WASHINGTON — A type of temporary artificial heart to help keep near-death patients alive long enough to receive a heart transplant has won the cautious backing of advisers to the Food and Drug Administration.
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The CardioWest Total Artificial heart is a complex and risky device that requires cutting out the bottom half of the heart to implant — with side effects such as infection, bleeding and stroke. Patients implanted with the device are tethered to a washing machine-sized power generator until they can receive a donor heart.
“This is not something any of us would subject ourselves to unless we were dying,” said Dr. Judah Weinberger of Columbia University.
Still, the device “will fill a very important niche” for a small number of patients who have run out of other options, Dr. Thomas Ferguson of the Washington University School of Medicine said Wednesday as the advisers voted 10-1 to recommend FDA approval.
The FDA isn’t bound by the panel’s advice but usually follows it.
A little time
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 unclear how many of the rest would qualify to try the CardioWest while they await a donor. Patients’ chests must be big enough for the somewhat bulky implant, and they must not be candidates for today’s standard therapy, implanted heart-boosting pumps.
Even a researcher who helped test the CardioWest, Dr. James Long of the University of Utah, acknowledged his own hospital treats no more than two to four patients a year who could benefit from it.
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. Tests are under way with other, more advanced technology that might one day offer that medical leap.
Maker SynCardia Systems Inc. says the CardioWest will buy a little time for end-stage, heart failure patients.
Heart failure eventually causes the heart’s bottom chambers, or ventricles, to become too weak to pump blood. When that happens, doctors now often attach a ventricular assist device, or VAD, to either the left or right ventricle to boost pumping power. But sometimes both ventricles fail, and rigging double VADs is difficult.
The CardioWest is a possible solution for that double-ventricle failure, and promises to be the first device to work by replacing, not just boosting, the ventricles. Surgeons remove the bottom heart chambers and sew the device onto the remaining atria, or top chambers.
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, said Dr. Jack G. Copeland, who led the CardioWest’s development at the University of Arizona.
Average CardioWest use was 11 weeks; the longest was 414 days.
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.
The device malfunctioned in 18 percent of cases mostly because kinks in the generator’s tubing 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 uncertain 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?”
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.
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