Men and women's hearts don't beat the same: Epicardial mapping of Bachmann's bundle.

Background: There is increasing evidence that presentation, progression, and management of atrial arrhythmias, such as atrial fibrillation (AF), differ between women and men. Bachmann's bundle (BB) is the main route for interatrial conduction, and sex-related differences in structural and electrical remodeling of BB may contribute to differences in AF development between women and men.

Objective: Investigate whether sex differences in the electrophysiological properties of BB assessed by high-resolution and density maps exist in patients with AF.

Methods: Sinus rhythm at BB was recorded for 5 s during cardiac surgery. Potential voltage, low-voltage area (LVA), conduction heterogeneity, unipolar potential morphology, and conduction velocity were assessed for both men and women.

Results: The study population consisted of 108 patients (73 men, 35 women). Women had significantly lower potential voltages (5th percentile: 0.7 mV [0.6-1.0] vs 1.1 mV [0.6-1.4], p = 0.028), more LVAs (10.8% [4.6-19.7] vs 4.3% [2.2-11.7], p = 0.012) and more long double potentials (11.1% [3.6-13.5] vs 5.0% [1.0-10.3], p = 0.015) compared to men.

Conclusions: We observed sex-related differences in the electrical remodeling of BB in AF patients. Women have a higher proportion of low voltage potentials, and more abnormal potential morphologies compared to men. These findings may reflect sex-specific differences in the underlying substrate of AF at BB.