Left Atrial Thrombus Formation After Successful Left Atrial Appendage Ligation: Case Series From a Nationwide Survey

Abstract

Percutaneous left atrial appendage (LAA) exclusion can be performed using endocardial occlusion devices or an endoepicardially placed suture delivery device (1-3). Thrombus formation on endocardial occlusion devices (Watchman, Boston Scientific, Marlborough, Massachusetts; or Amplatzer Cardiac Plug [ACP], St. Jude Medical, St. Paul, Minnesota) (1,2) has been attributed to platelet aggregation in the setting of a foreign body in the left atrium (LA). With the percutaneous endoepicardial ligation technique (Lariat, SentreHEART, Redwood City, California), there is no foreign body left behind, and the risk of thrombus formation should be insignificant. This study describes the clinical course of LA thrombi after the Lariat procedure in 19 patients. We conducted a nationwide survey of physicians performing procedures with the Lariat device in the United States to identify patients who developed LA thrombus after the procedure. Our study cohort comprised patients found to have LA thrombus post-procedure. Post-procedure surveillance imaging was not uniform across centers. Most patients underwent transesophageal echocardiogram (TEE)/computed tomography at 1 to 3 months post-procedure. Anticoagulation/antiplatelet therapy was initiated immediately after detection of LA thrombus. We collected demographic, clinical, and pre-procedural imaging characteristics of patients. Procedural variables and clinical course of patients after thrombus detection were recorded. Statistical analyses were performed using SPSS version 19.0 for Windows (SPSS, Inc., Chicago, Illinois). A total of 47 operators participated in the survey. Routine post-procedure imaging was performed by 44 (93.6%) operators. Three (6.4%) operators performed imaging only if clinically indicated. Routine post-procedure follow-up imaging was performed at 1 to 3 months and 3 to 6 months by 80% and 40% of the operators, respectively. Of the 964 patients who underwent the procedure, 19 (2%) had an LA thrombus. Table 1 lists some patient characteristics and includes follow-up data of the 19 patients. TABLE 1 Patient Characteristics and Follow-Up (n = 19) LA thrombus was detected within 90 days in 15 (79%) patients. TEEs performed in the first 6 months were negative for thrombi in 2 patients with clots discovered >200 days after the procedure. Eighteen patients received oral anticoagulants after detection of LA thrombus, whereas 1 patient received antiplatelet therapy. Thrombus remained unchanged at 90 days in the latter patient, requiring a switch to rivaroxaban. Serial TEEs were performed until thrombus resolution. Oral anticoagulation was discontinued in 16 patients after clot resolution, whereas 3 patients with unresolved thrombi remained on anticoagulation (30, 58, and 80 days, respectively). None of the patients had clinical evidence of stroke or peripheral embolism during follow-up. Our study highlights that the risk of LA thrombus formation with the device is low (2%). Most (79%) cases were detected within the first 90 days. Prompt initiation of anticoagulation can lead to thrombus resolution. This is the first investigation to describe the clinical course of LA thrombus post-procedure in a large cohort of patients receiving the Lariat device. In a clinical study involving 89 patients, no case of LA thrombus was detected on the 30-day post-procedure TEE. However, 1 patient had an LA thrombus away from the site of occlusion at 1-year follow-up (3). Our study is consistent in that, although uncommon, an LA thrombus can develop after the procedure. The pathophysiology of LA thrombus formation after the Lariat procedure remains unclear. Focal endocardial damage and inflammation around the LAA orifice secondary to tissue compression from the Lariat suture, causing edema and ischemic necrosis around the ligation site, can increase the propensity for LA thrombus formation. In our study, 17 of 19 (89%) patients developed a thrombus at the ligation site. Currently, there are no clear guidelines on LA thrombus surveillance after LAA ligation. We strongly support a follow-up TEE 30 to 90 days post-procedure. Given that the risk of thrombus formation is greatest during the first 3 months post-procedure, it may be appropriate for patients to receive antiplatelet or anticoagulant therapy during this period. The risk of LA thrombus in the absence of anticoagulation use post-procedure is low and is more frequently seen during the first 3 months after LAA ligation. Periodic imaging studies are essential for early detection of an LA thrombus. With prompt initiation of anticoagulation and close supervision, an LA thrombus can be managed safely.