Subclinical Leaflet Thrombosis Post Transcatheter Aortic Valve Replacement – An Update for 2020

ABSTRACT

The treatment of severe symptomatic aortic stenosis has undergone a paradigm shift over the last decade, paralleling the publication of several landmark trials showing efficacy and safety of transcatheter aortic valve replacement (TAVR) as compared to traditional open surgical aortic valve replacement (SAVR) across multiple risk strata. Hypoattenuating leaflet thickening (HALT) is a phenomenon that has been increasingly recognized since 2013. Patients with HALT are most often asymptomatic, have increased transvalvular gradients infrequently, and have overt prosthetic valve thrombosis rarely. HALT develops despite established post-procedure antiplatelet regimens and, in many cases, resolves completely on commencing anticoagulation. There is currently no data to suggest that this incidental imaging finding is associated with adverse clinical outcomes and therefore no current recommendation to perform routine post-TAVR computed tomography. Meanwhile, the use of TAVR is poised to expand into low-risk patients which means that transcatheter heart valve (THV) durability is going to be an increasingly important issue. While we await long-term data from the low-risk TAVR trials to better assess THV durability in this cohort, recent attention has focused on the mechanisms underlying structural valve degeneration (SVD). This review aims to provide an update on HALT and the definition of SVD and how the two entities may impact each other as the field advances.

ABBREVIATIONS: AS: aortic stenosis; BAV: bicuspid aortic valve; CT: computed tomography; DAPT: dual antiplatelet therapy; DVI: Doppler velocity index; EOAi: effective orifice area index; HALT: hypoattenuating leaflet thickening; HAM: hypoattenuation affecting motion; MACCE: major adverse cardiovascular or cerebral event; MG: mean gradient; MPR: multiplanar reconstruction/reformat; OAC: oral anticoagulation therapy; PHV: prosthetic heart valve; RLM/RELM: reduced leaflet motion; SAVR: surgical aortic valve replacement; SAPT: single antiplatelet therapy; SCCT: Society of Cardiovascular Computed Tomography; SVD: structural valve degeneration; TAVR: transcatheter aortic valve replacement; TEE: transesophageal echocardiography; THV: transcatheter heart valve; TIA: transient ischemic attack; TTE: transthoracic echocardiography; VIVID: Valve in Valve International Data

KEYWORDS:

• Hypoattenuating leaflet thickening
• reduced leaflet motion
• transcatheter heat valve durability
• structural valve degeneration
• subclinical leaflet thrombosis

Disclosure statement

RAB, ABR, MT, ALH, PLM, LK, SCT, no declarations. SLS is supported by fellowships from the Canadian Institutes of Health Research and the Michael Smith Foundation for Health Research. PB has served as a consultant for Edwards Lifesciences, Tendyne, Neovasc, Circle Cardiovascular Imaging, and Gore. PB has computed tomography core laboratory contracts with Edwards Lifesciences, Medtronic, Abbott, and Neovasc (no direct compensation). JAL has been a consultant for and holds stock in Circle Cardiovascular Imaging and HeartFlow and provides core lab services for NIH, Edwards Lifesciences, Neovasc, Abbott, and Medtronic. JAL has also been a member of the Speakers Bureau for GE Healthcare and Edwards LifeSciences, received research support from GE Healthcare and grant support from the Canadian Institutes of Health Research (CIHR), National Institutes of Health (NIH), GE Healthcare and HeartFlow. JAL is an associate editor of Structural Heart.

Additional information

Funding

The authors have no funding to report for this paper.