Left atrial volume index as a predictor for left atrial appendage thrombus in patients with non‐valvular atrial fibrillation receiving appropriate oral anticoagulation therapy: A prospective multi‐center study

Abstract Objectives We previously reported a higher left atrial volume index (LAVI) was independently associated with left atrial (LA) appendage (LAA) thrombus formation in 737 patients with non‐valvular atrial fibrillation (NVAF) receiving appropriate oral anticoagulation therapy. Since our previous study was a retrospective single‐center study, we designed and conducted a prospective multi‐center study to verify our findings for LAVI as a predictor of LAA thrombus in patients with NVAF receiving appropriate oral anticoagulation therapy. Methods This prospective multi‐center study comprised 746 consecutive patients with NVAF recruited between December 2021 and March 2023 from eight institutions in Japan, who were receiving appropriate oral anticoagulation therapy, had undergone transthoracic echocardiography and transesophageal echocardiography (TEE). Results LAA thrombi were observed in 21 patients (2.8%). The prevalence of LAA thrombus formation in patients with paroxysmal AF (PAF) was significantly lower than that in patients with non‐PAF (0.7% vs. 4.1%, p = .006). LAA thrombus formation was detected in none (0/171) of the patients with normal size LA (LAVI ≤ 34 mL/m 2 ). The prevalence of LAA thrombus formation in patients with mildly dilated LA (LAVI: 34–49.9 mL/m 2 ) was 2.1% (6/283), but that in PAF patients was low at 1.0% (1/104). Furthermore, this prevalence in patients with severely dilated LA (LAVI ≥ 50 mL/m 2 ) was high at 5.1% (15/292). Conclusions The findings of this prospective multi‐center study are consistent with those of our previous study. Thus, the need for TEE prior to catheter ablation or electrical cardioversion can be determined by the level of LAVI.