Cardiovascular disease is still the major killer of middle-aged men and by far the leading cause of death for North Americans overall. For about half of those who die from heart disease, the very first symptom is sudden death.
And for many who die this way, high cholesterol is not a factor. Although we continue to hear otherwise, using high cholesterol as a screening method fails to identify about 50% of the people who have heart attacks each year, because their total cholesterol is either normal or near normal.
"It is apparent that a substantial proportion of cardiovascular events occur in individuals without established risk factors," Dr. Daniel Hackam and Dr. Sonia Anand of McMaster University in Ontario wrote in the Journal of the American Medical Association. So it is clear that new methods of establishing heart attack risks must be identified.
One emerging marker is a substance called C-reactive protein, or CRP. It is a natural chemical produced in the liver and released into the bloodstream in the presence of acute or chronic inflammation. High levels of CRP, indicating inflammation, may explain why some people with low cholesterol develop heart disease, or why a cholesterol-lowering diet sometimes fails to prevent heart problems.
In the Physicians' Health Study of 22,000 men, 97 apparently healthy participants suffered sudden cardiac deaths. The only predictive factor of their fates over 17 years of study were elevated CRP levels (C. Albert et al, Circulation, 2002).
A study of 28,000 apparently healthy American women followed for an average of eight years, showed that CRP levels were directly related to the development of cardiovascular events, and were a much stronger predictor than cholesterol levels (P. Ridker et al, New England Journal of Medicine, 2002).
The role of C-reactive protein as a contributor to cardiovascular disease fits nicely into the understanding that inflammation is central to every stage of atherosclerotic disease, from the start of plaque formation in arteries to the rupture of those plaques, which can cause a heart attack or stroke.
Basic research has shown that CRP can enhance destruction of arterial lining cells, activate adhesion molecules and blood clotting factors, and interfere with substances that increase circulation to the heart.
According to a literature review, chronic low-grade inflammation appears to underlie many, if not most, cases of cardiovascular disease, and even small increases in CRP can predict future vascular events in apparently healthy individuals exhibiting no other symptoms.
C-reactive protein can be measured through a simple, inexpensive blood test.