Left Atrial Appendage Thrombus in Patients With Hypertrophic Cardiomyopathy and Atrial Fibrillation: Prevalence and Risk Factors

Background Atrial fibrillation (AF) is common in hypertrophic cardiomyopathy (HCM) and increases stroke risk, primarily due to thromboembolism from the left atrial appendage (LAA). Oral anticoagulation (OAC) is recommended, but data on LAA thrombus (LAAT) in HCM and AF are limited. The current study aimed to assess LAAT prevalence in patients with HCM and AF. Methods We retrospectively analyzed 170 patients with HCM and AF (mean age, 67.7±12.4 years; 57.1% men) who underwent at least one transesophageal echocardiogram (TEE) during a median follow‐up of 41.5 months (interquartile range, 15–77 months). Results At the time of TEE, 147 (86.5%) patients were undergoing OAC, with 52 (30.6%) taking vitamin K antagonists and 95 (55.9%) taking non–vitamin K antagonist oral anticoagulants. LAAT was found in 36 patients (21.2%), with prevalence rates of 23.1% (n=12) in vitamin K antagonist users, 16.8% (n=16) in non–vitamin K antagonist oral anticoagulant users, and 34.8% (n=8) in those without OAC. Non–vitamin K antagonist oral anticoagulant use was associated with a significant LAAT risk reduction compared with no OAC (odds ratio, 0.20 [95% CI, 0.05–0.73]; P =0.02). Decreased LAA flow velocity ( P <0.001) was independently linked to LAAT. Conclusions LAAT is common in patients with HCM and AF, even among those receiving OAC. Reduced LAA flow velocity may increase thrombus risk. TEE should be considered before rhythm‐control strategies, even in patients with HCM receiving anticoagulation, to minimize thromboembolic complications.