From the Guidelines
Premature atrial contractions (PACs) on an Apple Watch ECG typically appear as early beats with an abnormal P wave followed by a normal QRS complex, often with a compensatory pause afterward. The P wave may look different from normal P waves because it originates from an ectopic focus in the atrium rather than the sinoatrial node 1. On the single-lead ECG provided by the Apple Watch, you might notice an unexpected early beat that disrupts the regular rhythm pattern, followed by a return to the normal rhythm. Some key points to consider when identifying PACs on an Apple Watch ECG include:
- The Apple Watch's ECG capability is limited compared to clinical 12-lead ECGs, so while it can detect the presence of PACs, it may not provide the detailed view necessary for comprehensive analysis 1.
- PACs are generally benign and common in healthy individuals, especially during stress, after caffeine or alcohol consumption, or with inadequate sleep.
- However, frequent PACs might warrant medical evaluation as they can sometimes be associated with underlying heart conditions.
- If you notice frequent irregular beats on your Apple Watch ECG, it's advisable to consult with a healthcare provider who can perform a more comprehensive evaluation. It's also important to note that the Apple Watch and other wearable ECG devices have been shown to have clinical-level accuracy for the detection of arrhythmias such as AF 1. However, these devices are not a replacement for a comprehensive medical evaluation, and any concerns about irregular heart rhythms should be discussed with a healthcare provider.
From the Research
PACs on an ECG
- Premature atrial contractions (PACs) are a type of arrhythmia that can be detected on an electrocardiogram (ECG) 2.
- The Apple Watch has a built-in ECG feature that can detect heart rhythms and is approved by the FDA for screening and detecting atrial fibrillation 3, 4.
- However, there is limited information on what PACs look like on an ECG on an Apple Watch, as the studies primarily focus on the detection of atrial fibrillation and other arrhythmias.
ECG Readings on Apple Watch
- A study comparing the Apple Watch ECG with conventional ECG results found no significant differences in terms of ECG characteristics, and a strong positive correlation between heart rate measurements 4.
- The Apple Watch ECG can detect various abnormalities, including atrial fibrillation, first-degree atrioventricular block, and other arrhythmias 4.
- However, the specific appearance of PACs on an Apple Watch ECG is not described in the available studies.
Interpreting ECG Readings
- Interpreting ECG readings, including those from the Apple Watch, requires knowledge of normal and abnormal heart rhythms 5.
- PACs can be identified on an ECG by their characteristic premature P wave, but the appearance of PACs on an Apple Watch ECG is not explicitly described in the available studies 2, 6.