Background: Elevated plasma trimethylamine N-oxide (TMAO) levels, a metabolite derived from the intestinal microbiota, are closely related to atherosclerosis due to its involvement in increased inflammation, oxidative stress and cholesterol reverse transport.
Objectives: Blood samples were collected at admission from 81 patients who survived acute myocardial infarction (AMI) and from 10 healthy individuals. TMAO concentrations were measured by means of liquid chromatography-tandem mass spectrometry with an aim to evaluate the predictive value of this biomarker in terms of another major event during long-term follow-up.
Results: Patients with AMI have significantly higher median plasma TMAO concentration compared to healthy individuals (respectively, 1.62 (1.37 – 2.25) µM vs 0.55 (0.35 – 0.74) µM, p < 0.0001). Considering only patients with AMI, TMAO values positively correlated with pro-inflammatory markers CRP and TNF-α. In addition, TMAO positively correlated with creatinine and negatively correlated with GFR. Moreover, we noted the trend of higher TMAO values among patients with diabetes mellitus compared to patients without (1.68 (1.44 – 5.43) µM vs 1.59 (1.33 – 2.099) µM, p=0.065).
During a median follow-up of 61.74 (59.34 – 64.24) months, 10 patients suffered another infarction. Those individuals had significantly higher TMAO values compared to subjects without another ischemic event (respectively, 2.29 (1.60 – 6.49) µM vs 1.60 (1.34 – 2.09) µM, p = 0.026). Kaplan-Meier analysis confirmed that elevated values of TMAO were associated with the risk of another infarction (p=0.029), whereas multivariate Cox regression analysis did not demonstrate the prognostic value of TMAO towards re-infarction probably due to the small cohort.
Conclusions: Higher plasma TMAO values at admission in patients with AMI are associated with re-infarction at long-term follow-up.