Obstructive Hypoattenuated Leaflet Thickening in a Complex Valve-in-Valve TAVR Successfully Treated With Thrombolysis

BACKGROUND: Hypoattenuated leaflet thickening (HALT) is an important cause of bioprosthetic valve dysfunction after transcatheter aortic valve replacement. CASE SUMMARY: A woman in her mid-70s developed 1 week of exertional dyspnea and chest tightness 5 years after a complicated transcatheter aortic valve replacement in which a migrated 26-mm Medtronic Evolut PRO+ valve was snared into the distal ascending aorta, and a second 26-mm Evolut PRO+ valve was placed across the annulus. Echocardiography showed severe prosthetic valve obstruction, and computed tomography angiography revealed overlapping frames with leaflet hypoattenuation consistent with HALT. She received ultraslow, low-dose alteplase over 48 hours, followed by apixaban, resulting in marked improvement (mean gradient decreased from 66 to 28 mm Hg). DISCUSSION: Although HALT may resemble structural valve degeneration, it can respond well to medical therapy in selected patients with high procedural risk. TAKE-HOME MESSAGE: Ultraslow, low-dose thrombolysis followed by anticoagulation can safely restore function in obstructive HALT when reoperation is prohibitive.