Transcatheter Aortic Valve Implantation in Patients With Severe Aortic Valve Stenosis at Low Surgical Risk: A Health Technology Assessment

Abstract

Background: Surgical aortic valve replacement (SAVR) is the conventional treatment for patients with severe aortic valve stenosis at low surgical risk. Transcatheter aortic valve implantation (TAVI) is a less invasive procedure. We conducted a health technology assessment (HTA) of TAVI for patients with severe aortic valve stenosis at low surgical risk, which included an evaluation of effectiveness, safety, cost-effectiveness, the budget impact of publicly funding TAVI, and patient preferences and values.

Methods: We used the 2016 Health Quality Ontario HTA on TAVI² as a source of eligible studies and performed a systematic literature search for studies published since the 2016 review. Eligible primary studies identified both through the 2016 HTA and through our complementary literature search were used in a de novo analysis. We assessed the risk of bias of each included study using the Cochrane risk-of-bias tool and the quality of the body of evidence according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) Working Group criteria.An applicable, previously conducted cost-effectiveness analysis was available, so we did not conduct a primary economic evaluation. We analyzed the budget impact of publicly funding TAVI in people at low surgical risk in Ontario. We also performed a literature survey of the quantitative evidence of preferences and values of patients for TAVI. The Canadian Agency for Drugs and Technologies in Health (CADTH) conducted a review to evaluate the qualitative literature on patient and provider preferences and values for TAVI. To contextualize the potential value of TAVI, we spoke with people with severe aortic valve stenosis.

Results: We identified two randomized controlled trials that compared TAVI (transfemoral route) and SAVR in patients with severe aortic valve stenosis at low surgical risk. Both studies have an ongoing follow-up of 10 years, but 1-year and limited 2-year follow-up results are currently available. At 30 days, compared with SAVR, TAVI had a slightly lower risk of mortality (risk difference -0.8%, 95% confidence interval [CI] -1.5% to -0.1%, GRADE: Moderate) and disabling stroke (risk difference -0.8%, 95% CI -1.8% to -0.2%, GRADE: Moderate), and resulted in more patients with symptom improvement (risk difference 11.8%, 95% CI 8.2% to 15.5%, GRADE: High) and in a greater improvement in quality of life (GRADE: High). At 1 year, TAVI and SAVR were similar with regard to mortality (GRADE: Low), although TAVI may result in a slightly lower risk of disabling stroke (GRADE: Moderate). Both TAVI and SAVR resulted in a similar improvement in symptoms and quality of life at 1 year (GRADE: Moderate). Compared with SAVR, TAVI had a higher risk of some complications and a lower risk of others.Device-related costs for TAVI (about $25,000) are higher than for SAVR (about $6,000). A published cost-effectiveness analysis conducted from an Ontario Ministry of Health perspective showed TAVI to be more expensive and, on average, slightly more effective (i.e., it was associated with more quality-adjusted life-years [QALYs]) than SAVR. Compared with SAVR, the incremental cost-effectiveness ratios (ICERs) were $27,196 per QALY and $59,641 per QALY for balloon-expandable and self-expanding TAVI, respectively. Balloon-expandable TAVI was less costly (by $2,330 on average) and slightly more effective (by 0.02 QALY on average) than self-expanding TAVI. Among the three interventions, balloon-expandable TAVI had the highest probability of being cost-effective. It was the preferred option in 53% and 59% of model iterations, at willingness-to-pay values of $50,000 and $100,000 per QALY, respectively. Self-expanding TAVI was preferred in less than 10% of iterations. The budget impact of publicly funding TAVI in Ontario is estimated to be an additional $5 to $8 million each year for the next 5 years. The budget impact could be significantly reduced with reductions in the device price.We did not find any quantitative or qualitative evidence on patient preferences and values specific to the low-risk surgical group. Among a mixed or generally high-risk and population, people typically preferred the less invasive nature and the faster recovery time of TAVI compared with SAVR, and people were satisfied with the TAVI procedure. Patients with severe aortic valve stenosis at low surgical risk and their caregivers perceived that TAVI minimized pain and recovery time. Most patients who had TAVI returned to their usual activities more quickly than they would have if they had had SAVR. Our direct patient and caregiver consultations indicated a preference for TAVI over SAVR.

Conclusions: Both TAVI (transfemoral route) and SAVR resulted in improved patient symptoms and quality of life during the 1 year of follow-up. The TAVI procedure is less invasive and resulted in greater symptom improvement and quality of life than SAVR 30 days after surgery. The TAVI procedure also resulted in a small improvement in mortality and disabling stroke at 30 days. At 1 year, TAVI and SAVR were similar with regard to mortality, although TAVI may result in a slightly lower risk of disabling stroke. According to the study authors, longer follow-up is needed to better understand how long TAVI valves last and to draw definitive conclusions on the long-term outcomes of TAVI compared with SAVR beyond 1 year.The TAVI procedure might be cost-effective for patients at low surgical risk; however, there is some uncertainty in this result. We estimated that the additional cost to provide public funding for TAVI in people with severe aortic valve stenosis at low surgical risk would range from about $5 million to $8 million over the next 5 years.Among a mixed or generally high-risk population, people typically preferred the less invasive nature and the faster recovery time of TAVI compared with SAVR.