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Study Summary

The ATLANTIS trial was a multicenter, prospective, open-label, randomized, controlled trial comparing the blood thinner apixaban 5mg bid to standard of care among patients undergoing transcatheter aortic valve implantation (TAVI). The study enrolled 1500 patients who underwent TAVI in four countries between 2016-2019. The patients were subdivided into two strata following TAVI: those requiring anticoagulation were randomized 1:1 between a vitamin K antagonist (VKA) and apixaban (stratum 1) and those without indications for anticoagulation were randomized 1:1 between dual or single antiplatelet therapy and apixaban (stratum 2). At one year, there was no significant difference in the primary end point (a composite of all-cause death, stroke, myocardial infarction, valve thrombosis, deep vein thrombosis, embolism, or major bleeding), occurring in 18.4% of patients assigned to apixaban compared to 20.1% of patients assigned to standard care (HR 0.92, CI 0.73-1.16; see accompanying Hurst’s Central Illustration). However, post-hoc analysis showed that, among patients without indications for anticoagulation, apixaban resulted in higher noncardiovascular mortality compared to antiplatelet therapy (2.7% versus 1.0%, HR 2.99, 95% CI 1.07-8.35) and reduced valve thrombosis (1.1% versus 6.1%, HR 0.19, 95% CI 0.08-0.47).

Commentary

Study Strengths: The study was carried out across 50 sites and randomized patients in a balanced fashion with regards to age, gender, underlying cardiac co-morbidities, and TAVI type. Sub-stratification according to need for anticoagulation or antiplatelet therapy enabled additional cross-comparison with apixaban.

Study Limitations: The open-label nature of the trial predisposes to reporting and ascertainment biases, which were minimized with adjudication by an independent, blinded clinical events committee. The follow-up period of 1 year was relatively short.

Next Steps/Clinical Perspective: The results of ATLANTIS suggest that while apixaban is not superior to standard of care with either VKA or antiplatelet therapy following TAVI, it may be considered in lieu of VKA among patients with indications for long-term anticoagulation. In addition, apixaban reduced the rate of subclinical valve thrombosis (1.1% versus 4.7%, P <0.05), driven primarily by the stratum of patients that did not require anticoagulation (8.7% versus 15.9%, P = 0.011). This group may warrant further monitoring. The signal of noncardiovascular mortality observed in the subset of patients on apixaban not requiring anticoagulation was similar to that observed in GALILEO, which utilized low-dose rivaroxaban following TAVI. Longer term follow-up results should be evaluated to reassess primary and secondary outcomes.

Trial Reference

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Oral anti-Xa anticoagulation after trans-aortic valve implantation for aortic stenosis: the randomized ATLANTIS trial. Presented by Dr. Jean-Philippe Collet at the American College of Cardiology 2021 Scientific Sessions, May 15, 2021.

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