RESUMO
Background: Impairment of conduction across Bachmann's Bundle (BB) may cause advanced interatrial block (a-IAB), which in turn is associated with development of atrial fibrillation. However, the exact relation between a complete transverse line of conduction block (CB) across BB and the presence of a-IAB has not been studied. Objective: The aims of this study are to determine whether (1) a complete transversal line of CB across BB established by high resolution mapping correlates with a-IAB on the surface ECG, (2) conduction abnormalities at the right and left atria correlate with a-IAB, and (3) excitation patterns are associated with ECG characteristics of a-IAB. Methods: We included 40 patients in whom epicardial mapping revealed a complete transverse line of CB across BB. Pre-operative ECGs and post-operative telemetry were assessed for the presence of (a) typical a-IAB and de novo early post-operative AF (EPOAF), respectively. Total atrial excitation time (TAET) and RA-LA delay were calculated. Entry site and trajectory of the main sinus rhythm wavefront at the pulmonary vein area (PVA) were assessed. Results: Thirteen patients were classified as a-IAB (32.5%). In the entire atria and BB there were no differences in conduction disorders, though, patients with a-IAB had an increased TAET and longer RA-LA delay compared to patients without a-IAB (90.0 ± 21.9 ms vs. 74.9 ± 13.0 ms, p = 0.017; 160.0 ± 27.0 ms vs. 136.0 ± 24.1 ms, p = 0.012, respectively). Patients with typical a-IAB solely had caudocranial activation of the PVA, without additional cranial entry sites. Prevalence of de novo EPOAF was 69.2% and was similar between patients with and without a-IAB. Conclusion: A transverse line of CB across BB partly explains the ECG characteristics of a-IAB. We found atrial excitation patterns underlying the ECG characteristics of both atypical and typical a-IAB. Regardless of the presence of a-IAB, the clinical impact of a complete transverse line of CB across BB was reflected by a high incidence of de novo EPOAF.
RESUMO
BACKGROUND: Interatrial block (IAB) has been previously shown to predict atrial fibrillation (AF) in cardiac populations. This study sought to evaluate the relationship between IAB and new-onset AF in a population of patients undergoing clinically indicated coronary angiography who received carotid ultrasonography. METHODS: A population of 355 subjects undergoing coronary angiography and carotid ultrasound were retrospectively studied. Common carotid artery (CCA) far-wall intima-media thickness (CIMT), and total carotid plaque area were measured. Coronary artery disease was measured by angiography and IAB by electrocardiograph (ECG). RESULTS: The mean population age was 64.4 years, 70.4% male, mean BMI 29.9 kg/m2. IAB was a predictor of new-onset AF (OR =2.40, 95% CI: 1.33-4.29; P=0.003). There was a significant difference in AF free survival time between patients with IAB and without IAB via Cox proportional hazard analysis [52.9 months (95% CI: 47.1-58.7 months) vs. 62.6 months (95% CI: 58.8-66.5 months); P=0.006]. Patients with IAB had a significantly greater CIMT (0.883±0.193 vs. 0.829±0.192 mm; P=0.013) and a higher prevalence of significant (>70%) right coronary artery lesions than patients without (45.8% vs. 34.4%; P=0.026). Significant predictors of IAB on multivariate analysis were BMI ≥30 kg/m2 (OR =3.14, 95% CI: 1.14-6.71, P=0.003), male sex (OR =1.78, 95% CI: 1.05-3.03, P=0.034), increased mean CIMT (per 0.1 mm increase) (OR =1.75, 95% CI: 1.00-3.07, P=0.050) and increased age (per 10-year increase) (OR =1.46, 95% CI: 1.14-1.88, P=0.003). CONCLUSIONS: IAB is a predictor of new-onset AF in patients with carotid and coronary artery disease. Both carotid and coronary artery disease are associated with a higher prevalence of IAB.