PARTNER investigators announce dramatic trial results for the treatment of aortic stenosis

The challenge

Surgical replacement, either with tissue or mechanical valve prostheses, has been the gold standard for treatment of extensive valve stenosis. Improvements in surgical technique, durable valve prostheses, and better anticoagulation regimens have resulted in excellent patient survival and functional status.

Nevertheless, approximately a third of individuals with symptomatic aortic stenosis are not candidates for open surgical replacement or repair because of advanced age, the presence of comorbid conditions, or both. Complications such as renal failure, prolonged ventilator dependence, and wound-healing problems occur more frequently in these high-risk patients.

Evaluating a nonsurgical approach

Mayo Clinic in Rochester, Minnesota, is now participating in a multicenter, prospective, randomized trial — PARTNER — to evaluate a new cardiac valve designed to be placed without the need for a median sternotomy.

This new valve is a balloon-expandable, stented bioprosthesis designed to be delivered through either the transfemoral or the transapical route. It has been approved in some European countries and has been placed in almost 4,000 patients worldwide.

Conducted at 21 centers in the United States, Canada, and Germany, the PARTNER study is comparing in parallel 2 large patient cohorts:

Deployment of percutaneous aortic valve bioprosthesis

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Investigational aortic valve after deployment

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• Cohort A will directly compare the transfemoral or transapical placement of the investigational prosthesis with traditional surgical aortic valve replacement (via median sternotomy).
• Cohort B will compare transfemoral prosthesis implantation with standard medical management (which can include balloon valvuloplasty if clinically indicated) in patients whose medical condition precludes them from being candidates for open surgical replacement.

Preliminary results

The PARTNER study has released results for the 358 patients in cohort B (investigational valve placement vs medical therapy only), while the surgical arm of the trial is ongoing. Although the 30-day rates of stroke and vascular complications were higher in the cohort B patients treated with the investigational valve, survival at 1 year was dramatically higher in this group (69.3%) than in patients who received only medical therapy (49.3%).

Furthermore, patients who received the investigational valve had significantly fewer hospitalizations and improved symptom relief when compared with those receiving standard medical therapy.

Some patients are not candidates for the investigational valve, due to characteristics of the valve annulus or because they have severe peripheral vascular disease. Mayo researchers believe that the new valve's design and improved delivery systems, however, should enable the deployment of percutaneous valves in more of these patients in the future, with a reduced risk of stroke, vascular damage, and major bleeding.

Mayo researchers also stress that the results of this cohort should not be extrapolated to other patient groups, as the long-term durability of this investigational valve is as yet unknown. Until the results of the surgical cohort provide further insight, the standard surgical approach to aortic valve replacement and repair may still be the best option in patients with low operative risk. Ultimately, trials in other patient subsets and long-term patient follow-up will determine the role of percutaneous valves in the treatment of valvular heart disease.

Potential PARTNER study candidates may be referred directly to the Mayo Clinic Valvular Heart Disease or Interventional Clinics by calling 507-284-3994 or 800-471-1727 (toll-free), or by contacting the Mayo Clinic trial coordinator at 507-255-7100.

Points to remember

• As many as 300,000 individuals in the United States currently have symptomatic aortic stenosis, and the prevalence is increasing as the population ages.
• Approximately a third of individuals with symptomatic aortic stenosis are not candidates for open surgical replacement or repair because of advanced age, the presence of comorbid conditions, or both.
• Mayo Clinic is participating in a randomized clinical trial — the Placement of AoRTic TraNscathetER Valve Trial (PARTNER) — to evaluate a new balloon-expandable cardiac valve designed to be placed through the transfemoral or the transapical route, without the need for a median sternotomy.