The PARTNER cohort A study, which compared transcatheter aortic valve implantation (TAVI) with surgical aortic valve replacement in high-risk patients with severe aortic stenosis, found that after three years, the valve did not show any signs of structural deterioration and that TAVI is comparable to surgery.
Presenting the three-year data of the PARTNER cohort A study at the annual meeting of the American College of Cardiology (ACC; 9–11 March, San Francisco, USA), Vinod Thourani (Co-Director of the Structural Heart and Valve Center, Emory University School of Medicine, Atlanta, USA) stated that the PARTNER cohort A study has already shown that TAVI with the Sapien valve (Edwards Lifesciences) is associated with a similar rate of mortality to the rate observed with surgical valve replacement. This data showed that TAVI was associated with a higher rate of stroke within the first 30 days of the procedure, but not at three years. However, there was a higher rate of aortic regurgitation in TAVI patients. He said: “Longer term outcomes following transcatheter aortic valve replacement (TAVR) are unknown and are necessary to assess valve performance to analyse late complications before TAVR can be applied more widely.”
Last year at ACC, Susheel Kodali (Heart Valve Center, Columbia University Medical Center, New York, USA) presented the two-year data for cohort A of the PARTNER study, which showed TAVI to still be effective as surgery in high-risk patients and also showed that there was no difference in the rate of stroke between TAVI and surgery after 30 days. Therefore, the purpose of the current study was to assess the rate of mortality, stroke, clinical and procedural predictors of mortality, valve performance by echocardiography after ≥3 years in high-risk patients who underwent TAVI compared with those who underwent surgery.
Of 699 patients in the study, 348 were randomised to receive TAVI (244 through transfemoral access and 104 through transapical access) and 351 were randomised to receive surgical aortic valve replacement. All patients were classified as having severe aortic stenosis and as being at high surgical risk (predicted risk of mortality ≥10% after surgery). Those undergoing TAVI received the Sapien transcatheter aortic valve. The primary endpoint was all-cause mortality and other key endpoints included cardiovascular mortality, rehospitalisation, strokes, vascular and bleeding events, and echocardiographic measures of valve performance.
After three years, the rate of the primary endpoint was not significantly different between the TAVI and surgical groups: 44.2% vs. 44.8%, respectively (p=0.483). Also, TAVI haemodynamic performance was maintained with similar valve gradients and areas compared with surgery. Thourani said in a press statement: “One of the concerns has been the durability of the valve, but there seems to be no structural deterioration thus far. It works as it is supposed to work and haemodynamic performance is excellent past the three-year mark and comparable to surgical valve replacement.”
Similar to what was seen with the two-year data, despite an increase incidence of periprocedural neurological events with TAVI, the rate of stroke was similar between TAVI and surgery at three years.
However, there were differences in the baseline predictors of mortality—predictors of mortality for TAVI patients included body mass index and peripheral vascular disease while predictors for mortality in surgical patients included Society of Thoracic Surgeons (STS) score and moderate-to-severe mitral regurgitation. Furthermore, also as reported in the one- and two-year data of PARTNER cohort A, the rate of paravalvular leaks was significantly increased in the TAVI group and these leaks (even mild post-procedural aortic regurgitation) was associated with increased subsequent mortality. Thourani said: “Future efforts should be directed towards reducing TAVI procedure-related complications, including strokes, vascular events, and paravalvular regurgitation.”
The results of the PARTNER II were also presented at the ACC meeting. This study compared the Sapien XT, a redesigned version of the Sapien heart valve, with the Sapien heart valve in patients who were not candidates for surgery (cohort B of the original PARTNER study). Martin Leon, Center for Interventional Vascular Therapy, New York-Presbyterian Hospital/Columbia University, Medical Center, New York, USA, explained that the new version of the Sapien valve had: new frame geometry, less metal content and a lower crimp profile; new frame material (cobalt-chromium, greater tensile and yield strength); and new leaflet geometry (partially closed). The primary endpoint of the PARTNER II study, Leon reported, was: “A non-hierarchical composite of all-cause mortality, disabling stroke, and re-hospitalisation for symptoms of aortic stenosis and/or complications of the valve procedure.” He added that patients were followed for one-year for a non-inferiority comparison.
Following randomisation, 276 patients received the Sapien valve and 284 received the Sapien XT valve (560 patients overall). According to Leon, anaesthesia time was significantly reduced with the Sapien XT valve (p=0.02) and so was the number of patients requiring ≥2 valves (p=0.05). Furthermore at 30 days and at one-year, the rate of the primary endpoint did not significantly differ between patients who received the newer valve and those who received the Sapien valve. Leon commented: “Sapien XT represents a worthwhile advance with incremental clinical value and is the preferred-expandable transcatheter heart value system.”