Organized patterns of excitation during persistent atrial fibrillation in humans relate to tissue structure and activation rate

Abstract

Abstract Background The contribution of organized patterns of excitation as mechanisms maintaining persistent atrial fibrillation (PAF) is questioned. Purpose We aim to analyze the relationship of focal and reentrant activities, identified with the CARTO-Finder system, with tissue structure and activation rate to explain potential link with mechanisms and outcomes. Methods 33 patients with PAF of at least 6 months (24±4 months) were admitted for right and left atrial (RA & LA) mapping with the CARTO-Finder system. The biatrial geometry, bipolar Penta-Ray`s signals (30 sec long) and activation patterns were exported for off-line analysis (MatLab environment). A fast-Fourier transform was computed on 30 sec bipolar signal length segments to compute dominant frequency (DF) and represented on atrial shells. Focal and reentrant patterns of activation were superimposed, and correlation with DF and bipolar voltage analyzed. Results Biatrial mapping was performed obtaining 15.3±5 Finder maps from the RA and 15.9±5 Finder maps from the LA. Focal activities (182±151 at the RA & 270±21 at the LA) were documented in all patients at both atria. Rotational activities (more than 2 consecutive) were documented in the left atria in 4 patients (22.5±16.8 rotations) and in the right atria in 9 patients (35.5±32 rotations). 30 sec long activation rate was higher at places with focal activities compared with areas without organized patterns (DF: 6.11±0.09 Hz vs 5.7±0.09 Hz; p<0.001). The higher the number of consecutive focal activities, the higher the tissue activation rate (DF no focal activities 5.7±0.09 Hz vs DF 1-5 focal activities 6.0±0.14 Hz vs DF>5 focal activities 6.2±0.14 Hz; p<0.001). In addition, DF at focal activities strongly correlates with DF at areas without organized patterns (Pearson 0.91; p<0.001). The bipolar voltage was higher at places with focal activities compared with areas without organized patterns (1.0±0.04 mV vs 0.5±0.04 mV; p<0.001). None of the previous were observed at places with rotational activities (DF: 5.9±0.16 Hz vs 5.7±0.09 Hz; p=0.204 & Volt: 0.6±0.08 mV vs 0.5±0.04 mV; p=0.364). During follow-up after ablation (24±7 months), a cox regression model including number of focal activities, number of rotations, mean tissue activation rate (mean DF) and bipolar voltage, identified bipolar voltage as a unique independent predictor of survival free of AF recurrence (p=0.04). Conclusions Focal activities identified with the CARTO Finder system during PAF in humans correlate with tissue structure and activation rate, suggesting a potential link with mechanisms.