ICD Electrograms Can Identify Ventricular Tachycardia Events
Implantable cardioverter-defibrillator EGMs useful when 12-lead electrocardiograms not available
WEDNESDAY, Sept. 8 (HealthDay News) -- Electrograms (EGMs) produced by implantable cardioverter-defibrillators (ICDs) can be used to distinguish episodes of post-infarction clinical ventricular tachycardia (VT) from other types of VT when 12-lead electrocardiograms (ECGs) of the episodes are not available, according to a study in the Sept. 14 issue of the Journal of the American College of Cardiology.
Kentaro Yoshida, M.D., of the University of Michigan in Ann Arbor, and colleagues induced 124 VTs and recorded ICD EGMs in 21 patients awaiting catheter ablation for post-infarction VT (clinical VTs had been previously documented with 12-lead ECGs in 15 of the patients). The researchers compared the 12-lead ECGs to the ICD EGMs to assess the latter's ability to distinguish clinical VTs. Pace mapping was used to identify VT exit sites for both the 12-lead ECGs and the ICD EGMs.
Analysis of EGMs accurately distinguished clinical VTs from 98 percent of the other inducible VTs. The mean spatial resolution of a 12-lead ECG pace map for the VT exit site was 2.9 cm², compared to 8.9 cm² for ICD EGM pace maps. The researchers found that visual examination of the ICD EGMs distinguished 96 percent of the clinical VTs from prior, undocumented VTs.
"Stored ICD EGMs usually are an accurate surrogate for 12-lead ECGs for differentiating clinical VTs from other VTs. Pace mapping based on ICD EGMs has variable resolution but may be useful for identifying a VT exit site," the authors write.
One author disclosed a patent pending for the technique described in the study.