Premature Atrial Contraction (PAC) is one of the common heart rhythm disorders. It occurs when an electrical impulse originates in the atria earlier than expected, causing a heartbeat to occur before the next normal heartbeat. Some people may experience palpitations, a fluttering sensation in the chest, or the feeling that the heart has skipped a beat, while others may not notice any symptoms at all.In many cases, Premature Atrial Contractions are harmless and do not indicate a serious heart problem. However, frequent PACs or the presence of unusual or concerning symptoms may require medical evaluation to identify the underlying cause and determine the appropriate management. In this article on Dalili Medical, we discuss the causes and symptoms of Premature Atrial Contractions, factors that may increase their occurrence, ways to prevent them, and when treatment and medical follow-up may be necessary.

What Is a Premature Atrial Contraction (PAC)?

A Premature Atrial Contraction (PAC) is an extra heartbeat that occurs earlier than expected. It results from an early electrical impulse originating in the atria. When it occurs, a person may feel as though the heart has skipped a beat, added an extra beat, or suddenly produced a stronger heartbeat. However, some people may not feel PACs at all.

Is a Premature Atrial Contraction Dangerous?

A premature atrial contraction is usually not dangerous, especially when it occurs occasionally in a person without heart disease. However, frequent PACs or PACs accompanied by other symptoms should be evaluated by a doctor to determine the cause and ensure that there is no underlying heart problem.

Does Caffeine Cause Premature Atrial Contractions (PACs)?

Caffeine may increase palpitations or premature beats in some people, while it may have little noticeable effect on others. The response varies depending on an individual's sensitivity and the amount of caffeine consumed.

Can PACs Develop Into a Heart Rhythm Disorder?

The presence of premature atrial contractions does not necessarily mean that a serious heart rhythm disorder will develop. However, a high frequency of PACs may be associated with an increased likelihood of developing certain heart rhythm disorders in some people. Therefore, frequent PACs may require medical evaluation and follow-up, particularly when other symptoms are present.

When Should You See a Doctor About PACs?

A person should consult a doctor and undergo medical evaluation if PACs are frequent, occur for the first time, become more frequent, or are accompanied by persistent palpitations or unusual symptoms.

If PACs are accompanied by chest pain, difficulty breathing, loss of consciousness, or severe dizziness, urgent medical attention should be sought to rule out a significant heart rhythm disorder or another cardiac problem.

Types of Premature Atrial Contractions (PACs)

A Premature Atrial Contraction (PAC) is a heartbeat that occurs earlier than expected because of an early electrical impulse originating in the atria. PACs can be classified into several types according to their site of origin, how the impulse travels to the ventricles, and their appearance on an electrocardiogram (ECG).

1. Unifocal PAC

In this type, all premature atrial beats originate from a single electrical focus within the atrium. As a result, the premature P wave has a similar appearance each time it occurs.

2. Multifocal PACs

In this type, premature atrial beats originate from more than one electrical focus within the atria. Therefore, the premature P waves have different shapes from one beat to another on the ECG.

3. Conducted PAC

The premature atrial impulse travels to the ventricles, resulting in a QRS complex after the premature P wave. Conduction may be normal, or abnormal conduction may occur, causing a change in the appearance of the QRS complex.

4. Non-Conducted or Blocked PAC

A premature atrial impulse occurs but does not conduct to the ventricles, so it is not followed by a QRS complex. The premature P wave may sometimes be difficult to identify because it can be hidden within the preceding T wave, making the PAC more difficult to recognize on an ECG.

5. PAC Patterns: Bigeminy and Trigeminy

PACs may sometimes occur in a repetitive pattern. Common patterns include:

• Bigeminy: One normal heartbeat followed by a PAC, with this pattern repeating.
• Trigeminy: Two normal heartbeats followed by a PAC, with this pattern repeating.

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Causes of Premature Atrial Contractions (PACs)

Several factors and conditions may increase the likelihood of premature atrial contractions. The causes can vary from one person to another. Common factors include:

1. Stress and Anxiety

Stress, anxiety, and emotional tension can increase nervous system activity and the release of stress hormones, which may make the heart more susceptible to premature beats.

Some people may notice increased palpitations during stressful periods, such as examinations, emotional stress, or inadequate rest.

