What exactly is the definition of "valvular" atrial fibrillation?
This comes up not infrequently for me as we are discussing A/C options for stroke prevention in patients with mitral valve disease. So, I wanted to better understand the primary literature using this term.
I started with the AHA/ACC/ACCP/HRS 2023 guidelines on afib, which actually state that the term is obsolete and shouldn't be used anymore, and that previous studies excluded patients with mostly moderate and severe mitral stenosis (and prosthetic valves). They also state it's a Class I guideline to use DOACs over warfarin except in cases of moderate/severe mitral stenosis and mechanical valves.
I then dove into the primary ARISTOTLE and ROCKET-AF trials, both of which list significant mitral stenosis as an exclusion criteria. But, we don't know anything about how many of these patients had mild mitral stenosis or rheumatically-mediated mitral regurgitation.
There's a decent JACC article from 2019 that talks about the real world practice of using DOACs in patients with mitral stenosis. It's a study from Korea so maybe external validity is limited but they looked at patients with any degree of mitral stenosis who had afib and received A/C for at least three weeks, and propensity score matched them between warfarin and a DOAC. Initially, they found that about a quarter of these patients got a DOAC, and three quarters warfarin. The propensity score matched groups were similar in terms of baseline characteristics.
They found that the risk of stroke and death was lower in patients receiving a DOAC, with no significant difference in bleeding risk.
Figure 2. Kaplan-Meier Curves of the Primary Efficacy and Safety Outcomes (Warfarin vs. DOAC)
I found a lot of good points in this study and am attaching it so you can read the whole thing. In addition to the pathophys discussion, the authors point out that some studies of patients with afib on warfarin show a time in therapeutic range of only 25-31%, compared to the usual ~60%. This low range may be the reason we see the difference that we do; it also makes me think these patients are perhaps not so different from ours at Grady.
A major limiting factor in this retrospective review is we don't know about the specific degrees of mitral stenosis. I would have found that really helpful. Still, overall, this data makes me feel better than I did before about the idea of using a DOAC in a patient with mitral stenosis.
Lastly, I read a pharmacology review on off-label use of DOACs, which cited several post-hoc studies showing comparable rates of prevention between DOACs and warfarin in patients with varying degrees of mitral stenosis, other valvular heart disease, and bioprosthetic valves.
I have traditionally avoided using DOACs even for mild mitral stenosis if I thought the etiology was rheumatic. Going forward, I'm going to stop using the term "valvular afib," and I'll have a more nuanced conversation with my patients with mitral stenosis about the role of DOACs in their care plan.
Joglar JA, Chung MK, Armbruster AL, et al. 2023 ACC/AHA/ACCP/HRS guideline for the diagnosis and management of atrial fibrillation: A report of the American College of Cardiology/American Heart Association Joint Committee on clinical practice guidelines. Circulation2023;149(1). doi:10.1161/CIR.0000000000001193
Kim JY, Kim SH, Myong JP, et al. Outcomes of Direct Oral Anticoagulants in Patients With Mitral Stenosis. Journal of the American College of Cardiology2019;73(10):1123-1131. doi:10.1016/j.jacc.2018.12.047
