Cryptogenic stroke. Part 1: Aorto-arterial embolism

Abstract

The article discusses the concept of embolic stroke from an unspecified source and the role of aorto-arterial embolism in its development. Potential causes of embolic cryptogenic stroke such as aortic atheromatosis, non-stenotic atherosclerosis of the cervical arteries, carotid web and intracranial atherosclerosis are discussed in detail. The discussion of each cause covers epidemiology, pathogenesis, and current approaches to diagnosis and secondary prevention. The diagnostic search is presented in the form of an algorithm. To identify aorto-arterial sources of embolism and to determine their clinical significance, a comprehensive examination including CT angiography with targeted assessment of the aortic arch, transesophageal echocardiography, MRI of the arterial wall and transcranial Doppler is required. When mechanical thrombectomy is performed, histological examination of the thromboembolus is advisable. Given that atherosclerosis is usually systemic, the search for a possible cause of aorto-arterial embolism should be a diagnostic priority in patients with cryptogenic stroke and other arterial (coronary, lower extremity) lesions. With regard to secondary prevention of cryptogenic stroke in the presence of potential sources of aorto-arterial embolism, the principle ‘the more embologenic the source, the more aggressive the prevention’ applies. The arsenal of secondary prevention includes strategies such as strict control of vascular risk factors, achieving target blood pressure, short- and medium-term dual antiplatelet therapy, and intensive hypolipidemic therapy. Surgical prophylaxis is warranted for stroke against a carotid background, the efficacy of which in non-stenotic atherosclerosis requires early evaluation in randomised trials. Each potential cause of cryptogenic stroke considered is illustrated by a clinical example.