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Deepak L. Bhatt, MD, MPH, FACC, FAHA, FSCAI, FESC, discusses the clinical presentation of atrial fibrillation in patients and assesses the relationship between atrial fibrillation and syncope.
Deepak L. Bhatt, MD, MPH, FACC, FAHA, FSCAI, FESC: The presentation of A-Fib [atrial fibrillation] runs the whole gamut. There are patients who present with palpitations, a sense that their heart is beating irregularly or quickly, which often prompts an emergency department visit. For sure, palpitation can prompt recognition of atrial fibrillation. In some ways that’s a good thing because it brings the atrial fibrillation to light and the patient can be treated appropriately. This includes, in many cases, anticoagulation to markedly reduce the risk of stroke or other systemic embolic complications. So palpitations is one way.
Another way patients present is with symptoms of heart failure, such as shortness of breath, fatigue, dyspnea on exertion, dyspnea at rest, swelling in the lower extremities, or edema. There are a variety of presentations. Sometimes it’s with heart failure with reduced ejection fraction [HFrEF], where the EF [ejection fraction] is low. These days, 50% is often quoted as a cutoff. In other situations like heart failure with preserved ejection fraction [HFpEF], the ejection fraction is about 50%. It’s important to always think of atrial fibrillation.
It can trigger heart failure in people who didn’t have it before, and it can worsen heart failure in people that already have it, either whether it’s HFrEF or HFpEF. In some cases there can be a tachycardia-mediated heart failure, which is when the atrial fibrillation is very fast. That very fast heart rate leads to cardiomyopathy. If that’s detected early enough, it can reverse the cardiomyopathy. It’s on the list of reversible causes of atrial fibrillation.
Patients can present with stroke, heart failure, nonspecific symptoms like fatigue, palpitations. There are a lot of presentations for atrial fibrillation. It’s also on the list of acute coronary syndromes [ACSs] and causes. It’s a rare cause of acute coronary syndrome, but every now and then a coronary embolus from atrial fibrillation can lead to an acute coronary syndrome, even an ST segment elevation MI [myocardial infarction], but that’s pretty rare. Maybe 1% to 3% of ACSs have an embolic cause.
It can also precipitate ACS in terms of someone who has severe underlying coronary artery disease but now is having a rapid sustained heart rate from atrial fibrillation. It’s basically a stress test in which they’ll have a positive troponin and indeed have a myocardial infarction. In some cases it’s a type 2 demand-based ischemia myocardial infarction. Less frequently, it’s a type 1 where plaque rupture is promulgated by that rapid heart rate, and they’re having an occluded artery or partially occluded artery and might benefit from a stent. But more often, it’s type 2 MI, where the troponins are elevated. Perhaps they’re having chest pain, but it’s not a case where we’d say go ahead and stent them. But many times they end up needing a cardiac catheterization that potentially induces additional health care costs, inconvenience, or burden, and a small risk of potential complications to the patient from an invasive procedure. Be aware that ACS can be prompted and chest discomfort might be the presenting symptom, but that might just be chest discomfort, because the heart rate is going so quickly.
We need to be aware that there’s a full spectrum of symptoms that the patient might present with. A challenge is that there might be patients who don’t have symptoms. Those are people who can be sitting at home having atrial fibrillation at risk for stroke without knowing it. That’s the unfortunate reason why, for some patients who present with stroke, that’s the first presentation and manifestation of their atrial fibrillation.
In terms of other ways of presenting and detecting atrial fibrillation, generally speaking, there are no lab values that are useful. Of course, patients in an emergency department setting or admitted to the hospital would be placed on telemetry and monitored for atrial fibrillation and other arrhythmias. There are also patients in the outpatient setting who can be monitored for atrial fibrillation and other arrhythmias if it’s not clear what the cause of their palpitations are. If they’re in the not normal sinus rhythm when they’re in the office on a 12-lead ECG [electrocardiogram], there are many times historically when a Holter monitor has been placed for 24 or 48 hours. A short-term recording can be useful, but it’s very easy to miss things in that time frame.
There are other ways—for example, patches that can be worn for 30 days or longer. Patches can be replaced to see if there are any arrhythmias going on. There are also systems that can be implanted. Implantable loop recorders are devices—really, minimally invasive procedures—that can be inserted in an outpatient setting. It’s a quick, safe, easy procedure that allows for even longer-term monitoring. For example, if a patient is having palpitations that are troubling but relatively infrequent, and we haven’t been able to capture them another way—say, on a 12-lead ECG or on a patch—that can be a very useful way. For patients that have unexplained things like syncope, fainting, that can be a very useful way if the occurrences are relatively infrequent. Obviously, that can be a serious complication, not just of atrial fibrillation but of other arrhythmias, like ventricular tachycardia, sinus pauses, or a variety of arrhythmic causes. That can be useful if there’s a desire to monitor for long period of times, like for a year or so. It can be quite useful to make a diagnosis that has, up to that point, been elusive.
Syncope can be a tough diagnosis. Even making the diagnosis can be tough. Sometimes patients are dizzy or light-headed because of inner ear problems, but they might report that as syncope or near syncope. Sometimes patients can be dehydrated or vasovagal and have near-syncopal or syncopal episodes. Sometimes seizures can be confused with syncope. There’s a broad differential for what can cause what appears to be near syncope or syncope, but on that list of things are cardiac causes. Arrhythmias are a subset of things that can indeed cause syncope.
If someone syncopizes, we always worry if they had ventricular tachycardia, ventricular fibrillation. It was long believed that in ventricular fibrillation, humans can’t spontaneously come out of it. I was always taught that, but now we’re monitoring patients’ long term with things like pacemakers or defibrillators to capture events, or various implantable and insertable devices. In fact, it’s pretty rare. There are people who have apparent ventricular fibrillation and come out of it, but without defibrillation, most of the time that’s going to be death. Patients with ventricular tachycardia can sometimes come out of it spontaneously, and that’s a worrisome potential cause of syncope.
Bradyarrhythmias—a slow heart rate or sinus pauses, for example—complete heart block. These are potential causes of syncope, where a pacemaker can make a huge difference. With the ventricular tachycardias, medications and ICDs [implantable cardioverter defibrillators] can be useful. Atrial fibrillation is on the list of potential causes of syncope. It’s not the most common causes of syncope, but any tachyarrhythmia, including atrial fibrillation, can lead to syncope. Perhaps that’s more likely if there’s concomitant other cardiac disease rather than in a young healthy person. For example, someone who had an aortic stenosis. Aortic stenosis that’s severe can cause syncope; but in addition to atrial fibrillation, that can contribute to syncope. If people have cardiomyopathies, low ejection fraction, and atrial fibrillation, that can certainly precipitate syncope. On the list of things to think about in syncope are cardiac causes and arrhythmic causes, including the ones I mentioned.
Transcript Edited for Clarity