Evaluation of aortic regurgitation severity using flow convergence from the parasternal window: comparison with cardiac magnetic resonance and traditional Doppler parameters

Aims: To assess whether two-dimensional measurements of flow convergence (FC) from the standard parasternal long-axis (PLA) window relate to aortic regurgitation (AR) severity. Methods and results: Patients with chronic AR who underwent transthoracic echocardiography and cardiac magnetic resonance imaging (CMR) within 4 h were included. FC_PLA was assessed using 3 parameters: the maximum length (L_max), width (D_max), and hemispheric area. Traditional echo/Doppler parameters of AR severity were measured per guidelines. FC and other echo/Doppler results were compared to CMR-derived regurgitant volume (RegV). A total of 80 patients were evaluated. AR was significant by CMR (RegV > 45 mL) in 41% of patients. FC_PLA parameters were measurable in 83% of patients whereas apical PISA quantitation was feasible in only 39%. FC_PLA measurements correlated well with CMR RegV: Spearman ρ = 0.75 for L_max, ρ = 0.65 for D_max, and ρ = 0.78 for area. The AUC values of L_max = 0.55 cm, D_max = 0.65 cm, and FC_PLA area = 0.35 cm² for identifying significant AR were 0.98, 0.84, and 0.94, respectively, with Lmax and FC area demonstrating significantly higher AUCs. They were comparable to those of vena contracta width (AUC = 0.94) and left ventricular end-diastolic volume index (AUC = 0.91) and superior to those of jet width/LVOT diameter (AUC = 0.80), descending aorta end-diastolic velocity (AUC = 0.74), and pressure half-time (AUC = 0.71). Conclusion: In chronic AR, flow convergence is more identifiable from the parasternal long axis window compared to traditional PISA measured from the apical window. FC_PLA nonvolumetric parameters relate well to AR severity by CMR and are comparable to conventional echo/Doppler parameters.