Atrial Fibrillation (Afib): Diagnosis & Tests Menu

How Is Atrial Fibrillation Diagnosed?

Atrial fibrillation (AF) is suspected from symptoms of ineffective cardiac output (syncope or cognitive changes), palpations, tachycardia, fatigue, or dyspnea; or signs that include an irregularly irregular pulse. It is often associated with exercise, emotional stress, or alcohol. A medical history for conditions associated with AF, such as diabetes or stroke, can lead to a diagnostic workup that includes electrocardiogram (ECG) or long-term monitoring, such as with a Holter monitor. Occasionally, such continuous monitoring done for other reasons may pick up an AF arrhythmia incidentally.

Anyone who has previously had or is currently experiencing a cerebrovascular accident (stroke) or other arterial thromboembolism, for which AF is a major cause, should be evaluated for AF.

Physical exam may demonstrate an irregularly irregular pulse. (Some irregular pulses have patterns, but not with AF).

Electrocardiogram (ECG)

An ECG can discern abnormalities in the electrical conduction through the heart. Each chamber of the heart has a characteristic depolarization wave that is seen on ECG with a contraction, but in atrial fibrillation, its wave–the P wave–is absent, the atrial quivering consistent with a rate of firing of >300/minutes. There is no consistent beat-to-beat rhythm nor any repetitive patterns.


An ultrasound of the heart is used to identify the structure and function of the atria and ventricles and to identify any valve abnormalities. Thrombi in the atrium can be identified to further justify the rationale for anticoagulation therapy.

Stress Testing

Stress testing in conjunction with ECG and echocardiography can be used to determine heart rate control in those prone to AF.

Blood Tests

Tests for other causes, such as thyroid function testing, serum creatinine for kidney appraisal, and blood sugar to screen for diabetes are included in the diagnostics for AF.


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This information is provided by Vascular Health Clinics and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition.

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