BackgroundCardiac computed tomography (CCT) is an emerging non-invasive modality for assessing left atrial appendage (LAA) thrombus, but the results were conflicting. Our study aims to evaluate the accuracy of CCT for detecting LAA thrombus in patients undergoing catheter ablation of atrial fibrillation (AF), using transesophageal echocardiography (TEE) as the reference standard.MethodsFrom May 2017 to December 2022, 726 patients (male: 60.2%, age: 61±11 years) who had both TEE and CCT before catheter ablation of AF were retrospectively included. The CCT protocol consisted of one angiographic phase and one delayed scan 30 seconds later. LAA thrombi were defined as solid masses on TEE or persistent defects on CCT. The thrombus dimension and location, the LAA filling and emptying flow velocity were assessed by TEE.ResultsOf the 57(7.9%) patients with LAA thrombi identified by TEE, 29(50.9%) were located at the LAA ostium, and 28(49.1%) were in the LAA. The former showed higher motility following blood flow and heartbeats than the latter. The CCT detected 14(48.3%) of the LAA-ostium thrombi but 25(89.3%) of those in the LAA (p= 0.001). The LAA-ostium thrombi with the LAA mean flow velocity higher than 0.35m/s and maximum diameters shorter than 10mm were more prone to have CCT false-negative results.ConclusionFor patients undergoing catheter ablation for AF, CCT with a 30s delay scan is less sensitive to LAA thrombi than TEE, especially LAA-ostium thrombi with smaller sizes and higher LAA flow velocity.Clinical perspective sectionWhat are new?Over half of the LAA thrombi were located at the LAA ostium.The CCT was less sensitive to the LAA-ostium thrombi with smaller sizes and higher LAA flow velocity.What is the clinical implication?1. The CCT using a 30s delay scan did not reliably exclude the LAA thrombi for the patients scheduled for pulmonary vein isolation, especially those located at the LAA ostium.

Background: Patients with nonischemic dilated cardiomyopathy (NIDCM) are prone to arrhythmias, and the cause of mortality in these patients is either end-organ dysfunction due to pump failure or malignant arrhythmia-related death. However, identification of patients with NIDCM at risk of malignant ventricular arrhythmias (VAs) is challenging in clinical practice. The aim of this study was to evaluate whether Cardiovascular magnetic resonance feature tracking (CMR-FT) may help in identification of patients with NIDCM at risk of malignant VAs. Methods: 263 NIDCM patients who underwent both CMR, 24-hour Holter electrocardiography (ECG) and inpatient ECG were retrospectively evaluated. The patients with NIDCM were divided into two subgroups: NIDCM with VAs and NIDCM without VAs. From CMR-FT, the global peak radial strain (GPRS), global longitudinal strain (GPLS), and global peak circumferential strain (GPCS) were calculated respectively from left ventricle (LV) model. We investigated the possible predictors of NIDCM combined with VAs by univariate and multivariate logistic regression analyses. Results: The percent LGE (15.51±3.30 vs. 9.62±2.18, P<0.001) was higher in NIDCM patients with VAs than in NIDCM patients without VAs. Furthermore, the NIDCM patients complicated with VAs had significantly lower GPCS compared with the NIDCM patients without VAs (P< 0.05). Subgroup analysis based on LGE negative, the NIDCM patients complicated with VAs had significantly lower GPRS,GPCS,GPLS compared with the NIDCM patients without VAs (P<0.05 for all). Multivariate analysis showed that both GPCS and % LGE were independent predictors of NIDCM combined with VAs. Conclusions: CMR global strain can early differentiate of NIDCM patients complicated with VAs specifically when LGE was not present. GPCS < −13.19% and % LGE > 10.37% are independent predictors of NIDCM combined with VAs.