Methods: The investigators will enroll approximately 200 patients aged 18 and older. The first study of silent myocardial ischemia, will include patients without cardiovascular disease undergoing urgent or elective surgery for benign abdominal diseases. The second group will include patients with STEMI undergoing primary coronary angiography. Patients will also complete a questionnaire on folate intake. Subsequently, the investigators will collect blood for standard laboratory tests as well as troponin T, N terminal-pro BNP, homocysteine, and folic acid. Blood will be also collected for biomarker analysis. On the third day of hospitalization, blood will be collected again for troponin T, NT-proBNP and biomarkers. After that, the investigators will follow up the patients for another year every three months for the possible occurrence of major adverse cardiovascular events (MACE). Peripheral blood and blood from the coronary sinus will be collected in patients from the second study group for biomarker research. Expected results and significance for science and medicine: the investigators anticipate that the study will improve the understanding of clinical, biochemical, and biological markers of silent ischemia and cardiovascular complications following non-oncological abdominal surgeries. Knowledge of these factors would enable early identification of patients at higher risk of such complications, leading to more targeted preoperative preparation for non-oncological abdominal surgeries.