CHOICE Trial, TVT Registry Shed Light on Evolving TAVR Outcomes, Risks

WASHINGTON, DC—Two presentations at the American College of Cardiology/i2 Scientific Session provided important updates on device success and risk profiles for transcatheter aortic valve replacement (TAVR). While one study demonstrated superiority of a balloon-expandable over a self-expandable valve, the other identified female gender as the sole factor predisposing patients to stroke following the procedure.

For the head-to-head CHOICE study, reseachers led by Mohamed Abdel-Wahab, MD, of Segeberger Kliniken GmbH (Bad Segeberg, Germany), studied 241 high-risk patients who underwent TAVR at 5 major hospitals in Germany. Patients were randomly assigned to be treated with the balloon-expandable Sapien XT valve (Edwards Lifesciences, Irvine, CA; n = 121) or the self-expandable CoreValve (Medtronic, Minneapolis, MN; n = 120).

The study was simultaneously published online ahead of print in the Journal of the American Medical Association.

Balloon-Expandable Emerges on Top

Device success, a technical composite endpoint, was higher for the balloon-expandable compared with the self-expandable valve (95.9% vs 77.5%; P < 0.001). This was attributed to less frequent occurrence of more-than-mild aortic regurgitation (4.1% vs 18.3%; P < 0.001) and less frequent need for more than 1 valve (0.8% vs 5.8%; P = 0.03).

At 30 days, cardiovascular mortality, a secondary endpoint, was similar at 4.1% in the balloon-expandable group and 4.3% in the self-expandable group (RR 0.97; 95% CI 0.29-3.25; P = 0.99). The combined safety endpoint occurred in 18.2% of those in the balloon-expandable valve group and 23.1% of the self-expandable valve group (RR 0.79; 95% CI 0.48-1.30). The rate of MACCE was 6.6% in the balloon-expandable group vs 3.4% in the self-expandable group (P = 0.38).

Patients receiving a balloon-expandable valve were less likely to be rehospitalized for heart failure, require a perment pacemaker, and had higher quality of life (QoL) scores and greater NYHA class improvement than those receiving the self-expandable valve.

Significant Differences Compared with US Trial

Panelist Roxana Mehran, MD, of Mount Sinai Medical Center (New York, NY), asked Dr. Abdel-Wahab if he could explain some of the significant differences seen in the German CHOICE trial compared with the 45-center controlled, randomized US CoreValve trial presented at the same meeting, particularly in rates of permanent pacemaker and paravalvular leak.

He suggested that the explanation may lie in the smaller numbers of patients included in CHOICE and exclusion of patients with permanent pacemaker, which was not an exclusion in the Corevalve trial. Additionally, he noted that criteria for permanent pacemaker after TAVR differ from center to center so “perhaps some of the participating centers had a lower threshold” than centers in the Corevalve trial. As for paravalvular leak, he said while the angiographic data are different, the echocardiographic data comparisons for both trials are similar.

 Registry Refines Death, Stroke Risk

For the other study, David Holmes Jr, MD, of the Mayo Clinic (Rochester, MN), presented 1-year outcomes from the STS/ACC Transcatheter Valve Therapy (TVT) registry, which contains comprehensive data on virtually all patients in the United States undergoing ‘real-world’ TAVR with the Sapien valve.

In the cohort of 5,980 patients, rates of in-hospital stroke, transient ischemic attack (TIA) and valve complications were low, as was conversion to open heart surgery (table 1). The rate of in-hospital death was 5.3%.

Table 1. In-hospital Complications after TAVR

 

Mortality was 26.2% at 1 year. Stroke was 3.6%, while death or stroke was 28.4%. Mortality was associated with several baseline characteristics:

• Age
• Male gender
• Severe COPD
• End-stage renal disease
• Access site
• STS predicted risk of mortality score

However, multivariable analysis identified female gender as the sole characteristic associated with stroke after TAVR.

Dr. Holmes said identification of these associations is essential for developing risk prediction models and will aid in developing selection criteria for TAVR. He added that the increased stroke risk in women vs men has been noted in other specialties, including electrophysiology, and could be due to differences in hypertension or risk factors associated with hypertension, or may be related to catheter size, among other factors.

Data Collection Questioned

Session co-chair Gregg W. Stone, MD, of Columbia University Medical Center (New York, NY), said the TVT registry contains information on a broader cross-section of patients with different risk scores than the pivotal TAVR trials. He added that he was “struck by the powerful relationship between access site and mortality, and that remains a somewhat controversial issue.” The 1-year mortality rate for non-femoral access site procedures was 28.8% compared with 24.4% for transfemoral (HR 1.42; P < 0.001) 

Dr. Stone asked Dr. Holmes if he believes there is a true increase in mortality in non-femoral based TAVR procedures and whether the registry collects data on operator/center experience.

“I think unmeasured confounding variables are responsible for most of this difference,” Dr. Holmes explained. He added that the experience analysis is underway.

Panelist David L. Brown, MD, of The Heart Hospital Baylor (Plano, TX), asked about “real-world risk creep” as TAVR rolls out to more centers in the United States.

Dr. Holmes said the risk creep issue is being addressed through development of a risk-specific model for TAVR but added that the largest unmeasured confounder “that we don’t have a very good handle on” is individual physician assessment and judgment when selecting patients for TAVR.

Dr. Mehran  asked whether the registry collects data on antiplatelet and anticoagulation regimens, which could be important in understanding rates of out-of-hospital strokes.

Dr. Holmes replied that the registry does not have specific medication data for the cohort “and that is going to be something we will have to try to address.”

Note: Drs. Stone and Mehran are faculty members of the Cardiovascular Research Foundation, which owns and operates TCTMD.

 

 

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Sources:

1. Abdel-Wahab M, Mehilli J, Frerker C, et al. Comparison of balloon-expandable vs self-expandable valves in patients undergoing transcatheter aortic valve replacement: the CHOICE randomized clinical trial. JAMA. 2014;Epub ahead of print.
2. Holmes DA. One year outcomes from the STS/ACC transcatheter valve therapy (TVT) registry.  Presented at: American College of Cardiology/i2 Scientific Session; March 31, 2014; Washington, DC.

 

 

 

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