From the Guidelines
Premature atrial complexes (PACs) are significant because they can be associated with increased cardiovascular risk and mortality, particularly if they are frequent or multifocal, and therefore, their detection is crucial for evaluating underlying conditions that may warrant further treatment. The presence of PACs on electrocardiograms (ECGs) or Holter monitoring has been linked to increased risk of ischemic heart disease events, mortality, and cardiovascular adverse outcomes, including stroke 1. According to the 2017 AHA/ACC/HRS guideline for management of patients with ventricular arrhythmias and the prevention of sudden cardiac death, frequent PACs, defined as at least 1 PAC on a 12-lead ECG or >30 PACs per hour, are associated with increased cardiovascular risk and mortality 1.
Some key points to consider about PACs include:
- PACs are common and increase in frequency with age, found in about 50% of all people with or without heart disease on longer-term monitoring 1
- The detection of PACs, particularly if multifocal and frequent, is generally considered a risk factor for adverse cardiovascular outcomes 1
- Treatment of PACs 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 considered as a treatment option for PACs, but the decision to treat should be individualized based on the patient's underlying condition and risk factors 1.
Overall, the significance of PACs lies in their potential association with increased cardiovascular risk and mortality, highlighting the importance of their detection and evaluation in clinical practice.
From the Research
Significance of PACs
- Premature atrial contractions (PACs) have been considered a benign phenomenon, but recent studies suggest they may be a predictor of atrial fibrillation (AF) and a relevant marker of atrial cardiomyopathy 2.
- An increased burden of PACs has been linked to adverse cardiovascular outcomes, including AF, ischemic stroke, and excess mortality 2, 3.
- The relationship between PACs and cardiovascular outcomes is still being investigated, with some studies suggesting a cutoff value of 720 PAC/24 hr for prediction of AF 3.
- PAC burden is associated with increased AF and supraventricular tachycardia (SVT) episodes, but not with cardiomyopathy (CM) 4.
Clinical Implications
- The management of PACs is crucial, as they may be a predictor of AF and other cardiovascular outcomes 2, 3.
- Further research is needed to determine the optimal cutoff value for PACs and to investigate the relationship between PACs and cardiovascular outcomes 3, 4.
- The use of antiarrhythmic drugs, such as flecainide, may be effective in reducing PAC burden and preventing AF recurrences 5, 6.
Association with Atrial Fibrillation
- PACs have been shown to be a predictor of new-onset AF, with a significant association between frequent PACs and AF 3.
- The risk of AF is higher in patients with more than 3,000 PAC/24 hr, with an 11-fold increased risk compared to those with less than 3,000 PAC/24 hr 3.
- The association between PACs and AF is still being investigated, with further research needed to determine the underlying mechanisms and optimal management strategies 2, 3.