[Diagnosis of intracardiac thrombi by various imaging techniques and activation of platelets and coagulation-fibrinolysis in patients with cardioembolic stroke].

Recent epidemiological studies have suggested that 15 to 30% of all ischemic stroke is comprised of cardioembolic stroke. The presence of intracardiac thrombi might prove to be the most reliable tool when making a diagnosis of cardioembolic stroke, although not always easy to determine even with recent advanced technique. In this study, sensitivities to detect intracardiac thrombi of transthoracic echocardiography (TTE), transesophageal echocardiography (TEE), cardiac-enhanced CT (CCT) and scintigraphy with indium-111-tropolone-labelled platelets (PSG) were compared, in order to provide a relevant guideline for the diagnosis of intracardiac thrombi in 83 patients suspected of cardioembolic stroke. Also studied was the correlation of intracardiac thrombi with activation of platelets and coagulation-fibrinolysis through performing various hemostatic tests in order to investigate their utility for the evaluation of in situ thrombosis or prothrombotic state in the heart chamber. Detection rates of intracardiac thrombi were 35% in TEE, 26% in CCT, 19% in PSG, and 11% in TTE. There was a significant difference in the sensitivity between TEE and TTE (p < 0.05). Left atrial thrombi were frequently detected in TEE (4 out of 5 patients) and CCT (7 out of 10), while they were found less in PSG (2 out of 4) an TTE (4 out of 10). Thrombi in the left appendage were visualized in 3 out of 3 by TEE, while only in 1 out of 3 by PSG, 1 out of 4 by TTE and 1 out of 4 by CCT. Left ventricular thrombi; CCT (3 out of 3), TTE (2 out of 3), PSG (1 out of 1); TEE was not performed since this technique could not be expected to provide high-quality images of left ventricular thrombi. Thus, left atrial thrombi were considered to be more sensitively detected by TEE and CCT, left appendage thrombi by TEE, and left ventricular thrombi by TTE and CCT. There was no patient in whom an intracardiac thrombus was visualized by PSG alone. On the basis of the results above, we propose the following guideline for the detection of intracardiac thrombi in patients presented with cardioembolic stroke. First, TTE and CCT appear to be relevant for screening tests because of simple and non-invasive techniques. These two tools might be sensitive enough to find left ventricular thrombi. Second, TEE should be recommended when a thrombus is suspected in the left atrium or appendage. Finally, PSG may be used to determine the activity of the thrombus, according to its necessity. Among the patients having intracardiac thrombi, frequently observed was the increase of beta-thromboglobulin, platelet factor 4, platelet lysis, thrombin-antithrombin III complex, D-dimer in 67%, 75%, 71%, 80% and 80%, respectively, as well as the shortening of platelet survival in 100%, while anrithrombin III was reduced in only 38%. In addition, when hemostatic abnormalities were compared between positive and negative groups of intracardiac thrombi, the shortening of platelet survival (p < 0.0001), the increase of platelet lysis, and the increase of D-dimer (p < 0.04) were more frequent in the positive group than in the negative group. These results indicate that the findings of activation of platelets and coagulation-fibrinolysis, except for the reduction of antithrombin III, especially the findings of platelet consumption and lysis as well as fibrinolysis activation are useful as sensitive parameters of in situ thrombosis or prothrombotic state, which may lead to the formation of intracardiac thrombi.