What are vagal-induced premature ventricular contractions (PVCs)?

Vagal-Induced Premature Ventricular Contractions (PVCs)

Vagal-induced PVCs are premature ventricular contractions that occur in response to increased vagal tone or parasympathetic activity, particularly in patients with vasovagal syncope, and may be identified by their correlation with periods of increased cardiac vagal activity. 1

Characteristics and Mechanisms

Vagal-induced PVCs represent a specific subtype of premature ventricular contractions with distinct features:

• They demonstrate a positive correlation between their occurrence and measures of vagal tone such as deceleration capacity (DC) 1
• They often originate from the ventricular outflow tract region 1
• They may be associated with vasovagal syncope or other conditions with autonomic imbalance 1
• They can be distinguished from other PVCs by their relationship to autonomic modulation 1

Diagnosis and Evaluation

When evaluating suspected vagal-induced PVCs, the following diagnostic approach is recommended:

• 24-hour Holter monitoring is essential to quantify PVC burden and document correlation with vagal tone 2
• Analysis of circadian patterns of PVCs to identify correlation with periods of increased vagal tone 1
• Assessment of deceleration capacity (DC) as a quantitative measure of cardiac vagal activity 1
• Evaluation for underlying structural heart disease with echocardiography and possibly cardiac MRI 2

Clinical Significance

The clinical significance of vagal-induced PVCs varies:

• In most cases, isolated PVCs without structural heart disease are benign 3, 2
• PVCs with a burden <2,000/24 hours are generally considered low risk 2
• Higher PVC burden (>10-15% of total heartbeats) may lead to PVC-induced cardiomyopathy, regardless of mechanism 2, 4
• In patients with vasovagal syncope, vagal-induced PVCs may contribute to symptoms 1

Management Approaches

Management should be guided by symptoms, PVC burden, and presence of underlying heart disease:

First-line therapies:

• Beta-blockers or non-dihydropyridine calcium channel blockers are recommended as first-line therapy for symptomatic PVCs 2
• For vagal-induced PVCs specifically, these medications may be particularly effective by modulating autonomic tone 1

Advanced interventions:

• Catheter ablation should be considered for:
  • Symptomatic patients who are medication-intolerant 2
  • PVC burden >15% with predominantly one morphology 2
  • PVC-induced cardiomyopathy 2, 4
  • In cases of vagal-induced PVCs associated with vasovagal syncope, ablation of ganglionated plexi may be beneficial 1

Special Considerations

• Vagal-induced PVCs may spontaneously improve with modulation of autonomic tone 1
• In patients with vasovagal syncope and symptomatic PVCs, addressing both conditions may be necessary 1
• Regular follow-up with echocardiography is important to monitor for development of cardiomyopathy in patients with high PVC burden 2

Prognosis

• Most vagal-induced PVCs have a benign prognosis, especially when not associated with structural heart disease 3, 2
• Treatment of vagal-induced PVCs in patients with vasovagal syncope has shown good outcomes with low recurrence rates 1
• Some patients may experience spontaneous improvement without specific interventions 1