Interatrial block as a prognosticator of new-onset atrial fibrillation: prospective observational study of 8012 adults

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. Introduction There has been an increasing interest in Interatrial block (IAB) in recent years, especially regarding its role in atrial fibrillation (AF). The aim of the present study was to compare the characteristics of inpatients and outpatients who developed new-onset AF versus those who did not. Material and methods This single-centre, prospective observational cohort study on consecutive inpatients and outpatients referred to our institution for routine evaluation. ALl participants (n=8012) aged ≥18 years (mean 69.6±13.3 years, male 51.1%) underwent 12-lead ECG and transthoracic echocardiography. Patients were scheduled for the followup visits and new-onset AF was documented as an outcome. Enrollment lasted from June 2000 to June 2013, with the mean follow up time of 7.3 years. AF was defined as irregular RR intervals without any distinct detectable P-waves for at least 30 seconds. New onset AF is defined as a new onset or a first detectable episode of AF whether symptomatic or not. IAB was diagnosed when P-wave duration was ≥120 ms and positive in inferior leads (partial IAB) or biphasic (advanced IAB). Results The frequency of new-onset AF was 9.8%. IAB was found in 1251 patients (15.6%); advanced and partial IAB were found in 1.3% and 14.3%, respectively. IAB was more common in AF than in the sinus rhythm (33.1%; n=255 vs. 13.8%; n=996) as AF was more common in patients with IAB than without it (20.4%; n=255 vs. 7.8%; n=525). In the multivariate model, both advanced (OR 7.45, 95% CI 4.97-11.17) and partial IAB (OR 2.75 95% CI 2.31-3.37) were associated with increased risk of AF. Conclusion Both partial and advanced IAB are associated with increased risk of AF; however, the risk of AF was lower for partial than advanced IAB.