Isolated potentials during sinus rhythm and pace-mapping within scars as guides for ablation of post-infarction ventricular tachycardia.
OBJECTIVE
The purpose of this study was to identify ventricular tachycardia (VT) isthmus sites by pace-mapping within scar tissue and to identify electrogram characteristics that are helpful in identifying VT isthmus sites during sinus rhythm (SR).


BACKGROUND
Pace-mapping has been used in the scar border zone to identify the exit site of post-infarction VT.


METHODS
In 19 consecutive patients (18 men, mean age 66 +/- 9 years, mean ejection fraction 0.24 +/- 0.12) with post-infarction VT, a left ventricular voltage map was generated during SR. Pace-mapping was performed at sites with abnormal electrograms or isolated potentials. Radiofrequency ablation was performed at isthmus sites as defined by pace-mapping (perfect pace-map = 12/12 matching electrocardiogram leads; good pace-map = 10/12 to 11/12 matching electrocardiogram leads) and/or entrainment mapping.


RESULTS
A total of 81 VTs (mean cycle length 396 +/- 124 ms) were inducible. In 16 of the 19 patients, a total of 41 distinct isthmus areas of 41 distinct VTs were identified and successfully ablated. All but one displayed isolated potentials during SR. Furthermore, 22 of the 81 VTs (27%) for which no isthmus was identified became noninducible after ablation of a targeted VT. The 16 patients in whom > or =1 isthmus was identified and ablated were free of arrhythmic events during a mean follow-up of 10 months.


CONCLUSIONS
During SR, excellent or good pace-maps at sites of isolated potentials within areas of scar identify areas of fixed block that are protected and part of the critical isthmus of post-infarction VT. Shared common pathways might explain why non-targeted VTs might become noninducible after ablation of other VTs.
Bogun
Frank
F
University of Michigan Medical Center, Ann Arbor, Michigan, USA. fbogun@umich.edu
Good
Eric
E
Reich
Stephen
S
Elmouchi
Darryl
D
Igic
Petar
P
Lemola
Kristina
K
Tschopp
David
D
Jongnarangsin
Krit
K
Oral
Hakan
H
Chugh
Aman
A
Pelosi
Frank
F
Morady
Fred
F
D000200:Action Potentials; D000368:Aged; D017115:Catheter Ablation; D002921:Cicatrix; D004562:Electrocardiography; D022062:Electrophysiologic Techniques, Cardiac / Q000379:methods*; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000503:physiopathology*; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000209:etiology / Q000503:physiopathology* / Q000628:therapy*