Comparison of mapping criteria for hemodynamically tolerated, postinfarction ventricular tachycardia.

BACKGROUND: Mapping criteria for hemodynamically tolerated, postinfarction ventricular tachycardia (VT) have been evaluated in only small series of patients.
OBJECTIVES: The purpose of this study was to evaluate the utility of various mapping criteria for identifying a critical VT circuit isthmus in a post hoc analysis.
METHODS: Ninety VTs (cycle length 491 +/- 84 ms) were mapped in 48 patients with a prior myocardial infarction. The mapping catheter was positioned within a protected area of the reentrant circuit of the targeted VTs at 176 sites. All sites showed concealed entrainment. The predictive values of the following mapping criteria for a successful ablation site were compared: discrete isolated potential during VT, inability to dissociate the isolated potential from the VT, endocardial activation time >70 ms, matching electrogram-QRS and stimulus-QRS intervals, VT termination without global capture during pacing, stimulus-QRS/VT cycle length ratio <or=0.7, and postpacing interval. For each criterion, the receiver operating characteristic curve was constructed, and the area under the curve was calculated to assess the discriminatory value of the criterion.
RESULTS: Seventy-eight of 90 VTs (87%) were successfully ablated. The area under the receiver operating characteristic curve was largest (0.89) for matching stimulus-QRS and electrogram-QRS intervals. In combination with an isolated potential that could not be dissociated from the VT, the area under the receiver operating characteristic curve increased to 0.93.
CONCLUSION: At sites with concealed entrainment, matching stimulus-QRS and electrogram-QRS intervals were superior to other criteria in differentiating a critical isthmus from bystander or noncritical sites in postinfarction VT.