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The TransMedics Organ Care System (OCS) Heart System got closer to regulatory approval as it emerged victorious from a contentious .

Members of the agency's Circulatory System Devices Panel voted 12-5 (with one abstention) that the OCS Heart System's benefits outweigh its risks as a device that could potentially widen the pool of donor hearts -- perhaps even reduce waitlist times -- by preserving non-standard donor hearts longer than traditional cold storage during transport.

Panelists voting in favor did so despite complaining of flimsy safety and effectiveness data in the , , and studies.

"While the data is certainly not robust, it seems to me it is safe and effective, particularly given the choice of not using a heart, and hopefully the final decision will be that the chosen donors will be appropriate," said George Vetrovec, MD, of VCU Health Pauley Heart Center in Richmond, Virginia. He voted yes for OCS Heart's approval.

Voting no was Murray Kwon, MD, of UCLA School of Medicine, who said he did so "in the purest sense" based on the data submitted by TransMedics.

"I don't know if it's snake oil or if it's doing something. We don't have the proper controls," he said.

FDA staff noted that the sponsor, in producing a packet with few animal studies and no myocardial histologic analysis, had not followed agency recommendations. But TransMedics CEO Waleed Hassanein, MD, fought against FDA's analysis of the submitted data, saying "something's not adding up here."

TransMedics had proposed the OCS system as a "portable extracorporeal heart perfusion and monitoring system" for donor hearts with 4 or more hours in expected cross-clamp or ischemic times -- or 2 or more hours plus criteria such as older donor age and donor history of alcoholism or diabetes.

Committee members had a problem with the last part of the proposed indication, noting that there was not enough evidence of OCS Heart's benefit in these cases, and worrying that these expanded criteria could lead to overlap with standard hearts.

"There's definitely a place for this, and that place is 4 or longer hours," said Jason Connor, PhD, of ConfluenceStat in Orlando. He voted against recommending approval because of the proposed indication.

"I do think there are a lot of hearts that go in the bucket, and I think this is a challenging population," said Keith Allen, MD, of St. Luke's Hospital of Kansas City, Missouri, who voted yes. "I just hope that the PAS [post approval study] is designed in a collaborative way and the FDA can provide controls for preventing creep in indication."

The panel advised FDA to require more animal work and a large, carefully designed registry to show the OCS Heart System's safety.

Concerns had been raised regarding the system's association with decreased transplant recipient survival in the long term compared with standard of care. Additionally, there was a 25% rate of mechanical circulatory support use among transplant recipients and evidence of potential myocardial injury in turned-down organs.

TransMedics reported that 13% of initially accepted donor organs were ultimately turned down after OCS heart preservation. Lactate level was the principal reason for turn-down, yet it is unclear if lactate can be relied on as a marker of transplant-ability.

The ongoing production of lactate and longer out-of-body ischemic times with the OCS were two reasons Joaquin Cigarroa, MD, of Oregon Health & Science University in Portland, cited for voting no.

In the end, the FDA advisory committee voted 9-7 (with two abstentions) that the OCS was safe and 10-6 (with two abstentions) that it was effective.

FDA is not required to follow the advice of the advisory committee, but it often does.

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