Key result
Switching VKA-experienced AF patients to dabigatran is linked to ~61% higher ischemic stroke risk.
Why the study?
A substantial proportion of atrial fibrillation patients initiating DOACs are VKA-experienced, prompting a need to evaluate the effectiveness and safety of DOACs versus VKAs in this real-life population.
Does switching to DOACs from VKA affect the risk of arterial thromboembolism and bleeding in VKA-experienced atrial fibrillation patients?
Meta-Analysis
Does switching to DOACs from VKA affect the risk of arterial thromboembolism and bleeding in VKA-experienced atrial fibrillation patients?
Effect estimate: aHR 1.61 (95% CI 1.19-2.19)
Switching from VKA to dabigatran in real-world AF patients is associated with increased risks of ischemic stroke, MI, and GI bleeding, though this is likely confounded by the clinical reasons prompting the switch.
May warrant caution switching VKA-experienced AF patients to dabigatran; leaves open confounding and need for randomized confirmation.
A substantial proportion of atrial fibrillation patients initiating direct oral anticoagulants (DOAC) are vitamin K antagonists (VKA)‐experienced, for example switchers from VKA to DOAC. With this study, we aimed to summarize available evidence on the effectiveness and safety of DOAC vs VKA in real‐life VKA‐experienced atrial fibrillation patients. We searched EMBASE, MEDLINE and Cochrane Library systematically for English‐language studies indexed any time before October 2018. We included studies of VKA‐experienced atrial fibrillation patients initiating DOAC therapy, with continued VKA therapy as comparator. Outcomes included arterial thromboembolism and bleeding. When appropriate, meta‐analysis was performed by calculating pooled, weighted and adjusted hazard ratios (aHR) with 95% confidence intervals (CI). Eight cohort studies comparing VKA‐experienced DOAC (dabigatran or rivaroxaban) users with continued VKA users were included. When comparing DOAC to VKA, an increased risk of ischaemic stroke and myocardial infarction was found for dabigatran (pooled aHR of 1.61 [95% CI 1.19‐2.19, I 2 = 65%] and 1.29 [95% CI 1.10‐1.52, I 2 = 0%], respectively), but not for rivaroxaban. The use of dabigatran in VKA‐experienced users was associated with an increased risk of gastrointestinal bleeding (pooled aHR 1.63 [95% CI 1.36‐1.94, I 2 = 30%]), but a decreased risk of intracranial bleeding (pooled aHR 0.45 [95% CI 0.32‐0.64, I 2 = 0%]). In conclusion, the use of dabigatran in prior VKA users in clinical practice was associated with a slightly increased risk of arterial thromboembolism and gastrointestinal bleeding, but a decreased risk of intracranial bleeding. Importantly, observational studies of real‐life VKA‐experienced oral anticoagulant users may be confounded by the reason for switching.
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Hellfritzsch et al. (2019) conducted a meta-analysis in Atrial fibrillation. DOAC (dabigatran or rivaroxaban) vs. Continued VKA therapy was evaluated on Ischaemic stroke (dabigatran vs VKA) (aHR 1.61, 95% CI 1.19-2.19). Switching to dabigatran in VKA-experienced atrial fibrillation patients was associated with an increased risk of ischaemic stroke (aHR 1.61; 95% CI 1.19-2.19) compared to continued VKA use.
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