New Information On Afib Stroke Risk And Blood Thinners From The 2016 AF Symposium
At the recent Atrial Fibrillation Symposium, held January 14-16, 2016, in Orlando, I gleaned many interesting nuggets of information about stroke risk and blood thinners from the expert’s presentations. While we already knew some of these things, some are totally new information from research studies and from best practices by top experts and their institutions. Many of these experts are regularly part of the guidelines process, so their opinions are well worth listening to.
When mentioned below, “new blood thinners” (often referred to as NOACs for new/novel oral anticoagulants) refers to the following drugs: Pradaxa (dabigatran), Xarelto (rivaroxaban), Eliquis (apixaban), and Savaysa (edoxaban).
I’m sharing these nuggets as food for thought and for discussion with your doctors, but not as a replacement for your doctor’s advice. As always, please consult your doctor.
- According to recent studies, those with paroxysmal afib have a lower stroke risk than those with persistent afib.
- Getting high blood pressure (hypertension) under control is very important in reducing stroke risk for those with afib.
- Warfarin has a 40-hour half-life, but may be up to 60 hours in some older patients; the new blood thinners have a half-life of 12-17 hours.
- The FDA advised caution in switching among blood thinners, but switching is actually easier on the new oral anticoagulants because startup is so fast on them. Switching from them to warfarin should be undertaken with care.
- One EP has had blood clots resolve in a month with the new blood thinners. In one study, rivaroxaban caused a 60% resolution in six weeks.
- Studies measuring afib using implanted devices, such as pacemakers and implantable loop recorders, have given us more insight into the stroke risk with afib:
- TRENDS Study — having multiple hours of afib doubled the risk of stroke and that increased risk lasted for 30 days.
- ASSERT Study — afib of six minutes or more in the first three months can be a risk factor for strokes as much as a year or more later. It is likely that afib causes a pro-thrombotic (favoring the formation of clots) state that causes strokes long after normal sinus rhythm returns.
- VA CareLink Study — long periods of afib raised the risk of stroke and this study supported the transient use of the new rapidly-acting blood thinners.
- REACT.com is an ongoing study of “pill-in-the-pocket” use of the new blood thinners — patients have an Implantable Loop Recorder (Reveal) and if they have an episode of afib lasting more than one hour, they are to take a blood thinner. This leads to a 94% reduction in blood thinner exposure and there have not been any strokes.
- It is important to note that many of the experts were very concerned about using the new blood thinners as “pill-in-the-pocket” without an implantable loop recorder and under doctor’s supervision; they recommend against doing it outside of this study.
- Should those with just one episode of afib be put on blood thinners? One expert stated that a test called NT-proBNP is a very powerful predictor of stroke risk and can be used as a tie-breaker if a doctor is on the fence as to whether or not to start the patient on blood thinners.
- Adding aspirin to Plavix (clopidogrel) doesn’t decrease strokes, but does increase bleeds. Triple therapy — being on a blood thinner, aspirin, and Plavix (clopidogrel) for stents, all at the same time — leads to a four-fold risk of bleeds. (This is why patients who have to be on blood thinner for afib and Plavix after a stent are often advised to avoid aspirin.)
- Reversal agents for the new blood thinners include:
- Praxbind, for Pradaxa, which was approved by the FDA last year.
- Andexanet alfa, for Xarelto, Eliquis, and Savaysa, is in testing and is expected to be approved this year.
- Ciraparantag, for all of the new blood thinners, is in testing.
- Studies are indicating that bridging with heparin for procedures is dangerous and causes more bleeding; thus, many electrophysiologists on the panel stated that they leave patients on blood thinners for cardioversions and catheter ablation.
- Work at the University of Utah is showing that:
- Left atrial shape, as well as ventricle shape, is starting to provide us with some information for determining stroke risk. While this is really early — much too soon to make judgements from – this gives us insight into some of the research that may yield useful information in the future.
- For those with small amounts of fibrosis (scar tissue in the heart), denoted as a Utah 1 (0%-5% fibrosis) or Utah 2 (5%-20% fibrosis) score, and with certain shapes of atria or ventricles, blood thinners should be continued.
- For those with large amounts of fibrosis, denoted as having a Utah 3 (20%-35% fibrosis) or Utah 4 (more than 35% fibrosis) score, it is important to continue blood thinners regardless of the risk factors or amount of afib.
- Their data shows that 70% of those over age 60 have 15% fibrosis or more, regardless of whether or not they have afib.
- Learn more about fibrosis, Utah scores, and stroke risk at
This blog post reflects the opinion of the author and does not necessarily reflect the opinions of the AHA.