Objectives The purpose of this study was to compare the diagnostic impact of stress echocardiography (SE) in patients with suspected low-flow low-gradient aortic stenosis (LFLGAS) but normal resting transvalvular flow rate.
Background SE may help to distinguish between true LFLGAS, and pseudo severe stenosis in patients with low aortic valve area (AVA) and mean gradient (MG). However, if rest flow rate is normal then SE may not confer any additional diagnostic value, irrespective of resting left ventricular ejection fraction (LVEF) and indexed stroke volume (SVi).
Methods Thirty-nine patients with suspected LFLGAS who underwent SE in a single institution were retrospectively studied. Following stratification by rest LVEF, SVi and flow rate – using cut-offs of 40%, 35 ml/m2 and 200 ml/sec respectively – we tested for significant changes in AVA during SE.
Results Mean age was 77 ± 8 years and 72% were male. Mean values for rest variables were: AVA 0.79 ± 0.13 cm2; MG 26 ± 6 mmHg; flow rate 186 ± 37 ml/s; SVi 33 ± 8 ml/m2 and LVEF 44 ± 15%. During stress, significant increases in AVA were observed regardless of resting LVEF and SVi status, and only in patients with low rest flow rate. In patients with rest flow rate >200 ml/s, AVA did not increase significantly during stress (rest AVA 0.90 cm2 vs stress 0.97 cm2, p = 0.11). In adjusted analyses, rest flow rate was the only parameter associated with severe AS (OR=0.94, p = 0.01).
Conclusions Rest AVA measured under normal flow rate conditions is likely to reflect the true severity of AS – and unlikely to change significantly with SE. Flow rate normalisation during stress may only be required in patients with AVA < 1 cm2 and transvalvular mean gradient < 40 mmHg when the flow rate is <200 ml/s.
- stress echocardiography
- flow rate
- aortic stenosis
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