Trimethylamine N-oxide (TMAO) is a gut microbiota-dependent metabolite of dietary choline, L-carnitine, and phosphatidylcholine-rich foods. On the basis of experimental studies and patients with prevalent disease, elevated plasma TMAO may increase risk of atherosclerotic cardiovascular disease (ASCVD). However, to our knowledge, no data is available on its impact on coronary microcirculation.

Inclusion Criteria:

1. Patient diagnosed with STEMI
2. Availability of non- left anterior descending artery (LAD) non culprit lesion, which is planned for a staged Percutaneous coronary intervention (PCI)

Exclusion Criteria:

1. patient undergoing cardiopulmonary resuscitation;
2. patients with a history of old myocardial infarction or history of coronary artery bypass grafting (CABG) or Percutaneous coronary intervention PCI
3. Patients with signs of chronic infection, prolong usage of corticosteroids or compromised immune system
4. patients had thrombolysis before primary Percutaneous coronary intervention (pPCI)
5. had contraindication of adenosine triphosphate (ATP);
6. had a history of liver or renal function dysfunction
7. Patients with dementia
8. Patients being referred to CABG after primary PCI
9. unable to provide informed consent;
10. had pregnancy or life span < 1 year.
11. Presence of sever structural valvular heart disease
12. Presence of significant left main disease
13. Unability to measure the index of microcirculatory resistance due to (death or retraction from the study ...etc)
14. Inability to perform successful PCI

This is a prospective, cohort study, conducted in the Hospital of the Lithuanian University of Health Sciences Kaunas Clinics.