Optimal Anticoagulation for Massive Left Atrial Appendage Thrombus in Atrial Fibrillation With a History of Gastrointestinal Bleeding

Abstract

Systemic embolism is a serious complication of atrial fibrillation (AF), most commonly originating from thrombi in the left atrial appendage (LAA). Thrombi that are large (≥15 mm) or exhibit mobility carry particularly high embolic risk, yet management can be challenging in patients with elevated bleeding risk. Advanced echocardiographic techniques now allow quantification of thrombus mobility, and dense spontaneous echo contrast (SEC) on transesophageal echocardiography has been identified as an independent predictor of thromboembolic events. We report the case of an 80-year-old woman with paroxysmal AF, non-Hodgkin lymphoma in remission, hypothyroidism, and a history of perforated gastric ulcer, in whom a large, mobile LAA thrombus (8 × 15 mm) was incidentally detected and confirmed by transesophageal echocardiography. Anticoagulation with warfarin, titrated to an INR of 2.5-3.0, led to complete thrombus resolution within six weeks. This case illustrates the substantial embolic risk associated with mobile LAA thrombi and demonstrates that individualized anticoagulation with careful monitoring can achieve safe and effective thrombus resolution in patients at high risk of bleeding. The novelty lies in highlighting individualized management as a viable strategy in this complex clinical setting, providing an important teaching point for practice.

Introduction

Atrial fibrillation (AF) is the most common sustained arrhythmia, affecting over 37 million people worldwide and increasing in prevalence with age and comorbidities such as hypertension and structural heart disease [1]. AF increases the risk of ischemic stroke fivefold [1], with the left atrial appendage (LAA) being the source of ~90% of thrombi in nonvalvular AF [2,3]. The trabeculated anatomy of the LAA promotes blood stasis and thrombus formation, particularly when atrial contractility is impaired [4].

LAA thrombus (LAAT) is a major cause of cardioembolic events and is often detected incidentally on transesophageal echocardiography (TEE) performed before cardioversion or ablation [5,6]. Anticoagulation remains the cornerstone of treatment. Vitamin K antagonists such as warfarin have long been standard therapy [7], while direct oral anticoagulants (DOACs) are increasingly used and have shown comparable efficacy in thrombus resolution [8].

We present the case of an 80-year-old woman with paroxysmal AF and a history of perforated gastric ulcer, found to have a large, mobile LAAT that resolved completely after six weeks of warfarin therapy. This case is unique because the complete resolution of a large, mobile thrombus in a patient with significant bleeding risk is uncommon. Warfarin was preferred over DOACs in this context because INR monitoring allowed careful titration of anticoagulation intensity, providing greater control in a patient with prior gastrointestinal bleeding risk. The case supports clinical practice by highlighting the importance of individualized anticoagulation strategies in complex, high-risk patients.