Noncontact mapping electrograms did not reliably identify ventricular scar in an ovine model, showing only weak correlation for negative slope duration (r=0.23, P=0.004).
Does a noncontact mapping system reliably identify left ventricular scar compared to contact mapping and histology in an ovine model of myocardial infarction?
Noncontact electrograms do not reliably identify ventricular scar in an ovine model of myocardial infarction, suggesting alternative strategies like CT integration are needed.
Effect estimate: r=0.23
p-value: p=0.004
BACKGROUND: We assessed the hypothesis that "virtual electrograms" from a noncontact mapping system (EnSite 3000) could be used to localize myocardial scar. METHODS AND RESULTS: Myocardial infarctions were induced in sheep by inflating an angioplasty balloon in the left anterior descending coronary artery for 3 hours. Scar mapping was performed on 8 sheep without inducible ventricular tachycardia by use of the noncontact mapping system and a 256-channel contact mapping system. Transmural mapping needles were inserted into myocardial regions that were (1) scarred, (2) peripheral to the scar, and (3) distant from the scar. Unipolar electrograms were exported from both systems and analyzed on a personal computer workstation. The percentage of myocardial scarring at each needle site was assessed histologically. Pearson's correlation was used to assess the degree of association between various electrogram characteristics and the presence of myocardial scarring. The only noncontact electrogram characteristic that showed any association with the presence of myocardial scarring was the negative slope duration (contact, r=0.62, P<0.001; noncontact, r=0.23, P=0.004). The other electrogram characteristics studied were electrogram maximal deflection (contact, r=0.38, P<0.001; noncontact, r=0.03, P=0.75) and minimal slope (contact, r=0.42, P<0.001; noncontact, r=0.05, P=0.54). CONCLUSIONS: Noncontact electrograms do not reliably identify ventricular scar. Alternative strategies such as importing computed tomography images into the geometry should be used when scar localization is important.
Thiagalingam et al. (Wed,) conducted a other in Myocardial infarction and left ventricular scar (n=8). Noncontact mapping system (EnSite 3000) vs. 256-channel contact mapping system was evaluated on Correlation between electrogram characteristics and histological presence of myocardial scarring (r=0.23, p=0.004). Noncontact mapping electrograms did not reliably identify ventricular scar in an ovine model, showing only weak correlation for negative slope duration (r=0.23, P=0.004).