What are the additional tests for Premature Atrial Contractions (PACs)?

From the Guidelines

Additional tests for premature atrial contractions (PACs) should focus on identifying underlying causes and assessing cardiovascular risk, with a comprehensive evaluation starting with a 12-lead ECG to document the PACs and rule out other arrhythmias, as recommended by the 2014 AHA/ACC/HRS guideline for the management of patients with atrial fibrillation 1. When evaluating PACs, it is essential to consider the patient's symptoms, medical history, and risk factors for cardiovascular disease. A 24-hour Holter monitor or longer-term event recorder can be used to quantify PAC burden and detect any patterns or triggers, as suggested by the international recommendations for electrocardiographic interpretation in athletes 1. Some key points to consider when evaluating PACs include:

• Laboratory tests, such as electrolytes (particularly potassium, magnesium, and calcium), thyroid function tests, and a complete blood count, to identify potential underlying causes of PACs.
• Echocardiography to evaluate cardiac structure and function, looking for valvular disease, chamber enlargement, or reduced ejection fraction.
• Exercise stress testing for patients with risk factors or concerning symptoms to determine if PACs worsen with exertion or are associated with ischemia.
• In selected cases, additional testing may include cardiac MRI to assess for structural abnormalities or infiltrative diseases, and sleep studies if sleep apnea is suspected as a contributor. The choice of additional tests should be guided by the patient's individual clinical presentation and risk factors, with the goal of determining whether PACs are benign or markers of underlying cardiac disease, and guiding appropriate management strategies ranging from simple reassurance to specific treatments for identified causes 1.

From the Research

Additional Tests for PACs

• To determine the appropriate treatment for premature atrial contractions (PACs), several tests can be conducted, including:
  • Echocardiogram to detect underlying heart disease 2
  • Electrolyte panel to rule out electrolyte abnormalities 2, 3
  • Thyroid function tests to exclude hyperthyroidism 2, 3
  • Holter monitor to assess the frequency and burden of PACs 4, 5
• In some cases, catheter ablation may be considered to eliminate symptomatic, frequent, and drug-refractory PACs 3, 4
• The effectiveness of these tests and treatments can be evaluated through follow-up studies, including quality of life questionnaires and recurrence of PACs 4

Electrophysiological Features of PACs

• The electrophysiological features of PACs can be characterized using techniques such as point-by-point and/or circular mapping 3
• The coupling intervals (CoIs) of PACs can be compared to determine the origin of the ectopic foci 3
• The location of the ectopic foci can be identified, with common sites including the pulmonary vein, crista terminalis, and para-Hisian area 3, 4

Association between PACs and Atrial Fibrillation

• Frequent PACs have been associated with an increased risk of atrial fibrillation (AF), stroke, and mortality 3, 5
• The presence of ≥1 PAC on standard 12-lead ECG may not be sufficient to conclude an association with future AF detection 5
• However, frequent PACs on 24-48 h Holter monitor have been significantly associated with AF, first stroke, and all-cause mortality in older patients without a history of AF 5