Transient Rotors in Persistent Atrial Fibrillation | Journal Scan

Study Questions:

What is the spatiotemporal stability of rotors in longstanding persistent atrial fibrillation (AF)?

Methods:

Ten patients undergoing cardiac surgery underwent epicardial mapping. Electrograms were recorded over 10 minutes using a triangular plaque (area: 6.75 cm2; 117 bipoles; spacing: 2.5 mm) applied to the left atrial posterior wall and the right atrial free wall. Activation patterns were observed over six discrete 10-second segments of AF spanning 10 minutes. Dynamic activation mapping was performed. The distributions of 4,557 generated activation patterns within each mapped region were compared between the six temporal segments.

Results:

The dominant activation pattern was the simultaneous presence of multiple narrow wave fronts (26%). Twelve percent of activations represented transient rotors, seen in 85% of mapped regions, with a median duration of 3 rotations. A total of 87% were centered on an area of short cycle-length (CL) activity (<100 ms), although such activity had a positive predictive value for rotors of only 0.12. The distribution of activation patterns and wave-front directionality were highly stable over time, with a single dominant pattern within a 10-second AF segment recurring across all six segments in 62% of mapped regions.

Conclusions:

In patients with longstanding, persistent AF, activation patterns are spatiotemporally stable over 10 minutes. Transient rotors can be demonstrated in the majority of mapped regions, are spatiotemporally associated with short CL activity, and, when recurrent, demonstrate anatomical determinism.

Perspective:

Since the majority of AF triggers appear to arise in the pulmonary veins, PV isolation has become the cornerstone of AF ablation for paroxysmal AF. Unfortunately, the mechanisms implicated in persistent AF are much less well understood. Most contemporary data are consistent with a hierarchical model of AF with a high frequency rotor perpetuating the arrhythmia. The purported degree of rotor stability, however, varies across studies, perhaps due to technical and methodological differences. Whether the rotors are stable over prolonged time periods has significant implications on the possibility of targeting them with catheter ablation. The present study supports the existence of transient rotors in the majority of patients and majority of mapped regions, with a median of 3 rotations. The vast majority of rotors were centered on an area of short CL activity, but short CL activity was nonspecific for the identification of rotors. According to the present study, although short-term activation is unstable, patterns of atrial activation consistently repeat over a 10-minute period. The study does not answer the question of whether the rotors are active drivers of fibrillation or simply represent a passive phenomenon.

Clinical Topics: Arrhythmias and Clinical EP, Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Cardiac Surgery and Arrhythmias

Keywords: Arrhythmias, Cardiac, Atrial Fibrillation, Cardiac Surgical Procedures, Catheter Ablation, Epicardial Mapping, Heart Atria, Heart Conduction System, Pulmonary Veins, Rotation


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