The aim of this study is to test the potentially protective role of myonectin in patients with a first episode of ST elevation myocardial infarction (MI) treated with primary percutaneous coronary intervention (PCI). The main questions which are assumed to be answered after study completion: 1. Does higher myonectin concentration influence the in-hospital and 30-day course of the first ST-elevation MI in patients treated with primary coronary angioplasty 2. Is there a relationship between the serum myonectin concentration, related to patient's nutritional status and physical activity with the patient's physical activity declared as usually before the coronary event occurrence, the cardiac biomarkers level, and myocardial and skeletal muscle mass determined in order to objectify the relationship of physical activity before the infarction with 30-day and one-year mortality, and the other primary and secondary outcomes measured at 12-month visit, e.g. the extent of myocardial infarction, 3. Is there a relationship between the baseline concentration of myonectin and troponin with the control of atherosclerosis risk factors, declared physical activity and parameters of body composition, outcome of treadmill exercise test, values of echocardiographic parameters and myonectin concentration 12 months after a cardiovascular incident