Premature Atrial Complexes (PACs) Causes and Treatment

Premature atrial complexes (PACs) are extra heartbeats in the atria. The atria are two chambers in the heart that receive blood from the veins.

PACs are the most common variety of cardiac arrhythmias. This is when the heart beats irregularly, too slow, or too fast.

An estimated 50% of all people with or without heart disease have PACs. While PACs themselves are usually harmless, some research suggests they may be associated with increased cardiovascular risk.

This article will explain the symptoms and causes of PACs and how they are treated.

What Are PACs?

The heart's rhythm is controlled by a tiny structure called the sinus node, which is located near the top of the heart's right atrium. The sinus node generates the electrical signal that initiates the heartbeat and controls the heart rate. The steady heartbeat originating from this node is called sinus rhythm.

PACs are early (i.e., premature) electrical impulses that are generated within the cardiac atria, but not from the sinus node. PACs momentarily interrupt the normal sinus rhythm by inserting an extra heartbeat.

Because a PAC can reset the sinus node, there is usually a short pause before the next normal heartbeat occurs. This is why PACs are often felt as a skip in the heartbeat.

PAC Symptoms

In the large majority of people, PACs do not cause any symptoms at all. However, some people will experience palpitations that they usually describe as:

• A "skipping" sensation
• An unusually strong heartbeat

Causes

Often, PACs have no known cause. Most people will experience them from time to time.

Some PACs may be caused by something you consumed. For example, experiencing palpitations with PACs is more likely after drinking alcohol, smoking nicotine, or taking medications containing stimulants.

Many experts believe caffeine may cause PACs, but studies have yet to confirm this relationship in the general population.

How Significant Are PACs?

PACs generally are considered by most healthcare providers to be a variation of normal.

That said, PACs may be risky in people who have episodes of atrial fibrillation. Atrial fibrillation (called AFib for short) causes an irregular heart rhythm. Rather than beating regularly, the atria quiver rapidly.

In some people with AFib, PACs are thought to trigger episodes of this arrhythmia. Some research links having PACs, especially more than 76 PACs each day, with an increased risk of developing atrial fibrillation, stroke, or heart disease.

Treatment

Unless PACs are thought to be triggering episodes of AFib, it is almost never necessary to treat them. However, there are situations in which treatment will be considered.

Medications and Procedures

In rare cases, PACs are uncomfortable enough that it may be worth trying to control them with medication or other interventions.

• Beta blockers may help reduce symptoms of PACs in some people and are generally recommended as the first step.
• Antiarrhythmic drugs may also be effective in reducing PACs, but these drugs are often quite toxic. They are not recommended unless PACs are causing severe and intolerable symptoms.
• Ablation, a procedure in which a layer of tissue is removed from the atria, is another possible approach, but this form of treatment is invasive and carries the risk of serious complications. Ablating PACs is usually reserved for those patients in whom PACs are symptomatic, drug-resistant, very frequent, and/or triggering more serious arrhythmias, such as AFib.

Summary

Premature atrial complexes are the most common type of cardiac arrhythmia. Many people with PACs have no symptoms at all. Others may feel a skipping sensation or an unusually strong heartbeat.

PACs themselves are usually harmless, but they may be associated with increased cardiovascular risk in some people, in which case treatment may be recommended.

A Word From Verywell

If you have been told you have PACs, rest assured you are in the majority. Almost everyone has them and they rarely require treatment. If PACs are causing palpitations or you are concerned about your heart disease risks, discuss treatment options with your healthcare provider.