Unexplained thrombosis of the aortic arch with distal embolization in a patient with altered fibrin clot properties occurrence of unexplained arterial thrombosis. Moreover, altered fibrin clot structure/function may be associated with an unusual location of throm- bus formation. Mechanisms underlying the fibrin clot charac- teristics in the current patient remain unclear and most likely combine environmental as well as genetic factors [3]. Although a positive familial his- tory of AAT suggests a genetic background, we can- not definitely rule out in our patient other factors such as inflammatory, lipoprotein (a) (not meas- ured in the present study) [9], or the effect of platelets and blood cells. An influence of other as yet unidentified genetic factors is also suggested. It is unknown whether prolonged heparin admin- istration, thrombolysis, high-intensity anticoagu- lant or a surgical excision is the best therapeutic option in such cases. Our study supports VKA ther- apy in AAT as shown in previous reports [3]. This approach is likely to prevent thrombus recurrence and its embolic complications. Our patient was also successfully treated with VKA since low thrombin activity during stable anticoagulation facilitates clot lysis. In conclusion, the current report suggests that unfavorable fibrin clot features predispose to unex- plained arterial thrombosis and embolism in young patients without thrombophilic factors, thus repre- senting potential novel risk factors for thrombosis at untypical locations. Acknowledgments We would like to thank M. Maciejewski MD for echocardiographic images. The study was given approval by the ethics committee of the Medical University of Lodz and informed consent was giv- en by the subject. R e f e r e n c e s 1. Kullo IJ, Gau GT, Tajik AJ. Novel risk factors for atherosclerosis. Mayo Clin Proc 2000; 75: 369-80. 2. Reitsma PH, Rosendaal FR. Past and future of gene- tic research in thrombosis. J Thromb Haemost 2007; 5 (Suppl 1): 264-9. 3. Scott EM, Ariens RAS, Grant PJ. Genetic and environmental determinants of fibrin structure and function: relevance to clinical disease. Arterioscler Thromb Vasc Biol 2004; 24: 1558-66. 4. Laperche T, Laurian C, Roudaut R, Steg PG. Mobile thromboses of the aortic arch without aortic debris. A transesophageal echocardiographic finding associated with unexplained arterial embolism. Circulation 1997; 96: 288-94. 5. Choukroun EM, Labrousse LM, Madonna FP, Deville C. Mobile thrombus of the thoracic aorta: diagnosis and treatment in 9 cases. Ann Vasc Surg 2002; 16: 714-22. 6. Undas A, Zawilska K, Ciesla-Dul M, et al. Altered clot structure/function in patients with idiopathic venous thromboembolism and in their relatives. Blood 2009; 114: 4272-8. 7. Undas A, Podolec P, Zawilska K, et al. Altered fibrin clot structure/function as a novel risk factor for cryptogenic ischemic stroke. Stroke 2009; 40: 1499-501. 8. Kaminski KA, Knap M, Werel D, Musial WJ. Aortic thrombosis as a complication of intraaortic ballon. Arch Med Sci 2009; 4: 640-3. 9. Undas A, Stepien E, Tracz W, Szczeklik A. Lipoprotein(a) as a modifier of fibrin clot permeability and susceptibility to lysis. J Thromb Haemost 2006; 4: 973-5. Arch Med Sci 4, August / 2012 735