WASHINGTON — A type of artificial heart moved a step closer to the U.S. market Wednesday, but it’s not a permanent replacement — just a temporary device to keep certain near-death patients alive long enough to receive a heart transplant.
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There are serious questions about who should get the CardioWest Total Artificial Heart, a complex and risky device that requires cutting out the bottom half of the heart to implant, scientific advisers to the Food and Drug Administration cautioned.
Still, they concluded it should sell because it could benefit a small number of patients.
“These people are dying who don’t have any good alternative,” said Dr. Judah Weinberger of Columbia University as the panel voted 10-1 to recommend FDA approval.
The FDA isn’t bound by the panel’s advice, but usually follows it.
'A niche technology'
Some 3,460 people were on the national waiting list for a heart transplant as of Wednesday; just over 2,000 receive a heart each year. It’s not clear how many of the rest would qualify to try the CardioWest device while they await a donor.
“This is going to be a niche technology,” acknowledged Dr. James Long of the University of Utah, who helped test the CardioWest and says his own hospital treats no more than two to four patients a year who could benefit from it.
But, “these are very sick patients who are dying. They have no alternative,” added Dr. Jack G. Copeland, who led the CardioWest’s development at the University of Arizona.
The CardioWest isn’t what the average person thinks of when hearing “artificial heart.” Initial attempts to use it as a permanent heart replacement 22 years ago, under the name Jarvik-7, failed. Experiments are under way with other, more advanced technology that might one day offer that medical leap.
'Bridge' for end-stage heart patients
Instead, maker SynCardia Systems Inc. wants the CardioWest to compete with existing heart pumps, called ventricular assist devices or VADs, as a “bridge” to transplant for end-stage heart failure patients.
When one of the heart’s bottom chambers, or ventricles, becomes too weak, attaching a VAD can significantly boost pumping power. But sometimes both ventricles fail, and rigging double VADs is difficult.
That’s where the CardioWest may help — by replacing, not just boosting, the ventricles, potentially the first U.S. device to offer that step. Surgeons remove the heart’s bottom half and sew the device onto the remaining atria, or top chambers.
Tubes snake from the patient’s body to a washing machine-sized generator that powers the implanted device, making the CardioWest for in-hospital use, at least for now. (It’s sold with more portable generators in parts of Europe.)
Eighty-one patients were implanted with a CardioWest in a study spanning the 1990s. Some 79 percent survived long enough to get a transplant — and 69 percent were out of bed and recovering well a month after that transplant, Copeland said.
Average CardioWest use was 11 weeks; the longest was 414 days.
Device highly risky
It’s risky: 40 percent of patients suffered serious bleeding, 22 percent developed device-related infections, and 8 percent had blood clots, FDA scientists said.
In 18 percent of cases the device malfunctioned; most were kinks in the generator’s tubing that temporarily cut power.
New treatments typically are compared to existing alternatives or placebo. This study attempted to use “historical controls,” tracking the survival of people awaiting a transplant before the CardioWest experiment began or who didn’t qualify for it. But the FDA said they weren’t comparable groups — leaving the advisory panel struggling to decide if using the device really was better than doing nothing.
“This leaves all of us in a hamstrung position,” complained Dr. Mitchell Krucoff of Duke University. “Where is the data?”
But VADs typically have survival-to-transplant rates around 70 percent with similar side effects, suggesting the CardioWest is at least equivalent, said FDA reviewer Dr. Julie Swain.
Ultimately, what convinced some FDA advisers: Heart failure leads to other organ damage, but some CardioWest recipients had liver and kidney damage clear up — potentially making them better transplant candidates.
“This machine is so vitally important,” said Leo Corbet, 67, of Phoenix, who spent 110 days on the CardioWest before getting a heart transplant in 2001. He’d listen to the machine’s loud whirring and “I knew I was alive.”
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