Tohoku J. Exp. Med., 2004, 203(1)

Case Report

Warfarin-Intractable, Intraatrial Thrombogenesis in A 52-Year-Old Woman with Mitral Stenosis and Chronic Atrial Fibrillation

MITSUMASA FUKUCHI, KOJI KUMAGAI, MASAHITO SAKUMA, YUTAKA KAGAYA, JUN WATANABE, KOICHI TABAYASHI¹ and KUNIO SHIRATO

Department of Cardiovascular Medicine and ¹Department of Cardiovascular Surgery, Tohoku University Graduate School of Medicine, Sendai 980-8574

Thromboembolic events are serious complications of atrial fibrillation (AF). We histologically investigated intraatrial thrombogenesis in a 52-year-old woman with mitral stenosis and chronic AF who had recurrent attacks of cerebral infarction despite continuous warfarin therapy. She underwent cardiac surgery for mitral valve replacement and maze procedure including left atrial thrombectomy. Macroscopic thrombi were found on the endocardium and their surfaces appeared rough and dark red in most areas. Histological examination showed that a single thrombus mass was composed of several tissue layers or blocks on the endocardium. Immunohistochemistry revealed stratum-like accumulations of small platelet aggregate/fibrin clot complexes in the superficial, fresh thrombus layers and multiple neovessel formation in the basal organized tissue layers. This case study suggests that intraatrial thrombi may develop in a stepwise fashion on the endocardium involving platelet aggregate/fibrin clot complex formation.

keywords —— thrombosis; atrial fibrillation; immunohistochemistry; platelet; fibrin

© 2004 Tohoku University Medical Press

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Received January 6, 2004; revision accepted for publication March 12, 2004.

e-mail: shirato@cardio.med.tohoku.ac.jp