Abstract Background The RAC (retroaortic anomalous coronary artery) sign, visible in transthoracic echocardiography (TTE) as an abnormal tubular structure located retroaortically in the atrioventricular groove, is typical of an anomaly of the coronary artery origin. Purpose Assessment of the incidence of the RAC sign in the population of outpatient clinic of a tertiary academic hospital. Evaluation of the anatomy of coronary vessels in patients in whom the symptom was described. Assessment of the specificity of the RAC sign in the study population. Methods Consecutive patients, who underwent TTE in the outpatient clinic of the cardiology department between 04/2022 and 02/2024 were included in the prospective study. The echocardiography examinations were performed by a cardiologist with an EACVI (European Association of Cardiovascular Imaging) TTE certification. The anatomy of coronary vessels in patients with RAC was assessed by classic coronary angiography or computed tomography. Results 2310 patients were included in the study. RAC sign was found in 8 (0,35%) individuals - 3 women (average age 70); 5 men (average age 58). In patients with RAC sign indications for TTE were as follows: history of anterior ST-segment elevation myocardial infarction (STEMI) treated by primary angioplasty of left anterior descending coronary artery (2 patients), history of inferior STEMI treated by primary angioplasty of right coronary artery (1 patient), history of pacemaker implantation (1 patient), history of myocarditis (1 patient), hypertension (1 patient), history of venous thromboembolism (1 patient), atypical chest pain (1 patient). Anomaly of the origin and retroaortic course of the coronary artery was confirmed by CT or coronary angiography in all subjects with RAC sign on TTE. In all patients with RAC sign, the retroaortic vessel was identified as circumflex artery (Cx). In 4 patients (50%), Cx originated from the right coronary artery, in 4 patients (50%) there was a direct origin of the Cx from the right sinus of Valsalva. In all patients the anomaly of the coronary vessel origin was not associated with increased risk of sudden cardiac death (interseptal course, course between large vessels and acute angle take-off were excluded). The specificity of the RAC sign was 100%. Conclusions The RAC sign is a relatively rare finding in the TTE evaluation. In our analysis, visualization of the retroaortic course of the coronary vessel was equivalent to the diagnosis of a mild anomaly of the origin and the retroaortic course of the circumflex coronary artery.
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