QT dispersion in acute myocardial infarction with special reference to left ventriculographic findings

QT and QT dispersion, which is the time difference between QT maximum and QT minimum, were evaluated in 22 patients with anterior myocardial infarction approximately one month after onset. The purpose of this study was to observe how LV wall motion abnormally is related to these variables. Twenty age-matched patients without overt heart disease were also studied as a control group. QT and QT max in patients with acute myocardial infarction (AMI) were markedly prolonged compared to those in normal controls (472.8 +/- 48.0, 483.2 +/- 32.1 vs 390.2 +/- 18.8, and 418.0 +/- 21.0 msec, respectively). QT dispersion and QTc dispersion in patients with AMI were significantly more prolonged than in normal controls (111.2 +/- 33.9, (113.4 +/- 32.9 vs 54.3 +/- 15.0, and 60.3 +/- 17.2 msec, respectively). QT dispersion has a positive correlation with QT max in AMI patients. Ejection fraction (EF) of the left ventricle was relatively well maintained in cases where only one segment of the left anterior ventricular wall was impaired in its motion. It decreased, however, in accordance with the extent of wall motion abnormality QT max and QTc max were prolonged as the number of LV wall segments with impairment increased. This, however, was not statistically significant. QT dispersion and QTc dispersion had no relation to the extent of LV wall motion abnormality nor to EF of the left ventricle In conclusion, no definite relationships between QT dispersion (QTc dispersion) and EF of the left ventricle, or between these variables and the extent of left ventricular wall motion abnormality were found in patients with anterior myocardial infarction in our study. Although both QT max and QT dispersion were prolonged in patients with myocardial infarction, this suggests that electrical heterogeneity or regional variation in electrical ventricular recovery did not always parallel the severity of mechanical abnormality of the left ventricle.