2. Lack of Sleep and Fatigue

Insufficient sleep and physical or mental fatigue may be associated with increased palpitations and premature atrial contractions in some people.

Symptoms may become more noticeable after a night of inadequate sleep or during periods of significant fatigue.

3. Caffeine and Stimulants

Excessive caffeine intake may increase palpitations or premature beats in some people.

Sensitivity to caffeine varies from person to person, so the occurrence of PACs after consuming caffeine does not necessarily mean that caffeine is the only underlying cause.

4. Dehydration

Inadequate fluid intake may be associated with increased palpitations in some people. Significant dehydration can also affect the body's electrolyte balance, which may in turn influence the heart's electrical activity.

5. Electrolyte and Mineral Imbalances

Changes in certain electrolyte levels can affect the heart's electrical activity. Important electrolytes include:

• Potassium.
• Magnesium.

Significant abnormalities in these levels may increase the likelihood of heart rhythm disturbances.

6. Heart Disease

PACs may occur more frequently in people with certain heart conditions, including:

• Coronary artery disease.
• Some heart valve diseases.
• Cardiomyopathy.
• Certain congenital heart conditions.
• Other conditions affecting the structure or electrical system of the heart.

However, the presence of PACs does not necessarily mean that a person has heart disease. These premature beats can occasionally occur in people with otherwise healthy hearts.

7. Thyroid Disorders

Thyroid disorders can affect heart rate and rhythm. In particular, hyperthyroidism may cause an increased heart rate, palpitations, and a greater tendency toward certain heart rhythm disturbances.

8. Certain Medications

Some medications may increase palpitations or affect heart rhythm in certain people. These may include some medications used to treat:

• Colds.
• Allergies.
• Certain respiratory conditions.

Therefore, it is important to tell your doctor about all medications and supplements you are taking, particularly if new or recurrent palpitations develop.

9. Smoking and Nicotine

Nicotine can affect the nervous system and the heart. In some people, it may increase heart rate or contribute to palpitations and premature beats.

10. Hormonal Changes

Certain hormonal changes may affect heart rhythm and the sensation of palpitations. These may occur during:

• Pregnancy.
• Menopause.
• Other hormonal changes.

11. Certain Lung Diseases

Premature atrial contractions may be more common in some people with lung diseases, including chronic obstructive pulmonary disease (COPD), due to the effects of the condition and other associated factors on the heart and nervous system.

12. Physical Activity and Increased Adrenaline

Physical activity or intense emotional reactions can increase nervous system activity and adrenaline levels, which may affect heart rhythm in some people.

PACs may occur during rest or physical activity, depending on the individual and the underlying cause.

Symptoms of Premature Atrial Contractions (PACs)

A Premature Atrial Contraction (PAC) is an early heartbeat that originates in the atria before the expected time of the next normal heartbeat. PACs are common and may occur in some people without causing any noticeable symptoms.

Symptoms vary from person to person depending on the frequency of the premature beats and how sensitive the individual is to them. Common symptoms may include:

1. Feeling Heart Palpitations

A person may feel that the heart is beating rapidly or unusually. The palpitations may occur intermittently and last for a short period.

2. Feeling a Sudden or Strong Heartbeat

A person may feel a strong or sudden beat in the chest, which is often caused by the heartbeat following the premature contraction.

3. Feeling an Extra Beat or a “Jump” in the Heartbeat

The person may feel as though the heart has added an extra beat or suddenly changed its rhythm.

4. Feeling as Though the Heart Skipped a Beat

Some people may feel as though a heartbeat is missing or that the heart briefly stopped.

In most cases, the heart has not actually stopped. Instead, a premature beat may be followed by a short pause, making the next heartbeat feel stronger and more noticeable.

5. Fluttering or Trembling Sensation in the Chest

Some people may experience a brief sensation resembling fluttering or rapid movement in the chest.

6. Feeling a Sudden, Forceful Beat

The heartbeat following a premature beat may be stronger than usual, making it more noticeable than normal heartbeats.

7. Feeling an Irregular Heartbeat

A person may feel that the heartbeat has become irregular for a few seconds. There may be a single premature beat or several scattered premature beats.

