The doctor will often begin by asking the patient about their medical history to help determine the severity of symptoms. The doctor will assess if any associated factors (for example, alcohol or caffeine intake) may be contributing to the patient’s symptoms. The doctor will also listen to the patient’s heartbeat and lungs. The evaluation may include the following tests:
Electrocardiogram (ECG or EKG): This is the primary test to determine when an arrhythmia is atrial fibrillation. The ECG can help the doctor distinguish A fib from other arrhythmias that may have similar symptoms (atrial flutter, supraventricular tachycardia, or runs of ventricular tachycardia). The test can also sometimes reveal damage (ischemia) to the heart, if there is any.
The following illustrations show the usual ECG tracing from a patient with A fib; the second figure shows the different appearance between a normal (single lead) ECG tracing and the irregular appearance of an atrial fibrillation (single lead) ECG tracing. The atrial tracing for the A fib tracing shows a slowed irregular heartbeat of A fib, where the irregular waves are easily seen before the heartbeat (Figure 2). These waves can be seen if the heartbeat is slowed; they are difficult to see in patients with a rapid heartbeat shown in Figure 3.