Conditions That Can Look Like AFib

Medically Reviewed by James Beckerman, MD, FACC on March 14, 2023
4 min read

Atrial fibrillation, or AFib, causes an uneven and sometimes rapid heart rate. It can lead to a higher chance of a stroke, heart failure, or other heart problems.

AFib usually brings symptoms like shortness of breath, weakness, fatigue, dizziness, lightheadedness, chest pain, and heart palpitations. But it’s not the only condition that can cause these things. Here’s what you should know about other health issues that may feel like AFib.

Anxiety disorders can cause intense and constant fear or concern about everyday activities. They may also lead to panic attacks, which is when you have sudden episodes of extreme anxiety or terror. Anxiety can disrupt your daily life and might be hard to control.

Like AFib, panic attacks can cause a rapid heart rate, shortness of breath, chest pain, dizziness, or lightheadedness. But with anxiety and panic attacks, you’ll usually also notice an overall sense of fear, trembling, hot flashes, sweating, or a feeling of unreality.

Most people know that high blood pressure is unhealthy, so you might think low blood pressure is a good thing. But if it goes down too much, it could be dangerous. Your blood pressure may be too low if the first number on your reading is below 90 millimeters of mercury (mm/Hg) or the second number is under 60 mm/Hg. This is usually when you’ll start to notice symptoms.

You may feel dizzy, lightheaded, or very tired, or have rapid breathing. But unlike AFib, low blood pressure will also usually cause nausea, dehydration, trouble focusing, blurry vision, clammy or cold skin, or depression.

Heart arrhythmias, or problems with heart rhythm, happen when the electrical impulses that manage your heartbeat don’t work the way they should. They may cause your heart to beat too fast, too slow, or unevenly. Premature atrial contractions (PAC) and premature ventricular contractions (PVC') may also feel irregular.

Common types of arrhythmias could be:

Tachycardia. This is a fast heartbeat when your resting heart rate is more than 100 beats per minute. AFib can cause one type of tachycardia. Others include atrial flutter, supraventricular tachycardia, Wolf-Parkinson-White syndrome, and ventricular tachycardia

Atrial flutter is like AFib, but the heartbeats in this condition are better organized. It can also cause serious issues like a stroke.

Bradycardia. This is a slow heartbeat, with a resting heart rate of fewer than 60 beats a minute. Types of bradycardia include sick sinus syndrome and conduction block.

Sometimes, you won’t notice any symptoms with an arrhythmia. But if you do, they may include a flutter in your chest, shortness of breath, chest pain, fatigue, anxiety, dizziness, lightheadedness, fainting, or sweating.

If you start to feel any of these things, get medical care as soon as possible. A doctor will be able to find out if your symptoms are from AFib or another type of arrhythmia.

Coronary artery disease (CAD) happens when plaque builds up in the walls of your arteries. It’s the most common type of heart disease in the United States.

The most common symptom of CAD is chest pain or discomfort, which can also happen with AFib. Many people who have CAD will first learn about it after a heart attack. Heart attack symptoms include weakness, lightheadedness, a cold sweat, nausea, pain in your shoulder or arm, and shortness of breath.

CAD can also make you more likely to have AFib. Over time, the plaque growth will clog your arteries. If one of them becomes severely blocked, it can lower the blood flow to your heart. In some cases, this can even cause a heart attack.

An overactive thyroid, also known as hyperthyroidism, happens when your thyroid gland makes too much of a hormone called thyroxine. Without treatment, it can lead to several problems.

Hyperthyroidism may have some similar symptoms to AFib, like a rapid or uneven heartbeat, heart palpitations, fatigue, or muscle weakness. But with an overactive thyroid, you’ll usually also notice things like unplanned weight loss, a higher appetite, nervousness or anxiety, sweating, changes in your period, being sensitive to heat, swelling at the base of your neck (a larger thyroid gland), skin and hair thinning, trouble sleeping, trembling in your hands and fingers, and having to poop more often.

Older adults may have no signs or very subtle symptoms.

There are two kinds of heart valve disorders. The first, regurgitation, is when one or more of your heart valves don’t close all the way. Blood can flow backward in the valve, giving you too much blood in your heart.

The other problem, stenosis, is when one or more valves become narrow. This limits the flow of blood, so your heart has to use extra force to pump. Either of these problems can cause heart failure.

Like AFib, heart valve disorders can cause symptoms including chest pain, fatigue, heart palpitations, shortness of breath, or dizziness. But you’ll usually also have low or high blood pressure, pain in your abdomen, or leg swelling.