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Are Nonfasting Better Than Fasting Triglyceride Levels at Predicting Cardiac Events?

In two large cohort studies, CVD risk correlated more strongly with nonfasting than with fasting levels, but the clinical significance of hypertriglyceridemia is still unclear.

Hypertriglyceridemia has many varieties, and its relationship to atherosclerosis remains controversial. Several investigators have suggested that increased plasma lipoprotein remnant particles may contribute to atherogenesis. Postprandial hypertriglyceridemia, reflecting an elevated concentration of lipoprotein remnant particles, might therefore indicate increased risk for MI, ischemic heart disease, and death. In two new studies, researchers explored the utility of fasting and nonfasting triglyceride (TG) levels in predicting cardiovascular events.

In the first, investigators used data from the Women’s Health Study, a prospective analysis involving 39,876 initially healthy women, to examine the association of TG levels (fasting vs. nonfasting) with risk for cardiovascular events. Hazard ratios were calculated for incident nonfatal MI, nonfatal stroke, coronary revascularization, and cardiovascular death; median follow-up duration was 11.4 years. Fasting TG levels were available for 20,118 participants, and nonfasting levels were available for 6391. At baseline, elevated TG levels coincided with traditional cardiac risk factors and with markers of insulin resistance, irrespective of fasting state. Overall, 3.46 cardiovascular events occurred per 1000 person-years of follow-up; after adjustment for demographic and cardiovascular risk factors, both fasting and nonfasting TG levels independently predicted cardiovascular events. Additional adjustment for total and HDL cholesterol levels and insulin resistance weakened the association of fasting, but not nonfasting, TG levels with events. When stratified by postprandial time, TG levels measured 2 to 4 hours since last meal had the strongest association with cardiovascular events (HR for highest vs. lowest tertile of TG levels, 4.48).

In the second study, investigators analyzed data from a prospective study of 7587 women and 6394 men in Denmark (aged 20 to 93 years), from whom nonfasting TG levels were collected from 1976 to 1978. Hazard ratios were calculated for incident MI, ischemic heart disease (IHD), and death; mean follow-up duration was 26 years. In multivariable analysis, increasing nonfasting TG levels were independently associated with increasing incident MI, IHD, and death. The hazard ratios and the strength of the associations were greater in women than in men.

Comment: In these two large, prospective studies, one of female health professionals and one of a general population, nonfasting triglyceride levels were significantly associated with incident cardiovascular events. Further studies are required to clarify the role of postprandial triglycerides in atherosclerosis as well as the applicability of these results to clinical practice. For now, instituting postprandial TG screening in routine cardiovascular risk stratification is probably premature; however, based on these findings, high TG levels may serve as a readily obtainable clinical indicator of risk, particularly in women.

— JoAnne M. Foody, MD

Published in Journal Watch Cardiology August 8, 2007

Citation(s):

Bansal S et al. Fasting compared with nonfasting triglycerides and risk of cardiovascular events in women. JAMA 2007 Jul 18; 298:309-16.

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Nordestgaard BG et al. Nonfasting triglycerides and risk of myocardial infarction, ischemic heart disease, and death in men and women. JAMA 2007 Jul 18; 298:299-308.

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McBride PE. Triglycerides and risk for coronary heart disease. JAMA 2007 Jul 18; 298:336-8.

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• Medline abstract (Free)