Triglycerides and Cardiovascular Risk
When assessing coronary risk, blood triglycerides have traditionally not been considered a major coronary risk factor. The reason is that when you statistically adjust for blood cholesterol (LDL and HDL), fasting triglyceride levels cease to be a significant predictor of risk.
Two new studies shed new light on this subject and may change risk assessment standards in the future. The first report comes from the Women’s Health Study,1 a cohort of over 26,000 healthy women. More than 20,000 of these women had fasting triglyceride tests, and 6,391 had nonfasting triglyceride tests. Over the next 11.4 years, researchers monitored the number of cardiovascular events that occurred (heart attacks, coronary hear disease, and strokes) and compared these to the women’s blood triglyceride levels.
Here is what they found:
- Fasting triglyceride levels were not a significant predictor of risk after adjusting for other coronary risks including cholesterol levels (confirming earlier research).
- Nonfasting triglycerides, however, were a significant, independent predictor of coronary risk, even after adjusting for other risks. Women with nonfasting triglycerides greater than 170 mg/dL were twice as likely to develop cardiovascular disease compared to women with triglycerides less than 105 mg/dL.
- Nonfasting triglycerides were most predictive of future cardiovascular event when they were measured 2-4 hours after a meal (triglycerides peak at about 4 hours after a meal). In this group, women with high triglycerides (170+ mg/dL) were 4.5 times as likely to develop cardiovascular disease as women with healthy nonfasting triglyceride levels (less than 105 mg/dL).
The second study2 on triglycerides studied the risk of heart disease related to nonfasting triglycerides in both men and women. Researchers found nonfasting triglycerides to be independent risk factors for cardiovascular disease in both men and women, although the risk was stronger in women. In men, nonfasting triglyceride levels of 180+ mg/dL resulted in a 60% increased risk of heart disease, and those with triglyceride levels of 260+ mg/dL were 2.3 times more likely to have a heart attack than men with healthy triglyceride levels (less than 90 mg/dL). Women with high triglycerides (180+ mg/dL) had a 2.5 times increased risk of a heart attack.
This is good news for screening programs because you don’t have to ask people to fast 12 hours before their blood test. Traditionally, people have been asked to fast because LDL cholesterol is based on a calculation using fasting triglyceride levels. In an editorial in the same JAMA issue as these two studies,3 the editors suggest that using the non-HDL cholesterol test result may be a better method of assessing risk than testing for LDL cholesterol because a non-HDL cholesterol test can be done nonfasting and reflects the risk from both LDL cholesterol and nonfasting triglycerides. Non-HDL cholesterol is simply Total cholesterol – HDL cholesterol. Norms for non-HDL cholesterol as set by NIH (ATP-3 report) are shown below, along with the better known LDL cholesterol risk standards for comparison:
Risk Rating |
Ideal risk |
Low risk |
Moderate risk |
High risk |
LDL cholesterol, (mg/dL) |
<100 |
100-129 |
130-159 |
160+ |
Non-HDL cholesterol (mg/dL) |
<130 |
<160 |
<190 |
190+ |
Norms set by NIH, National Heart, Lung, and Blood Institute, ATP-3 report4.
References:
- Bansal S, et al. Fasting compared with nonfasting triglycerides and risk of cardiovascular events in women. Journal of the American Medical Association. 2007;298(3):309-316.
- Nordestgaard BG, et al. Nonfasting triglycerides and risk of myocardial infarction, ischemic heart disease, and death in men and women. Journal of the American Medical Association. 2007;298(3):299-308.
- McBride PE. Triglycerides and risk for coronary heart disease. Journal of the American Medical Association. 2007;298(3):336-339.
- NIH. Clinical Guidelines, National Heart, Lung, and Blood Institute. Website accessed Jan. 2008.
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