JTCVS Open (Dec 2023)

The robustness of the flow-gradient classification of severe aortic stenosisCentral MessagePerspective

  • Bart J.J. Velders, MD,
  • Michiel D. Vriesendorp, MD, PhD,
  • Federico M. Asch, MD,
  • Michael G. Moront, MD,
  • Francois Dagenais, MD,
  • Michael J. Reardon, MD,
  • Joseph F. Sabik III, MD,
  • Rolf H.H. Groenwold, MD, PhD,
  • Robert J.M. Klautz, MD, PhD

Journal volume & issue
Vol. 16
pp. 177 – 188

Abstract

Read online

Objectives: A flow-gradient classification is used to determine the indication for intervention for patients with severe aortic stenosis (AS) with discordant echocardiographic parameters. We investigated the agreement in flow-gradient classification by stroke volume (SV) measurement at the left ventricular outflow tract (LVOT) and at the left ventricle. Methods: Data were used from a prospective cohort study and patients with severe AS (aortic valve area index ≤0.6 cm2/m2) with preserved ejection fraction (>50%) were selected. SV was determined by an echocardiographic core laboratory at the LVOT and by subtracting the 2-dimensional left ventricle end-systolic from the end-diastolic volume (volumetric). Patients were stratified into 4 groups based on SV index (35 mL/m2) and mean gradient (40 mm Hg). The group composition was compared and the agreement between the SV measurements was investigated using regression, correlation, and limits of agreement. In addition, a systematic LVOT diameter overestimation of 1 mm was simulated to study flow-gradient reclassification. Results: Of 1118 patients, 699 were eligible. The group composition changed considerably as agreement on flow state occurred in only 50% of the measurements. LVOT SV was on average 15.1 mL (95% limits of agreement −24.9:55.1 mL) greater than volumetric SV. When a systematic 1-mm LVOT diameter overestimation was introduced, the low-flow groups halved. Conclusions: There was poor agreement in the flow-gradient classification of severe AS as a result of large differences between LVOT and volumetric SV. Furthermore, this classification was sensitive to small measurement errors. These results stress that parameters beyond the flow-gradient classification should be considered to ensure accurate recommendations for intervention.

Keywords