Science & Technology: Heart Disease
Hope Is Where the Heart Is
Tiny electrical implants hold out new promise in the battle against congestive heart failure
Congestive heart failure is sometimes referred to as the silent epidemic, because it gets so little notice. But this progressive weakening of the heart muscle affects 22 million people in the industrialized world. And more than 50% die within five years of diagnosis. Victims suffer from extreme breathlessness, painfully swollen ankles, and exhaustion so severe they sometimes are confined to bed. It is the only major cardiovascular disease that is on the rise, and there is no cure other than a heart transplant.
Cardiac specialists, however, are cautiously optimistic about a new pacemaker-like device called a ventricle resynchronizer, which may be the first effective treatment for the sickest heart failure victims. In these patients, the left and right sides of the heart contract slightly out of sequence, so blood no longer circulates efficiently. The resynchronizer, a silver-dollar-size device implanted in the chest, uses electric pulses to prod the four chambers to work in sync.NORMAL LIFE. Medical experts disagree on how many heart failure patients have out-of-sync hearts: Estimates range from one-third to one-half. The resynchronizer does not offer these patients a cure, nor has it been proved to extend their life span. It will not even eliminate the need for drugs. Its purpose is to enable patients to resume a normal life without pain or exhaustion--but that is a major gain for 55-year-olds who can no longer walk a block, sleep through the night, or complete the simplest tasks. "These are patients who are not being served with existing therapies," notes David Lothson, an analyst at PaineWebber.
Most important, resynchronizers are widely expected to reduce hospitalizations, potentially producing a huge savings that will more than offset the device's $10,000 price tag. Heart failure is the leading cause of hospital visits in the U.S., costing $8 billion to $15 billion each year, more than twice the amount spent on all forms of cancer.
Two Minnesota medical-device outfits, Medtronic Inc. and Guidant Corp., are in a neck-and-neck race to be the first to win U.S. approval, and medical experts are hard-pressed to choose one over the other. Each company recently reported promising results from small clinical trials that indicate the resynchronizer improves symptoms and reduces hospital visits.DETERIORATING. Isabelle Westcoat of Absecon, N.J., typifies those results. In 1995, when she was 54, Westcoat was diagnosed with heart failure--and told she probably had only 18 months to live. She retired from her job as a tax preparer and was placed on the long waiting list for a heart transplant. An experimental medicine kept her in good shape until 1998, when it was discontinued because of worrisome side effects. Despite taking six other drugs a day, Westcoat's heart deteriorated until she could not fold laundry without collapsing from exhaustion.
That all changed, she says, on Oct. 28, 1999, when her Medtronic resynchronizer was activated: "I knew it had been turned on on Friday because on Saturday morning I woke up breathing easily." Westcoat says she has felt better every day since, and within three months she was taken off the transplant list. "It has changed my whole morale," she says. "Some days I almost feel guilty because I feel so good."
Unqualified raves from patients are almost universal. Although the trials announced to date cover only a few hundred people, their quality of life has almost always been upgraded. "The improvements are pretty strong," says Dr. Evan Loh, a clinical investigator for the Medtronic device at the University of Pennsylvania Medical Center in Philadelphia. "These patients aren't just feeling a little better. They are feeling a lot better."
Medtronic's InSync and Guidant's Contak CD both won regulatory approval in Europe last year, and the two companies are expected to win Food & Drug Administration approval in early 2001. At that point, say cardiologists, the main issue will be which heart failure patients will benefit most.
There is no shortage of candidates. Some 5 million people in the U.S. have heart failure, with 400,000 to 700,000 new cases diagnosed each year, according to the National Institutes of Health. The number of deaths from the condition has more than doubled since 1979, to about 250,000 annually. Those numbers are sure to rise as the population ages, since congestive heart failure is most common in people over 65.CYCLE OF HARM. Despite the disease's name, the heart does not suddenly fail. Rather, it deteriorates slowly, as the heart muscle weakens and loses its ability to pump adequate blood. The disease develops after damage to the heart caused by a heart attack, high blood pressure, diabetes, or other disorders. The healthy parts of the heart must work harder to compensate for the damaged ones, creating a cycle of harm.
Heart failure is often not diagnosed until it is well advanced. By then, fluid is leaking from the heart valves into the lungs, legs, and feet. Treatment usually consists of a strict no-salt diet and a complex drug regimen of diuretics, digoxin, and blood vessel dilators such as ACE inhibitors. But the heart inevitably continues to fail, often ending in what doctors call sudden cardiac death.
For patients with out-of-sync hearts, other implantable devices are useless. Pacemakers speed up a dangerously slow heartbeat, caused by a disease known as bradycardia. Implantable defibrillators, sometimes called "a rescue squad in the chest," go into action when the heart starts twitching rapidly and erratically, thus preventing sudden cardiac death.
The resynchronizers are more like a mechanic in the chest. They have three wires--pacemakers and implantable defibrillators only have two--that lead to the left and right sides of the heart. An electrical charge balances out the chambers so that all four beat in a steady, synchronized rhythm.
There has been a surge of interest in the devices following recent trial results. In March, Medtronic reported on a study of its InSync device in 103 patients in Europe and Canada: Quality of life in most cases showed great improvement, and the improvement was maintained over 12 months. A 42-patient European study of Guidant's Contak, reported in May, found that heart-pumping efficiency improved by 15% after one month, and longer-term use appeared to reduce hospitalization.EARLY STAGES. Doctors caution that the devices have been tried only in patients with advanced disease. "I think that some heart failure patients will benefit, but I don't think it is anywhere near half of all patients," says Dr. David L. Hayes, director of the pacemaker division of the Mayo Clinic in Rochester, Minn. Hayes says that the device will have a far larger impact if it is able to prevent patients in the early stages of heart failure from getting sicker. "From the early data, is seems as though some subset would clearly improve, but until we've tested it in large numbers of patients we just don't know."
Ultimately, Medtronic and Guidant hope that mortality rates will improve if their resynchronizers are combined with an implantable defibrillator. The two companies are closely watching the NIH's 2,400-patient Sudden Cardiac Death in Heart Failure Trial, which is comparing implantable defibrillators with drug therapy for heart failure. Scheduled to conclude in 2003, the trial is widely expected to provide the necessary clinical evidence that implantable defibrillators will increase life expectancy.
That will trigger much broader use of both resynchronizers and defibrillators, says Lothson. "This technology is really going to change the outlook for heart failure."By Catherine Arnst in New YorkReturn to top