Why do almost half of heart attacks strike men and women with perfectly normal cholesterol levels, and few other risk factors?
New discoveries about a substance called C-Reactive Protein (CRP) may have cracked that medical mystery. They're offering millions of people a new chance to stay healthy.
Medical researchers have been piling up evidence that heart attacks, America's No. 1 cause of death, aren't just a matter of cholesterol-clogged arteries.
Most heart attacks and many strokes result from a blood-vessel disease called atherosclerosis, “hardening of the arteries.” People with atherosclerosis develop deposits, or “plaques,” inside blood vessels.
Plaques are biology's counterpart to the rust that plugs old steel water pipes.
They can reduce blood flow to a trickle so that the heart can't get enough blood to pump hard enough during exercise or stress. In that case, people with atherosclerosis may feel chest pain, a warning sign. If the artery gets completely blocked, a heart attack can occur.
Those blockages contain a lot of cholesterol. Scientists once blamed atherosclerosis on too much cholesterol in the diet - from eggs, red meat, and dairy products - that gets deposited inside arteries.
Modern research, however, has unmasked atherosclerosis as an inflammatory disease, almost like arthritis.
Here's the storyline:
Some still-unidentified agent or process injures the inside of a blood vessel. A plaque starts to form, drawing in a little cholesterol from the blood. But the plaque may never become dangerous unless inflammation jumps in. Inflammation makes it grow and become more likely to burst open, like an angry pimple, so that a blood clot forms and completely blocks the artery.
CRP is a substance produced in the liver when inflammation occurs in the body. It can be measured with a simple blood test.
Dozens of studies in the 1990s showed that people with high CRP levels had a higher risk of heart attacks or strokes.
Last November researchers published results of an eight-year study of 27,939 women - the biggest CRP study ever.
It found that CRP tests were better than cholesterol tests in predicting a person's risk of a heart attack or stroke. People with normal cholesterol levels sometimes had high CRP levels.
Researchers estimated that 25 percent of Americans are in the same boat - with normal cholesterol levels but high CRP.
In its wake, health agencies are rewriting guidelines for heart-disease detection. The American Heart Association already has recommended limited use of the CRP test. Federal guidelines soon may recommend wider use.
It's time to check with your doctor about CRP. If you get the test, be sure it is the “high-sensitivity” (hs-CRP) version. Less than 1.0 is means low risk; 1.0-3.0 is average risk, and above 3.0 is high risk. People in the high-risk group have about double the risk of a heart attack or stroke.
Drugs are available to lower CRP, including some used for high cholesterol. Lifestyle changes, like avoiding cigarettes, also may lower it.