PACs vs. PVCs: What’s the Difference and Why It Matters

Your heart is an incredibly responsive organ, adapting beat by beat to your emotions, activity level, and physiological needs. But what happens when it skips a beat or adds an extra one? While it might feel alarming, not all irregular heartbeats are cause for panic. Two of the most common culprits behind these extra beats are Premature Atrial Contractions (PACs) and Premature Ventricular Contractions (PVCs). Though often benign, understanding the difference between them is essential for anyone looking to monitor and manage their cardiovascular health.

In this blog, we’ll break down what PACs and PVCs are, how they differ, what causes them, and how continuous ECG monitoring can help detect, interpret, and manage these irregular rhythms.

Understanding the Basics: What Are PACs and PVCs?

Premature Atrial Contractions (PACs) are early heartbeats that originate in the atria, the upper chambers of the heart. Essentially, an extra electrical signal fires before the normal heartbeat is due, causing the atria to contract prematurely.

Premature Ventricular Contractions (PVCs), on the other hand, are extra beats that originate in the ventricles, the lower chambers of the heart. They occur when an ectopic focus in the ventricle sends out an impulse too early, disrupting the regular heartbeat.

While both PACs and PVCs are classified as types of ectopic (or out-of-place) beats, the location of their origin defines their impact and potential significance.

What Do They Feel Like?

Both PACs and PVCs can feel like:

• A skipped beat 
• A fluttering sensation 
• A brief pounding in the chest 
• A pause followed by a stronger heartbeat (due to the compensatory pause) 

However, many people don’t feel them at all. These irregularities are often discovered incidentally during routine ECGs or while wearing a heart monitor.

How Are They Different?

1. Point of Origin

• PACs originate in the atria. 
• PVCs originate in the ventricles. 

2. ECG Characteristics

• PACs appear as early P waves with abnormal shapes, often followed by a normal QRS complex. 
• PVCs present as wide and bizarre-looking QRS complexes not preceded by P waves. 

3. Clinical Implication

• PACs are often benign and may not require treatment. 
• PVCs, particularly when frequent or in patterns like couplets or triplets, may require further evaluation as they could signal underlying heart disease. 

Common Causes

Shared Causes:

• Stress or anxiety 
• Caffeine, alcohol, or stimulant use 
• Electrolyte imbalances 
• Fatigue or lack of sleep 
• Fever or dehydration 

Specific to PACs:

• Hyperthyroidism 
• Lung disease (e.g., COPD) 

Specific to PVCs:

• Structural heart disease 
• Post-heart attack scar tissue 
• Cardiomyopathy 

Are They Dangerous?

In healthy individuals, occasional PACs and PVCs are usually harmless. However, their context matters:

• Isolated PACs are rarely dangerous and often resolve on their own. 
• Frequent PACs may increase the risk of developing atrial fibrillation (AFib). 
• Isolated PVCs are often benign, especially in younger people. 
• Frequent PVCs (more than 10,000 per day) may be linked to a higher risk of cardiomyopathy or sudden cardiac events, particularly if accompanied by symptoms like dizziness or shortness of breath. 

When Should You Be Concerned?

If you experience any of the following, it’s time to seek medical attention:

• Palpitations that persist or worsen 
• Lightheadedness or fainting 
• Chest pain or discomfort 
• Shortness of breath 
• Irregular heartbeat during exertion 

These symptoms could point to underlying cardiac issues, and further diagnostic workup including echocardiogram, stress testing, or longer-term ECG monitoring may be necessary.

The Role of Continuous ECG Monitoring

Standard in-clinic ECGs or even short-duration Holter monitors may miss intermittent PACs and PVCs. This is where continuous ECG monitoring makes a difference. These wearable monitors allow for:

• 24/7 real-time ECG capture of arrhythmic events 
• Event tagging, so users can record symptoms like palpitations or dizziness 
• Long-duration use, increasing the chances of detecting infrequent ectopic beats 
• Detailed rhythm analysis, distinguishing between PACs, PVCs, and other arrhythmias 

By tracking heart rhythms across sleep, activity, and stress states, continuous monitors help paint a more accurate picture of your cardiac health.

How Continuous ECG Monitoring Helps Different Populations

• Athletes: Who often report skipped beats post-training. Continuous monitoring can help differentiate benign PACs/PVCs from more concerning arrhythmias. 
• Post-COVID patients: Some individuals report new-onset palpitations or ectopic beats during recovery. Monitors can assist in determining if these are PACs, PVCs, or signs of myocarditis. 
• Older adults: As age increases, so does the prevalence of ectopic beats. Monitoring ensures early detection of progression to more serious arrhythmias like AFib. 
• Patients with known heart disease: Continuous data allows clinicians to assess risk, medication effectiveness, and potential need for electrophysiological intervention. 

Interpreting the Results

Only a qualified medical professional can determine whether your ectopic beats are harmless or a warning sign. After your continuous ECG data is reviewed, your doctor might suggest:

• Lifestyle adjustments (reducing caffeine, stress, or alcohol) 
• Medication to suppress ectopic beats if symptomatic 
• Further testing, such as echocardiograms or stress tests 
• Electrophysiology referral, if the burden of PVCs or the complexity of PACs is high 
• Good Sleep  

Final Thoughts

While PACs and PVCs can be unsettling, they are extremely common and often benign. The key to managing them is context: understanding when they occur, how frequently, and whether they are accompanied by symptoms or structural heart abnormalities.

Continuous ECG monitoring provides the long-term, detailed data needed to demystify these extra beats and ensure they don’t go undetected or misunderstood. With the right tools and guidance, individuals can take charge of their heart health with clarity and confidence.

If you’ve ever felt your heart skip a beat or flutter unexpectedly, know that answers are within reach. Speak to your healthcare provider about whether continuous ECG monitoring could help uncover what your heart is really telling you.