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“Silent” atrial fibrillation – New epidemic or unfounded fear?

Atrial fibrillation, also known as “afib” or “AF,” is a heart condition in which the upper chambers of the heart beat irregularly. AF can cause shortness of breath, fatigue, and nausea in the short term, but is also associated with serious complications such as cardiac arrest, stroke, and death.

As detection technology has improved, we are diagnosing more cases of asymptomatic AF incidentally, leading some to recommend “opportunistic” screening for older people at high risk for AF. The idea is that identifying cases of asymptomatic AF can lead to more people given preventive treatment for strokes. 

A randomized controlled trial published in JAMA this month found that patients with high risk for AF were diagnosed with significantly more cases of asymptomatic or “silent” AF using a wearable ECG patch after four months, compared to a control group. The study results support the idea we can find more cases of AF by screening asymptomatic high-risk patients.  

But here’s the $64,000 question, posed by Dr. Benjamin Steinberg and Dr. Jonathan Piccini, in an accompanying editorial in JAMA: “Does earlier or more sensitive detection of AF improve clinical outcomes?” The original study found that patients who used the ECG monitor were more likely to start taking anticoagulants and visit a cardiologist, but the study did not follow patients long enough to know whether these interventions reduced their risk of stroke or death. 

While there is evidence that treatment of symptomatic AF patients with anticoagulants and rhythm control improves clinical outcomes, there is much less evidence on whether treating patients with irregular or “low-burden” AF has the same beneficial effect. In a recent evaluation of clinical trials of AF, researchers Dr. Ravi Patel and others find that few studies measure the burden of AF (how severe the condition is), making it less clear how traditional AF treatment will help those with low AF burden. 

The JAMA study set off a lively discussion on Twitter among cardiologists and others about the potential costs and benefits of screening asymptomatic people for AF. Some mentioned that an AF diagnosis can help patients manage risk factors, such as sleep apnea, diabetes, and high blood pressure. Diagnosing AF can also prompt clinicians to talk with their patients about making healthier lifestyle choices like losing weight (shouldn’t  clinicians be doing this anyway though?).

Others pointed out that having a diagnosis of AF can cause anxiety and stress, lead to higher insurance premiums or restricting activities because of perceived illness, and cause side effects from treatment. Anticoagulants, or blood thinners, are not risk-free drugs. Warfarin, a popular anticoagulant, was implicated in one third of ER visits for adverse drug events, according to a 2011 study.  

 

In short, screening asymptomatic patients will likely find more cases of “silent AF,” but the effect of screening on outcomes remains to be seen. It’s possible that treating silent AF could lead to reduced strokes and death — or it could simply lead to overdiagnosis and increased profit for drug and device companies that will benefit from a larger pool of AF patients. 

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