Case Report: Serial 4D-CT evolution from focal leaflet thickening to multileaflet HALT after transcatheter aortic valve replacement in a hemodialysis patient

Background Electrocardiographically gated multiphase cardiac computed tomography (4D-CT) is the reference imaging technique for detecting hypoattenuated leaflet thickening (HALT) and assessing associated leaflet-motion abnormalities after transcatheter aortic valve replacement (TAVR). The significance of an isolated abnormality detected during the first postoperative week remains uncertain. Case description A 51-year-old woman receiving maintenance hemodialysis for 13 years underwent transfemoral TAVR with a 23-mm Edwards SAPIEN 3 valve. A visible prosthetic waist was treated by balloon post-dilatation, reducing the invasive transvalvular gradient from 60 to 1 mmHg. Routine postoperative day-7 ECG-gated 4D-CT, reconstructed in 10 phases across the cardiac cycle, showed focal noncoronary cusp thickening measuring 2.5 mm on short-axis and 2.4 mm on long-axis images, with preserved leaflet motion. The immediate post-TAVR mean gradient was 4 mmHg; the nearest early follow-up examination on postoperative day 6 showed a mean gradient of 11 mmHg and a Doppler velocity index of 0.50. Serial echocardiography subsequently showed progressive hemodynamic deterioration. At approximately 7.5 months, limited-phase ECG-gated CT comprising paired systolic and diastolic reconstructions demonstrated multileaflet HALT with predominant right coronary cusp involvement. The abnormal tissue measured approximately 85 HU, extended 14.7 mm longitudinally, reached a maximal thickness of 3.1 mm, and was associated with an estimated 75% reduction in systolic leaflet excursion. The contemporaneous mean gradient was 25 mmHg and increased to 30 mmHg approximately 3 weeks later. Conclusion This case documents a temporal sequence from an early focal leaflet abnormality with preserved motion to multileaflet HALT, marked motion restriction, and prosthetic valve hemodynamic deterioration. The sequence supports integrated longitudinal assessment but does not establish that the early focal lesion predicted or caused the subsequent HALT.