But scientists are working on a host of promising new technologies to diagnose and treat the condition.
One development uses gene therapy to create "cellular pacemakers" for the heart. Instead of implanting an electric pacemaker in a patient's weak heart, this technology might one day allow doctors to change the body chemistry so the heart can function despite its weak cells.
The therapy stands atop the American Heart Association's "top 10" list of the most important developments in heart disease and stroke research in 2002.
"There's still a long way to go before the biologic pacemaker is ready for prime time. But 2002 marks the year that researchers showed 'proof of concept,' " says Dr. Robert Bonow, president of the American Heart Association and chief of cardiology at Northwestern University in Chicago.
The heart rate is controlled by two sets of "pacing cells" that signal the heart to beat. These timekeepers work by controlling the level of potassium in the heart. But as the pacing cells age, they can't supply the heart with enough potassium, preventing the heart's cells from firing, the AHA says.
The gene therapy works by disabling the cellular channel that keeps potassium from reaching heart cells. To date, researchers have only tested the therapy on the heart of a guinea pig.
Number two on the "top 10" list is the use of internal defibrillators. Although defibrillators have long been used by doctors and paramedics to stabilize a person in cardiac arrest, doctors have just started implanting them into the heart.
Unlike a pacemaker, which sends a subtle electrical current through the heart when it beats too slowly, a defibrillator shocks the heart with a much larger current when it beats too fast. After the heart is shocked, it often returns to its natural rhythm, according to the American College of Cardiology.
A 20-month study reported last year at the college's scientific sessions showed that the implanted defibrillator was much more effective in saving patients who have abnormal heart rhythms. In a group of more than 1,200 such patients, 14 percent of those with the device died during the trial, compared to 20 percent of those without it.
Another advance -- which has implications for all surgeries and implants -- involves stents, small tubes that are inserted in an artery or blood vessel to keep it open. Stents are generally used to strengthen a weak section of an artery or relieve a clogged area. But after one is implanted, the body's immune system tries to heal blood vessels damaged by the insertion of the stent, often closing off the artery, Bonow says.
The innovation here is coating the metal or plastic stent with a medicated polymer, which slowly releases a drug directly onto the damaged blood cells, thereby preventing the immune system from responding to the stent. Such coatings could be applied to other implanted devices or transplanted organs to stabilize the immune system, Bonow says.
"I hate to use the word 'revolutionize,' but this has the potential to have a major impact on treatment," Bonow says, adding that he expects the U.S. Food and Drug Administration to approve the new stents within a few months.
Other recent advances shift the focus from treatment of cardiovascular disease to prevention. Better medications are now available to cholesterol and high blood pressure for extended periods of time.
And the assessment of heart-disease risk now includes subtle relationships between multiple factors, such as weight, diabetes, family history of heart disease, blood pressure and cholesterol, Bonow says.