Resolution of Left Atrial Appendage Thrombus by 64‐Detector CT Scan

A 66-year-old man with hypertrophic cardiomyopathy and persistent atrial fibrillation was referred for percutaneous pulmonary venous isolation. He had been maintained on coumadin with an international normalized ratio (INR) target between 2.0 and 3.0, and was transitioned to enoxaparin (1 mg/kg) in preparation for the procedure. The day prior to the scheduled ablation, he suffered an episode characterized by a minor motor vehicle accident and confusion. He presented for his ablation and did not initially mention this episode. Preparatory testing for ablation included a cardiac CT (Aquilion 64, Toshiba Medical, Japan) with slice collimation of 0.5 × 64 for use in the electroanatomic mapping system (Carto, Biosense Webster Inc., Diamond Bar, CA, USA). The scan showed thrombus in the left atrial appendage (Fig. 1). This finding was confirmed by transesophageal echocardiography (TEE) (Fig. 1, inset). The ablation was deferred on the basis of these findings and further workup for TIA was unrevealing aside from the LAA thrombus. The patient was discharged on coumadin with a higher INR target of 2.5–3.5. Several months later, he returned for repeat attempt at ablation. He was admitted for intravenous heparin 4 days prior to the procedure. Repeat CT scan using the same technique showed resolution of the LAA thrombus (Fig. 2), and this was also confirmed by TEE (Fig. 2, inset). The patient then underwent an unremarkable electrophysiologic study and ablation of his atrial fibrillation without complication. He was maintained on intravenous heparin for 5 days following the ablation, until his INR was over 2.5, and was discharged in sinus rhythm. Cardiac CT performed prior to the ablation procedure can reveal left atrial thrombus with good image quality. MDCT's performance in identifying LAA thrombus is still undefined, but a positive MDCT could potentially save a TEE study. CT view of the LA (left atrium) with the left atrial appendage showing a contrast filling defect compatible with a thrombus (unfilled arrows). The respective transesophageal echo image is shown in the inset and confirms the presence of a thrombus in the appendage (closed arrow). LA = left atrium. Similar views of the CT (unfilled arrows) and transesophageal echo images (inset, closed arrow) show resolution of the thrombus. LA = left atrium.