Aims The morphology of unipolar single potentials (SPs) contains information on intra-atrial conduction disorders and possibly the substrate underlying atrial fibrillation (AF). This study examined the impact of AF episodes on features of SP morphology during sinus rhythm (SR) in patients with mitral valve disease. Methods and results Intraoperative epicardial mapping (interelectrode distance 2 mm) of the right and left atrium (RA, LA), Bachmann’s bundle (BB), and pulmonary vein area (PVA) was performed in 67 patients (27 male, 67 ± 11 years) with or without a history of paroxysmal AF (PAF). Unipolar SPs were classified according to their differences in relative R- and Swave amplitude ratios. A clear predominance of S-waves was observed at BB and the RA in both the no AF and PAF groups (BB 88.8% vs. 85.9%, RA 92.1% vs. 85.1%, respectively). Potential voltages at the RA, BB, and PVA were significantly lower in the PAF group (P < 0.001 for each) and were mainly determined by the size of the Swaves amplitudes. The largest difference in S-wave amplitudes was found at BB; the S-wave amplitude was lower in the PAF group [4.08 (2.45–6.13) mV vs. 2.94 (1.40–4.75) mV; P < 0.001]. In addition, conduction velocity (CV) at BB was lower as well [0.97 (0.70–1.21) m/s vs. 0.89 (0.62–1.16) m/s, P < 0.001]. Conclusion Though excitation of the atria during SR is heterogeneously disrupted, a history of AF is characterized by decreased SP amplitudes at BB due to loss of S-wave amplitudes and decreased CV. This suggests that SP morphology could provide additional information on wavefront propagation.

Atrial fibrillation • Sinus rhythm • High-resolution epicardial mapping • Cardiac electrophysiology • Mitral valve disease • Mitral valve surgery,
Department of Cardio-Thoracic Surgery

Van Schie, M.S., Starreveld, R., Roos-Serote, M.C, Taverne, Y.J.H.J., Van Schaagen, F.R.N., Bogers, A.J.J.C, & de Groot, N.M.S. (2020). Classification of sinus rhythm single potential morphology in patients with mitral valve disease. Europace, 22(10), 1509–1519. doi:10.1093/europace/euaa130