Acute coronary syndrome (ACS) represent emergency state in an intensive cardiovascular care unit, which implies immediate and specific treatment. Of peculiar interest for cardiologists are young patients with acute myocardial infarction (AMI). The family history taking for premature coronary artery disease (CAD) and establishment of genetic factors, responsible for coagulation, both are on target for this group of patients. Gold standard for AMI diagnosis is coronary angiography (CA), which usually implies endovascular treatment (EVT). When coronary thrombus formation is found in young patients, different diagnostic opportunities are possible. Thrombophilia (TF) represents blood coagulation abnormality resulting in an increased risk of thrombosis. It could affect different sections of the cardiovascular system, most commonly venous, but also arterial. This clinical condition could be confirmed by performing laboratory genetic tests. We studied a group of forty-one young patients with first appearance of ACS ≤ 55 years old included for a five-year period. All of them were evaluated with CA and received EVT. According to the thrombotic risk, we defined a high-risk group, treated with anticoagulant (AC) on top of dual antiplatelet therapy (DAPT). The patients were followed-up for recurrent ischemic and bleeding events. We performed laboratory tests for the most frequent TF gene mutations in Bulgarian population. There is a conflicting data about this issue in different ethnic origins. The aim of our study is to estimate the possible relationship between the TF and the arterial thrombosis in young ACS patients, to defi ne specific treatment strategies, improving the prognosis of the patients.