It used to be thought that cholesterol alone was the major marker for atherosclerosis. This is no longer the case. Inflammation, not cholesterol, has been identified as a significant factor in the development of coronary artery disease, plaque instability and plaque rupture.
Inflammation and Heart Disease
Pro-inflammatory messengers, called cytokines, are now recognized as behind-the-scenes culprits. Cytokines are similar to hormones. They're produced naturally by the body and may act on tissue anywhere in the body.
When inflammation is present, the body causes cytokine messengers such as interleukin-6 to instruct the liver to release inflammatory mediators—such as C-reactive protein (CRP) and serum amyloid A—into the blood. That's why we use these substances to measure how much chronic inflammation you have.
WATCH: Learn About the "Dirty Dozen" Risk Factors that Contribute to Inflammation and Heart Disease
Video courtesy of HeartMDInstitute
CRP Is Indicative of Cardiac Risk
The inflammatory marker C-reactive protein is directly associated with atherosclerotic plaque. In multiple studies, C-reactive protein has been identified as a potent predictor of future cardiovascular events in otherwise healthy men and women—one that’s far more reliable than elevated cholesterol levels.
Here are the highlights from a study of CRP in 28,000 American women. Researchers looked at CRP and LDL levels in women who developed coronary artery disease and put them into one of four possible categories:
- High CRP/High LDL cholesterol
- High CRP/Low LDL cholesterol
- Low CRP/High LDL cholesterol
- Low CRP/Low LDL cholesterol
The results were quite surprising.
Most cardiologists would have expected that women with higher levels of LDL would have been at the highest risk for inflammation and heart disease. But in this large study, not only was elevated CRP the best indicator of risk, women with high LDL and high CRP were also at the MOST risk. This is because inflammation is prompting the LDL to oxidize and form into plaque, rather than circulate freely, which explains the close connection between inflammation and heart disease.
This finding is significant because this study shows once again that LDL cholesterol is not the lone culprit in coronary artery disease. In fact, this study reported that out of 12 possible risk factors, elevated CRP was the strongest predictor of future cardiac events for postmenopausal women. And, by the way, high CRP levels also predicted greater risk for men.
Interleukin-6 May Be An Even Greater Predictor
Next, let’s look at results from the Iowa 65+ Rural Health Study, where investigators studied interleukin-6. (Interleukin-6 stimulates the liver to produce CRP in the first place.)
The Iowa study demonstrated that elevations of interleukin-6 and CRP were associated with increased risk of both cardiovascular disease and general mortality in healthy older people. In another project—the large Physicians Health Study (PHS)—higher levels of CRP were found to predict risk for heart attack and ischemic (low blood oxygen) stroke in men.
The Bottom Line on Inflammation and Heart Disease
Biological characteristics that are associated with high CRP levels include infections, high blood sugar, overweight status and stickiness of the blood. Any one of these situations literally feeds pro-inflammatory mediators, ratcheting up the chances that you’ll develop atherosclerosis.Therefore, whether you are talking CRP or interleukin-6, stopping inflammation is the key to stopping atherosclerosis, heart disease and even sudden cardiac death.