8. Feeling the Pulse in the Neck or Throat

In some cases, the unusual heartbeat may be felt in the neck or throat rather than primarily in the chest.

9. Anxiety or Discomfort

An unusual heartbeat may cause anxiety or discomfort, particularly when it occurs for the first time or when the person does not know what is causing it.

Can PACs Occur Without Symptoms?

Yes. Many people with premature atrial contractions do not feel them at all. PACs may be discovered incidentally during an electrocardiogram (ECG) or while using a heart rhythm monitoring device.

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Diagnosis of Premature Atrial Contractions (PACs)

A Premature Atrial Contraction (PAC), also known as a premature atrial beat, is a heartbeat that originates in one of the atria earlier than expected. When it occurs, a person may experience sudden palpitations, a sensation that the heart has skipped a beat, or an extra or unusually strong heartbeat.

PACs are often harmless, but frequent PACs or PACs accompanied by other symptoms may require medical evaluation.

1. Medical History and Symptoms

The diagnostic process begins with the doctor asking about the nature of the symptoms, such as:

• Heart palpitations or a fluttering sensation in the chest.
• Feeling an extra or strong heartbeat.
• Feeling as though the heart skipped a beat or stopped briefly. This sensation is often caused by a premature beat followed by a short pause before the next heartbeat.
• Shortness of breath or discomfort in some cases.
• Anxiety associated with palpitations.

Some people have no symptoms at all, and PACs may be discovered incidentally during an ECG.

The doctor may also ask about the timing, duration, and frequency of palpitations, whether they occur during rest, physical activity, or sleep, as well as the medications being taken, overall health, and factors that may trigger or worsen the symptoms.

2. Physical Examination

The physical examination may include listening to the heart, checking the pulse and blood pressure, and assessing the person's general condition.

However, a physical examination alone cannot confirm or rule out PACs, because a premature beat may not occur while the person is in the clinic. For this reason, an ECG or longer-term heart rhythm monitoring may be more useful, particularly when the premature beats occur intermittently.

3. Electrocardiogram (ECG / EKG)

An electrocardiogram is one of the most important tests for confirming PACs. If a premature beat occurs while the ECG is being recorded, the doctor can identify it based on the heart's electrical pattern.

Possible ECG findings include:

• A P wave appearing earlier than expected.
• The premature P wave having a different shape from the normal P wave because the electrical impulse originated from a different atrial focus than the usual sinus node.
• The premature P wave usually being followed by a normal or nearly normal QRS complex when ventricular conduction is normal.
• A brief pause may occur after the premature beat.
• The premature P wave may sometimes be difficult to identify if it occurs very early and becomes hidden within the preceding T wave.

These features help the doctor distinguish PACs from premature ventricular contractions (PVCs) and other heart rhythm disorders.

4. Holter Monitoring and Long-Term Monitoring

If a standard ECG is normal because the premature beats or palpitations do not occur during the examination, the doctor may use a portable monitoring device such as a Holter monitor for 24–48 hours or longer, depending on the individual's condition.

The device records the heart's electrical activity during daily activities, helping detect premature atrial contractions that occur intermittently.

The timing of symptoms can also be compared with the heart rhythm recording to determine whether the palpitations are actually caused by PACs.

If symptoms occur rarely, the doctor may recommend another type of heart rhythm monitor that can be worn or used for a longer period.

5. Determining the Number and Frequency of PACs

Heart rhythm monitoring does not only confirm the presence of PACs. It can also help the doctor determine:

• The number of PACs during the monitoring period.
• Whether the premature beats occur individually or repeatedly.
• Whether they occur in groups or recurring patterns.
• Whether other heart rhythm abnormalities are present.
• Whether the PACs correlate with the symptoms experienced by the person.

There is no single fixed number that defines “frequent” PACs for everyone, as definitions may vary between studies and clinical situations.

6. Echocardiogram

A doctor may recommend an echocardiogram, particularly when there are frequent PACs, recurrent symptoms, or factors suggesting a possible underlying heart condition.

An echocardiogram can assess:

• The size of the heart chambers.
• The heart's pumping function.
• The heart valves.
• The structure of the heart muscle.
• Other structural abnormalities.

