What is the significance of a low burden of premature atrial contractions (PACs) and premature ventricular contractions (PVCs) on a Holter monitor?

From the Guidelines

A low burden of premature atrial contractions (PACs) and premature ventricular contractions (PVCs) on a Holter monitor is generally considered benign and does not require specific treatment, especially if the patient is asymptomatic. The presence of PVCs is common and increases with age, with about 50% of people with or without heart disease having PVCs on longer-term monitoring 1. However, frequent PVCs, defined as more than 30 PVCs per hour, are associated with increased cardiovascular risk and mortality 1.

Key Considerations

• The detection of PVCs, particularly if multifocal and frequent, is generally considered a risk factor for adverse cardiovascular outcomes 1.
• Treatment of PVCs with antiarrhythmic medications has not been shown to reduce mortality and may even increase the risk of death in certain populations, such as post-myocardial infarction patients 1.
• Beta blockers may be prescribed for symptomatic patients, but the primary consideration should be the symptom burden rather than the absolute number of ectopic beats.

Management Approach

• For patients with minimal symptoms, reassurance is appropriate, and lifestyle modifications, such as reducing caffeine, alcohol, and stress, should be tried first.
• If symptoms are bothersome, beta-blockers like metoprolol (25-100 mg twice daily) or calcium channel blockers such as diltiazem (120-360 mg daily in divided doses) may be prescribed.
• Further evaluation with an echocardiogram is warranted if PVCs exceed 10-15% of total heartbeats or cause significant symptoms to rule out structural heart disease 1.

Ongoing Care

• Regular follow-up is recommended, especially if symptoms worsen, as rarely, high-burden PVCs (>20% of beats) can lead to cardiomyopathy over time.
• The threshold for treatment should be based primarily on symptom burden rather than the absolute number of ectopic beats, and treatment should be individualized based on the patient's specific needs and risk factors 1.

From the Research

Significance of Low Burden of Premature Atrial Contractions (PACs) and Premature Ventricular Contractions (PVCs)

• A low burden of PACs and PVCs on a Holter monitor is associated with a relatively benign condition, as suggested by a study 2 that found PVCs with a lower burden or origin from the left ventricular papillary muscle and the fascicle were relatively benign.
• In contrast, a high burden of PVCs (>10%) has been associated with an increased risk of ischemic stroke and cardiac dysfunction, as reported in studies 2 and 3.
• The origin site of PVCs also plays a significant role in determining the risk of cardiac dysfunction, with PVCs originating from the tricuspid annulus having the highest burden and NT-proBNP level 2.
• A low burden of PVCs may also be beneficial for patients undergoing catheter ablation, as it can make the procedure easier and more successful, as demonstrated in a case report 4 that used non-invasive mapping to guide ablation of PVCs with a low burden.

Clinical Implications

• Patients with a low burden of PACs and PVCs may not require aggressive treatment, as their condition is relatively benign.
• In contrast, patients with a high burden of PVCs (>10%) may require more intensive medical therapy and close clinical follow-up to prevent cardiac dysfunction and stroke-like symptoms, as suggested by a study 3.
• The use of non-invasive mapping and 12-lead Holter monitoring can help guide catheter ablation and improve outcomes for patients with PVCs, particularly those with a low burden or multiple morphologies 4.
• Multidisciplinary teamwork is essential for overcoming unexpected events and achieving a safe and successful outcome in catheter ablation procedures, as demonstrated in a case report 5.