Catheter ablation of ventricular tachycardia after myocardial infarction: relation of endocardial sinus rhythm late potentials to the reentry circuit.
OBJECTIVE
We sought to determine whether endocardial late potentials during sinus rhythm are associated with reentry circuit sites during ventricular tachycardia (VT).


BACKGROUND
During sinus rhythm, slow conduction through an old infarct region may depolarize tissue after the end of the QRS complex. Such slow conduction regions can cause reentry.


METHODS
Endocardial catheter mapping and radiofrequency ablation were performed in 24 patients with VT late after myocardial infarction. We selected for analysis a total of 103 sites where the electrogram was recorded during sinus rhythm and, without moving the catheter, VT was initiated and radiofrequency current applied in an attempt to terminate VT.


RESULTS
Late potentials were present at 34 sites (33%). During pace mapping, the stimulus-QRS complex was longer at late potential sites, consistent with slow conduction, than at sites without late potentials (p < 0.0001). Late potentials were present at 15 (71%) of 21 sites classified as central or proximal in the reentry circuit based on entrainment, but also occurred frequently at bystander sites (13 [33%] of 39) and were often absent at the reentry circuit exit (3 [23%] of 13). Late potentials were present at 20 (54%) of 37 sites where ablation terminated VT, compared with 14 (21%) of 66 sites where ablation did not terminate VT (p = 0.004). Ablation decreased the amplitude of the late potentials present at sites where ablation terminated VT.


CONCLUSIONS
Although sites with sinus rhythm late potentials often participate in VT reentry circuits, many reentry circuit sites do not have late potentials. Late potentials can also arise from bystander regions. Late potentials may help identify abnormal regions in sinus rhythm but cannot replace mapping during induced VT to guide ablation.
Harada
T
T
Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
Stevenson
W G
WG
Kocovic
D Z
DZ
Friedman
P L
PL
D000200:Action Potentials; D017115:Catheter Ablation / Q000592:standards; D004562:Electrocardiography; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008991:Monitoring, Physiologic; D009203:Myocardial Infarction / Q000150:complications*; D011930:Reaction Time; D012008:Recurrence; D017180:Tachycardia, Ventricular / Q000209:etiology* / Q000503:physiopathology / Q000601:surgery*; D016896:Treatment Outcome