Effects of ischemia on QT dispersion during spontaneous anginal episodes

Myocardial ischemia induced by pacing, angioplasty, or stress results in a significant increase in QT dispersion (QTd = QT maximum - QT minimum). This study investigated the effects of ischemia on QTd and the rate-corrected Q Td (QT(C)d) during spontaneous anginal episodes in patients with coronary a rtery disease (CAD). Ninety-five patients with CAD and typical angina pecto ris and 15 control subjects complaining of anginalike symptoms were studied . QTd and QT(C)d were calculated from 12-lead surface electrocardiograms re corded during and after the relief of pain. QTd and QT(C)d were significant ly higher during the anginal episode (84 +/- 31 ms and 98 +/- 51 ms) compar ed to the painless conditions (69 +/- 24 ms and 71 +/- 24 ms) (P = .003 and P = .001 for QTd and QT(C)d, respectively) only in the 57 CAD patients who had a history of an old previous myocardial infarction. QTd and QT(C)d are significantly increased during spontaneous angina in patients with documen ted CAD and history of previous myocardial infarction.