The clinical significance of premature atrial contractions: how frequent should they become predictive of new-onset atrial fibrillation

Abstract

Background: although previous studies reported frequent premature atrial contractions(fPACs) increased the risk of adverse cardiovascular outcomes, especially atrial fibrillation(AF), there is a substantial inconsistency between reports concerning the definition of fPAC. In this study, we aimed to investigate the relationship between fPAC and cardiovascular outcomes, especially AF. We further searched for a cutoff value of fPAC for prediction of AF. Methods: we retrospectively analyzed the ambulatory 24-hr Holter monitoring records and 392 patients included. Frequent PAC was defined as more than 720 PAC/24 hr as used for frequent ventricular premature beats. Patients’ baseline characteristics, echocardiographic variables and medical history were recorded. Results: there were 189 patients with fPAC and 203 patients without fPAC. Patients with fPAC had more comorbidities in terms of hypertension, diabetes mellitus, coronary artery disease and congestive heart failure. CHA2DS2-VaSc was higher in patients with fPAC. Mean follow-up duration was 31 months, and the number of patients with new-onset AF during follow-up was significantly higher in fPAC group (22% vs. 5%, p <.001). fPAC was significantly and independently associated with new-onset AF and predicted AF with a cutoff value of 3,459 PAC/24 hr, and the risk of AF was 11-fold higher than those with <3,000 PAC/24 hr. In addition, an increased CHA2DS2-VaSc score was also associated with new-onset atrial fibrillation. Conclusion: in our study, we have demonstrated that fPAC is significantly associated with new-onset AF, and this association is the strongest among those patients who have more than 3,000 PAC in 24 hr.