Sex-specific differences in trimethylamine N-oxide (TMAO) concentrations before and after cardiac rehabilitation in acute myocardial infarction patients

Trimethylamine N-oxide (TMAO) is a biomarker of cardiovascular risk and may enhance the progression of atherosclerosis. The aim of the study was to determine whether there are sex-specific differences in TMAO concentrations before and after cardiac rehabilitation in acute myocardial infarction (AMI) patients. A total of 56 participants [45/56 (80.4 %) males, 11/56 (19.6 %) females] were drawn from AMI inpatients hospitalized at the Division of Cardiology, Medical University of Graz, Austria. For the assessment of TMAO, serum samples were collected within the first day after hospital admission due to AMI and at the start and end of cardiac rehabilitation. Shortly after hospital admission due to AMI, females had significantly higher TMAO blood concentrations than males. These initially high TMAO levels remained almost unchanged in the female AMI patients until the start of cardiac rehabilitation and only reached the lower TMAO concentrations observed in the male patients after rehabilitation [female patients: TMAO (acute myocardial infarction) = 5.93 μmol/L (SE = 1.835); TMAO (start of rehabilitation) = 5.68 μmol/L (SE = 1.217); TMAO (end of rehabilitation) = 3.89 μmol/L (SE = 0.554); male patients: TMAO (acute myocardial infarction) = 3.02 μmol/L (SE = 0.255), TMAO (start of rehabilitation) = 3.91 μmol/L (SE = 0.346), TMAO (end of rehabilitation) = 4.04 μmol/L (SE = 0.363)]. After AMI, women might be at higher cardiovascular risk due to persistently higher levels of TMAO. High TMAO levels in women might decrease after cardiac rehabilitation due to cardiac rehabilitation-associated lifestyle modifications. These lifestyle modifications after AMI might also prevent increases in TMAO concentrations in men.