Aims: Evaluation of the severity of the aortic stenosis (AS) is based on echocardiographic assessment of peak velocity/mean transaortic pressure gradient (MPG) by continuous-wave Doppler and calculation of the aortic valve area (AVA) using the continuity equation. Pioneering echocardiographic studies have shown that MPG should be measured from the apical and right parasternal views using non-imaging continuous-wave Doppler transducer (NI-CWD). Nowadays, ultrasound systems are often sold without NI-CWD due, at least partially, to the improvement of two-dimensional continuous-wave Doppler transducers (2D-CWD). Whether this evolution translated into misevaluation of AS severity was uncertain. Our aim was to evaluate the additional diagnostic value of the use of NI-CWD and the right parasternal view for the evaluation of AS severity in the modern area.
Methods and results: We prospectively evaluated MPG and AVA using the 2D-CWD (apical view) and the NI-CWD (right parasternal view) in 100 patients (78 +/- 5 years, 65% male) consecutively enrolled in an ongoing prospective study. Aortic stenosis severity was graded as mild (AVA > or = 1.5 cm(2)), moderate (1-1.5 cm(2)), or severe (AVA < 1 cm(2)). Misclassification was defined as at least a one grade difference and DeltaAVA > 0.15 cm(2) (twice the intra-observer variability). Feasibility of the 2D-CWD was 100%, MPG 20 +/- 13 mmHg, and AVA 1.52 +/- 0.45 cm(2). Fifty-three per cent had a mild AS, 34% a moderate AS, and 13% a severe AS. Using the NI-CWD, feasibility was 85%, MPG 25 +/- 16 mmHg, AVA 1.33 +/- 0.41 cm(2) (both P < 0.005 compared with 2D-CWD). Thirty-five per cent (n = 30) had a mild AS, 46% (n = 39) a moderate AS, and 19% (n = 16) a severe AS. Using only the 2D-CWD and the apical view, 21 patients (21%) would have been misclassified: 17 as mild instead of moderate AS and 4 as moderate instead of severe AS. In those misclassified patients, MPG was 9 +/- 6 mmHg higher with the NI-CWD and 33% had an MPG difference >10 mmHg.
Conclusion: The use of the NI-CWD and the right parasternal view must be performed to evaluate AS severity, especially in case of discrepancy between symptoms and AS severity or for precise evaluation of AS progression.