Mechanisms of Arrhythmogenesis and Risk Factors for Thromboembolic Events in Patients with Atrial Fibrillation without Concomitant Coronary and Valvular Heart Disease

Abstract

Aimsidentification the correlates between parameters of tissue Doppler imaging, EF thickness by MRI and biochemical markers of fibrosis and inflammation in patients with nonvalvular AF. Retrospectively to evaluate clinical and instrumental parameters influencing the development of thromboembolic events.Methods.Data analysis was performed on 151 patients with different type of AF. A retrospective analysis included 112patients. 15 (13%) had a history of LAA thrombosis and/or thromboembolic events (stroke, TIA). The prospective analysis included 39patients. We identified groups with idiopathic AF (N = 21), AF with arterial hypertension (N = 18). And also a group with normal or slightly enlarged (4.5 sm) LA s (N = 29), and with LA 4.5 sm (N = 10). Echocardiography with tissue Doppler imaginе and cardiac MRI were performed. The level of: matrix metalloproteinases (MMP-2, MMP-9), tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), transforming growth factor beta-1 (TGF beta-1), soluble intercellular adhesion molecule (sICAM) was assessed.Results.The following parameters were significantly associated with LA thrombosis and thromboembolic events: age over 50 years (p = 0.001), obesity (p = 0.036), persistent AF (p = 0.003), the phenomenon of spontaneous ECHO contrast in LA (p = 0.03), the blood flow velocity in the LAA less than 30 sm / s (p = 0.005), morphological type III of LAA (p = 0.012). The greatest correlation between the thickness of the EFT and biomarkers was observed relative to: MMP-9 ( =0.65; Tcr= 0.16), TIMP-1 ( = 0.71; Tcr= 0.18) in the group of idiopathic AF; and TGF-beta1 ( = 0.22; Tcr= 0.19) in the general group. The percentage of left atrial myocardial fibrosis was correlated with TIMP-1 levels. There was a correlation between E/e and MMP-9, TIMP-1 in patients with idiopathic AF ( = 0.65; Tcr= 0.16 and = 0.56; Tcr= 0.21 respectively).Conclusion.The increasing levels of MMP-9 and TIMP-1 are associated with epicardial fat thickness by MRI. In addition to CHA2DS2VASc scale, we identified novel predictors of LA thrombosis and/or thromboembolic events, which are: chronic type AF, low LAA blood flow velocity, the phenomenon of spontaneous ECHO contrast in LA and the morphological LAA type III by CT.