Prof. Bernard Iung,
Appropriate technique and standardized measurements key to accurate assessment of low-gradient aortic stenosis
This joint session with the ESC Working Group on Valvular Heart Disease was dedicated to low- gradient aortic stenosis (AS). Echocardiography plays a key role, but should pay particular attention to potential errors of measurement before concluding as to the association of a mean aortic gradient ≤40 mmHg and a valve area ≤1.0 cm² (or 0.6 cm²/m² body surface area), defining low-gradient severe AS. This highlights the importance of using the appropriate technique and standardized measurements. The potential impact of hypertension and atrial fibrillation on the measurements should also be taken into account.Other imaging techniques should be used when doubts remain regarding the severity of AS or for prognostic assessment. Dobutamine stress echocardiography makes it possible to differentiate between true and pseudo-severe AS when left ventricular ejection fraction is impaired. Flow reserve is a strong incentive for intervention. Recent findings also suggest that dobutamine stress echocardiography may be helpful to confirm the severity of paradoxical low-flow low-gradient AS. The quantitative assessment of aortic calcifications with calcium scoring using computed tomography is a complementary means of assessing the severity of AS.Cardiac magnetic resonance imaging shows more extensive myocardial fibrosis in low-gradient than in conventional high-gradient severe AS, which may have an impact in prognostic assessment. As regards interventions, TAVI seems particularly promising in patients with low gradient AS given their age and the frequency of comorbidities. The lower risk of patient-prosthesis mismatch is also an advantage. However, discrepancies in the results of interventions are incentives to pursue further outcome studies in patients with low-gradient AS.
The low-gradient aortic stenosis
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