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Transcatheter aortic valve replacement (TAVR) began in 2002 as a treatment for desperate patients with severe aortic stenosis (AS) and no other option. Multiple subsequent randomized trials demonstrated safety and efficacy comparable to or better than surgery in patients with high or intermediate surgical risk. Now, two manufacturer-funded comparison trials have published results in low-risk patients.
Mack and colleagues randomized 1000 patients at low 30-day mortality risk (mean Society of Thoracic Surgeons [STS] score, 1.9%; mean age, 73) to TAVR with the balloon-expandable Sapien 3 prosthesis or surgery (PARTNER 3; NCT02675114); 950 received the assigned treatment. The primary combined endpoint at 1 year (all-cause mortality, stroke, or rehospitalization) was 8.5% with TAVR and 15.1% with surgery (P<0.001 for TAVR superiority). The combined endpoint of death and disabling stroke at 1 year was 1.0% with TAVR and 2.9% with surgery. Hospital stay was shorter with TAVR than with surgery (3 vs. 7 days) and quality of life improved more rapidly. The groups had similar rates of new pacemakers, although TAVR was associated with more-frequent new left bundle-branch block (24% vs. 8%) and mild paravalvular regurgitation (29% vs. 2%).
In a similar trial of self-expanding TAVR prostheses (NCT02701283), Popma and colleagues randomized 1468 patients to any of three TAVR prostheses or surgery (mean age, 74; STS risk score, 1.9%). In a prespecified 12-month interim analysis of 784 patients, TAVR and surgery were estimated to have similar rates of death or disabling stroke (2.9% and 4.6%, respectively). At 30 days, the groups had similar rates of death (0.5% and 1.3%) and disabling stroke (0.5% and 1.7%). However, TAVR was associated with a higher 30-day rate of new pacemakers (17.4% vs. 6.1%) and moderate/severe paravalvular aortic regurgitation (3.5% vs. 0.5%), though only 22% of the study population received the latest generation of this device.
Mack MJ et al. Transcatheter aortic-valve replacement with a balloon-expandable valve in low-risk patients. N Engl J Med 2019 Mar 16; [e-pub]. (https://doi.org/10.1056/NEJMoa1814052)
Popma JJ et al. Transcatheter aortic-valve replacement with a self-expanding valve in low-risk patients. N Engl J Med 2019 Mar 16; [e-pub]. (https://doi.org/10.1056/NEJMoa1816885)
Comment
These studies are game-changing and open the door to TAVR as the default approach for most patients (those with bicuspid aortic disease were excluded from these studies, as in other randomized trials). Although some cardiologists and surgeons may be concerned about uncertainties with TAVR's long-term durability, other studies' 5- to 8-year follow-up data look promising. The current studies will publish 10-year follow-up data to help answer this concern. The studies' differences will likely not change most physicians' practices in choosing between the two valve types but might help inform some borderline decisions. TAVR will likely be quickly approved as an alternative for low-risk patients who will prefer the less-invasive approach. Physicians will need a reason to refer for surgery, and hospitals will be forced to confront the lower profitability of the TAVR procedure as it replaces surgery for even more patients.