CoreValve, TAVR valves are “as durable as SAVR valves, if not more so.”
Although 10-year follow-ups for the recently presented Evolut Low Risk, and the PARTNER 3 trial, will provide definitive information on the durability of both THVs and surgical bioprosthesis, “we do not believe that patients and physicians will wait for 10 years before offering TAVR to young patients,” the authors added.
Interim data, therefore, will be crucial to informing patient discussions, while future studies should push for adherence to European Association of Percutaneous Cardiovascular Interventions/European Society of Cardiology guidelines or Valve Academic Research Consortium guidelines when reporting valve-related outcomes.
Risk for Coronary Obstruction with TAVR-in-TAVR
“It is important to recognize that coronary obstruction during TAVR-in-TAVR remains a hypothetical concern at this time, but we caution against assuming that TAVR-in-TAVR is the solution for failed THVs for all patients.
“These considerations are pertinent if TAVR is to be offered to very young patients, who may need more than 1 bioprosthetic aortic valve during their lifetimes,” the authors wrote.
Surgical Explantation of THVs
“As the number of TAVR explantations increases, we expect to learn more about this issue. It is a significant clinical problem, and early evidence suggests that these surgical valve explantation procedures should be performed at experienced aortic centers,” the paper states.
“In patients with severe mitral regurgitation from primary causes, careful evaluation is needed of who would benefit from double valve surgery. Also, it should be noted that operative mortality is higher with concomitant mitral surgery,” the authors wrote.
The authors warned that, although the pivotal TAVR trials in low-risk patients that are available have demonstrated “excellent clinical outcomes,” caution should be exercised when extrapolating these results to younger patients.
“Hypothetically, as one considers the lifetime management of young patients with severe aortic stenosis, patients may require more than 2 aortic valve interventions during their lifetimes,” they noted.
“Strategies for the lifetime management of patients with aortic stenosis should be balanced within the heart team and tailored to individual patients.
“Until unanswered questions are addressed with further evidence, these issues should be discussed with patients, taking into consideration their priorities and expectations.”
Yerasi C, Rogers T, Forrestal BJ, et al. Transcatheter Versus Surgical Aortic Valve Replacement in Young, Low-Risk Patients With Severe Aortic Stenosis. JACC: Cardiovasc Interv 2021;14:1169-80.