Risk factors and prognosis for clot formation on cardiac device leads.

Background: Clot formation on cardiac device leads is poorly understood. We sought to determine how often clot is seen on device leads by transthoracic echo (TTE), identify risk factors, and to describe the natural history of this phenomenon.

Methods: We reviewed 71,888 echocardiographic studies performed at the University of California, San Francisco from 2005 to 2011.