Findings from the ongoing PARTNER 3 trial were published in the Journal of the American College of Cardiology and presented at TCT 2019 by Dr. Suzanne J. Baron. The findings of this study further support the use of transcatheter aortic valve replacement (TAVR) over surgical aortic valve replacement (SAVR).
Previously, both the PARTNER 3 and Evolut Low Risk trials have demonstrated that transfemoral TAVR is a safe and effective alternative to SAVR in patients with severe aortic valve stenosis who are at low surgical risk. However, there is little long term data surrounding any late health status benefit with TAVR as compared to SAVR. The investigators aimed to this current gap of knowledge using the PARTNER 3 trial. Additionally, the investigators aimed to identify any factors associated with a difference in health status between the TAVR and SAVR groups.
“We found that there was a persistent health status benefit at 6 months and a year with TAVR. It was small but it was there and it was persistent. This was something we hadn’t seen before.” – Dr. Suzanne J. Baron, M.D.
In the PARTNER 3 trial, patients with severe aortic stenosis and who were determined to be at a low surgical risk (Society of Thoracic Cardiology (STS) score of 4% or less) were randomized to either a transfemoral TAVR with the SAPIEN-3 balloon expandable valve or SAVR. Measures of health status were collected at baseline, 1 month, 6 months, 1 year and then annually (up to 10 years). Patients with bicuspid aortic valve, severe untreated coronary artery disease, unfavorable aortic valve anatomy, or severe renal or lung disease were excluded. The primary endpoint of this study was a difference in the Kansas City Cardiomyopathy Questionnaire Overall Score (KCCQ-OS) at 12 months. A higher KCCQ-QS score would be consistent with a better quality of life. Additionally, the KCCQ-OS score was also compared at 6 months. A categorical analysis was also performed that incorporated both survival and health status. Finally, the Short Form 36 Health Survey Questionnaire (SF-36) scores were compared between the two groups.
A total of 943 subjects were included in the analysis. Of those, 494 (52.4%) were in the TAVR group and 449 (47.6%) were in the SAVR group. The baseline characteristics, including age, gender and the prevalence of cardiac and pulmonary co-morbidities were well balanced between the two groups. Additionally, the baseline health status, as determined by both the KCCQ and SF-36 scores were similar between the two groups. At 12 months, the quality of life scores increased in both the TAVR and SAVR groups. With regards to the primary outcome of the KCCQ-OS score, patients in the TAVR group had a higher score at both 6 months (difference of 2.6, p = 0.002) and 12 months (difference of 1.8, p = 0.03). However, there was no difference in the components of the SF-36 (Mental and physical) between the two groups at 12 months. In a subgroup analysis, investigators found a significant interaction between change in KCCQ-OS score at 12 months and New York Heart Association (NYHA) class (p = 0.02). Patients who were considered NYHA III or NYHA IV had a greater difference in KCCQ-OS from baseline (Difference of 5.0 points, 95% CI 1.9 – 8.1). Finally, when the categorical analysis was performed that incorporated both survival and change in health status, the investigators found that the TAVR group had fewer deaths and a greater increase in the KCCQ-OS score (consistent with the primary outcome).
In summary, the investigators found that among patients with severe aortic stenosis at low surgical risk, both TAVR and SAVR resulted in a substantial improvement in health status at 12 months. However, this difference was greater in the TAVR group. Dr. Baron discussed the findings of this study and its implications with Dr. C. Michael Gibson, Professor of Medicine at Harvard Medical School and an interventional cardiologist at Beth Israel Deaconess Medical Center. “We found that there was a persistent health status benefit at 6 months and a year with TAVR. It was small but it was there and it was persistent. This was something we hadn’t seen before.”
However, the study still has its limitations. The results of this study may not be generalizable to other prosthesis types or alternative access routes. The trial was also unblinded which could have led to a greater degree of subject ascertainment bias. Additionally, whether the difference in health status persists beyond 1 year is not known. Regardless, the study still provides further evidence to support the use of TAVR in patients with severe aortic stenosis who are at low surgical risk.