• Seiji Fukamizu, Harumizu Sakurada, Takekuni Hayashi, Rintaro Hojo, Kota Komiyama, Yasuhiro Tanabe, Tamotsu Tejima, Mitsuhiro Nishizaki, Youichi Kobayashi, and Masayasu Hiraoka.
• Department of Cardiology, Tokyo Metropolitan Hiroo Hospital, Tokyo, Japan. nh6s-fkm@tc4.sonet.ne.jp
• J. Cardiovasc. Electrophysiol. 2013 Apr 1;24(4):404-12.

IntroductionMacroreentrant atrial tachycardia (MRAT) has been described most frequently in patients with prior cardiac surgery. Left atrial tachycardia and flutter are common in patients who undergo atrial fibrillation ablation; however, few reports describe left atrial MRAT involving the regions of spontaneous scarring. Here, we describe left atrial MRAT in patients without prior cardiac surgery or catheter ablation (CA) and discuss the clinical and electrophysiological characteristics of tachycardia and outcome of CA.Methods And ResultsAn electrophysiological study and CA were performed in 6 patients (3 men; age 76 ± 6 years) with MRAT originating from the left atrial anterior wall (LAAW). No patient had a history of cardiac surgery or CA in the left atrium. Spontaneous scars (areas with bipolar voltage ≤ 0.05 mV) were observed in all patients. The activation map showed a figure-eight circuit with loops around the mitral annulus (4 counterclockwise and 2 clockwise) and a low-voltage area with LAAW scarring. The mean tachycardia cycle length was 303 ± 49 milliseconds. The conduction velocity was significantly slower in the isthmus between the scar in the LAAW and the mitral annulus than in the lateral mitral annulus (0.17 ± 0.05 m/s vs 0.94 ± 0.35 m/s; P = 0.003). Successful ablation of the isthmus caused interruption of the tachycardia and rendered it noninducible in all patients.ConclusionSpontaneous LAAW scarring is an unusual cause of MRAT, showing activation patterns with a figure-eight configuration. Radiofrequency CA is a feasible and effective treatment in such cases.© 2012 Wiley Periodicals, Inc.

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