A relatively inexpensive drug already on the market could prevent as many as 100,000 heart attacks in the United States each year, researchers reported last week.
The drug is clopidogrel, a blood thinner now used to stave off clotting in patients undergoing angioplasty. For people who suffer mild heart attacks or ominous chest pain, it could be the biggest advance in heart care since the widespread introduction of prophylactic aspirin therapy, experts said.
"This is a breakthrough," said Dr. Valentin Fuster of the Mount Sinai School of Medicine in New York, a past president of the American Heart Assn. "It will change the practice of medicine."
The research was reported at a meeting of the American College of Cardiology, or ACC, in Orlando, Fla. Several other promising studies and at least one negative one were also presented at the meeting, but the most notable was the clopidogrel research.
As many as 2 million Americans are hospitalized with mild heart attacks and bad chest pain every year--a condition often called acute coronary syndrome, unstable angina, or non-q-wave myocardial infarction--and a significant percentage of them go on to suffer more serious heart attacks or strokes when clots form in their bloodstream.
If every one of these patients received clopidogrel as part of a regimen of heart drugs, the drug would prevent 50,000 to 100,000 heart attacks and strokes and save 5,000 to 10,000 lives, Dr. Salim Yusuf of McMaster University in Hamilton, Canada, said in addressing the meeting. Worldwide, it could prevent 250,000 to 500,000 cardiac events if used on just one-fifth of those who might benefit, he added.
Yusuf led a team that studied 12,562 patients at 482 hospitals in 28 countries, all with acute coronary syndrome. All of the patients received standard treatment for the condition, including aspirin. In addition, half got clopidogrel; half got a placebo.
Yusuf told the meeting that 11.47% of those receiving standard therapy alone suffered an additional heart attack or stroke or died, compared with 9.28% of those receiving clopidogrel--a 20% reduction.
"This is really a super aspirin that lives up to its name," said Dr. Christopher P. Cannon of Brigham and Women's Hospital in Boston.
The principal side effect of the treatment was increased bleeding, Yusuf said. About six of every 1,000 patients receiving the drug needed a transfusion, he said--about the same rate observed for aspirin.
Clopidogrel costs about $2 to $3 a day. The $50-million study was paid for by Sanofi-Synthelabo, which sells the drug as Plavix, and Bristol-Myers Squibb, which markets it as Iscover. The study was conducted independently of the companies, however.
Among the other presentations at the meeting was a particularly intriguing report that looked at secondary effects of the family of cholesterol-lowering drugs called statins.
Statins have proved highly effective in warding off heart attacks and strokes, even among patients who have normal levels of blood lipids. Researchers have thus suspected that it must be exerting other effects as well. The new report suggests that it may be combating inflammation of blood vessels, an immune response triggered by infections that is increasingly recognized as an important contributor to heart disease.
One measure of inflammation is the blood level of C-reactive protein, which is produced by the liver. High levels of C-reactive protein are a harbinger of heart attacks.
A team led by Dr. Paul Ridker of Harvard Medical School studied 2,400 subjects without a history of heart disease but with an increased risk. Half were given pravastatin, trade named Pravachol, and half a placebo.
Ridker told the ACC meeting that the drug reduced levels of C-reactive protein by 13%, independent of its effects on cholesterol levels. In a similar study on patients with a history of heart disease, an equivalent reduction was observed, he said. The study did not determine whether the decreases lowered the risk of heart attacks.
Another study demonstrated that a new kind of pacemaker can improve the care of patients with congestive heart failure, in which the heart does not pump effectively, producing fatigue, shortness of breath and accumulation of fluids in the lungs and limbs.
Pacemakers are generally used to treat hearts that beat erratically. Electrical stimulation prods the organ into a regular rhythm. Some types of congestive heart failure also arise, at least in part, because different segments of the heart are not all beating in unison. The new pacemakers use three electrodes to stimulate each of these areas simultaneously so that they march to the same beat.
Between 2 million and 3 million Americans suffer from congestive heart failure, with 400,000 new cases diagnosed each year. It causes 39,000 deaths annually and contributes to 225,000 more. Between 25% and 50% of the victims suffer from poor synchronization between the right and left ventricles of the heart, reducing pumping efficiency.