Diagnosis of Atrial Fibrillation

Deepak L. Bhatt, MD, MPH, FACC, FAHA, FSCAI, FESC: As far as different ways of diagnosing atrial fibrillation [A-Fib], it starts with history and physical exam, as everything does. Getting a history of palpitations from the patient can be useful, but many things cause palpitations: premature atrial contractions, premature ventricular contractions. Atrial fibrillation is on that list, but the presence of palpitations isn’t specific for atrial fibrillation. Certainly, if a patient says they’re having palpitations, it’s worthwhile to check and see if they have atrial fibrillation or other arrhythmias, but many times atrial fibrillation is asymptomatic. That’s a big problem because asymptomatic atrial fibrillation is still a risk factor for stroke. A physical exam is also useful. It can detect an irregular pulse. That’s diagnostic for atrial fibrillation, but physical exams aren’t always easy. A patient may not be in atrial fibrillation as you’re examining them but might have been yesterday or might be tonight or have so-called paroxysmal atrial fibrillation. They’re still at increased risk of stroke. The history and physical can be useful, but a normal physical exam or a normal history doesn’t preclude that there might be atrial fibrillation, especially in people at risk.

The predominant risk we worry about is stroke. So is systemic embolism, primarily left atrial appendage thrombus going to the brain causing stroke, but it can go elsewhere as well. It can have emboli to the coronary arteries, for example, causing a myocardial infarction. It’s an unusual cause of myocardial infarction, but 1% to 3% of myocardial infarctions and acute coronary syndromes are due to emboli from the left atrial appendage from atrial fibrillation, or sometimes the left ventricle from thrombus after a big myocardial infarction. Other places that systemic emboli can lodge are in the kidneys and the feet, causing acute peripheral limb ischemia or kidney failure. Those are much less common than stroke, but systemic embolism is also on the list of bad things that atrial ablation can cause. But by far, Nos. 1, 2 and 3 are thromboembolic stroke.

Other complications include heart failure, and atrial fibrillation can contribute to heart failure. It can prompt episodes of heart failure, including in patients with heart failure with preserved ejection fraction, where the ejection fraction is normal, but also in those with reduced ejection fraction, where it can cause an outright decompensation in patients who otherwise had stable compensated heart failure with reduced ejection fraction. Sometimes it can be the sole cause for heart failure, not just worsening heart failure that otherwise exists but promoting or causing that heart failure. In particular, if the rate of atrial fibrillation is very high, that can cause a tachycardia-induced cardiomyopathy, and controlling the rate might be sufficient to reverse that if the atrial fibrillation is detected early enough. In any work-up for heart failure, you always want to see if atrial fibrillation is a cause and screen for things like thyroid disease. It can lead to heart failure and atrial arrhythmias, so it’s important to remember that. In terms of bad things that atrial fibrillation can do, stroke is at the top of the list, but you always want to think that it can cause or promote heart failure.

Among the arrhythmias, atrial fibrillation creates the greatest burden. It’s a burden in terms of the patient’s morbidity and mortality, in terms of stroke and heart failure risk. Beyond the patients, it’s also a burden to the health care system. It’s a major cause of health care costs. A-Fib is a growing burden for reasons I cited previously, in terms of an aging population and other risk factors that are increasing the prevalence of atrial fibrillation. This is atrial fibrillation that we’re detecting clinically because it’s jumping up and getting our attention. It doesn’t even capture atrial fibrillation that’s silent. That’s a big issue because for a nontrivial proportion of strokes, the first presentation of atrial fibrillation is with a stroke, sometimes a very disabling stroke. Strokes in the context of atrial fibrillation can be quite disabling. There’s the burden of A-Fib–induced stroke, the disability it causes to patients, and downstream health care costs. Sometimes the strokes can be fatal, not just disabling. A lot of burden is placed on patients who have atrial fibrillation, including the ones who have silent atrial fibrillation but then go on to have complications such as stroke, which is an enormous burden on the health care system.

Transcript Edited for Clarity