Does increased QT dispersion in the acute phase of anterior myocardial infarction predict recovery of left ventricular wall motion?

Abstract

QT dispersion has been recognized as an undesirable marker because of its association with arrhythmogenicity in patients with myocardial infarction, but the relation between QT interval dispersion and wall motion abnormalities has not been clarified. After the introduction of reperfusion therapy, it was recognized that T waves were inverted twice in the course of myocardial infarction. An investigation was made of the clinical significance of QT dispersion in relation to the presence of inverted T waves and left ventricular wall motion abnormalities in 34 patients (mean age, 59 years) with acute anterior myocardial infarction who underwent successful reperfusion therapy. The amplitude of the deepest inverted T waves occurring within the first 3 days (T 1) and after 3 days (T 2) of myocardial infarction were measured in electrocardiographic (ECG) lead V 3. On the ECGs on which T 1 and T 2 were recorded, QT dispersion was calculated (QTd 1, QTd 2), and T 1 and T 2 were correlated with QTd 1 ( r = .65) and QTd 2 ( r = .47), respectively. The difference between the extent of asynergy in the acute phase and the chronic phase, which was evaluated by the centerline method, was correlated with T 1 ( r = .63) and QTd 1 ( r = .67). Patients with a QTd 1 of 0.1 second or longer showed a greater change in the extent of asynergy (23.4 ± 13.1% vs 4.9 ± 9.8%, P < .01) and less asynergy in the chronic phase (19.9 ± 15.6% vs 46.5 ± 14.0%, P < .01) than patients with a QTd 1 of less than 0.1 second. Thus, QT dispersion in the acute phase of anterior myocardial infarction indicates recovery of left ventricular wall motion. Prolongation of the local action potential duration of the myocardium that recovers from severe ischemia may be a contributor to the increased QT dispersion that results in inversion of T waves in the acute phase of myocardial infarction.