Characteristics of Atrial Tachycardia due to Small versus Large Reentrant Circuits after Ablation of Persistent Atrial Fibrillation.

Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan, USA.
Heart rhythm: the official journal of the Heart Rhythm Society (Impact Factor: 4.92). 12/2012; 10(4). DOI: 10.1016/j.hrthm.2012.12.018
Source: PubMed

ABSTRACT BACKGROUND: While macro-reentrant atrial tachycardias (AT) have been reasonably well described, little is known about small reentrant circuits. OBJECTIVE: The goal of the study was to compare characteristics of large and small reentrant circuits after ablation of persistent atrial fibrillation (AF). METHODS: Seventy-seven patients (age=61±10 years; LA=46±6 mm; EF=0.52±0.13) underwent a procedure for post-ablation AT. The p-wave duration, circuit size, electrogram characteristics, and conduction velocity were determined. RESULTS: AT was due to macro-reentry in 62 patients (80%), a small reentrant circuit in 13 (17%), and a focal mechanism in 2 (3%). The p-wave duration during small reentrant ATs was shorter than that during macro-reentry (174±12 vs. 226±22 ms; p<0.0001). The duration of fractionated electrograms at the critical site was longer in small vs. large circuits (167±43 vs. 98±38 ms, respectively, p<0.0001), and accounted for a greater percentage of the tachycardia cycle length (59±18 vs. 38±14%, respectively, p<0.0001). The mean diameters of macro-reentrant vs. small reentrant circuits were 44±7 and 26±11 mm, respectively (p<0.0001). The mean conduction velocity along the small circuits was lower (0.5±0.2 vs. 1.2±0.3 m/s, p<0.0001). Catheter ablation eliminated the AT in all 77 patients. CONCLUSIONS: AT due to a small reentrant circuit after ablation of AF may be distinguished from macro-reentry by a shorter p-wave duration, and the presence of long-duration electrograms at the critical site owing to extremely slow conduction. These features may aid the clinician in mapping of post-ablation ATs.

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