PARTNER Cohort A Published: Surgical Candidates Obtain Similar 1-Year Survival with TAVI, Surgery

For high-risk patients with severe aortic stenosis, transcatheter aortic valve implantation (TAVI) is noninferior to traditional aortic valve surgery in those eligible for either treatment. However, periprocedural risks vary greatly between the 2 therapies: stroke and vascular complications are more common with TAVI, while bleeding and new-onset atrial fibrillation (A-fib) occur more frequently with surgery.

The findings from Cohort A of the PARTNER (Placement of Aortic Transcatheter Valves) trial were published online June 5, 2011, ahead of print in the New England Journal of Medicine and simultaneously presented at the Transcatheter Valve Therapies meeting in Vancouver, Canada. They had previously been released on April 3, 2011, at the American College of Cardiology Scientific Session/i2 Summit in New Orleans, LA.

For the PARTNER trial’s Cohort A, Craig R. Smith, MD, of Columbia University Medical Center (New York, NY), and colleagues randomized 699 patients at high surgical risk to receive TAVI (via transapical or transfemoral access) or surgery at 1 of 25 centers in the United States, Canada, and Germany. Results were analyzed according to intention to treat. Crossover between the 2 groups was not permitted, except when findings or events during the assigned procedure prevented the planned treatment.

Different Risks with TAVI vs. Surgery

At 30 days, the TAVI group had numerically fewer deaths from any cause compared with the surgery group; the difference diminished by 1 year. Rates of major stroke, however, were higher with TAVI both at 30 days and 1 year, although in the differences were not statistically significant. At 30 days, major vascular complications were more frequent with TAVI, while major bleeding and new-onset A-fib were more common after surgery. Those discrepancies were largely maintained at 1 year (tables 1 and 2).

Table 1. Thirty-Day Outcomes

 

 

Table 2. One-Year Outcomes

 

^a Primary endpoint.

Many Clinical Benefits Greater with TAVI

Subgroup analyses favored TAVI over surgery with regard to 1-year mortality in women and patients without a history of CABG.

In terms of functional status, more patients in the TAVI group than the surgical group had a reduction in symptoms to NYHA class II or lower at 30 days (P < 0.001). Moreover, at 1 year, patients in the 2 groups showed similar improvements in cardiac symptoms and 6-minute walk distance.

Both treatment groups also had significant improvements in aortic-valve gradients at 30 days and 1 year, but at the latter follow-up, TAVI was slightly superior to surgery with respect to aortic-valve gradient (10.2 ± 4.3 mm Hg vs. 11.5 ± 5.4 mm Hg; P = 0.008) and valve area (1.59 ± 0.48 cm² vs. 1.44 ± 0.47 cm²; P = 0.002). On the other hand, moderate or severe paravalvular regurgitation was more frequent after TAVI than after surgery at 30 days (12.2% vs. 0.9%) and at 1 year (6.8% vs. 1.9%; P < 0.001 for both comparisons).

TAVI patients spent fewer days in the intensive care unit than surgical patients (3 days vs. 5 days) and had a shorter index hospitalization (8 days vs. 12 days; P < 0.001 for both comparisons).

Stroke Still Worrisome

The authors acknowledge that the approximately 2-fold higher rate of new neurologic events (including major strokes) seen with TAVI remains a concern, one that has been debated since the main findings of the PARTNER trial were unveiled.

Most strokes appeared to be procedure-related, and the rates were similar with either transfemoral or transapical access. However, Dr. Smith and colleagues point out that, despite the higher stroke rate, the composite endpoint of death from any cause or major stroke was similar in the 2 groups over follow-up.

In a telephone interview with TCTMD, Dr. Smith said that although the neurologic complications are certainly an issue, the data demonstrate “very compelling perioperative mortality benefit for TAVI. And actually [the benefit is] impressive as well for surgery, which makes the finding of noninferiority that much more impressive.”

Questioning the Price of TAVI

In an editorial accompanying the study, Hartzell V. Schaff, MD, of the Mayo Clinic (Rochester, MN), voices concern that the preference for TAVI to avoid sternotomy “appears to come at the price of some potentially serious vascular and technical complications and increased hazards of embolic stroke and paravalvular leakage.”

According to Dr. Schaff, the Cohort A data are revealing in the sense that they affirm that “for patients who would not be candidates for surgical replacement, such an increased rate of neurologic complications might be acceptable, but for those who are candidates for either transcatheter or surgical replacement, the findings present a dilemma in balancing the risks of increased neurologic complications against the benefits of avoiding sternotomy and cardiopulmonary bypass.”

He adds that technological refinement of transcatheter valves as well as increasing use of embolic protection devices may improve outcomes, “but these new devices should be evaluated in controlled trials with randomization against current standard techniques.”

“Stroke remains a big issue in everyone’s mind,” Dr. Smith commented. “Statistical significance aside, stroke is present about twice as often with TAVI as surgery. [But] it is still a much lower stroke risk than many of us would have predicted when we first saw this valve and how you got it where it has to go.”

At present, TAVI “is a moving target, and we won’t know until the next milepost how fast it’s moving,” Dr. Smith said. “The improvement that has occurred in the last few years, and the world experience is pretty remarkable, so the possibility that there will continue to be major progress seems very high.”

Note: Several coauthors are faculty members of the Cardiovascular Research Foundation, which owns and operates TCTMD.

 

 

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Sources:1. Smith CR, Leon MB, Mack MJ, et al. Transcatheter versus surgical aortic-valve replacement in high-risk patients. N Engl J Med. 2011;364:2187-2198.

 

2. Schaff HV. Transcatheter aortic-valve implantation: At what price? N Engl J Med. 2011;364:2256-2258.

 

 

 

Related Stories:

• PARTNER Finds Higher Rate of Neurological Events with TAVI vs. Surgery
• NEJM Letters Take on PARTNER Trial
• PARTNER: All-Cause, CV Mortality Lower in Patients Treated with TAVI vs. Standard Therapy at 1 Year