Gut Bacteria Byproduct Predicts Heart Attack

A microbial byproduct of intestinal bacteria contributes to heart disease and serves as an accurate screening tool for predicting future risks of heart attack.

A relationship has been discovered between the biochemical by product trimethylamine N-oxide (TMAO) levels and future cardiac events like heart attack, stroke, and death, even in those with no prior evidence of cardiac disease risk.

Scientists at the Cleveland Clinic (Cleveland, OH, USA) examined the relationship between fasting plasma levels of TMAO and the incidence of major adverse cardiovascular events, including death, myocardial infarction, or stroke during three years of follow-up in 4,007 patients undergoing elective coronary angiography.

The investigators used a stable-isotope-dilution assay and high-performance liquid chromatography with online electrospray ionization tandem mass spectrometry on the QTRAP 5500 mass spectrometer (AB SCIEX; Framingham, MA, USA) to quantify the TMAO, trimethylamine, choline, betaine, and their d9-isotopologues.

The scientists found that higher TMAO blood levels were associated with higher future risks of death and nonfatal heart attack or stroke over the ensuing three-year period, independent of other risk factors and blood test results. Participants who had major adverse cardiovascular events also had higher baseline levels of TMAO with a median of 5.0 μM, as compared with those who did not have cardiovascular events, whose median was 3.5 μM, which was statistically significant.


The authors concluded that intestinal microbes participate in phosphatidylcholine metabolism to form circulating and urinary TMAO. They established a correlation between high plasma levels of TMAO and an increased risk of incident major adverse cardiovascular events that is independent of traditional risk factors, even in low-risk cohorts. Stanley L. Hazen, MD, PhD, a lead author of the study, said, “These studies show that measuring blood levels of TMAO could serve as a powerful tool for predicting future cardiovascular risk, even for those without known risk factors. More studies are needed to confirm that TMAO testing, like cholesterol, triglyceride or glucose levels might help guide physicians in providing individualized nutritional recommendations for preventing cardiovascular disease.” The study was published on April 25, 2013, in the New England Medical Journal.

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Cleveland Clinic
AB SCIEX