Previous studies in patients with sustained ventricular tachycardia (VT) have demonstrated the efficacy of surgical and catheter-mediated ablative procedures based on activation mapping during VT. Since extensive preoperative or intraoperative mapping may be impractical due to time constraints or patient intolerance, we sought to define characteristics of the 12-lead electrocardiogram (ECG) during VT that could suggest a particular endocardial region of origin and thus facilitate mapping studies. Endocardial mapping was performed during 182 VTs in 108 patients with prior myocardial infarction of either the anterior or inferior wall. Endocardial sites of origin (sites from which ≥ 40 msec of presystolic electrical activity was consistently recorded) were identified with use of catheter (154 VTs) or intraoperative (85 VTs) activation mapping (both methods used in 57 VTs). Twelve-lead ECGs obtained during these VTs were characterized by four features: location of infarction, bundle branch block type configuration, quadrant of QRS axis, and precordial R wave pregression pattern. A specific combination of these four features was associated with a particular endocardial region containing the mapped site of origin in 87 VTs (48% of total). An association (≥ 70% positive predictive accuracy) was more likely to be found in the presence of left, as opposed to right, bundle branch block type patterns (53/73 [73%] vs 34/109 [31%]; p < .001) and in the presence of VT related to inferior, as opposed to anterior, infarction (40/54 [74%] vs 47/128 [37%]; p < .001). An algorithm developed with the above criteria was then applied prospectively to 110 VTs (all mapped) in an additional 63 patients. Each author, blinded to mapping data, used the algorithm to correctly predict endocardial region of origin for a mean of 60 of 65 (93%) VTs to which the algorithm could be applied. These data indicate that the 12-lead ECG during VT can be used to suggest an endocardial region of origin in approximately one-half of VTs in patients with a single site of myocardial infarction. Although this information should not be a substitute for careful mapping when such studies are possible, the findings of this study may be used to facilitate placement of recording electrodes in areas likely to contain sites of origin and thus expedite mapping.
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)