Medically reviewed by Nachiket J. Patel, MD, FACC, FSCAI. Last reviewed July 2026.
Atrial fibrillation, or AFib, is an irregular heart rhythm that begins in the upper chambers of the heart. It may come and go, persist for days, or become continuous.
Some people feel a racing or fluttering heartbeat. Others mainly notice fatigue, breathlessness, or reduced stamina. AFib can also be silent and discovered on an electrocardiogram or monitor.
The central questions are not simply whether AFib is present. It is also important to understand stroke risk, how much the rhythm affects daily life, and whether another condition is helping drive it.
What happens during atrial fibrillation?
Normally, the heart’s electrical system produces an organized signal. In AFib, electrical activity in the atria becomes chaotic. The atria quiver instead of contracting in a coordinated way, and the pulse is often irregular.
Blood can move less efficiently through the atria. In some patients, that creates an opportunity for a clot to form and later travel to the brain. This is why stroke prevention is a separate part of AFib care, even when palpitations are mild or absent.
What does AFib feel like?
Symptoms vary from episode to episode and from person to person. A normal-feeling pulse does not prove that AFib is absent, and a fast pulse does not always mean AFib.
- A fluttering, pounding, or irregular heartbeat
- Rapid pulse
- Shortness of breath
- Fatigue or exercise intolerance
- Lightheadedness
- Chest discomfort
- Weakness or anxiety during an episode
When should AFib symptoms be treated as an emergency?
Call 911 for chest pressure, severe shortness of breath, fainting, or signs of stroke such as facial droop, arm weakness, new speech difficulty, or sudden loss of balance or vision.
A sustained very rapid rhythm with significant symptoms also needs urgent evaluation. Do not wait for an office callback if you feel seriously unwell.
How is atrial fibrillation confirmed?
An electrocardiogram can diagnose AFib when the rhythm is happening. If episodes are intermittent, a Holter patch, event monitor, mobile cardiac telemetry, or an implanted monitor may be considered based on how often symptoms occur.
An echocardiogram evaluates heart function, chamber size, and valve disease. Blood tests may look for thyroid disease, anemia, electrolyte problems, or other contributors. Sleep apnea, high blood pressure, alcohol use, obesity, and lung disease may also deserve attention.
How is AFib treated?
Treatment is individualized around three goals: preventing stroke when indicated, controlling the heart rate, and reducing the burden of AFib when symptoms or heart function warrant a rhythm-control strategy.
Stroke-prevention decisions use clinical risk factors rather than symptoms alone. Some people benefit from an anticoagulant; others do not. Aspirin is not an interchangeable substitute for anticoagulation in patients who need it.
Rate-control medication may be enough for some patients. Rhythm control can involve antiarrhythmic medication, electrical cardioversion, or catheter ablation. The best choice depends on duration of AFib, symptoms, heart structure, other illnesses, and patient preference.
Daily habits that can support AFib care
Regular activity, weight management when appropriate, blood-pressure control, restorative sleep, and treatment of sleep apnea can all support the medical plan. Tobacco should be avoided, and alcohol may trigger or worsen AFib in some people.
Caffeine affects individuals differently. Rather than assuming every cup of coffee is harmful, track whether it consistently provokes symptoms and discuss the pattern at your visit.
Frequently asked questions
Can AFib occur without a fast heart rate?
Yes. AFib describes the rhythm in the atria. The pulse may be fast, normal, or occasionally slow depending on conduction and medication.
If I cannot feel AFib, is stroke risk gone?
No. Stroke risk is based largely on clinical factors and can remain present even when AFib causes no symptoms.
Will a smartwatch diagnose AFib?
A consumer device can record useful rhythm information, but alerts and single-lead tracings should be reviewed in clinical context. They do not replace a full evaluation.
Related heart and vascular information
Schedule an appointment
If you have a stable heart or circulation concern, request an appointment with Flow Heart & Vascular in Mesa, Arizona. Call 911 for emergency symptoms.
This page provides general education and does not replace individualized medical advice.
