BACKGROUND: Progressive disorganization of electrical activity at the onset of atrial fibrillation (AF) has been reported.
PURPOSE: To study the time-course of electrogram organization from the onset of induced AF in the coronary sinus (CS) and right atrium (RA) in sustained (>5min) versus non-sustained (<5min) episodes.
METHODS: We studied 75 patients (age 60±12, 80% men) undergoing paroxysmal AF ablation. Sample entropy (SampEn, increasing with signal complexity) was measured in the CS and RA on 10-second windows with 50% overlap during the first minutes of burst-pacing-induced AF before (n=25) and after (n=50, CS recordings only) pulmonary vein isolation (PVI). Spearman rank correlation was used to detect time-dependent trends in SampEn on individual patients and significant coefficients were retained for analysis while time-courses with non-significant correlation were attributed a coefficient r=0.
RESULTS: Sustained induced episodes before PVI (n=20) showed a time-dependent increase in SampEn during the first 30 seconds after induction (strongest correlation in the anterolateral RA: r=0.48, 95% CI 0.25-0.71, p<0.0005), while non-sustained episodes (n=5) exhibited no time-dependent SampEn change. This resulted in diverging time-courses (Figure) between both groups in the proximal CS and most significantly in the anterolateral RA (129±157% SE increase in sAF versus 11±30% increase in nsAF, p<0.005). Likewise, SampEn values at 30 seconds in the anterolateral RA most strongly predicted AF sustainability (p<0.005). In sustained AF, SampEn kept increasing during 5 minutes, at which point a plateau was reached without further increase in SampEn after up to 9 minutes of waiting time (n=7). In contrast, SampEn remained low in non-sustained AF until self-termination. Induced AF following PVI showed similar behavior: during the initial 30 seconds, non-sustained episodes (n=25) showed a downwards evolution of SampEn in the mid-CS (r=-0.15, 95% CI (-0.30)-(-0.005), p<0.05) while sustained episodes (n=25) showed an increase, most significantly in the proximal CS (r=0.20, 95% CI 0.03-0.36, p<0.05). Time-course divergence was most significant in the mid-CS (45±62% increase in sustained versus 8±29% decrease in non-sustained AF, p=0.001). SampEn values at 30 seconds most strongly predicted post-PVI AF sustainability (p<0.001 in all CS locations).
CONCLUSIONS: Induced sustained AF episodes in paroxysmal AF patients are characterized by an early and gradual increase in electrogram disorganization in both the CS and RA, starting from AF onset and reaching a plateau after 5 minutes. In contrast, non-sustained AF shows more organized electrograms characterized by the absence of any time-dependent disorganization. The resulting divergence in SampEn time-course predicts AF sustainability as early as 30 seconds after onset of induced AF both before and after PVI. These findings provide relevant insights for short duration sequential mapping during AF.
Abstract P1437 Figure.
