21 Oct 20. Featured Paper

Link to paper on Heart

Authors

Mhairi Katrina Doris, William Jenkins, Philip Robson, Tania Pawade, Jack Patrick Andrews, Rong Bing, Timothy Cartlidge, Anoop Shah, Alice Pickering, Michelle Claire Williams, Zahi A Fayad, Audrey White, Edwin JR van Beek, David E Newby, Marc R Dweck

Abstract

Objective: CT quantification of aortic valve calcification (CT-AVC) is useful in the assessment of aortic stenosis severity.

Our objective was to assess its ability to track aortic stenosis progression compared with echocardiography.

Methods: Subjects were recruited in two cohorts: (1) a reproducibility cohort where patients underwent repeat CT-AVC or echocardiography within 4 weeks & (2) a disease progression cohort where patients underwent annual CT-AVC &/or echocardiography.

Cohen’s d-statistic (d) was computed from the ratio of annualised progression & measurement repeatability & used to estimate group sizes required to detect annualised changes in CT-AVC & echocardiography.

Results: A total of 33 (age 71±8) & 81 participants (age 72±8) were recruited to the reproducibility & progression cohorts, respectively.

Ten CT scans (16%) were excluded from the progression cohort due to non-diagnostic image quality.

Scan-rescan reproducibility was excellent for CT-AVC (limits of agreement −12% to 10 %, intraclass correlation (ICC) 0.99), peak velocity (−7% to +17%; ICC 0.92) mean gradient (−25% to 27%, ICC 0.96) & dimensionless index (−11% to +15%; ICC 0.98).

Repeat measurements of aortic valve area (AVA) were less reliable (−44% to +28%, ICC 0.85).

CT-AVC progressed by 152 (65–375) AU/year.

For echocardiography, the median annual change in peak velocity was 0.1 (0.0–0.3) m/s/year, mean gradient 2 (0–4) mm Hg/year & AVA −0.1 (−0.2–0.0) cm²/year.

Cohen’s d-statistic was more than double for CT-AVC (d=3.12) than each echocardiographic measure (peak velocity d=0.71 ; mean gradient d=0.66; AVA d=0.59, dimensionless index d=1.41).

Conclusion: CT-AVC is reproducible & demonstrates larger increases over time normalised to measurement repeatability compared with echocardiographic measures.

Keywords

• Aortic stenosis
• Computed tomography (CT)
• CT quantification of aortic valve calcification (CT-AVC)
• Echocardiography