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Purpose: We wanted to illustrate the right-to-left impulse propagation routes during sinus in patients with paroxysmal atrial fibrillation (PAF), as alterations in conduction patterns have been linked to the pathogenesis of PAF, and as no large patient materials have been published.Methods: Patients underwent 3-D electroanatomical contact mapping prior to catheter ablation. The site of the earliest left atrial (LA) activation was determined.Results: Three different interatrial routes were identified, either as solitary pathways (36/50 patients, 72%) or in their combinations (14/50). Bachmann's bundle (BB) was involved in the majority of the cases with solitary routes (25/36). More seldom, impulse propagation occurred near the oval fossa (FO) (7/36) or the coronary sinus ostium (4/36). In patients with combined routes, both the BB (10/14) and FO routes (11/14) were included in most cases.Conclusions: In PAF patients, LA can be activated during sinus rhythm through three distinct connections, either encompassing a single route or via any combination of these connections. In one third, the earliest LA activation occurs outside BB. The knowledge of the propagation patterns may give insight into the pathophysiology of PAF and into refining ablation therapy. [ABSTRACT FROM AUTHOR]

Background: Patients with hypertrophic cardiomyopathy (HCM) have a high incidence of atrial fibrillation. They also have a longer P-wave duration than healthy controls, indicating conduction alterations. Previous studies have demonstrated orthogonal P-wave morphology alterations in patients with paroxysmal atrial fibrillation. In the present study, the P-wave morphology of patients with HCM was compared with that of matched controls in order to explore the nature of the atrial conduction alterations.Methods and Results: A total of 65 patients (45 men, mean age 49 +/- 15) with HCM were included. The control population (n = 65) was age and gender matched (45 men, mean age 49 +/- 15). Five minutes of 12-lead ECG was recorded. The data were subsequently transformed to orthogonal lead data, and unfiltered signal-averaged P-wave analysis was performed. The P-wave duration was longer in the HCM patients compared to the controls (149 +/- 22 vs 130 +/- 16 ms, P < 0.0001). Examination of the P-wave morphology demonstrated changes in conduction patterns compatible with interatrial conduction block of varying severity in both groups, but a higher degree of interatrial block seen in the HCM population. These changes were most prominent in the Leads Y and Z.Conclusion: The present study suggests that the longer P-wave duration observed in HCM patients may be explained by a higher prevalence of block in one or more of the interatrial conduction routes. [ABSTRACT FROM AUTHOR]