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MUNICH -- A transcatheter interatrial shunt device (IASD) showed a promising safety signal in a small phase II trial, although it didn't make a difference in outcomes for patients with heart failure with preserved ejection fraction (HFpEF).

The IASD System II from Corvia Medical was not significantly less safe than was a sham procedure, according to Ted Feldman, MD, of Evanston Hospital in Illinois, presenting here at the annual congress of the European Society of Cardiology (ESC).

The primary safety endpoint at 1 year — namely cardiovascular death, embolic stroke, device-associated and/or procedure-associated adverse cardiac events, or new onset or worsening of kidney dysfunction — came out similar between the shunt and sham (9.5% [two of 21] versus 22.7% [five of 22], P=0.41).

Yet the REDUCE LAP-HF I trial was really underpowered to detect significant differences in 12-month endpoints, Feldman and collaborators said in the report published simultaneously online in . They attributed this to factors including the small size of the study.

"However, it is reassuring that IASD placement appears safe up to 12 months," the researchers wrote. "In particular, there were no strokes or transient ischemic attacks in the IASD-treated patients."

That the device does what it's supposed to do mechanistically was shown in a that reported a drop in pulmonary capillary wedge pressure at 1 month. By 1 year, shunts were still patent in all individuals who had been randomized to the IASD.

Notably, there was an increase in right ventricle (RV) size among the IASD recipients at 6 months (average +7.9 versus -1.8 mL/m², P=0.002), consistent with left-to-right shunting through the device, Feldman's group said. There was no further enlargement by 12 months.

"Some changes in cardiac structure and function are to be expected after implantation of an IASD. With shunting of blood from the overloaded LA [left atrium] to the lower-pressure RA [right atrium], the RV must accommodate an increase in preload."

Even so, the change in RV volume will need further scrutiny as that has been a concern for the creation of such shunts no matter how small they are, according to Paul Sorajja, MD, of Minneapolis Heart Institute at Abbott Northwestern Hospital, who was not involved in the study.

The device in question in REDUCE LAP-HF-I creates an 8-mm diameter shunt.

Patients were eligible for the trial if they were categorized as having New York Heart Association (NYHA) class III or ambulatory class IV heart failure; had a left ventricular ejection fraction of at least 40%; had elevated left atrial pressure with a pressure gradient between the LA and RA; and had no clinically important right heart dysfunction.

The experimental and sham groups shared similar baseline characteristics except that the IASD arm was less racially diverse.

Feldman and co-authors reported that in addition to the primary endpoint, there were no significant differences between groups in terms of the following:

• All-cause death: 4.8% for IASD versus 13.6% for sham (P=0.61)
• Cardiovascular death: 4.8% versus 4.6% (P>0.99)
• Improvement in NYHA class: median one versus zero (P=0.08)
• Clinical summary score of the Kansas City Cardiomyopathy Questionnaire: median 44.3 versus 44 (P=N.S.)
• Exercise capacity: 299.5 versus 242.5 meters on the 6-minute walk test (P=N.S.)

"The results are provocative as a sham-control study with prior results from this same cohort showing hemodynamic benefit from the IASD device," Sorajja said. "The small size of the study limits the ability to make definitive conclusions on efficacy, but the trends are in the right direction."

A larger pivotal trial of this therapy in HFpEF is currently underway, the researchers noted.

In the current study, IASD recipients showed a larger median LA volume index than RA volume index, "which is indicative of chronically increased LV filling pressures without considerable right-sided HF.

"A significant reduction in LA volume in response to the IASD, if corroborated in a larger trial, could be a promising finding, given that LA plays a central role in the pathogenesis of HFpEF and that reduction in LA volume over time may be associated with improved outcomes in this patient population."

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