What is the rhythm associated with an extra heartbeat?

Premature Heartbeats (Extrasystoles): Types, Significance, and Management

An extra heartbeat is called an extrasystole, which can be classified as either a premature atrial contraction (PAC) or premature ventricular contraction (PVC) depending on its origin in the heart. These are commonly experienced as a sensation of a skipped beat or pause followed by a stronger heartbeat.

Types of Extrasystoles

• Premature Atrial Contractions (PACs): Extra beats originating from the atria, described as irregular heartbeats that occur when the atrial tissue fires an impulse before the next normal impulse from the sinoatrial node 1, 2
• Premature Ventricular Contractions (PVCs): Extra beats originating from the ventricles, characterized by early depolarization of the ventricular myocardium 1, 2
• Patients typically describe extrasystoles as pauses or skipped beats followed by a sensation of a strong heartbeat 3

Clinical Significance

Premature Atrial Contractions (PACs)

• Occur in nearly all individuals and were previously considered benign 2
• Frequent PACs are now recognized as associated with developing atrial fibrillation 2, 4
• PAC burden correlates with increased episodes of supraventricular tachycardia (SVT) and atrial fibrillation 5
• Unlike PVCs, even frequent PACs are not associated with cardiomyopathy or reduced ejection fraction 5

Premature Ventricular Contractions (PVCs)

• Common in the general population, occurring in more than two-thirds of people 2
• Frequent PVCs (>20% of all QRS complexes on 24-hour Holter monitoring) can be associated with left ventricular dysfunction and cardiomyopathy 6
• PVCs with shorter coupling intervals and longer post-PVC pauses are more likely to cause symptoms 7
• In infants and children, isolated PVCs are common and typically benign in the absence of structural heart disease 1

Evaluation

• ECG evaluation is essential to determine if extrasystoles are supraventricular or ventricular in origin 3
• Assess for underlying structural heart disease with echocardiography, as this impacts treatment approach and prognosis 3
• Rule out reversible causes including:
  • Electrolyte abnormalities
  • Hyperthyroidism
  • Stimulant use (caffeine, alcohol)
  • Stress 3, 2
• Benign extrasystoles are often more noticeable at rest and tend to decrease with exercise 3

Management Approach

For Symptomatic PACs:

1. First-line: Eliminate triggering factors (caffeine, alcohol, stress) 3
2. Second-line: Consider beta-blockers for symptom control if lifestyle modifications are insufficient 3, 2
3. For PACs triggering paroxysmal SVT: Teach vagal maneuvers to terminate episodes 3

For Symptomatic PVCs:

1. First-line: Eliminate triggering factors (caffeine, alcohol, stress) 3
2. Second-line: Consider beta-blockers provided significant bradycardia (<50 bpm) has been excluded 3, 2
3. For frequent PVCs with left ventricular dysfunction: Consider catheter ablation, which has been shown to improve or normalize ventricular function 2, 6

Important Cautions:

• Antiarrhythmic treatment with Class I or Class III drugs should not be initiated without documented arrhythmia due to risk of proarrhythmia 3
• More aggressive rhythm control is needed for patients with tachycardia-induced cardiomyopathy from frequent extrasystoles 3
• In infants with sustained ventricular arrhythmias, avoid administering intravenous digoxin or verapamil for presumptive SVT as this has been associated with ventricular fibrillation and sudden cardiac death 1

Special Considerations

• Only a minority of patients with frequent PVCs have symptoms directly related to their PVCs 7
• Women and patients with anxiety are more likely to experience symptoms from PVCs 7
• Reversibility of PVC-induced cardiomyopathy is possible with effective treatment of the arrhythmia 3, 6