Assessment of Left Atrial Appendage Morphology in Patients After Ischemic Stroke (ASSAM)

Stroke remains the most dangerous and frightening complication of atrial fibrillation (AF). Numerous factors predisposing to peripheral embolism in patients with AF have been well defined, documented and included in the CHA2DS2VASC score. Although proper anticoagulation minimizes the risk attributable to "known" risk factors, stroke may still occur. Thus, "unknown" risk factors may play an important role in stroke risk stratification in patients with AF. The investigators assume that one of the important "unknown" risk factor is left atrial appendage (LAA) morphology. The ASSAM study is planned to include 100 patients after ischemic stroke or transient ischemic attack (TIA) and known status of anticoagulation at the time of stroke. The control group will consist of 100 patients scheduled for AF ablation without a history of stroke or TIA.

This group will consists of patients scheduled for atrial fibrillation ablation without history of stroke.

CT angiography will be performed with a dual-source CT scanner using prospective ECG gating, with detector collimation of 128x0.6 mm, a gantry rotation time of 280 ms, tube voltage of 100-120 kV, tube current of 280-380 mAs depending on the patient's body mass.

The LAA morphology in patients with an elevated risk of peripheral thromboembolism defined as CHA2DS2-VAScore >2

The investigators will examine association of specific type of LAA morphology with ischemic stroke taking in to account anticoagulation in the time of stroke/TIA. The morphology of LAA will be divided into 4 types: the chicken wing - LAA with only one lobe, its length exceeds 40 mm and its bend angle is less than 100 degrees the windsock - LAA with one dominant lobe (length > 40 mm) and several secondary, or even tertiary ones, its length exceeds 40 mm and its bend angle exceeds 100 degrees the cauliflower - LAA with a variable number of lobes with lack of a dominant lobe, its total length is less than 40 mm the cactus - LAA with a dominant central lobe with several secondary ones, its total length less than 40 mm

Inclusion Criteria: history of ischemic stroke or transient ischemic attack history of AF/AL known status of anticoagulation at the time of stroke (treatment dose, INR level) Exclusion Criteria: hemorrhagic stroke serious renal impairment with GFR <30 ml/min hyperthyroidism allergy to the contrast agent mental inability to sign the informed consent receptive aphasia