Black Defects in Severe Spontaneous Echo Contrast Teach Us the Protective Aspect of Mitral Regurgitation Visually

A 74-year-old Japanese female was diagnosed as chronic atrial fibrillation, and anticoagulant therapy with warfarin started. One year after anticoagulant therapy, she was referred to our center for evaluation of cardiac function. Transthoracic echocardiography by Philips iE33 ultrasound system with S5-1 transducer (Philips Medical Systems, Andover, MA, USA) revealed huge left atrial thrombus (53 × 36 mm) (Fig. 1A). Left ventricular ejection fraction was 44% with no focal asynergy. Her blood coagulation study revealed no significant problems. At that time, her prothrombin time-international normalized ratio (PT-INR) was 1.7, therefore we adjusted warfarin dose to maintain PT-INR levels at 2.0-3.0. Several weeks later, we performed transthoracic echocardiography by Siemens ACUSON SC2000 ultrasound system with 4V1 transducer (Siemens Ultrasound, Mountain View, CA, USA) and found the huge thrombus had almost disappeared (Fig. 1B). Trans-esophageal echocardiography by ACUSON SC2000 ultrasound system with V5M trans-esophageal transducer (Siemens Ultrasound, Mountain View, CA, USA) also revealed no thrombus in the left atrium and revealed severe spontaneous echo contrast (Fig. 1C-F). Left atrial appendage flow velocity was about 10 cm/sec. Black defects of spontaneous echo contrast are completely same region shown as mild mitral regurgitation in color Doppler imaging (Fig. 1D vs. C, F vs. E, and Supplementary movie 1).