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Organ Replacement Technologies: A New Frontier: Implantable Assist Devices Aid the Failing Heart


Implantable Assist Devices Aid the Failing Heart

In the United States, heart failure affects 4.7 million people and contributes to 250,000 deaths each year. Direct and indirect health cost estimates range from $10 billion to $40 billion annually, according to John T. Watson, PhD,[3] Director of Clinical and Molecular Medicine at the National Heart, Lung, and Blood Institute.

Although the 5-year survival for all heart failure patients is approximately 50%, about half of all patients who receive heart transplantation are still alive at 9 years, according to the International Society for Heart and Lung Transplantation registry analysis of 52,195 patients. "It would be easy to make the argument for transplanting everyone with heart failure, if only the organs were available," said Eric A. Rose, MD,[4] of the College of Physicians and Surgeons at Columbia University in New York, NY. But, in fact, there were only 2733 donor hearts available worldwide in 1999, a much lower figure than the 4000 patients in the United States alone awaiting heart transplantation.

The Randomized Evaluation of Mechanical Assistance for the Treatment of Congestive Heart Failure (REMATCH) Trial

Implantable devices are most practical for organs that have primarily mechanical as opposed to metabolic functions, such as the heart. "The clinical era of permanent left ventricular assist device (LVAD) implantation to support end-stage heart failure patients is about to begin," Dr. Rose told Medscape (personal communication, 2/16/03). Implantable LVADs have historically been used to buy time for patients with end-stage heart failure awaiting transplantation, but the REMATCH trial was the first to evaluate long-term survival and quality of life (QOL).[5] This study took place from May 1998 through July 2001 at 20 cardiac transplant centers nationwide. Of 129 patients with symptomatic end-stage heart failure (New York Heart Association [(NYHA] class IV) who were ineligible for cardiac transplantation, 68 were randomized to LVAD therapy and 61 to medical standard of care, which included angiotensin-converting enzyme (ACE) inhibitors.

The LVAD met the 2-year goal of reducing all-cause mortality by one third in about half of the patients. All-cause mortality was 48% lower in the LVAD group than in the medical standard of care group (relative risk, 0.52; 95% confidence interval, 0.34 to 0.78; P = .001). Survival rates at 1 year were 52% in the LVAD group and 25% in the medical standard of care group (P = .002), and at 2 years were 23% and 8%, respectively (P = .09). Although 3 patients have had the LVAD for longer than 2 years, no patient on optimal medical management has survived beyond 27 months.

At 1 year, QOL was better in the LVAD group than in the medical standard of care group, as reflected in several measures: emotional state, Beck depression inventory, physical function, and NYHA functional class mobility. Dr. Rose described QOL in the LVAD group as "unquestionably improved but not normal, similar to that of patients on hemodialysis."

Serious adverse events in the LVAD group occurred about twice as frequently as they did in the medical standard of care group. Infection, bleeding, and LVAD malfunction caused most deaths. Device infection rate at 3 months was 28%, and device failure rate at 2 years was 35%. Ten patients required LVAD replacement. By contrast, the major cause of death in the medical standard of care group was heart failure.

The REMATCH investigators concluded that the LVAD offers a clinically meaningful survival benefit and improved QOL to patients with advanced heart failure, and that it is a viable therapeutic option in selected patients who are not candidates for cardiac transplantation. Treatment with the LVAD could avert 270 deaths per 1000 patients treated annually, giving it 4 times the impact of treatment with ACE inhibitors and beta-blockers.

Dissemination of Permanent LVAD Technology

Dr. Rose discussed the policy-making implications for dissemination of this technology, including whether LVAD insertion should be limited to select centers and the need to streamline the evaluation process for patient selection. The cost of implanting the LVAD in 10,000 patients is approximately $1 billion, which seems trivial compared with the $11 billion spent annually for ice cream in Europe or $12 billion spent for perfume in Europe and the United States. Solving the problem of pump housing infection could reduce costs by 50%, and eliminating secondary sepsis could slash costs by up to 75%.

The HeartMate vented electric (VE) device, an LVAD manufactured by Thoratec Corporation (Pleasanton, California), was the first such device to receive approval from the US Food and Drug Administration on November 6, 2002, and it is currently being reviewed for Medicare coverage. This device, about the size of a compact disc player, is fully implantable in the upper abdominal wall or the peritoneal lining. Its textured interior surface helps prevent thrombosis and reduces the need for anticoagulants. The external battery pack is worn as a shoulder holster, and the beeper-sized control system is worn on a belt. "The HeartMate VE device has crossed the threshold in terms of proof of concept," Dr. Rose said. According to Dr. Watson, second-generation LVADs designed for a 5-year minimum lifetime will soon be tested in FDA-approved and European clinical trials.

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