Use of Apixaban and Post TAVR Valve Thrombosis

TAVR can be associated to early valve thrombosis, characterized by thrombi formation near or attached to the prosthetic valve, with or without valve dysfunction. This dysfunction is associated with increased leaf thickening and reduced leaflet motion, as well as reduced orifice area or increased transvalvular gradient. Triggered multislice CT allows dynamic valve assessment and thrombosis vs fibrosis differentiation.

Subclinical thrombosis detected by CT is characterized by hypoattenuated leaflet thickening (HALT) and reduced leaflet motion (RLM). This phenomenon can be identified in 10% to 30% of patients, and some studies have linked subclinical thrombosis to thromboembolic events. Registries such as the GALILEO (Global Study Comparing a Rivaroxaban-Based Antithrombotic Strategy to an Antiplatelet-Based Strategy After Transcatheter Aortic Valve Replacement to Optimize Clinical Outcomes) and ATLANTIS (Anti-Thrombotic Strategy to Lower All Cardiovascular and Neurologic Ischemic and Hemorrhagic Events after Trans-Aortic Valve Replacement for Aortic Stenosis) suggest the potential use of anticoagulants to prevent subclinical thrombosis.

The ATLANTIS multicenter and randomized study, compared the use of apixaban vs standard of care after TAVR. The substudy ATLANTIS-4D-CT aimed at assessing subclinical obstructive thrombosis incidence at 90 days, its link to clinical events at 1 year and therapy effect.

Primary end point was the presence of at least one leaflet with motion reduction grade III or IV, defined as moderate and severe dysfunction. Secondary end point was thrombus presence and mean valve are measured by 4D mapping, in addition to ischemic events at one year.

Read also: Intramural Hematoma.

Of 762 patients undergoing 4D CT, 370 received Apixaban and 392 were treated with standard of care. Patients were mostly women, mean age 82.

Primary end point occurred in 13% of patients receiving standard of care vs. 8.9% in the Apixaban group. The use of Apixaban significantly reduced the percentage of patients with marked dysfunction vs. standard of care (1.4% vs. 7.1%). Apixaban also reduced grade III or IV RLM or HALT in 49% in patients with no anticoagulation indication, with no differences vs patients with anticoagulation indication. There were no differences in secondary end point.

Conclusion

The use of Apixaban as antithrombotic strategy after TAVR reduces the risk of valve thrombosis in patients with no anticoagulation indication in the long run, with no increase in thromboembolic events or bleeding. However, we should not interpret these outcomes lightly because of the substudy’s design. Further research is necessary to assess the use of low doses of Apixaban in low risk populations.