{
  "abstract": "Introduction Symptomatic severe aortic stenosis (AS) carries high mortality, requiring timely intervention. Discordant echocardiogram findings occur in ~33% cases. While CT aortic valve calcification is prognostic, it lacks correlation with aortic valve area (AVA), particularly in fibrotic disease. CT derived geometric AVA (CT-GOA) lacks specificity for severe AS raising concern that CT may underestimate stenosis severity. We examined the relationship between CT-GOA and continuity equation derived echocardiographic Effective orifice area (CE-EOA) using the contraction coefficient (CC), a concept from the Gorlin equation, assessing its value across flow states and whether variation meaningfully alters CT-GOA thresholds.Methods A retrospective cohort study of 106 symptomatic patients with possible severe AS was stratified by flow state: Normal Flow High Gradient (NF HG, n=69) and Low Flow Low Gradient (LFLG, n=17; 15 classical, 2 paradoxical). Bicuspid valves (n=7) were excluded. Mixed aortic valve disease patients were included (n=13). CE-EOA and CT-GOA were used. CC was calculated as CE-EOA/CT-GOA. Mann–Whitney U tests compared flow state groups.Results Median age was 81 [IQR: 77–85]; 72% male. CE-EOA was lower than CT-GOA (0.71 [0.62–0.88] vs 0.98 [0.80–1.24] cm2), consistent with prior studies. Overall EOA–GOA correlation was modest (Spearman’s rho=0.31, p=0.007). When stratified by flow state, correlation was moderate in low flow (rho=0.47) and weak in normal flow (rho=0.27). Neither GOA nor EOA differed significantly between flow states (p=0.296 and p=0.650 respectively). Median CC was 0.73 [0.59–0.88] overall, lower in low flow at 0.70 [0.61–0.83] versus 0.77 [0.63–0.91] in normal flow, with no significant difference (p=0.590) (figure 1).Conclusion CC values were comparable to prior studies. Neither CC nor GOA differed significantly between flow states. CT AVA as a geometric orifice area remains a useful tool for assessing AS severity across flow states. A 82-year-old male with symptomatic low-flow, low-gradient (LFLG) aortic stenosis undergoes multi-modality imaging. Transthoracic echocardiography (TTE) demonstrates a Continuity Equation Effective Orifice Area (CE-EOA) of 0.70cm2, while CT-derived Geometric Orifice Area (CT-GOA) is measured at 0.95cm2. Based on contemporary literature and the concept of the Contraction Coefficient (CC), which of the following statements best describes the relationship between these two parameters across different flow states?A) The discrepancy is likely due to CT overestimating the anatomical orifice in low-flow states compared to high-gradient states.B) The Contraction Coefficient (EOA/GOA) typically ranges between 0.7 and 0.8 and remains relatively stable regardless of whether the patient is in a high-flow or low-flow state.C) A CC of 0.73 indicates significant fibrotic disease where CT calcium scoring would be expected to correlate strongly with the EOA.Abstract 5 Figure 1D) The CT-GOA should be considered the ‘true’ physiological area, and a value of 0.95cm2 confirms that the stenosis is moderate, regardless of the EOA findings",
  "authors": [
    {
      "affiliations": [
        "University Hospitals Coventry and Warwickshire"
      ],
      "name": "Syed Rizwan Ali"
    },
    {
      "affiliations": [
        "University Hospitals Coventry and Warwickshire"
      ],
      "name": "Uzma Gul"
    }
  ],
  "title": "5 Geometric orifice area by CT planimetry across aortic stenosis flow phenotypes",
  "uid": "2cc6c028-1b59-5db5-88c0-91f476c2422f"
}