Abstract
Funding Acknowledgements
CVON-AFFIP [grant number 914728], NWO-Vidi [grant number 91717339], Biosense Webster USA [ICD 783454] and Medical Delta
Background
Voltage mapping is increasingly used for identifying the substrate of cardiac arrhythmias like atrial fibrillation (AF). Low bipolar voltage areas are regarded as indicators of structurally remodeled tissue. However, non-substrate related factors such as wavefront activation direction also influence voltages of bipolar EGMs. Unipolar electrograms (U-EGMs), on the other hand, are independent of the electrode orientation and atrial wavefront direction. It is for these reasons that U-EGMs are increasingly used in electrophysiological studies and newly developed mapping systems guiding ablation procedures.
Objective
The goal of this study is to examine U-EGM voltages at a high resolution scales during sinus rhythm (SR) in patients with mitral valve disease (MVD).
Methods
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). U-EGMs were analyzed according to their potential type and peak-to-peak voltage. Low voltage was defined as the proportion of potentials with an amplitude below 1.0 mV.
Results
In all patients, there was a considerable variation in voltage distribution between all atrial regions and clear inter-individual differences were found. In patients without AF, there were no statistical differences in median potential voltages between the various atrial regions (P = 0.869). In the PAF group, however, unipolar voltages of BB potentials were lower compared to RA potentials (3.30 [2.25–4.57] mV vs. 4.64 [3.85–6.08] mV, P = 0.006) and LA potentials (3.30 [2.25–4.57] mV vs. 4.86 [3.72–5.86] mV, P = 0.009). In addition, unipolar voltages at BB were lower in the patients with PAF compared to those without AF (no AF: 4.94 [3.56–5.98] mV, PAF: 3.30 [2.25–4.57] mV, P = 0.006). A larger number of low voltage potentials were recorded at BB in the PAF group (no AF: 2.13 [0.52–7.68] %, PAF: 12.86 [3.18–23.59] %, P = 0.001). In addition, a higher number of fractionated potentials was found in patients with PAF at the PVA (12.81 [9.19–18.03] % vs. 20.94 [13.54–27.37] %, P < 0.001) and LA (11.47 [7.30–18.30] % vs. 17.80 [12.93–21.34] %, P = 0.045). Lower voltages were found in potentials with a progressively higher degree of fractionation (R=-0.76, P < 0.001).
Conclusions
Even in SR, patients with MVD and AF episodes are characterized by decreased potential voltages at BB and a higher degree of low voltage potentials. Both considerable intra- and inter-individual variation in potential voltages were found in our study population, which underlines the interest of an individualized electrical signal profile which can be used to characterize complex conduction disorders.
Abstract Figure. Epicardial voltage maps
The relationship between complex fractionated electrograms and atrial low-voltage zones during atrial fibrillation and paced rhythm