This assessment is important because an underlying structural heart problem can influence how a heart rhythm disorder is evaluated.

7. Blood Tests

Depending on the symptoms and medical history, the doctor may order blood tests to look for factors that can affect heart rhythm, including:

• Potassium and magnesium and other electrolytes when an electrolyte imbalance is suspected.
• Thyroid function tests, particularly when symptoms suggest a thyroid disorder.
• Other tests as appropriate based on the person's symptoms and clinical condition.

8. Identifying the Underlying Cause

Confirming the presence of PACs does not necessarily mean that the person has heart disease. Premature atrial contractions may occur because of temporary factors or various health conditions, such as:

• Stress and fatigue.
• Lack of sleep.
• Certain stimulants.
• Electrolyte abnormalities.
• Thyroid disorders.
• Some heart conditions.

In many cases, no specific underlying cause can be identified.

9. Distinguishing PACs From Similar Conditions

Palpitations alone cannot determine the exact type of heart rhythm abnormality, as similar symptoms can occur with other conditions, including:

• PVC: A premature heartbeat originating from the ventricles rather than the atria.
• Supraventricular tachycardia.
• Atrial fibrillation.
• Other types of heart rhythm disorders. 

Treatment of Premature Atrial Contractions (PACs) With Medications

Treatment of Premature Atrial Contractions (PACs) depends on the number of premature beats, how much they affect the person, the severity of symptoms, and whether there is an underlying heart condition. In many cases, PACs do not require medication, particularly when they occur occasionally and there is no structural or functional heart problem.

1. Beta-Blockers

Beta-blockers are among the most commonly used medications when PACs occur frequently or cause bothersome palpitations and symptoms.

One example is metoprolol, along with other medications in the same class.

The main goal is to reduce palpitations and improve symptoms, rather than necessarily eliminating every premature atrial beat.

These medications should not be started or dosed without medical supervision because they may cause low blood pressure or a slow heart rate. They may also be unsuitable for some people, including certain individuals with asthma or other respiratory conditions.

2. Verapamil or Diltiazem

Certain calcium channel blockers, such as verapamil or diltiazem, may be used in selected cases of atrial rhythm disturbances.

However, they are not routine treatments for every case of PACs. The choice depends on the specific rhythm disturbance, symptoms, heart function, and overall health.

3. Antiarrhythmic Medications

In selected cases, a cardiologist may consider antiarrhythmic medications when PACs are very frequent, significantly symptomatic, and have not responded to simpler treatment measures.

Several classes of antiarrhythmic drugs are available, but they require careful medical supervision because some may cause side effects or, in certain circumstances, other heart rhythm abnormalities.

Therefore, medications such as flecainide, amiodarone, or sotalol should not be used simply because PACs were detected on an ECG. They should only be considered by a cardiologist when the potential benefits outweigh the risks and after an appropriate evaluation.

What Tests May Be Needed Before Starting Medication?

Before selecting treatment, the doctor may assess several factors, including:

• Electrocardiogram (ECG).
• The number and pattern of PACs, sometimes using a 24–48-hour Holter monitor or longer-term monitoring when needed.
• Whether an underlying heart condition is present; an echocardiogram (Echo) may be recommended in some cases.
• Medications, supplements, and stimulants that may increase palpitations.
• Potentially treatable causes, such as electrolyte abnormalities or thyroid problems, depending on the symptoms and medical history.

Does Everyone With PACs Need Medication?

No. If PACs are occasional, do not cause significant symptoms, and the heart is healthy, medication may not be necessary. In some cases, avoiding triggers and having appropriate medical follow-up may be sufficient.

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Surgical Treatment and Catheter Ablation for Premature Atrial Contractions (PACs)

In most cases, PACs do not require surgery or an invasive procedure, because they are generally benign and do not represent a serious heart problem. Surgery is therefore not performed simply because PACs are detected on an ECG or Holter monitor.

Is There a Surgical Treatment for PACs?

In typical cases, there is no conventional surgery specifically used to treat PACs. Management usually begins by identifying and reducing potential triggers or underlying causes, followed by medication when necessary.

