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Transcatheter Aortic Valve Replacement Using a Self-Expanding Bioprosthesis in Patients With Severe Aortic Stenosis at Extreme Risk for Surgery
Study Questions:
What are the outcomes of a self-expanding transcatheter aortic valve replacement (TAVR) in patients with severe aortic stenosis (AS) at extreme surgical risk?
Methods:
This study evaluated 489 patients from 41 sites with severe symptomatic AS deemed at extreme surgical risk undergoing attempted TAVR using a self-expanding TAVR device (CoreValve, Medtronic, Inc.). Extreme surgical risk was defined as an estimated ≥50% risk of mortality or irreversible morbidity at 30 days. The primary objective of this single-arm unblinded study was to compare the rate of death or major stroke at 12 months between enrolled patients to an objective performance goal of <43%, derived from prior literature including the PARTNER Cohort B trial.
Results:
Mean age was 83.2 ± 8.7 years, 52.1% were women, and 91.8% of patients had either New York Heart Association (NYHA) class III or IV symptoms. A total of 486 patients underwent the procedure (99.4%), with a device success rate of 84.6% and a procedural success rate of 77.6%. The 12-month rate of all-cause mortality or major stroke was 26.0% (95% confidence interval [CI], 22.1-29.9%), which was significantly lower than the objective performance goal (p < 0.001). Events at 30 days included all-cause mortality (8.4%), major stroke (2.3%), life-threatening/disabling bleeding (12.7%), significant vascular complications (8.2%), and requirement for permanent pacemaker (21.6%). Mean change in NYHA class between baseline and 12 months was 1.6 ± 0.9 (p < 0.001); over 90% of surviving patients had an improved functional status within 12 months. Between baseline and 12 months, mean gradient decreased from 47.3 ± 14.6 to 8.9 ± 4.1 mm Hg (p < 0.001), and orifice area increased from 0.7 ± 0.2 to 1.9 ± 0.5 cm2 (p < 0.001). Mild, moderate, and severe aortic regurgitation were observed in 35.2%, 11.1%, and 2.0% of patients post-procedure, and 31.6%, 6.4%, and 0% of patients at 12 months, respectively.
Conclusions:
Patients with severe symptomatic AS at extreme surgical risk treated with a self-expanding TAVR device have improved outcomes as compared to expected rates without AVR.
Perspective:
As a balloon-expandable TAVR device has already been demonstrated to improve mortality over medical therapy and potential valvuloplasty (PARTNER Cohort B trial), it would not have been ethical to design this study in the same manner; therefore, this was designed as a single-arm study in which all enrolled patients were planned for treatment with a self-expanding TAVR device, and outcomes were compared to an estimate derived from prior literature. The results demonstrate a marked reduction in all-cause mortality and major stroke as compared to expected estimates without AVR, and demonstrate significant functional improvements and valve hemodynamics, which were durable during the 12-month follow-up period. Of interest, the rate of at least moderate aortic regurgitation was relatively low and decreased during the follow-up period, which may be attributable to the valve design and the use of computed tomography for annulus sizing. Finally, the need for permanent pacemaker placement was relatively common with this device, with 26% requiring this at 1 year. These data suggest that this device is another option for patients with severe AS deemed at extreme surgical risk, and upcoming results using this device in high-risk patients will address its potential role in other populations.
Keywords: Heart Valve Prosthesis, Risk, Stroke, Follow-Up Studies, Bioprosthesis, Hemodynamics
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