Detection of atrial shunt lesions with a single echocardiographic parameter

Unrepaired left to right atrial shunt lesions can cause significant right ventricular (RV) volume overload. The parameter pulmonary to systemic shunt volume ratio (Qp:Qs) has been shown to detect even small differences between left and right ventricular stroke volume; however, four parameters are needed for its calculation. This study was carried out to evaluate the accuracy of the single parameter right ventricular outflow tract (RVOT) velocity time integral (VTI) to identify atrial shunt lesions.

All patients who underwent transesophageal echocardiography (TEE) examination at this institution between 1 January 2013 and 1 January 2018 were retrospectively analyzed. The RVOT-VTI was measured in the transthoracic echocardiography performed immediately before each TEE. The diagnostic accuracy for detection of atrial shunt lesions was tested.

A total of 2797 patients with a median age of 67 years (interquartile range, IQR 54-77 years) were included in the final analysis. A total of 113 (4%) patients had a relevant atrial shunt lesion. The mean RVOT-VTI of the shunt group was 25 cm (SD ± 8.1 cm) and was significantly higher than that of the non-shunt group with 17 cm (SD ± 4.8 cm) (p < 0.001). The area under the curve (AUC) was 0.81. A total of 106 patients (93.8%) of the shunt group had a VTI of ≥16 cm. If the RVOT-VTI was <16 cm, the negative predictive value was 99.3%. If the RVOT-VTI was ≥25 cm, 22% of patients proved to have a significant shunt lesion.

In this large retrospective analysis it could be shown that a low RVOT-VTI predicted the absence of significant atrial shunt lesions, while a high RVOT-VTI predicted the presence. The parameter should be applied in all patients with suspected atrial shunt lesions where calculation of Qp:Qs is impossible.