Serum trimethylamine N-oxide levels among coronary artery disease and acute coronary syndrome patients: a systematic review and meta-analysis.

BACKGROUND AND AIM: Recent studies have linked trimethylamine N-oxide (TMAO) to cardiovascular diseases; our study aimed to analyze the association between coronary artery disease (CAD), acute coronary syndrome (ACS), and TMAO.

METHODS: PubMed, Scopus, Embase, and Web of Science were searched using terms such as 'CAD' and 'TMAO'. Only observational controlled studies were included. RevMan software version 5.4 was used for the analysis.

RESULTS: A significant association was found between the CAD group and increased serum TMAO levels compared with the control group (MD=1.16, 95% CI=0.54-1.78, P =0.0003). This association remained significant among acute coronary syndrome patients (MD=0.98, 95% CI=0.73-1.23, P <0.00001) and was also detected among young and old CAD patients (MD=0.35, 95% CI=0.06-0.64, P =0.02 and MD=1.36, 95% CI=0.71-2.01, P <0.0001, respectively). On further analysis of intestinal metabolites, the authors detected an insignificant association between choline, betaine, carnitine, and CAD. According to our sensitivity analysis, TMAO is an acceptable diagnostic marker for CAD (0.721, SE was 0.0816, 95% CI: 0.561-0.881).

CONCLUSION: TMAO is an acceptable diagnostic marker for CAD, with significantly higher levels among these patients regardless of their age. Other metabolites did not show such an association. The role of serum level TMAO in the early diagnosis of CAD should be further explored.