Atrial fibrillation (AFib) is a common irregular and often rapid heart rhythm where the heart’s upper chambers, the atria, beat chaotically and out of sync with the lower chambers. Early detection of AFib is important to prevent serious complications like stroke and heart failure. Timely identification allows for appropriate management strategies, potentially reducing AFib’s progression and associated risks.
The Standard Test: Electrocardiogram (ECG or EKG)
The electrocardiogram (ECG or EKG) is the primary test used to detect AFib. This quick and painless test measures the electrical activity of the heart, showing its rate and rhythm. During an EKG, electrodes are placed on the skin to detect electrical signals, which the machine records as wavy lines for interpretation by a healthcare provider.
An EKG provides a snapshot of the heart’s rhythm at the exact moment the test is performed. While effective for diagnosing AFib if it is present during the test, its limitation lies in detecting intermittent episodes that are not occurring at that specific time. If AFib episodes are sporadic, a standard EKG may not capture the irregularity. This necessitates other monitoring methods for individuals whose symptoms are infrequent or unpredictable.
Monitoring Intermittent AFib: Ambulatory Devices
Because AFib can be intermittent, continuous monitoring devices are often used to capture these events. These ambulatory devices allow for heart activity to be recorded over extended periods as patients go about their daily lives. They provide a more comprehensive look at the heart’s rhythm than a single EKG.
The Holter monitor is a portable device typically worn for 24 to 48 hours, though some can be worn for up to 14 days. It continuously records the heart’s electrical activity through chest electrodes for later review by a healthcare professional. Patients often keep a diary of their symptoms and activities to correlate with the recorded rhythm.
Event recorders are similar but worn for weeks to months, activated by the patient when symptoms occur. Some can also automatically record irregular rhythms. Mobile Cardiac Outpatient Telemetry (MCOT) is an advanced form of continuous monitoring, automatically transmitting data wirelessly to a monitoring center for extended periods.
Advanced and Long-Term Detection Methods
For individuals with very infrequent or asymptomatic AFib, more advanced and long-term detection methods are available. These methods are designed to capture elusive episodes that might be missed by shorter-term monitoring.
An implantable loop recorder (ILR) is a small device placed just under the skin in the chest area, capable of monitoring and recording heart rhythms for up to three years. It is useful for detecting rare or asymptomatic AFib episodes that other tests might not catch. The ILR automatically records abnormal heart activity and can also be manually activated by the patient.
Wearable technology, such as smartwatches with ECG capabilities, offers another avenue for screening. While these devices can detect potential AFib rhythms and alert users, they are not considered diagnostic tools. Any findings from wearable devices require confirmation by a medical professional using a clinical EKG or other prescribed diagnostic tests.
Interpreting Test Results and Next Steps
A definitive diagnosis of AFib is made by a healthcare professional, who considers the test results alongside the patient’s medical history and reported symptoms. The EKG and other monitoring device recordings provide objective data on heart rhythm and rate, which are crucial for this assessment. The healthcare provider analyzes patterns and irregularities in the heart’s electrical activity captured by these devices.
Further evaluation may be conducted to understand any underlying causes of AFib. This can include blood tests to check for conditions that might influence heart rhythm, such as thyroid issues. An echocardiogram, an ultrasound of the heart, might also be performed to assess the heart’s structure and function. These additional tests help to provide a comprehensive picture of heart health, guiding any subsequent medical decisions.