Most reported cases of right anomalous coronary artery from the opposite sinus (R-ACAOS) have benign clinical outcomes. However, patients with left ACAOS (L-ACAOS) and some of the patients with R-ACAOS are more at risk for arrhythmias and sudden cardiac death, which remains a major concern. Here we report the prevalence and anatomical features of ACAOS patients. Moreover, we explore the high-risk morphological signs and evaluate their mid-term prognostic value in R-ACAOS patients without surgical intervention.Data from coronary computed tomography angiography (CTA) of 30,593 patients, pertaining to a single center over 5 consecutive years, were retrospectively analyzed. The image analysis included stenosis severity ranking and high-risk anatomy evaluation, based on the commercially available image post-processing software OsirX. Patients with R-ACAOS and without evidence of coronary atherosclerosis (CAD) were followed-up, with recording of the cardiovascular clinical events. Cox regression analysis was performed to identify the potential anatomical risk factors of cardiovascular clinical events for non-CAD R-ACAOS patients, using R project.The prevalence of ACAOS in the study population was 0.69% (211/30593). Significant differences were found between patients with mild (< 50%) and severe (> 50%) stenosis, in terms of height-to-weight ratio (HW ratio), take-off angle, and proximal stenosis length. A total of 54 cardiovascular clinical events were observed among 108 non-CAD R-ACAOS patients and an average follow-up of 27.8 ± 18.7 months. Among those patients' anatomical features, stenosis severity was the main risk factor for cardiovascular clinical events during the mid-term follow-up, with a risk ratio of 4.14 (95% CI: 1.78 to 9.63, P < 0.001).Among patients referred to coronary CTA, the overall incidence of ACAOS was 0.69%. For patients with R-ACAOS, severe stenosis was the independent risk factor of adverse clinical events in the mid-term follow-up, and positive clinical intervention might be needed to help them avoid the malignant clinical events.