P988
Classification of sinus rhythm potential morphology in patients with mitral valve disease

CVON-AFFIP [grant number 914728], NWO-Vidi [grant number 91717339], Biosense Webster USA [ICD 783454] and Medical Delta

The morphology of atrial electrograms (EGMs) contains information on intra-atrial conduction and hence conduction disorders giving rise to development of atrial fibrillation (AF). Prior studies have indeed demonstrated that areas of abnormal EGM morphologies are indicators of electropathology underlying AF. By creating an electrical signal profile obtained from high-resolution mapping data of the entire atria during AF -a so-called AF Fingerprint- the severity and extensiveness of electropathology can be determined. The first step towards development of an AF Fingerprint, is understanding characteristics of EGM morphology during sinus rhythm (SR).

The goal of this study is to examine EGM morphology at a high resolution scale during SR in patients with mitral valve disease (MVD).

Intra-operative epicardial mapping (interelectrode distance 2mm) of the right and left atrium (RA, LA), Bachmann’s Bundle (BB) and pulmonary vein area (PVA) was performed during SR in 67 patients (27 male, 67 ± 11 years) with or without a history of paroxysmal atrial fibrillation (PAF). Unipolar single potentials (SPs) were classified according to their differences in relative R- and S-wave amplitude ratios.

Epicardial EGMs revealed a wide variation of R/S ratios. A clear predominance of S-waves was observed at BB and the RA in both the no history of AF (no AF) and PAF group (BB 88.8% vs. 85.9%, RA: 92.1% vs. 85.1%, respectively). Differences between both groups were found at the RA, BB and LA (P = 0.021, P = 0.003 and P = 0.013, respectively). EGM voltages of the RA, BB and PVA in the no AF group were significantly higher compared to the PAF group (P < 0.001, P < 0.001 and P < 0.001, respectively), and are mainly determined by the size of the S-waves amplitudes.

Though excitation of the atria during SR is heterogeneously disrupted in patients with MVD, a history of AF in this patient group is characterized by decreased SP amplitudes at BB due to loss of S-wave amplitudes. This, together with our findings that variation in EGM morphologies in our population is considerable, emphasizes the need for a diagnostic tool enabling identification of electropathology in the individual patient.

Abstract Figure. Potential morphology distribution