Images in Cardiovascular Medicine Large Thrombus Originating From Left Atrial Diverticulum A New Concern for Catheter Ablation of Atrial Fibrillation

45-year-old man was admitted to our hospital forevaluation of a left atrial (LA) mass. The patient had ahistory of dilated hypertrophic cardiomyopathy, atrial fibril-lation (AF), diabetes mellitus, and sustained ventriculartachycardia that was treated by implantation of acardioverter-defibrillator. He had developed AF 1 year earlierand was followed up at the outpatient clinic. He had beentreated with warfarin at a dose that resulted in an internationalnormalized ratio of 2.0 to 3.0. The LA mass was detectedincidentally on routine transthoracic echocardiography. Hewas referred to our hospital because the size of the LA masswas unchanged after intensive anticoagulation with intrave-nous heparin infusion. The mobile LA mass along theinteratrial septum was detected by transthoracic echocardiog-raphy in the apical 4-chamber view (Figure 1 and Movie I inthe online-only Data Supplement). Transesophageal echocar-diography showed a huge mobile mass (2.6 1.4 cm) origi-nating from the roof of the LA (Figure 2A and Movie II in theonline-only Data Supplement) with remarkable spontaneousecho contrast. No evidence of thrombus formation was foundin the LA appendage (Figure 2B). The mass had a stalk thatcame from the diverticulum on the LA roof based on