However, in rare and carefully selected cases, a cardiologist may consider catheter ablation, particularly when PACs:

• Occur very frequently and repeatedly.
• Cause severe or persistent symptoms.
• Do not respond adequately to conservative treatment.
• Are associated with a significant heart rhythm disorder or, rarely, affect heart function.
• Repeatedly trigger another arrhythmia, such as certain cases of atrial fibrillation.

How Is Catheter Ablation Performed?

Catheter ablation is not open-heart surgery. It is a minimally invasive procedure performed through blood vessels and generally involves the following steps:

1. An electrophysiologist inserts a thin catheter through a blood vessel, commonly through the groin.
2. The catheter is guided into the chambers of the heart.
3. Specialized electrical mapping systems are used to identify the atrial focus responsible for the premature beats.
4. Once the focus is precisely located, the doctor may use radiofrequency energy (heat) or, in selected cases, freezing technology to treat the targeted area.
5. The heart's electrical activity is then tested to determine whether the premature beats have been reduced or eliminated.
6. The catheter is removed, the access site is treated, and the patient is monitored afterward according to the medical team's instructions.

Does Every Patient With PACs Need Catheter Ablation?

No. The presence of PACs on an ECG or Holter monitor does not automatically mean that catheter ablation is necessary.

The decision depends on several factors, including:

• The number and frequency of PACs.
• The severity of symptoms and their effect on daily life.
• Whether the source of the PACs can be accurately identified and targeted.
• The presence of other heart conditions.
• Whether PACs are affecting heart function.
• The response to other treatment approaches.

Before considering ablation, a comprehensive evaluation may include an ECG, Holter monitoring or longer-term monitoring, an echocardiogram when appropriate, and selected blood tests.

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Prevention of Premature Atrial Contractions (PACs)

Prevention focuses on reducing factors that may trigger premature beats and treating correctable underlying causes. However, it is not always possible to prevent every PAC.

1. Getting Enough Regular Sleep

Lack of sleep and fatigue may increase palpitations and premature beats in some people.

Helpful measures include:

• Maintaining regular sleep and wake times.
• Getting enough sleep appropriate for your age.
• Avoiding frequent late nights.
• Consulting a doctor if persistent sleep problems are present.

2. Limiting Excessive Caffeine

Large amounts of caffeine may increase palpitations or premature beats in some people.

Common sources of caffeine include:

• Coffee.
• Tea.
• Energy drinks.
• Some soft drinks.
• Certain products containing stimulants.

This does not mean everyone needs to completely avoid caffeine. Instead, it is useful to notice whether caffeine consumption actually increases symptoms.

3. Staying Hydrated

Dehydration may contribute to palpitations in some people, while significant dehydration can affect the body's fluid and electrolyte balance.

Regular fluid intake is therefore important, particularly during hot weather or physical activity.

Potassium or electrolyte supplements should not be taken without medical advice, because excessive levels of certain minerals can also be harmful.

4. Reducing Stress and Emotional Tension

Stress and emotional tension may increase palpitations in some people.

Helpful approaches may include:

• Slow, calm breathing.
• Relaxation techniques.
• Organizing study, work, and rest periods.
• Getting adequate sleep.
• Engaging in age-appropriate physical activity.

5. Avoiding Stimulants

Some stimulant substances may increase heart rate or palpitations, including energy drinks and certain stimulant-containing products.

Some cold medications and decongestants may also contain stimulant ingredients. It is therefore advisable to consult a doctor or pharmacist before using them and not to stop a prescribed medication without medical advice.

6. Avoiding Smoking and Nicotine

Nicotine can affect the nervous system and the heart. Avoiding smoking and nicotine products supports overall cardiovascular health.

7. Treating Associated Causes

When PACs occur frequently, a doctor may look for associated factors or medical conditions, such as:

• Thyroid disorders.
• Electrolyte abnormalities.
• Certain heart conditions.
• Certain medications or stimulants.
• Sleep disorders.

Treating an underlying cause, when present, may help reduce premature beats.

8. Engaging in Appropriate Physical Activity

Regular physical activity appropriate for the person's age is generally beneficial for heart health.

However, if palpitations occur during physical activity and are accompanied by chest pain, severe shortness of breath, severe dizziness, or loss of consciousness, the activity should be stopped and medical evaluation should be sought.