Premature Atrial Contraction (Couplet) Vs. Supraventricular Tachycardia (Non-Sustained) on Your Watch ECG

PAC Couplet SVT ECG
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Qaly is built by Stanford engineers and cardiologists, including Dr. Marco Perez, a Stanford Associate Professor of Medicine, Stanford Cardiac Electrophysiologist, and Co-PI of the Apple Heart Study.

Key Takeaways

Introduction

Our heart rhythm is the cornerstone of heart health, and deciphering our heart's electrical activity is crucial in understanding various heart conditions. In this article, we delve into the realms of premature atrial contraction (PAC) and supraventricular tachycardia (SVT) on your watch ECG. By understanding the rhythms of "PAC vs SVT", you can gain deeper insights into your heart's function and potential anomalies that may need attention. Let’s dive in.

What’s a PAC Couplet?

Premature atrial contractions are early beats that originate from the atria — the upper chambers of the heart. When they occur in pairs, they are referred to as a couplet. While occasional PACs are usually benign, frequent PACs can sometimes indicate underlying heart disease or trigger other arrhythmias. 

PAC Couplet read on a Fitbit ECG through the Qaly app. Notice that the Fitbit ECG app would've read this entire ECG as Sinus Rhythm, without the extra analysis of the Qaly ECG reader.
PAC Couplet read on a Fitbit ECG through the Qaly app. Notice that the Fitbit ECG app would've read this entire ECG as Sinus Rhythm, without the extra analysis of the Qaly ECG reader.

On an ECG, PACs are identified by an early and often different-looking P wave, followed by a QRS complex and a compensatory pause. Here’s more on what a PAC looks like on your watch ECG.

Another PAC Couplet read on a Fitbit ECG through the Qaly app. Notice here, too, that the Fitbit ECG app would've read this entire ECG as Sinus Rhythm, without the extra analysis of the Qaly ECG reader.
Another PAC Couplet read on a Fitbit ECG through the Qaly app. Notice here, too, that the Fitbit ECG app would've read this entire ECG as Sinus Rhythm, without the extra analysis of the Qaly ECG reader.

What’s SVT?

SVT is an abnormal fast heart rhythm starting in the upper chambers (atria) of the heart, leading to a heart rate often between 150 to 250 beats per minute.

On an ECG, SVT is identified by a rapid, regular rhythm with typically narrow QRS complexes. Often, P waves are difficult to see. 

SVT read on a Fitbit ECG through the Qaly app. Notice that the Fitbit ECG app labeled this as an Inconclusive ECG.
SVT read on a Fitbit ECG through the Qaly app. Notice that the Fitbit ECG app labeled this as an Inconclusive ECG.

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“Non-sustained” SVT lasts less than 30 seconds, whereas “sustained” SVT lasts longer, sometimes even up to several hours. Here’s more on what SVT looks like on your watch ECG.

SVT read on a Samsung Watch ECG through the Qaly app. This heart hero is based in France 🇫🇷
SVT read on a Samsung Watch ECG through the Qaly app. This heart hero is based in France 🇫🇷

What’s the Difference Between a PAC Couplet and SVT?

When comparing "PAC vs SVT," several differences emerge. Primarily, the origin and frequency of these rhythms differentiate them. PACs originate from the atria and may occur sporadically, whereas SVT is a condition characterized by rapid heartbeats, often over 100 beats per minute and runs for 3 or more consecutive beats.

However, both PACs and non-sustained SVT may cause similar sensations, such as palpitations or the feeling of a fluttering heart. Both rhythms may also be triggered by stress, excessive caffeine or alcohol intake, and certain medications.

It's important to remember that while your watch ECG can assist you in identifying and monitoring these rhythms, any persistent or symptomatic arrhythmias should warrant a consultation with a healthcare provider. Understanding and recognizing these rhythms is a significant step in proactive heart health management. Stay informed, stay proactive, and stay heart healthy!

Still Not Sure if It’s Premature Atrial Contraction (Couplet) or Supraventricular Tachycardia (Non-Sustained) on Your ECG?

Differentiating between PAC Couplet vs SVT on your ECG can be tricky. If you’re still looking for help interpreting your ECG further, check out the Qaly app on App Store or Play Store. On Qaly, human experts will interpret your ECGs within minutes, day or night. Try out the Qaly app for free today!

Wondering if it's PAC or SVT? On the Qaly app, human experts will interpret your ECGs for PAC and SVT within minutes. Get started for free today.

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Wondering if it's PAC or SVT? On the Qaly app, human experts will interpret your ECGs for PAC and SVT within minutes. Get started for free today.

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