Left Atrium and Left Atrial Appendage Screening Prior to Atrial Fibrillation Ablation: A Comprehensive Review of the Literature

In the past decade, certain patient groups have been observed to have a presumptive lower incidence of left atrial (LA)/LA appendage (LAA) thrombus, particularly those who have no or minimal comorbidities. This has led to the question of whether a preprocedural evaluation of the LA/LAA is necessary in every patient, or if it can be avoided in certain patient populations. The answer to this is further complicated by the possibility of newer anticoagulation approaches affecting the incidence of intracardiac thrombus, including uninterrupted warfarin therapy and uninterrupted novel oral anticoagulant (NOAC) therapy, both of which are becoming more common. In this study, we conducted a comprehensive review of the literature addressing these questions in an attempt to summarize current approaches to evaluating the LA/LAA prior to ablation in order to elucidate the strategies that are currently being employed, to determine which strategies are becoming more favorable for use, and to identify what topics can or should be targeted for future study. In addition, this paper seeks to address the following specific questions: is ruling out LA/LAA thrombus necessary in all patients prior to atrial fibrillation (AF) ablation? Are there any identifiable patient populations at reliably lower risk who could potentially avoid LA/LAA thrombus screening prior to AF ablation? What are the current strategies being employed by electrophysiologists in the published literature? What is the opinion of the current literature on warfarin and NOAC drugs as they pertain to the incidence of LA/LAA thrombus prior to AF ablation, and how does each fit into the current treatment strategies for the prevention of procedural thromboembolism? Finally, what is the future of preprocedural intracardiac thrombus evaluation prior to AF ablation, and what steps can be taken to ensure that the risk to the patient is minimized while improving laboratory efficiency and avoiding unnecessary costs?