Daniel Singer, MD: The GUARD-AF Intent

Being that atrial fibrillation is both highly common in older patients and the most significant risk factor for stroke, it’s critical for physicians to know where the most at-risk patients persist. The GUARD-AF trial will seek that clarity.

The new 52,000-patient screening trial, announced last week during the American Heart Association (AHA) 2019 Scientific Sessions in Philadelphia, will look to provide evidence which will dictate federal advisory on atrial fibrillation-risk screening in certain patients.

In an interview with MD Magazine® while at AHA 2019, Daniel Singer, MD, professor of Medicine at Harvard Medical School and an internist with Massachusetts General Hospital, introduced the details and reasoning of the GUARD-AF trial.

MD Mag: What is the design and intent of the GUARD-AF trial?

Singer: I'm pleased to present to you our plans for GUARD-AF. It is a randomized trial, a very large, pragmatic, randomized trial testing whether the screening for atrial fibrillation in older individuals leads to a reduction in stroke.

MD Mag: How will the study seek its endpoint?

Singer: Let me give you some background. Atrial fibrillation is the most common, significant rhythm disorder. Its frequency is strongly age-dependent, so that by the time you look at people who are 80 or older, 10% have diagnosed atrial fibrillation.

Atrial fibrillation is also the strongest common risk factor for stroke. It increases the risk of ischemic stroke five-fold. The good news is that anti-coagulation largely prevents the stroke risk that's attributable to atrial fibrillation.

Additional good news is that newer anti-coagulants—so-called NOACs or DOACs—add a measure of safety over the older anticoagulant warfarin. The problem is there are lots of people out there who have undiagnosed atrial fibrillation, and sometimes they present with a stroke—and that's when they get their diagnose of AF.

Presumably, if we had identified them earlier, we could've put them on anticoagulants and prevented that stroke. That all makes sense. And there's no question you could use a number of modalities to screen for atrial fibrillation, and you could find it, particularly in older individuals—older than 65, older than 75.

The key issue is whether you can reduce stroke risk. One of the important motivations is that the United States Preventive Services Task Force has actually held off approving or recommending screening for atrial fibrillation in older individuals until there's clear evidence that it reduces stroke risk.

As a screening study, it takes very large studies to demonstrate a reduction in clinical endpoints. This is true for mammography, it's true for colonoscopy, it's true for screening for atrial fibrillation.

So, we're engaging in a very large study. It's 52,000 people, 26,000 randomized to usual care, 26,000 get randomized to use of a 14-day continuous-monitoring patch. And we look at that patch, and see if there's atrial fibrillation on that patch, and then we tell the referring physician that his or her patient has atrial fibrillation.

Then, we give them some guidance about the use of anticoagulants, but fundamentally, the decision is up to the physician and patient to discuss it. This is not a drug trial, it's a screening trial.

But of course, you don't get any benefit if all you do is identify atrial fibrillation. You have to identify atrial fibrillation, make a judgement about the risks and benefits, and in those ways in which you think it's going to benefit, prescribe anticoagulants, and have the patients take anticoagulants.