Vitamin K antagonists may be best treatment option in thrombotic antiphospholipid syndrome
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CHICAGO — In patients with thrombotic antiphospholipid syndrome, vitamin K antagonists were linked to lower odds of arterial thrombotic events compared with direct oral anticoagulants, according to a meta-analysis.
Behnood Bikdeli, MD, MS, instructor in medicine at Harvard Medical School and an associate physician at the division of cardiovascular medicine at Brigham and Women’s Hospital, and colleagues conducted a meta-analysis of four open-label randomized trials of patients with thrombotic antiphospholipid syndrome (APS) comparing outcomes between vitamin K antagonists and direct oral anticoagulants (DOACs). The results were presented at the American Heart Association Scientific Sessions and simultaneously published in the Journal of the American College of Cardiology.
“Direct oral anticoagulants are now widely used for treatment of venous thromboembolism and other forms of thrombotic diseases,” Bikdeli told Healio. “However, there were uncertainties about their efficacy and safety in patients with APS, a condition that is associated with excess risk of recurrent thrombotic events. Individual randomized trials were relatively small and were unable to provide clear signals about presence or absence of risk.”
The analysis included 472 patients (mean age, 48 years; 68% women; 56.5% with triple-positive thrombotic APS) who had a mean time in therapeutic range of 60%. Mean follow-up was 19 months.
The first primary efficacy endpoint of arterial thrombotic events occurred more frequently in patients assigned DOACs than in patients assigned vitamin K antagonists (10.3% vs. 1.3%; OR = 5.43; 95% CI, 1.87-15.75; P < .001; I2 = 0%), driven by stroke (8.6% vs. 0%; OR = 10.74; 95% CI, 2.29-50.38; P < .001; I2 = 0%), the researchers found.
The second primary efficacy endpoint of VTE did not differ between the groups (DOACs, 1.7%; vitamin K antagonists, 1.3%; OR = 1.2; 95% CI, 0.31-4.55; P = .79; I2 = 0%), nor did the primary safety endpoint of major bleeding (DOACs, 4.3%; vitamin K antagonists, 4.2%; OR = 1.02; 95% CI, 0.42-2.47; P = .97; I2 = 0%), according to the researchers.
The composite of arterial thrombotic events or VTE occurred more often in the DOAC group (11.5% vs. 2.5%; OR = 4.46; 95% CI, 1.12-17.84; P = .03; I2 = 0%), Bikdeli and colleagues found.
There were no differences between the groups in MI, major acute limb events, pulmonary embolism, deep vein thrombosis or clinically relevant nonmajor bleeding.
“We learned that, compared with vitamin K antagonists, DOACs were associated with clinically meaningful and statistically significant risk of subsequent arterial thrombotic events, largely driven by excess risk of stroke. Considering these results, I believe that vitamin K antagonists (or, in the right setting, low-molecular-weight heparins) would be preferred for management of patients with thrombotic APS,” Bikdeli told Healio. “DOACs have shown a lot of promise and have been a very important class of drugs for prevention or treatment of thrombotic diseases. However, we have now seen several conditions (mechanical valves, thrombotic APS and others), in which they have been inferior to vitamin K antagonists. So, I believe the nuances of thrombosis and hemostasis should not be underestimated. Finding the right treatment for the right patient is more complex than ‘thinning the blood.’”
In a related editorial published in JACC, Mark A. Crowther, MD, chair of the department of medicine at McMaster University, Hamilton, Ontario, Canada, and colleagues wrote that “Why DOACs are less effective than VKAs in certain circumstances (but superior in others) requires further explanation but may include the fact that in patients at higher risk of thrombosis, targeted inhibition of a single clotting factor may not be sufficient to provide adequate suppression of the clotting factor cascade.”
References:
- Crowther MA, et al. J Am Coll Cardiol. 2022;doi:10.1016/j.jacc.2022.10.015.
- Khairani CD, et al. J Am Coll Cardiol. 2022;doi:10.1016/j.jacc.2022.10.008.
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Bejjani A, et al. Abstract MO4219. Presented at: American Heart Association Scientific Sessions; Nov. 5-7, 2022; Chicago (hybrid meeting).
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