Two articles here - one on Abiomed's Totally Artificial Heart, and another on the REMATCH study, where data on the long term effects of LVADs is being gathered. The comment at the end of that article is interesting - 30% of bridge to transplant LVAD patients are still dying due to organ failure.
Another Artifical Heart Nears Trial
ABioMed Inc says that its Implantable Replacement Heart has reached an important milestone in their reliability
testing program. All the artificial heart's systems, including internal batteries and electronics, have now met the
company's reliability standards for actual use in bridge to transplant patients. Actual use requires FDA approval. Dr.
David M. Lederman, CEO, explained that "it is a formal testing program intended to study performance and durability of
the heart under many conditions. The tests are done in the lab. Each successive version gets better, as we learn from our
mistakes in previous models." The company plans to apply for regulatory permission to begin clinical trials by the year
2000.
In contrast to many other implantable heart assist devices, which leave failing natural hearts in place, the ABioMed
Replacement Heart replaces the severely diseased heart entirely. Based in Danvers, Massachusetts, ABioMed
manufactures heart assist and replacement systems. Their BVS-5000 is the most widely used FDA-approved cardiac
assist device and the only FDA-approved device for all patients with reversible heart failure.
LVADs Tested For Heart Failure
A multi-center clinical trial will soon begin recruiting patients to see if ventricular assist devices (VADs) are an
effective long-term treatment for patients with advanced heart failure. Although these implantable heart assist pumps are
now used as short-term "bridge to transplant" - keeping patients alive until a donor organ is found - they have not been
approved for long-term therapy. The REMATCH (Randomized Evaluation of Mechanical Assistance and Treatment of
Congestive Heart Failure) trial will study whether VADs and medical treatment are better than medical treatment alone
in improving patient survival and quality of life, said Eric A. Rose, MD. Rose is Chairman of the Department of Surgery
at Columbia University's College of Physicians and Surgeons in New York. At the 44th conference of the American
Society for Artificial Internal Organs, Rose said the trial is recruiting only patients with end-stage CHF who not
transplant candidates for some reason.
Each year, 3000 to 3500 donor hearts are available worldwide, while 10 times that many people need a heart. An
alternative to heart transplant is needed. According to Rose, several things have been learned from a decade of VAD
use as bridge to transplant. "You don't have to replace the whole heart in most patients," he said. "For most patients with
end-stage heart disease, left ventricular replacement is sufficient. We've also learned that using textured interior surfaces
results in dramatic reduction in blood clots. We have learned we can maintain a connection between the inside of the
body and the outside world for a long time without infection." Pumps' controls have shrunk from the size of a refrigerator
to beeper-sized objects worn on a belt. "We have learned that these wearable systems can keep patients alive out of the
hospital for long periods of time," Rose said.
REMATCH will study whether a wearable VAD increases 2-year survival from 25% to 50%-75% in patients with
end-stage heart disease who are not eligible for heart transplant. The reason for ineligibility may vary, including being
aged 65 years or older, or having advanced diabetes or abnormal kidney function. It will also study patients' quality of life
on these devices, and if it is as good as, or better than, quality of life for patients getting medical therapy.
The primary end point for the trial is a reduction in all-cause mortality of at least 33% Secondary end points include
quality-adjusted survival, functional status of the patient, health-related quality of life, adverse events, total length of
hospital stay, direct costs, cost-effectiveness of each additional year of life gained and device performance. Twenty
centers in the USA are about to begin recruiting patients for the trial. To be eligible, patients must be adults who can give
informed consent and who have been treated with state-of-the-art drugs like digoxin, diuretics, beta-blockers and ACE
inhibitors. They must have Class 4 heart failure and an EF less than 25. They also have to live within 2 hours of a
participating center and be willing to transfer their primary care to investigators at the center.
The investigators hope to recruit 136 patients during the next year and a half. An earlier study, called PREMATCH,
closed in March after studying 21 patients at 5 centers. Some of these patients have had their implanted pumps for more
than 600 days. Although there have been more infectious complications than expected in some of the patients, survival
rate has been encouraging, he said.
Rose estimates that the cost of keeping a patient on a VAD for 2 to 4 years is about $250,000, while the cost of best
medical therapy alone would be about $130,000. Cost for each additional year of life gained by implanting these devices
will be about $50,000. "This may sound high, but that would only be a little more expensive than for heart transplant or a
double bypass," he said. Although bullish about the future of implantable heart-assist devices, Rose is also cautious: "The
last time I was invited to speak at this meeting, I advocated xenotransplantation using primates as donors as the coming
wave for cardiac replacement. Needless to say, I've come around to LVADs. I was obviously wrong, and you should
take my talk with a grain of salt. I don't think we should fool ourselves by thinking that we have arrived in the promised
land; 30% of patients who receive an implantable VAD as a bridge to transplant still die of organ failure, often as a result
of infection or hemorrhage. We have learned that almost all these patients suffer some degree of inflammatory
disturbance, including a low-grade coagulopathy due to the device. We believe this may be intrinsic to all
blood-contacting devices at this point."
From: JAMA 1998;279:1509-1510 |
