Objective To investigate the mechanism of left atrial spontaneous echo contrast(SEC)in patients with nonvalvular atrial fibrillation(NVAF)and valvular atrial fibrillation(VAF).

目的研究瓣膜性心房颤动（房颤）和非瓣膜性房颤患者左心房自发声学显影（SEC）的形成机制。