title: Macroreentrant atrial tachycardia in patients without previous atrial surgery or catheter ablation: clinical and electrophysiological characteristics of scar-related left atrial anterior wall reentry.
abstract: BACKGROUND
  Macroreentrant 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.
  
  
  RESULTS
  An 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.
  
  
  CONCLUSIONS
  Spontaneous 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.
authors.affiliation: Department of Cardiology, Tokyo Metropolitan Hiroo Hospital, Tokyo, Japan. nh6s-fkm@tc4.sonet.ne.jp
authors.forename: Seiji
authors.initials: S
authors.lastname: Fukamizu
authors.forename: Harumizu
authors.initials: H
authors.lastname: Sakurada
authors.forename: Takekuni
authors.initials: T
authors.lastname: Hayashi
authors.forename: Rintaro
authors.initials: R
authors.lastname: Hojo
authors.forename: Kota
authors.initials: K
authors.lastname: Komiyama
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tanabe
authors.forename: Tamotsu
authors.initials: T
authors.lastname: Tejima
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Nishizaki
authors.forename: Youichi
authors.initials: Y
authors.lastname: Kobayashi
authors.forename: Masayasu
authors.initials: M
authors.lastname: Hiraoka
mesh_terms: D000200:Action Potentials; D000368:Aged; D000369:Aged, 80 and over; D017115:Catheter Ablation; D002921:Cicatrix / Q000209:etiology* / Q000473:pathology / Q000503:physiopathology; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac; D005240:Feasibility Studies; D005260:Female; D006325:Heart Atria / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D006329:Heart Conduction System / Q000473:pathology / Q000503:physiopathology* / Q000601:surgery; D006801:Humans; D008297:Male; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012307:Risk Factors; D013617:Tachycardia, Supraventricular / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery; D013997:Time Factors; D016896:Treatment Outcome