Delayed Enhancement Morphology on Cardiac Magnetic Resonance Imaging is Correlated with Signal-averaged Electrocardiogram and QT Dispersion in Myocardial Infarction

Abstract

Background In patients with myocardial infarction, ventricular tachycardia is related with nonconductive ventricular scar. Cardiac magnetic resonance imaging is an excellent modality to evaluate myocardial scars in myocardial infarction. Furthermore, late potential obtained from signal-averaged electrocardiogram and QT dispersion are both well-known parameters for predicting lethal arrhythmias. Methods and Results To investigate whether the pattern of necrotic scar tissue visualized by delayed enhancement on cardiac magnetic resonance imaging is associated with late potential and QT dispersion, we measured late potential and QT dispersion in 27 patients (68 ± 8 years old) with a prior myocardial infarction. Cardiac magnetic resonance imaging was also obtained using a 1.5-tesla cardiac magnetic resonance scanner, and delayed enhancement was analyzed in the short axis of the left ventricle. By conducting this, we tried to determine whether the pattern of necrotic scar tissue predicts lethal ventricular arrhythmias. Semiquantitative patchy scores were identified as the mean patchy score and the maximum patchy score in each patient. There were 9 patients with a positive late potential and 18 patients with a negative late potential. Patients with positive late potentials had significantly larger mean (1.7 ± 0.3) and maximum (2.2 ± 0.6) patchy scores than patients with negative late potentials (mean, 1.3 ± 0.2, P < .05; maximum, 1.7 ± 0.4, P < .05). QT dispersion was significantly correlated with the number of slices showing delayed enhancement, which reflects the size of necrotic scar tissue ( r = .59, P < .05). Conclusions These findings suggest that the pattern of necrotic scar tissue visualized by delayed enhancement with cardiac magnetic resonance imaging was correlated to the predictive indices of lethal ventricular arrhythmias.