Thrombus attenuation predicts natural history of hypo-attenuating leaflet thickening after transcatheter aortic valve replacement
Bibliographic record
Abstract
Abstract Background Hypo-attenuating leaflet thickening (HALT) after transcatheter aortic valve replacement (TAVR) occurs in up to 25% of patients and is characterized by diverse temporal dynamics. Several studies investigated the natural history of HALT in transcatheter and surgical cohorts, but little is known about the imaging features of persistent thrombus. Purpose To examine the association of quantitative HALT volume and attenuation from computed tomography angiography (CTA) with its natural history. Methods We prospectively examined patients with HALT present on CTA at 30 days after TAVR and who underwent a follow-up CTA at one year. Hypoattenuation affecting motion (HAM) was defined as the presence of HALT with at least moderately reduced (>50%) leaflet motion. HALT was quantified by segmenting the inner volume of the bioprosthetic frame at the level of the leaflets and extracting voxels between a threshold of -200 to 200 HU. Thrombus volume, mean thrombus attenuation and thrombus heterogeneity measured with standard deviation of attenuation were automatically calculated (Figure 1). Results A total of 37 patients (70% men, 71±7 years old) undergoing TAVR with balloon-expandable SAPIEN3 (86%) and self-expanding EVOLUT (14%) valves were evaluated. Hypoattenuation affecting motion (HAM) at 30 days after TAVR was present in 29 (74%) patients. Patients with HAM had higher thrombus volume than patients without reduced leaflet motion (0.40cm3 [IQR 0.16 – 0.61cm3] vs 0.14 [IQR 0.06 – 0.19 cm3], p=0.009) but comparable mean attenuation values (145HU [IQR 141-151HU] vs 123 [IQR 114 – 141HU], p=0.079). Only 3 patients were switched to oral anticoagulation following HALT detection. At one year, HALT resolution was observed in 18/37 (48%) and HAM resolution in 19/29 (65%). No difference in quantitative thrombus features was noted between patients with persistent and resolved HALT. Notably, patients with persistent HAM had higher mean thrombus attenuation (141HU [IQR 123-156HU] vs 123HU [IQR 110 – 138 HU), p=0.045; Figure 2) and thrombus heterogeneity (58HU [IQR 51-63HU] vs 48HU [IQR 41- 54HU], p=0.021) than resolved HAM. Mean thrombus attenuation (area under the curve of 0.732, p=0.044) and thrombus heterogeneity (area under the curve of 0.763, p=0.022) were predictive of HAM resolution at one year. The optimal cutoff values as determined by Youden index was 140HU for mean attenuation and 52HU for heterogeneity. There was an increase in the mean transvalvular gradients between measurements at 30 days and one year in patients with persistent HAM as compared to patients with HAM resolution (Δ3mmHg [IQR -3 – 11mmHg] vs Δ-1mmHg [IQR -4 – 0mmHg], p=0.049). The volume of thrombus at one year was associated with the magnitude of change in transvalvular gradients (β = 10.3, 95% CI 1.6- 19.0, p=0.025). Conclusion Quantitative evaluation of HALT by CTA may aid the identification of patients at risk of persistent thrombus.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.003 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".