The effect of ST resolution on QT dispersion after interventional treatment in acute myocardial infarction.

Abstract

It has been reported that reperfusion treatment reduces QT dispersion (QTD) in cases of acute myocardial infarction (AMI). Successful myocardial perfusion is not synonymous with Thrombolysis in Myocardial Infarction (TIMI) III flow. It has been demonstrated that in AMI, the grade of ST-resolution correlates strongly with left ventricular (LV) function, enzyme elevation, and mortality after primary angioplasty. This study investigated the relation between ST-resolution grade and QTD and the feasibility of using QTD as a determinant of successful myocardial tissue perfusion in patients in whom TIMI III flow in the infarct-related artery (IRA) is restored by interventional treatment for AMI. The study included 57 patients (38 men, 19 women, average age 54.4 +/- 11.6 years), whose IRA was perfused by primary angioplasty after the diagnosis of anterior AMI with ST elevation. Electrocardiograms of patients were taken 45 +/- 12 min post procedure, and patients were divided into three groups depending on the grade of ST resolution: Group 1, full ST resolution; Group 2, partial ST resolution; and Group 3, unsuccessful ST resolution. Full ST resolution was seen in 19 cases (33%), partial resolution in 26 cases (47%), and unsuccessful resolution in 12 cases (20%). There were no differences among groups in terms of risk factors, stent diameters, symptom onset-balloon time, LV function, and preprocedure corrected QTD (QTcD) (p = 0.274). After the procedure, a significant reduction in QTcD was found within the groups (p = 0.0001 in Group 1, p = 0.004 in Group 2, and p = 0.011 in Group 3). Reductions in QTcD post procedure were 24.21 +/- 14.27, 11.85 +/- 16.18, and 12.50 +/- 11.58 ms in Groups 1, 2, and 3, respectively. There was a statistically significant difference of p = 0.015 between Groups 1 and 2 and a difference of p = 0.028 between Groups 1 and 3. There was no statistically significant difference between Groups 2 and 3 (p = 0.916). In acute MI, TIMI III flow led to a reduction in QTcD, and full myocardial perfusion made an additional contribution to the electrical stability of the myocardium.