From the Research
Premature atrial complexes (PACs) are generally considered significant when they constitute more than 1% of the total R-R complexes on a 24-hour Holter monitor. This threshold is clinically important because PACs occurring at this frequency or higher may indicate underlying cardiac pathology requiring further evaluation, as suggested by a study published in 2019 1. While isolated PACs are common and often benign in healthy individuals, a PAC burden exceeding 1% has been associated with an increased risk of developing atrial fibrillation, stroke, and other cardiovascular complications.
Some key points to consider when evaluating PACs include:
- The frequency of PACs, with higher frequencies associated with increased risk of adverse outcomes 1
- The presence of underlying cardiac disease or risk factors, such as hypertension, coronary artery disease, or heart failure 2, 3
- The clinical context of the patient, including symptoms, age, and comorbidities 4, 5
- The need for additional cardiac workup, including echocardiography or extended monitoring, in patients with significant PAC burden 1, 5
The significance of PACs should always be interpreted in the clinical context of the patient, considering factors such as symptoms, age, and comorbidities. Patients with significant PAC burden may require additional cardiac workup including echocardiography to assess for structural heart disease, extended monitoring to rule out more serious arrhythmias, and possibly treatment if the PACs are symptomatic or associated with other cardiac conditions.