Atrial fibrillation or Afib is an arrhythmia caused by an electrical misfiring of the upper chambers of the heart called the atria. This misfiring causes the atria to quiver or fibrillate, instead of strongly contracting and dumping blood into the bottom two chambers of the heart called the ventricles. As a result, some patients experience palpitations, which feels like their heart is racing in their chest. Others experience chest pain, which should prompt patients to seek immediate medical attention. Some patients may not experience symptoms related to their heart rate or irregularity but complain of fatigue, exercise intolerance, and shortness of breath. Many patients with Afib are completely unaware they are in an abnormal rhythm because they either experience no symptoms or think they are related to something else.
A physician may suspect Afib during a routine physical exam based on symptoms or hearing an irregular heartbeat. However a definitive atrial fibrillation diagnosis is made when the arrhythmia is captured on an electrocardiogram (EKG or ECG). A 12-lead EKG can be done during a routine office visit and only takes a few minutes. An EKG is useful in diagnosing Afib if the patient’s heart is in the abnormal rhythm during the test. The challenge is that many patients have paroxysmal atrial fibrillation, meaning the arrhythmia can randomly start and stop. If the patient is not in atrial fibrillation during the EKG, the physician will likely order heart monitoring to be worn for a longer duration in an attempt to capture the arrhythmia on the monitor.
There are many types of heart monitors on the market today, so it is important for patients to understand how their monitor works. Some have wires connected to a small box that the patient will wear for 24 hours up to a month in duration. Some monitors will record every heart beat (loop recorder) while other monitors will only record if the patient has symptoms and triggers the monitor to store the EKG at that time (event monitor). For patients that have very infrequent symptoms, the physician may order a small, implantable cardiac monitor, which is inserted directly under the skin and can record for up to three years.
Some patients may only experience Afib while exercising. In this case, a physician may order an exercise stress test or treadmill test. During these tests, the patient is on a heart monitor while they exercise on a treadmill to see if the exercise results in Afib. If an irregular rhythm is captured during monitoring, an atrial fibrillation diagnosis is generally confirmed.