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WHAT seems to make Lp(a) so troublesome is its uniqe design. Ordinary LDL is a ball of cholesterol wrapped by a strand of a protein. As LDL travels through an artery, this protein can latch on to plague and deliver the cholesterol wrapped by a strand of a protein. As LDL travels through an artery, this protein can latch on to plague and deliver the cholesterol cargo. But Lp(a) has an extra protein strand that's shaped like a natural clotbuster in the blood. Since plagues are known to contain blood closts, scientists suspect this look-alike protein actually tricks blockages into soaking up more cholesterol instead of clotbuster.
Special blood tests can identify the problem, but neither a low-fat diet nor most drugs that Lower LDL will budge high levels of Lp(a). Two exceptions are physician-supervised doses of the B vitamin niacin and, for women past menopause, estrogen.
Homocysteine
This amino acid, found in everyone's blood, is estimated to figure in ten to 15 percent of heart attacks, and 30 to 40 percent of strokes. A high homocysteine level is considered to be above 14.
In the 1960's at Boston's Massachusetts General Hospital, doctors examine a young girl wiht a genetic disease that cause a buildup of homocysteine in the blood. The girl had a relative who had died at the age of eight from a similar illness 30 years earlier at the same hospital. When Dr. Kilmer McCully dug out the old records and peered through his microscope at tissue from the long-dead child, he realized that the boy had the arteries of an old man.
Several months later McCully's antennae were alerted by news of a two-month-old boy who died of another genetic disease that caused homocysteine buildups. When he looked at this baby's tissue samples, once again he saw clogged arteries. "I began to suspect that people whose homocysteine levels were high might be at risk for heart attacks," recalls McCully.
McCully's theory produced controversy and led to further research. Finally, three decades later, a major study at harvard and Bringham and Women's hospital looked at nearly 15,000 male physicians over five years. In this health-conscious group, only 271 suffered heart attacks. High homocysteine coincides with a deficiency of the B vitamin folic acid and, in some cases vitamin B-6 and B-12. "people who have five daily servings of green leafy vegetables, beans and citrus fruits or juices can get the required 400 micrograms of folic acid," says Dr. Jacob Selhub, a professor of nutrition.
But doctors estimate that only a small percentage of the population eats that much folic-acid-rich food. "If there's a choice between not getting the vitamin or taking supplements," says Dr. Meir Stampfer of the Harvard School of Public health, I'd choose the supplements." Stampfer adds that the ederly may need suplements because the ability to break down homocysteine declines with age.
Fibrinogen
This substance, protein that helps form blood clots, gained much attention in 1986 when British researchers measured fibrinogen levels in the blood of male workers at a food-processing plant over a five-year period. The scientists discovered that men with a fibrinogen level in the upper third had an 84-percent increased risk of ischemic heart disease over those in the lower third. Since then other studies have added to this evidence.
Although high fibrinogen levels are link to heart-attack risk, science hasn't yet demonstrated a cause and-effect relationship. But one theory is that the more fibrinogen, the bigger the clots that form after an atherosclerotic plaque breaks.
When Dominic Aievoli had a fatal heart attack at 55, his wife's grief was compounded by her fear that her two sons might also be in danger. Her worries were confirmed when doctors found excessive amounts of two troublemakers in 26-year-old David's blood. One was Lp(a0; the other, fibrinogen.
A first-line defense against surplus fibrinogen is to declare war on other substances that damage arteries. But it may also be possible to battle fibrinogen itself. "Since levels are higher with obesity or hypertension, controlling weight and blood pressure may lower readings," Rader says.
Exercise also lowers levels. David Aievoli has taken up running, and his fibrinogen has been cut.
Calcium Deposits
Calcium accumulates in arterial blockages, which are made up of cholesterol and other substances. One day Dr. Bruce Brundage, a cardiologist at Bend Memorial Clinic in Oregon, had a brainstrom while studying a new CAT scanner capable of taking X rays of the heart between heartbeats. "It dawned on me that this ultrafast scanner could capture sharper images of calcium," says Brundage. "If a scan showed a lot of calcium in a patient's arteries, that person was at increased risk of having dangerous obstructions."
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