With the launch of the Framingham Heart Study in 1948, scientists began gathering data on a variety of factors that increase a person's risk for heart disease. Thirteen years later, high serum cholesterol was implicated as a risk factor for heart attack. In the intervening years, researchers have learned that many other lifestyle and biochemical factors, such as elevated LDL cholesterol, contribute to your chances of developing cardiovascular disease.
Lipoproteins
Cholesterol, triglycerides and other lipids are not water-soluble. Therefore, they must be packaged within molecules called lipoproteins, which can be efficiently transported through your bloodstream and delivered to your cells and tissues, where their contents are either metabolized or stored. Low-density lipoprotein, or LDL, carries cholesterol from your liver to other sites in your body. Oxidized LDL is one of the principal culprits in the development of atherosclerosis, or hardening of the arteries; elevated LDL levels have been linked to an increased risk for coronary artery disease.
Bypass
Your coronary arteries supply oxygen-rich blood and nutrients directly to the metabolically-demanding muscle of your heart. If your coronary arteries are obstructed by atherosclerosis, the blood flow to your heart is compromised, resulting in chest pain, called angina, or possibly even a heart attack. When your coronary arteries become narrowed, doctors can either insert tubes called stents to open them, or they can use other vessels, such as veins from your legs, to reroute the blood flow around your obstructed arteries. The latter procedure is called a coronary artery bypass graft, or CABG.
LDL for CABG
If you have had a CABG, you are still considered to have coronary artery disease. Having had one bypass does not guarantee you won't need another. In fact, a study published in the May 2011 issue of "The Journal of the American Medical Association" shows that revascularization procedures -- operations to reopen clogged coronary arteries in patients who have had previous similar procedures -- are among the most commonly performed procedures in the United States. To reduce your need for another surgery, your LDL should be kept as low as possible. The National Cholesterol Education Program recommends treatment to lower your LDL level to less than 70 mg/dl.
Considerations
An elevated LDL cholesterol level is a major risk factor for coronary artery disease. If you have already undergone a coronary artery bypass graft, you still have coronary artery disease, despite the fact that your diseased arteries have been bypassed. Without treatment, the risk for recurrence of atherosclerosis in your grafted arteries is as high as it was for your original blood vessels. Current recommendations for people with known coronary artery disease include a LDL cholesterol level below 70 mg/dl, which often requires medications. Ask your doctor about appropriate management of your lipid levels.
References
- Framingham Heart Study: Research Milestones
- "The Journal of the American Medical Association"; Coronary Revascularization Trends in the United States, 2001-2008; A.J. Epstein, et al.; May 2011
- "European Heart Journal"; Lipids and CVD Management: Towards a Global Consensus; C. Ballantyne, et al.; November 2005
