Original Title: Transcatheter or Surgical Aortic-Valve Replacement in Intermediate-Risk Patients. PARTNER 2A.
Reference: Martin B. Leon et al. NEJM April 2, 2016
Courtesy of Dr. Juan A. Terré
Studies have shown mortality rates after transcatheter aortic valve replacement (TAVR) and surgical aortic valve replacement (SAVR) in high risk patients are similar (PARTNER 2 – Cohort B). This is the first randomized clinical study to assess the differences between these procedures in intermediate risk patients (Partner 2 – Cohort A).
The study used the SAPIEN XT valve that, compared to first generation valves, has a cobalt-chromium alloy frame with thinner struts that includes a 29 mm one, which reduces guide catheter caliber.
The study randomized 2032 severe aortic stenosis patients undergoing TAVR vs. SAVR in 57 centers between 2011 and 2013. In the TAVR group, 76% of patients were treated via transfemoral access, and the rest, via transthoracic access. Randomization was 1:1 to TAVR or SAVR.
Patients were considered at intermediate risk when their STS risk score (Society of Thoracic Surgeons) was between 4 and 8%. The study included patients with non-complex coronary artery disease and patients with an STS risk score lower than 4% presenting risk factors this model does not contemplate.
Primary end point was all cause death or disabling stroke. Events rates at two years were 19.3% for TAVR and 21% for SAVR in the intention to treat population (HR 89%, CI 95% 0.73 to 1.09; p0.25), and in the as-treated population (HR 0.78; CI 95% 0.61 to 0.99; p=0.04) with a risk ratio that met the non-inferiority criterion (p=0.001 in intention to treat and p=<0.0001 in as treated groups). In the transfemoral TAVR subgroup, death and disabling stroke were lower than in the SAVR group (HR 0.79, CI 95% 0.62 to 1.00; p=0.05). However, in the TAVR group with transthoracic access there were no significant differences (HR 1.14; CI 95% 0.79 to 1.65; p=0.47). The individual components of the primary end point were similar between TAVR and SAVR at two years, reporting 16.7 % and 18% mortality rates and 6.2 and 6.4% stroke rates, respectively.
The TAVR group showed increased final aortic valve area, lower acute kidney failure (1.3% vs 3.1%), severe bleeding (10% vs 43%) and new onset atrial fibrillation (9.1% vs 26%). The SAVR group presented lower major vascular complications (5 vs 7.9%) and paravalvular aortic regurgitation rates. Patients in the TAVR group spent half the time in the intensive care unit, in average (2 vs 4 days) and had shorter hospitalization time (6 vs 9 days).
There were no significant differences between TAVR and SAVR in rehospitalization (19.6% vs 17.3%) or definite pacemaker requirement (8.5% vs 6.9%).
Paravalvular aortic regurgitation rate was higher in the TAVR group, 22% presenting mild regurgitation and 3.7% moderate to severe regurgitation at 30 days.
This last group of patients (TAVR with moderate to severe paravalvular aortic regurgitation) saw higher mortality at two years, compared to those with mild regurgitation (34 vs 14%). There were no differences between patients with mild regurgitation and those with no trace of it. At the same time, it was shown that TAVR achieves larger post procedural valve area, and this difference is maintained at follow up. This is probably due to valve-sizing differences and the ability of transcatheter valves to expand to the anatomical annulus size.
Complications such as disabling stroke, severe bleeding, acute kidney failure and major vascular complications were independently associated to mortality increase at two year follow up.
Conclusion
This study has shown that TAVR and SAVR have similar outcomes in intermediate risk patients in terms of mortality and disabling stroke when using a second generation expandable balloon valve (SAPIEN XT). There was a remarkable benefit to primary end point when using the femoral access, probably due to increased operator experience, reduced-profile delivery catheters, advances in knowledge and planning of cases with the use of computed tomography. It is worth noticing that the complications rate associated to mortality was substantially lower in this study compared to prior studies. The TAVR group showed benefits in terms of major bleeding, acute kidney failure and new onset atrial fibrillation, and they were discharged fairly faster.
Editorial Comment
The PARTNER 2A encourages the discussion of minimally invasive treatments in intermediate risk patients with severe aortic stenosis. The better outcomes were shown with transcatheter intervention, which invites interventionists to perfect transcatheter closure techniques and to better understand CT images to avoid important complications.
The almost simultaneous presentation of the study comparing the new generation expandable balloon valve (SAPIEN 3) vs. the surgical group published in the Lancet and its recent summary by Dr. Carlos Fava, has seen a significant reduction in stroke, paravalvular aortic regurgitation and major valve complications.
At present, when considering a more or less invasive treatment, we should look at the durability of the transcatheter valve. It is said to be comparable to the 5 year durability of surgical valves. The rest of factors previously described have significantly improved with technological advances generation after generation. Therefore, it is essential that patients understand and, to that end, that we participate them of the final decision between TAVR and SAVR. For now, we’d rather offer TAVR to intermediate risk patients older than 75 or 80, with tricuspid valves and no important anatomical risk factors for potentially deadly complications.
Courtesy of Dr. Juan A. Terré
Interventional Cardiologist
Columbia University Medical Center / NY Presbyterian Hospital.
