Unsuitability of corrected QT dispersion as a marker for ventricular arrhythmias and cardiac sudden death after acute myocardial infarction

The present study investigated whether corrected QT (QTc) dispersion could play a role as a marker of ventricular arrhythmias and sudden cardiac death after acute myocardial infarction (MI). The study included 76 males and 24 females with a mean age of 60+/-11 years. Standard 12-lead ECGs were recor ded during the recovery phase (15+/-9 days) after the onset of MI. The QTc was calculated according to Bazett's formula and QTc dispersion was calcula ted as the difference between the maximum and minimum QTc intervals. Patien ts were divided into 2 groups: 21 patients (group A) had a QTc dispersion o f greater than or equal to 80ms, and the other 79 patients (group B) had a QTc dispersion of <80ms in the recovery stage (15+/-9 days). Clinical, angi ographical, and Holter monitoring data, and prognosis (mean follow-up perio d 29+/-18 months) were compared between these 2 groups. The frequencies of early coronary reperfusion and recanalization of infarct-related vessels du ring the recovery phase were significantly higher in group B than group A. The left ventricular ejection fraction was also higher in group B than grou p A (51+/-12 vs 43+/-12%, p=0.0029), There were no significant differences in the number of premature ventricular contractions, the percentage of pati ents with repetitive ventricular arrhythmias, or in the frequency of sudden cardiac death during the follow-up period between the 2 groups. In summary , QTc dispersion in the recovery stage is not a useful marker for ventricul ar arrhythmias or sudden cardiac death after acute MI, although increased Q Tc dispersion may correlate with an ineffective early coronary reperfusion and with the degree of depressed left ventricular function.