In-thrombus thrombin secretion: a new diagnostic marker of atrial fibrillation in cryptogenic stroke.

BACKGROUND: Endovascularly retrieved clots are a potential resource for diagnosing stroke etiology, which may influence secondary prevention treatment. In this study we measured thrombin activity eluted by serially washing clots. METHODS: Clots were retrieved from 68 patients with acute ischemic stroke, freshly frozen and classified by standard criteria into proven atrial fibrillation (AF, 18 patients), atherosclerotic origin (AS, 15 patients), cryptogenic stroke (Cr, 17 patients) and other known causes (18 patients). Thawed clot samples were washed by transferring them into 1 mL buffer in seven hourly cycles and a fluorescent substrate assay was used to measure secreted thrombin activity. The clots were also examined histologically. Artificial fibrin and red blood cell-rich clots were similarly assayed for wash-eluted thrombin activity as an external control. RESULTS: Thrombin activity eluted from clots of AF origin decreased significantly with time in contrast to steady levels eluted from AS origin thrombi (P<0.0001 by repeated measures ANOVA). The Cr stroke group was indistinguishable from the AF group and differed statistically from the AS group (P=0.017 by repeated measures ANOVA). In artificial clots we found a biphasic activity pattern, with initially decreasing levels of eluted thrombin (AF pattern) and then, with continuing washes, steady eluted thrombin levels (AS pattern). CONCLUSIONS: An assay measuring the change in thrombin in clots retrieved during acute stroke endovascular thrombectomy procedures may serve as a diagnostic marker of the origin of the clot. The suggested mechanism for these differences may be the clot location before its retrieval, with high blood flow causing thrombin washout in atherosclerotic clots, in contrast to atrium appendage low blood flow retaining high thrombin levels.

Calcification of the thoracic aorta by spiral computed tomography among hypertensive patients: associations and risk of ischemic cerebrovascular events.

BACKGROUND: Calcium is often deposited in the aorta, but the associations and clinical implications of calcification of the aorta have not yet been elucidated. METHODS: In a prospective cohort of 455 hypertensive patients with at least 1 additional risk factor for atherosclerosis that underwent dual slice spiral computed tomography of the chest for assessment of arterial calcification (mean age 65.7+/-5.8, range 52-80 years, 48% female), we assessed for calcifications of the ascending and descending aorta and their association with the risk of subsequent ischemic cerebrovascular events during 3-year follow-up. RESULTS: Calcification of the ascending or descending aorta was present in 342 (75%) patients (60% calcification of the ascending aorta and 56% of the descending aorta). The main associations of calcification of the thoracic aorta were increasing age and the presence of coronary calcification, mitral annulus calcification, and aortic valve calcification. In a logistic regression model the main predictors of ischemic cerebrovascular events (n=27) during follow-up were the presence of severe calcification (thickness of > or = 5 mm) of the descending aorta (OR 4.9, 95%CI 1.8 to 13.5) and cigarette smoking (OR 2.8, 95%CI 1.1 to 6.7). CONCLUSIONS: Calcification of the thoracic aorta is highly prevalent among women and men with hypertension, is age-related, and correlates with calcification of the coronary arteries and heart valves. Only severe calcification of the descending aorta is associated with subsequent ischemic cerebrovascular events, suggesting that calcification of the thoracic aorta is a marker of the burden of vascular disease.

Transcutaneous detection of aortic arch atheromas by suprasternal harmonic imaging.

OBJECTIVES: The goal of the present study was to examine whether suprasternal harmonic imaging (SHI) (i.e., harmonic imaging from the suprasternal windows) can visualize protruding arch atheromas (PAAs) and reliably predict the presence or absence of significant lesions. BACKGROUND: Protruding arch atheromas are a major source of cerebral and peripheral embolism and probably the most frequent cause of stroke during cardiac catheterization and open-heart surgery. Preprocedural screening by transesophageal echocardiography (TEE) would be desirable but is limited by the nature of the examination. METHODS: Of 354 patients who underwent a TEE study in our laboratory during the study period, 106 were referred for detection of a source of embolism. Findings were classified based on the French Aortic Plaque study criteria as: 1) no or minimal atherosclerotic changes; 2) PAAs < 4 mm; 3) PAAs > or =4 mm or presence of a mobile component. RESULTS: Adequate transcutaneous image quality could be achieved in 89 patients (84%). Protruding arch atheromas were present in 42 patients (47%) and absent in 47 (53%). Positive and negative predictive values for large PAAs on TEE were 91% and 98%, respectively. In one case, SHI detected a complex PAA inaccessible for TEE due to interposition of the left bronchus as demonstrated by dual helical computed tomography. Inter-observer agreement for SHI was 91%. CONCLUSIONS: Suprasternal harmonic imaging reliably predicted or excluded the presence of PAAs in a sizable, consecutive group of patients referred to TEE for detection of a source of embolism. It represents an excellent screening test and provides complimentary views of regions, which may be blind spots for TEE.