The latest guidelines dont tell physicians precisely how to deal with the so-called emerging risk factors, like lipoprotein(a), homocysteine, high-sensitivity C-reactive protein (hs-CRP), and fibrinogen.
These risk factors arent ready for prime time, says James Cleeman, coordinator of the National Cholesterol Education Program (NCEP), which is part of the National Institutes of Health.
Lowering a high hs-CRP level, for example, may not lower the risk of heart attacks. We can measure these things, but we dont know if treating them is going to make a difference, says the University of Texass Margo Denke.
In some cases, doctors dont even know how to lower them. If a patient has high fibrinogen levels, a physician might prescribe aspirin or an anti-clotting medicine like warfarin to prevent the clots that high fibrinogen levels can cause, she explains. But it wouldnt lower fibrinogen.
Instead, doctors can use the emerging risk factors to decide how aggressively to treat the known risk factors. If a doctor isnt sure whether a patient deserves intensive treatment, the presence of an emerging risk factor like high CRP may put him over the edge, says Cleeman.
In contrast, theres no question about the benefits of lowering the most powerful risk factor for heart disease: LDL (bad) cholesterol.
We have lock, stock, and barrel nailed down the evidence that lowering LDL can prevent heart attacks and enable people to live longer, says Denke. Its the driving force behind the guidelines because lowering LDL has a proven benefit.
First, the new report helps physicians decide on an LDL goal by determining how high the patients risk is. The higher the risk, the lower the LDL goal.
Then the guidelines go beyond LDL to address a new problemwhich they call the metabolic syndromethats caused largely by obesity and lack of exercise. Here are some of the key changes in the new report:
The guidelines encourage physicians to start most patients on lifestyle changes. When the guidelines came out, the headlines seized on the need for more people to take drugs, and those drugs are one of the great success stories of the decade, says Cleeman. But we shouldnt lose sight of the fact that lifestyle changes are the primary means of preventing heart disease in most people.
And the governments diet advice has gotten tougher. People who are above their LDL goal should immediately cut their saturated fat to less than seven percent of calories and their dietary cholesterol to no more than 200 milligrams a day (see Doing It With Diet, p. 8 of the Healthletter).
The diet now has more cholesterol-lowering power, says Cleeman.
Cutting saturated fat and cholesterol makes the biggest dent in LDL. But you can soup up the cholesterol-lowering by adding foods rich in soluble fiberlike beans, peas, corn, and oatmealas well as Take Control, Benecol, and other margarines that are made with plant extracts called sterol or stanol esters. Add them all together and the result is impressive.
If you start by lowering saturated fat and cholesterol, and add soluble fiber, stanol or sterol margarines, physical activity, and weight loss, you can get a 20 to 30 percent lowering of LDL, says Cleeman.
Diet and exercise are critical for slashing LDL. But theyre even more vital for people who have the metabolic syndrome.
The new report calls it the metabolic syndrome, but its also called syndrome X (see March 2000, cover story).
We estimate that a quarter of the adult population has the metabolic syndrome, says Cleeman. Its more important than before because so many people are overweight or obese.
Some researchers think that the metabolic syndrome is caused by insulin resistancethat is, the insulin secreted by the pancreas loses its ability to admit blood sugar into cells, where it can be stored or burned for fuel. Its as though the body resists the insulin.
If that leads blood sugar levels to soar out of control, the person is diagnosed with diabetes. But even if blood sugar never gets that high, insulin resistance still raises the risk of heart disease.
For the first time, the guidelines provide five criteria for the metabolic syndrome, says Cleeman. If you have three of the five, youve got it.
The five criteria are levels of triglycerides, HDL (good) cholesterol, blood pressure, blood sugar, and abdominal obesity (see Step Eight). We measure these things because we cant easily measure insulin resistance, says Denke.
Even if you dont have high blood pressure or high blood sugar, you still could have the metabolic syndrome. All the criteria for the metabolic syndrome are only borderline-high, not high, says Cleeman. The blood sugar cut-off isnt high enough to be diabetes. The blood pressure cut-off isnt high enough to be hypertension.
But if you add up all of the borderline-high risks, the total is worrisome. Thats because risks dont start and stop at each cut-off.
The definition of high blood pressure is 140 over 90, explains Cleeman. But that doesnt mean youre without risk if your blood pressure is 139 over 89.
The good news is that weight loss and exercisealone or, better yet, in combinationcan reverse insulin resistance. The bad news is that, if they fail, there is no wonder drug to take their place.
We have no one drug to fix the problems caused by obesity and inactivity, says Denke.
People who already have had a heart attack, coronary bypass operation, angioplasty, angina, or other signs of heart disease have an LDL goal of 100. Thats low. According to the new guide-lines, the 16 million Americans with diabetes fall into the same high-risk category...and have the same LDL goal.
A person with diabetes has the same risk of heart disease as a person without diabetes whos already had a heart attack, says Denke.
Diabetes also makes a heart attack more treacherous. A person with diabetes is more likely to die during or soon after a heart attack, so the name of the game is to prevent the first one, says Cleeman.
Diet is the first step for knocking LDL down below 100. For those who dont succeed, the new report recommends diet plus statins or other drugs.
Many of these people can get down to an LDL of 130 with lifestyle changes, says Cleeman, but they cant get down to 100 without drugs.
And there may be nothing magic about 100. Theres reason to suspect that the lower the LDL, the better, says Cleeman. Some trials have lowered LDL levels down to 70. They show a reduced risk of heart attacks, but we dont know if getting LDL down to 80 or 95 would be just as good.
That would mean even more people on statin drugs. But its not as though we can just put drugs in the drinking water.
Statins have a very impressive safety and efficacy record, says Cleeman. But one out of 100 people will get elevated liver enzymes. Although that may not mean any real danger of liver damage, its reason enough to take them off the drugs.
And maybe one in 1,000 will have muscle problems that almost always go away when the drug is stopped. Its important to be on the lookout for those problems.
Its not just people with diabetes who may end up on drugs. For example, an HDL below 35 used to be a risk factor for heart disease. Now an HDL below 40 is considered a risk.
Its incredibly important to remember that drugs should be combined with lifestyle changes, not substituted for them, says Cleeman. Diet and exercise keep the dose of drug as low as possible and can accomplish things that drugs dont.
Diet and exercise can raise HDL and lower blood sugar, blood pressure, LDL, triglycerides, and the tendency to form blood clots. Drugs can also do some of those things, but unless you want to take a handful each day, it makes sense to correct the source of the problem.
Says Cleeman: With diet and drugs, the overall effect on cardiovascular risk is broader.
For more information:
National Heart, Lung, and Blood Institute Home Page: http://www.nhlbi.nih.gov
Web site for the new guidelines: http://www.nhlbi.nih.gov/guidelines/cholesterol