Clinical Usefulness of Systolic Time Intervals and QT-QS2 Value as Complication Predictors in Myocardial Infarction

ABSTRACT

Over the physiologic range of heart rate, the duration of electrical systole(QT) is shorter than that of electromechanical systole(QS2), which reflects direct physiologic link between electrical repolarization and mechanical events of the cardiac cycle. The present study designed to test usefulness of systolic time intervals and QT-QS2(QT minus QS2) value as complication predictors, which may predict prognostic status of myocardial infarction. The studied subjects were consisted of 33 healthy adults as control(22 men, 11 women) and 35 patients with myocardial infarction. And studied patients were divided into 3 groups; group I of 14 patients with or without complication in acute stage, group II of 11 uncomplicated patients under recovery of chronic status, group III of 10 complicated patients under recovery or chronic status. The observation periods were 3 to 13 days in group I, 5 to 96 weeks in group II and III after their onset. The results were follows; 1) The normal ranges were defined as mean+/-2 standard deviations of the measured values of control, that of QTc were shorter than 431ms of man and 458ms of woman, that of QS2 I were longer than 503ms of man and 514ms of woman, that of PEP/LVET ratio was less than 0.40, that of QT-QS2 value was less than 0 ms respectively. 2) QTc of all patient groups were significantly prolonged compared with that of control, and that of group III was significantly longer than that of group II(481+/-25 vs 432+/-32, pQS2 in group I and III. and QTQS2 had positive predictive value of 82% for predicting probability of previous complicated status. We concluded that QT-QS2 value, including PEP/LVET ratio and QTc, could be used as complication predictors. But it is necessary to examine these indicators prospectively to confirm its clinical applicability.