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

PACs SVT ECG
Qaly Heart
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

Got other questions on PVC or SVT? See the Qaly guides on PVC and SVT:

Introduction

The complexity of our heart's rhythms is a fascinating facet of human health. Technological advances now allow us to track these rhythms in real-time using devices like a watch ECG. This article will explore and compare two specific heart rhythms: multiple premature atrial contractions (PACs) and non-sustained supraventricular tachycardia (SVT). We’ll explore PAC vs SVT on an ECG, and what these rhythms could mean for your heart health. Let’s dive in.

What’s a Premature Atrial Contraction (PAC)?

Premature atrial contractions are early beats that originate from the atria — the upper chambers of the heart. When multiple PACs occur, they appear as irregular early beats on an ECG. While occasional PACs are usually benign, frequent PACs can sometimes indicate underlying heart disease or trigger other arrhythmias.

PACs read on a Samsung Watch ECG through the Qaly app.
PACs read on a Samsung Watch ECG through the Qaly app.

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.

PAC read on a Fitbit Inconclusive ECG through the Qaly app.
PAC read on a Fitbit Inconclusive ECG through the Qaly app.

What’s Supraventricular Tachycardia (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 High Heart Rate ECG through the Qaly app.
SVT read on a Fitbit High Heart Rate ECG through the Qaly app.


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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 Fitbit Inconclusive ECG through the Qaly app.
SVT read on a Fitbit Inconclusive ECG through the Qaly app.

What’s the Difference Between Multiple PACs and SVT?

When discussing "SVT vs PAC", several key differences and similarities emerge. PACs, especially multiple PACs, originate from the atria and might be sporadic, while SVT is defined by a fast heartbeat often exceeding 100 beats per minute.

Both multiple PACs and non-sustained SVT can result in similar symptoms, such as palpitations or the sensation of a racing heart. Both may also be precipitated by stress, excessive caffeine or alcohol intake, and certain medications.

Despite these similarities, it's crucial to remember that while your watch ECG can help identify and monitor these rhythms, any persistent or symptomatic arrhythmias should prompt a visit to a healthcare professional. Understanding and identifying these rhythms are essential steps towards proactive heart health. As always: stay informed, stay proactive, and stay heart healthy.

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

Differentiating between PAC 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 today!

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

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

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