Optical Coherence Tomography to Visualize Endothelialization in Left Atrial Appendage Closure: Optical Reality or Illusion?

trial fibrillation (AF) is associated with a 3-to 5-fold increased risk of ischemic stroke. 1 AFrelated strokes are often more severe and fatal, making stroke prevention an integral component to AF management. 2 Oral anticoagulation (OAC) is the foundation of thromboembolic prevention in AF; however, many patients are unable to tolerate its long-term use.Left atrial appendage closure (LAAC) is a nonpharmacologic, mechanical option for patients with AF to prevent embolic events in those who necessitate an alternative to OAC.With growing experience and technical improvements, LAAC has been adopted worldwide and considered a safe and effective modality (PREVAIL [Watchman LAA Closure Device in Patients With Atrial Fibrillation Versus Long Term Warfarin Therapy], PROTECT AF [Watchman Left Atrial Appendage Closure Technology for Embolic Protection in Patients With Atrial Fibrillation], PRAGUE-17 [Left Atrial Appendage Closure vs. Novel Anticoagulation Agents in Atrial Fibrillation]). [3][4][5] However, device-related thrombus (DRT) is a recognized complication of LAAC and is associated with an increased risk of ischemic events.6 Incomplete endothelialization of the LAAC device is thought to be the underlying pathophysiology of DRT, given the prothrombotic surface that persists.7 Transesophageal echocardiography, computed tomography, and intracardiac echography are being used to evaluate peridevice leak, which is considered a predictor of incomplete endothelialization; however, poor spatial resolution makes direct visualization of endothelialization challenging.