PARTNER A: Equal Outcomes, Many Dead for Both TAVI, SAVR Arms

Shelley Wood

March 12, 2013

SAN FRANCISCO, California — There's good news and bad news in the three-year follow-up from the PARTNER A trial, comparing transcatheter aortic-valve implantation/replacement (TAVI/TAVR) with open surgical aortic-valve replacement (SAVR) in high-risk patients with severe aortic stenosis.

Dr Vinod Thourani

The good news is that rates of both stroke and all-cause mortality were similar between both groups of patients three years out.

The bad news is, more than two out of five patients were dead.

Presenting the results here at the American College of Cardiology 2013 Scientific Sessions, Dr Vinod Thourani (Emory University School of Medicine, Atlanta, GA) highlighted the similar rates of clinical outcomes between the TAVR and surgical groups, noting that periprocedural stroke concerns have diminished over time and that valve hemodynamics for the new device have remained stable, even though paravalvular (PV) regurgitation, or "leaks," have proved persistent and lethal.

"Future efforts should be directed toward reducing TAVR-procedure-related complications, including strokes, vascular events, and paravalvular regurgitation," he concluded.

But Dr Bernard Gersh, one of the panelists for this morning's late-breaker, where Thourani presented the PARTNER A late outcomes, pointed to the big picture, saying: "We've learned a number of things here, and one to my mind is that we still have 44% mortality at three years. What we have to learn is how to better select these patients."

PARTNER A: The Early Years

As previously reported by heartwire , PARTNER A randomized 699 elderly patients (median age 84.1) with severe aortic stenosis to either TAVR or conventional surgery at one of 26 centers in the US, Canada, or Germany, with patients in the TAVR group undergoing either a transfemoral procedure (244 patients) or a transapical procedure (104 patients). At one year, mortality was similar, but strokes and transient ischemic attacks (TIAs) were significantly higher in the TAVR group. In the two-year results, PV regurgitation leaped into the spotlight, with longer-term outcomes showing that even mild paravalvular regurgitation was associated with increased mortality.

In the three-year outcomes, as noted, all-cause mortality was nearly identical in both groups, at 44.8% for surgical AVR and 44.2% for TAVR. In a landmark analysis looking only at deaths between one and three years, 26.3% of TAVR patients still alive at 12 months were dead by year three, as compared with 24.5% of SAVR-treated patients.

Stroke rates, which diverged early on in PARTNER A, were no different at three years: 8.2% in the TAVR group and 9.3% in the surgical-AVR group. Rates of all-cause mortality or stroke, combined, were 47.1% in the TAVR group and 45.9% in the SAVR group.

 
We still have 44% mortality at three years. What we have to learn is how to better select these patients.
 

Mild, moderate, and severe PV aortic regurgitation remained significantly different between the two groups at one, two, and three years. And in a finding that continues to raise flags, moderate to severe PV aortic regurgitation was associated with mortality rates of 60.8%, compared with 35.3% in patients in patients with trace or no regurgitation. Even patients with mild regurgitation faced higher mortality at three years, at 44.6%.

"What we're seeing at one, two, and three years is that [stroke] is not an issue, [patients are] not continuing to have strokes, even though the majority of us take our patients off of Plavix after six months, although they are on lifelong aspirin for the most part," Thourani said. "The PV leaks that were happening early on, they are not increasing, and so once you get that PV leak at the index operation, there is some improvement, but for the most part they are staying stable and not getting worse, and that's something we can count on."

Dr Bernard Gersh

Gersh, in the panel discussion, noted that few people would have predicted that aortic regurgitation could be such a powerful predictor of mortality.

"This has surprised all of us," Thourani admitted. "Other people walk around with mild aortic regurgitation all day, every day, and they don't have a 40% mortality at two to three years. . . . I'm not sure anyone in in the room knows the answer to that, and that's something we need to work on."

Predicting Who Should Get What

Of particular interest today, different baseline predictors of mortality emerged between the surgical-AVR and TAVR groups. For example, key predictors in the TAVR group were body-mass index (BMI), atrial fibrillation, mean valve gradient, and renal disease. In the surgical-AVR group, the key predictors of three-year mortality were previous CABG, pacemaker implantation, moderate or severe mitral regurgitation, and STS risk score. In both groups, presence of liver disease increased risk of mortality later on.

Dr Michael Mack

During the panel discussion, Dr Michael Mack (Baylor Health Care System, Plano, TX) asked whether "we are now at the stage" where these baseline qualities can be used to help determine which high-risk patients should get TAVR vs surgery.

 
Other people walk around with mild aortic regurgitation all day, every day, and they don't have a 40% mortality at two to three years.
 

Thourani replied, "I think that clinically we're already doing that. . . . Now when a patient comes into my office who is 88, whom I would have operated on in PARTNER 1A, who had a previous coronary bypass, that patient may now head more toward transcatheter valve. And as we have more databases like the TVT registry, they will be able to help us tease out which patient populations we should be choosing for this very expensive, but very good operation."

Additional nonrandomized data from registries will also help with this type of refined patient selection, Thourani added.

Dr Christopher Cannon (Brigham and Women's Hospital, Boston, MA), also one of the panel discussants, noted that "the valves aren't falling apart after three years . . . so that's very encouraging."

In a press conference following the presentation, Thourani elaborated on this part to heartwire , noting that the trial represents three-year follow-up in all patients, but the very first patients were implanted in 2006.

To that point, Dr Patrick O'Gara (Brigham and Women's Hospital) pointed to the advanced age of the patients in PARTNER A.

"When we think about deploying this kind of technology in younger and healthier individuals . . . there remain concerns about durability and PV leaks, and only information of this sort will help us to be better informed," he said. "There's been so much time throwing darts at these outcomes, including statements like 'what can we do to reduce a 44% mortality over three years'; let's remember we are dealing with a group of patients who were 84 years of age on average, and our expectations for their outcomes need to be tempered by the context in which these procedures are offered."

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