Leaflet Immobility and Thrombosis in Transcatheter Aortic Valve Replacement

Arnold C. T. Ng; David R. Holmes; Michael J. Mack; Victoria Delgado; Raj Makkar; Philipp Blanke; Jonathon A. Leipsic; Martin B. Leon; Jeroen J. Bax

Disclosures

Eur Heart J. 2020;41(33):3184-3197. 

In This Article

Future Directions

Based on the current evidence, the diagnosis and management of THV thrombosis should be based on the combined anatomic (i.e. the presence of HALT with or without RLM on 4D MDCT), functional (i.e. transvalvular gradients on echocardiography), and clinical evaluation of patient's symptoms (e.g. dyspnoea from severe stenosis, patient–prosthesis mismatch, or thromboembolism) as shown in Take home figure. However, there are several questions on THV thrombosis that need to be answered in future research. The current foremost research question is the unclear clinical significance/implications of subclinical THV thrombosis. If it is not associated with increased adverse outcomes such as heart failure, thromboembolism, or death compared with controls, there will be no clinical indication for regular surveillance or treatment. It is likely that the current absence of clinical outcomes associated with subclinical THV thrombosis is due to the small number of patients in studies and the short duration of follow-up. Alternatively, thrombosis may be part of the natural healing response after TAVR without clinical sequalae in majority of patients. If future research suggests that regular surveillance is required, the variable natural history of THV thrombosis may entail regular echocardiography instead of 4D MDCT be used to detect haemodynamically severe and symptomatic valvular obstruction without the risks of repeated radiation exposure. However, the frequency and duration of periodic surveillance is unknown. Finally, the optimal type (anticoagulation vs. antiplatelet) and duration of therapy after TAVR is also unknown. As before, routine indiscriminate use of anticoagulation in all TAVR patients is likely inappropriate and anticoagulation should probably only be given to patients with symptomatic THV thrombosis (e.g. dyspnoea from severe stenosis or severe patient–prosthesis mismatch, or evidence of thromboembolism) or pre-existing indications. Some of these research questions may be potentially answered by several upcoming clinical trials. For example, the DAPT vs. Oral Anticoagulation for a Short Time to Prevent Cerebral Embolism After TAVI (AUREA) (NCT01642134) trial will compare DAPT against VKA. The Anti-Thrombotic Strategy After Trans-Aortic Valve Implantation for Aortic Stenosis (ATLANTIS) (NCT02664649) trial aims to demonstrate the superiority of monotherapy anticoagulation with Apixaban 5 mg twice daily compared with either VKA or DAPT. Finally, the Edoxaban Compared to Standard Care After Heart Valve Replacement Using a Catheter in Patients With Atrial Fibrillation (ENVISAGE-TAVI AF) (NCT02943785) trial compares Edoxaban vs. VKA in TAVR patients with atrial fibrillation. Since TAVR is increasingly utilized in lower-risk patients, it is of upmost importance to answer these clinical questions.

Take home figure.

Recommended flow chart for clinical decision-making for the diagnosis and treatment of transcatheter heart valve thrombosis. 4D, four-dimensional; HALT, hypoattenuated leaflet thickening; MDCT, multidetector computed tomography; NOAC, non-vitamin K oral anticoagulants; RLM, reduced leaflet motion; TTE, transthoracic echocardiography; VKA, vitamin K antagonist.

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