Cardiac causes can be distinguished between high and low-risk: [25] High risk: atrial fibrillation and  paroxysmal atrial fibrillation ,  rheumatic disease  of the  mitral  or  aortic valve  disease,  artificial heart valves , known cardiac thrombus of the atrium or ventricle,  sick sinus syndrome , sustained  atrial flutter , recent myocardial infarction, chronic