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Characterization of onset mechanism and waveform analysis in patients with atrial fibrillation using a
Stefan Weber1, Gjin Ndrepepa, Michael Schneider
1Deutsches Herzzentrum München and 1. Medizinische Klinik, Klinikum rechts der Isar, Technische Universität München, Munich, Germany. webers@dhm.mhn.de
Insights
Repetitive firing from triggering foci maintains most atrial fibrillation (AF) episodes. Atrial premature complexes (APCs) induce AF based on coupling interval and focus location, with the left atrium’s posterior wall showing earliest disorganization.
Area of Science:
- Electrophysiology
- Cardiology
- Arrhythmia Research
Background:
- Limited understanding of atrial fibrillation (AF) spatiotemporal organization at onset.
- Investigating the mechanisms driving AF initiation and early maintenance.
Purpose of the Study:
- To analyze the role of triggering foci and atrial activity organization in early AF.
- To identify factors influencing AF induction by atrial premature complexes (APCs).
Main Methods:
- Noncontact mapping of the left atrium (LA) in 26 AF patients.
- Analysis of AF cycle lengths and wavefronts at the site of APC origin and predefined LA sites.
- Classification of AF episodes based on repetitive firing from triggering foci.
Main Results:
- APCs inducing AF had shorter coupling intervals (300 +/- 41 ms) than non-inducing APCs (392 +/- 64 ms).
- Repetitive firing from triggering foci maintained 80% of AF episodes immediately after onset.
- The posterior wall of the LA exhibited the earliest disorganized activity (5.2 +/- 3.1 cycles after onset).
Conclusions:
- Repetitive firing from triggering foci is crucial for maintaining AF in the majority of episodes (80%).
- AF in 20% of episodes is maintained by mechanisms other than repetitive focal firing.
- AF induction capability depends on APC coupling interval and focus localization; posterior LA wall shows earliest disorganization.
Introduction:
Information on the spatiotemporal organization of atrial activity at the onset of atrial fibrillation (AF) is limited.
Methods And Results:
The study consisted of 26 consecutive patients (22 men and 4 women; mean age 56 +/- 9 years) with AF in whom the left atrium (LA) was mapped using a noncontact mapping system. At the onset of AF, the AF cycle lengths and wavefronts were analyzed at the site of origin of the triggering atrial premature complex (APC) and five predefined sites within the LA (superior, anterior, posterior, lateral, and septal walls). If repetitive activity was observed at the site of origin of APCs, triggered AF episodes were considered as focally driven. APCs that induced AF had shorter coupling intervals than APCs that did not induce AF (300 +/- 41 msec vs 392 +/- 64 msec, P < 0.001). Immediately after AF onset, repetitive firing was crucial for maintenance of arrhythmia in 52 (80%) of 65 AF episodes. In 13 AF onset episodes (20%), AF was maintained by other mechanisms. The number of LA wavefronts after AF onset was lower in focally driven AF episodes compared with episodes in which no focally driven activity was observed (1.9 +/- 0.6 v. 2.3 +/- 2.3 wavefronts, P < 0.05). After the onset of AF, the posterior wall of the LA showed the earliest disorganized activity (after 5.2 +/- 3.1 cycles).
Conclusion:
In the majority of AF episodes (80%), repetitive firing from the triggering foci may play an important role in maintaining AF immediately after arrhythmia onset. In 20% of the episodes, AF at early stages seems to be maintained by other mechanisms. The capability of APCs to induce AF depends on the coupling interval and the focus localization. The posterior wall of the LA shows the earliest disorganization of wavefronts at the onset of AF.