Four-dimensional flow provides incremental diagnostic value over echocardiography in aortic stenosis

Aims Four-dimensional flow cardiovascular MRI (4D flow CMR) has emerged as a promising technique for assessing aortic stenosis (AS). This study aimed to evaluate the agreement between 4D flow CMR and transthoracic echocardiography (TTE) in estimating peak aortic valve (AV) velocities (V-Peak), grading AS severity and predicting AV intervention in a real-world setting. Methods Participants from the PREFER-CMR registry who had consecutive TTE and 4D flow CMR were included. AS severity was graded using established protocols using three echocardiographic parameters (V-Peak, AV area and mean pressure gradient) and CMR-derived V-Peak. Results The study recruited 30 patients (mean age 75.4 years, 67% male), with 17 undergoing AV intervention. Continuous wave Doppler (CWD) V-Peak (3.4 vs 2.6 m/s, p=0.0025) and 4D flow V-Peak (4.2 vs 2.7 m/s, p<0.0001) were significantly higher in patients going for AV intervention. V-Peak by CWD was significantly lower to 4D flow with a bias of -0.5 (p=0.01) and a correlation of (R=0.55, p=0.002). The Cox-regression analysis reveals that 4D flow V-Peak significantly predicts AV intervention (HR=2.51, p<0.01), while CWD V-Peak (HR=0.54, p=0.76) shows no significant association; overall model fit is significant (chi(2)=9.5, p=0.02). Conclusion 4D flow CMR-derived V-Peak assessment is superior to echocardiographic CWD assessment for predicting timing of AV intervention. Trial registration number NCT05114785.