Wave similarity mapping shows the spatiotemporal distribution of fibrillatory wave complexity in the human right atrium during paroxysmal and chronic atrial fibrillation

Introduction: The complexity of waveforms during atrial fibrillation may reflect critical activation patterns for the arrhythmia perpetuation. In this study, we introduce a novel concept of map, based on the analysis of the wave morphology, which gives a direct evidence in the human right atrium on the spatiotemporal distribution of fibrillatory wave complexity in paroxysmal (PAF) and chronic (CAF) atrial fibrillation. Methods and Results: Electrograms were recorded from a 64-electrode catheter in the right atrium of 15 patients during PAF (n = 8) and CAF (n = 7). Wave similarity maps were constructed by calculating the degree of morphological similarity of activation waves (S) at each atrial site and by following its temporal evolution. During PAF the spatiotemporal distribution of the waveforms was highly consistent across the subjects and was determined by the anatomic location. Wave similarity maps showed the existence of an extended area with low similarity index, which covered the low posteroseptal atrium (S = 0.28 ± 0.09) and the septal region (S = 0.22 ± 0.04), and the presence of a large tongue with high similarity index, which penetrated the lateral wall (S = 0.55 ± 0.08) starting from the high anterolateral atrium (S = 0.54 ± 0.06). A completely different spatiotemporal pattern was seen during CAF. No distinct regions with different similarity indexes were recognized, but a uniformly distributed low similarity index (S = 0.27 ± 0.07) was found. The spatial pattern was highly stable in time with fluctuations of S < 0.04. Conclusion: Quantification of the spatiotemporal distribution of fibrillatory wave complexity is feasible in humans by wave similarity mapping. Anatomic anchoring of waveforms during PAF and pattern destruction during CAF was determined.