How to manage runs of premature atrial contractions (PACs)?

Management of Runs of Premature Atrial Contractions (PACs)

For patients with runs of premature atrial contractions, beta blockers are the first-line treatment option for symptom control and prevention of progression to atrial fibrillation. 1, 2

Understanding PACs and Their Significance

• PACs were previously considered benign but are now recognized as potential precursors to atrial fibrillation, with frequent PACs associated with increased risk of AF development, stroke, and death 2, 3
• PACs with shorter coupling intervals (particularly those <400ms) are more likely to trigger atrial fibrillation than those with longer coupling intervals 4
• Frequent PACs can impair left atrial contractile function and promote adverse left atrial remodeling, including increased left atrial volume 3

Evaluation of Patients with Runs of PACs

• Assess for potentially reversible causes of PACs, including:
  • Electrolyte abnormalities (particularly potassium, magnesium)
  • Hyperthyroidism
  • Stimulant use (caffeine, medications)
  • Sleep apnea
  • Alcohol consumption 2, 1
• Evaluate for structural heart disease with echocardiography, as PACs may be associated with underlying cardiac conditions 3
• Consider 24-hour Holter monitoring to quantify PAC burden, as higher PAC counts (>1,400/day) significantly increase risk of progression to AF 5

Treatment Algorithm for Runs of PACs

First-Line Management:

1. Address modifiable risk factors:

   • Treat underlying conditions (hyperthyroidism, electrolyte abnormalities)
   • Reduce alcohol and caffeine intake
   • Optimize management of hypertension, sleep apnea, and other comorbidities 1, 2

2. Pharmacologic therapy for symptomatic patients:

   • Beta blockers are first-line agents for symptom control 1, 2
   • Calcium channel blockers (non-dihydropyridine class like verapamil or diltiazem) are alternative options for patients who cannot tolerate beta blockers 1

Second-Line Management:

1. Antiarrhythmic medications for patients with severe symptoms despite first-line therapy:

   • Class IC agents (flecainide, propafenone) may be considered in patients without structural heart disease 6
     • Starting dose of flecainide is 50mg twice daily, may increase in 50mg increments every 4 days to maximum 300mg/day 6
     • Monitor for proarrhythmic effects, especially in patients with structural heart disease 6
   • Sotalol may be effective for both rate control and suppression of PACs 1
   • Amiodarone may be considered in patients with structural heart disease 1

2. Catheter ablation for highly symptomatic patients with drug-refractory PACs:

   • Most common sites of PAC origin include pulmonary veins, crista terminalis, and para-Hisian area 4
   • Success rates for ablation of symptomatic PACs approach 80-90% 4

Special Considerations

• Monitoring for progression to AF: Patients with frequent PACs should be monitored for development of atrial fibrillation, as they represent a high-risk group 5
• Anticoagulation: Not routinely indicated for PACs alone, but should be considered if AF develops based on CHA₂DS₂-VASc score 1
• Asymptomatic patients: Generally do not require specific treatment beyond risk factor modification and surveillance 2

Common Pitfalls and Caveats

• Avoid digoxin in patients with pre-excited AF (e.g., WPW syndrome) as it may accelerate ventricular rate 1
• Class IC antiarrhythmics (flecainide, propafenone) should be avoided in patients with structural heart disease due to increased risk of proarrhythmia 1, 6
• Beta blockers or calcium channel blockers should be given before initiating class IC agents to prevent rapid AV conduction if atrial flutter develops 1
• Recognize that runs of PACs may be a marker of underlying heart disease or a precursor to more serious arrhythmias, warranting thorough evaluation rather than dismissal as benign 3, 5