Symptoms of Premature Atrial Contractions (PACs)
Most patients with premature atrial contractions experience palpitations, which are often described as a sensation of a "skipped beat" or "pause followed by a stronger beat," though many individuals with PACs remain completely asymptomatic. 1
Common Symptoms
Palpitations: The most frequent symptom, often described as:
- "Skipped" or "missed" beats
- Irregular heartbeats
- A "pause" followed by a stronger heartbeat
- A "fluttering" sensation in the chest
Mild to moderate symptoms:
- Fatigue or easy fatigability
- Reduced exercise capacity
- Lightheadedness or dizziness
- Chest discomfort or pressure
- Dyspnea (shortness of breath)
Rare but severe symptoms:
- Presyncope (near-fainting)
- Syncope (fainting) - uncommon with isolated PACs 2
Symptom Patterns and Characteristics
PACs can produce different symptom patterns depending on their frequency and timing:
- Isolated PACs: May cause only occasional, brief sensations of "skipped beats"
- Frequent PACs: Can create a persistent feeling of irregular heartbeat
- Bigeminal PACs: When every other beat is a PAC, can create a pattern that mimics bradycardia 1
It's important to note that the severity of symptoms does not necessarily correlate with the frequency of PACs. Some patients with very frequent PACs may be completely asymptomatic, while others with only occasional PACs may experience significant symptoms 1.
Factors Affecting Symptom Perception
Several factors influence whether a person experiences symptoms from PACs:
- Heart rate: Symptoms are often more noticeable at slower heart rates
- Activity level: PACs may be more noticeable during rest or quiet activities
- Awareness: Some individuals are simply more sensitive to cardiac rhythm changes
- Anxiety: Can amplify perception of PACs and worsen symptoms
- Triggers: Caffeine, alcohol, stress, fatigue, and dehydration can increase both PAC frequency and symptom perception 1
Distinguishing Features from Other Arrhythmias
PACs have specific characteristics that differentiate them from other arrhythmias:
- Unlike sinus bradycardia, PACs create an "irregularly irregular" rhythm rather than a consistently slow heart rate 1
- Unlike atrial fibrillation, PACs produce distinct P waves with different morphology from sinus P waves, followed by a normal QRS complex (unless there is aberrant conduction) 1
- PACs typically have a longer coupling interval than premature atrial contractions that trigger atrial fibrillation 3
Clinical Significance
While PACs were once considered entirely benign, recent evidence suggests:
- Frequent PACs are associated with an increased risk of developing atrial fibrillation 4, 5
- PACs may be a marker of underlying atrial cardiomyopathy 5, 6
- Frequent PACs can impair left atrial contractile function and promote adverse left atrial remodeling 7
Understanding the symptom profile of PACs is essential for proper diagnosis and management, especially in distinguishing them from more serious arrhythmias that may require immediate intervention.