Top 3 Atrial Fibrillation Studies in 2018

Payal Kohli, MD, FACC

Figure. AF scoring sytem. A-Hamid I, et al. JACC. 2018;71:A334 (click to enlarge)

Every year, during the holidays, I look back on the new discoveries and developments in the world of atrial fibrillation and I am always impressed at all the ways in which our clinical practice continues to evolve as a result of these breakthroughs. This year, I selected three examples of that progress that I have written about for Patient Care; I offer highlights of the results and my commentary on why I believe they are so meaningful.

#1. Antidote for Factor Xa inhibitors: Approved

Perhaps the biggest and most clinically relevant breakthrough in the world of atrial fibrillation (AF) this year was the FDA approval in May 2018 of Andexxa (andexanet alfa) for the reversal of apixaban and rivaroxaban in situations of life-threatening or uncontrolled bleeding.

As we have seen time and time again, oral anticoagulation is underused in AF. Warfarin use is hampered by drug-drug interactions, dietary cautions, and difficult dose titration. Despite their lower risk of bleeding and favorable efficacy profile, there has been dramatic underutilization of the direct oral anticoagulants (DOACs), including the direct factor Xa inhibitors. Part of this low uptake has been the fear and concern (among both patients and providers) about the lack of a reversal agent for these drugs in life-threatening situations. We hope the approval of this antidote will shift the needle favorably towards greater use of these drugs and help allay fear and anxiety among patients with AF who have to take lifelong oral anticoagulation.

So what’s the next challenge for 2019?  Getting providers comfortable with the use of andexanet alfa and lowering its cost to make it more accessible.

Next: CABANA

#2. The CABANA Trial and Ablation Complications: Proceed with Caution.

In an era where catheter-based interventions have completely altered the landscape of cardiology disease management, the world of AF management has kept pace. One of the biggest game-changers in 2018 was the randomized CABANA (Catheter Ablation versus Antiarrhythmic Drug Therapy for Atrial Fibrillation) trial, which showed for the first time that AF ablation is a safe alternative to pharmacologic management of AF, and potentially even superior in certain patients types (ie,  younger patients and those with heart failure).

But beware if you are an “early adopter.” There were some concerns about conclusions drawn from the intention-to-treat analysis vs the on-treatment analysis. And, of course there are studies out there that have highlighted the relatively high rate of ablation complications in “real world” settings outside of high-volume clinical trial centers. Time will tell.

Next: A2FIBS2+PAF+0.8?

#3. New AF Scoring System: Really  New or Just Different? 

At the American College of Cardiology 2018 Scientific Sessions, researchers presented a new scoring system for AF (see Figure; please click to enlarge) that was developed to address many of the limitations inherent in the now widely used CHA₂DS2-Vasc risk calculator. I found the proposal of a new risk stratification rule of note this year for several reasons. First, it highlights the ongoing challenge of getting risk stratification right in the management of AF. One of the attractions of CHA₂DS₂ and then the CHA₂DS₂-Vasc when it was introduced was the streamlined approach to predicting thromboembolic risk in AF and determining whether oral anticoagulants should be used. But it has become clear that it may be an oversimplified approach. It doesn’t always perform optimally and has many limitations, especially at the extremes of risk (very low or very high risk). Are all patients with similar CHA₂DS₂-Vasc scores created equal? For example, is a score of 3 based on patient age and female gender equivalent to a score of 3 that reflects prior stroke and congestive heart failure? Most clinicians would instinctively stratify the latter into a higher risk category.

Second, the new formula highlights the strong desire in medicine to develop scoring systems for assessment of risk and application of guideline-based therapies ie, CHA₂DS₂-Vasc, HAS-BLED, ASCVD risk, STS risk, and the list goes on.

Finally, I found it interesting that the proposed new system uses the same components of the CHA₂DS₂-Vasc score and yet touts itself as easier to use because there is no table (or memorization of same) needed to assess risk. My take?  It’s a little too complicated with the multiple acronyms and the 0.8 at the end (A2FIBS2+PAF+0.8). What do you think?

For more information on these studies:

Antidote for Factor Xa Inhibitors: Approved

New Afib Scoring System: Is it New or Just Different?

The CABANA Trial in AF: A Quiz and a Practice Question

Ablation Complications: Proceed with Caution