The thesis devoted to estimation of a rate of thrombo-embolic events, cardiovascular and all-cause mortality and evaluation of their clinical and echocardiographic predictors, to create means for lowering a risk of these complications, to validate instruments for evaluation of health related quality of life and to perform analysis of its predictors in patients with non-valvular atrial fibrillation-flutter (AF-AFl).In prospective study, were examined 548 patients with AF-AFl and 82 patients with sinus rhythm (SR) without history of AF-AFl. There were to parts of the study: cross-sectional and observational. The mean age of AF-AFl group was (60,1±9,9) years, 180 (32,85 %) were females. Patients with AF-AFl and SR were comparable with their baseline characteristics. It was found that the rate of left atrial appendage (LAA) thrombus and sludge and left ventricle (LV) thrombus were the same in groups with AF and AFl. For indirect estimation of LAA velocity (LAAV) was created a formula LAAV=23,8+0,77xЕm-0,15xLAVI, where Em is the early diastolic velocity on the lateral segment of mitral valve and the LAVI is the left atrial volume index. It was proved that CHA2DS2VASc score and LV ejection fraction (EF) <40 % independently associated with LAAT, sludge and LV thrombus. It was found that complete resolution rate for thrombus was 66,7 % and for sludge 40,9 %, so residual thrombi are frequent founding on repeated transoesophageal echocardiography and it seems to be that cardioversion may be considered in patients with reduced and immobile thrombi and who are adherent to anticoagulation therapy. It was found that LAVI >=49 ml/m2 (odds ratio (OR) 2,14 (95 % confidence interval (CI) 1,08-4,23); р=0,03) was independently associated with recurrence of arrhythmia episode and EF2-EF1 >=10 % was independently associated with SR maintenance (OR 0,27 (95 % CI 0,09-0,77); р=0,015). It was also found that amiodarone use (OR 0,16 (95 % CI 0,05-0,52); р=0,0017) and angiotensin-converting-enzyme inhibitors/angiotensin-receptor antagonists use (OR 0,2 (95 % CI 0,08-0,52); р=0,001) were independently associated with SR maintenance. On the other hand arterial hypertension (OR 2,7 (95 % CI 1,08-6,78); р=0,032), LAA spontaneous echo contrast (SEC) 3-4+ (OR 3,74 (95 % CI 1,58-7,61); р=0,002) and EHRA I-II were independently associated with arrhythmia progression into permanent form.It was found that silent cerebral infarctions (SCI) were associated with AF (OR 3,1 (95 % CI 1,1-8,8); р=0,03) and that the SCI related to AF had diameter >=15 mm and cortical-subcortical localization. There was no association between cardiovascular events and SCI in 2 years follow up.The SEIL scale was invented (SEC 3-4+ - 1 point, EHRAm III-IV - 1 point, interventricular septal thickness (IVS)>=1,7 cm - 1 point, LAVI>=49 ml/m2 - 1 point) and it was an independent predictor of occurrence of ischemic stroke (IS) relative risk (RR) 2,38 ((95 % CI 1,68-3,37); p<0,001). Adherence to recommendations to anticoagulation therapy (ACT), but not a rhythm control strategy was independently associated with reduction of the risk of IS (OR 0,072 (95 % CI 0,016-0,3); р<0,001). On the other hand, rhythm control strategy (RR 0,06 (95 % CI 0,01-0,48); р=0,008) as well as adherence to recommendations to ACT (OR 0,07 (95 % CI 0,014-0,34); р=0,001) were independently associated with reduction of the risk of cardio-vascular death. Moreover, patients who had a SR at the end of the study had significantly lower rate of stroke 5 (4,13 %) vs 27 (15,7 %) in patients with arrhythmia (р=0,002). For the first time, specific and generic instruments for evaluation of health related quality of life in patients with AF-AFl were validated and predictors of reduced quality of life were estimated
