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PHOENIX -- The functional and quality-of-life benefits of creating a left-to-right shunt in the interatrial septum to offload failing hearts held up over the midterm in a series of small feasibility studies.

Across the ALLEVIATE-HF early phase trial program, Alleviant System shunts remained patent in all 38 patients at 6 months, and the peak exercise pulmonary capillary wedge pressure remained 5.4 mm Hg below baseline (P=0.011) -- twice that seen with another investigational interarterial shunt device in the sham-controlled REDUCE LAP-HF II trial (2.5 mm Hg).

Exercise capacity and quality-of-life scores held steady or even increased compared with previously reported 1-month and 3-month results, Molly Szerlip, MD, of Baylor Scott & White The Heart Hospital-Plano in Texas, reported at the Society for Cardiovascular Angiography and Interventions meeting here.

Six-minute walk distances were up 40% (by 105 m, P<0.001) from baseline at 6 months among the heart failure with preserved ejection fraction (HFpEF) patients and up 51% (by 151 m, P=0.029) over baseline in the HF with reduced EF (HFrEF) patients, holding steady or even increasing compared with previously reported 1- and 3-month results.

Kansas City Cardiomyopathy Questionnaire (KCCQ) overall summary scores through 6 months showed the same trend for improvement over time -- up 83% over baseline (26 points on the 100-point scale, P<0.001) in the HFpEF patients and up 77% from baseline (19 points, P=0.003) in the HFrEF patients.

"It looks really good based on KCCQ and 6-minute walk test," commented session moderator George Hanzel, MD, of Emory University in Atlanta. "However, we have to acknowledge that this was not a sham-controlled, double-blinded study. And so we've got to really temper any enthusiasm until we have a larger, randomized, sham-controlled study that's done."

Other concerns were the relatively short follow-up and small sample size even when pooling the trials, he noted. "There's not much clinical data that exists for it."

He pointed to the "underwhelming" results. In it, another device in development to create a similar shunt via hardware left in the heart -- the Corvia shunt device -- did not reduce the total rate of heart failure events or improve health status compared with a sham procedure in patients with heart failure and ejection fraction of greater than or equal to 40%, despite selecting patients with pulmonary capillary wedge pressure during exercise of at least 25 mm Hg while exceeding right atrial pressure by at least 5 mm Hg.

Nor were there advantages in KCCQ overall summary score, which improved to a similar extent in both groups at 1 year (median change 10.2 with the shunt vs 9.4 with sham).

"So I'm personally skeptical about the size of benefit seen in the KCCQ-12 and the 6-minute walk test in an unblinded study," he concluded.

When asked at the session whether the numbers were too good to be true, Szerlip responded: "I can't honestly say why that is. I don't know. It shouldn't have anything to do with not leaving a device behind."

That being said, she argued for the advantage of a no-hardware shunt procedure, which she described as akin to a punch biopsy delivered via radiofrequency to create a 7-mm diameter shunt from the left atrium to right atrium. The circle of excised tissue is captured by the device to prevent embolic complications.

"I don't think that having a device in there that stays is particularly good because of the increase in atrial fibrillation and device infection and all the other things that leaving a device behind [causes]," Szerlip said. And "you can always get back across the septum somewhere else, but there is interaction with these other devices."

With the ALLEVIATE program results, a pivotal trial dubbed ALLAY-HF is underway with sham control in an adaptive design with 400 to 700 patients with EF of at least 40%, powered for time to cardiovascular mortality, heart failure events, and KCCQ at 12 months.

"I think this ALLAY trial would be really important to kind of see from a sham procedure does it really help," Hanzel said. "I hope it does. There's so many people that could potentially benefit if it works."

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