Unusual ECG responses to exercise stress testing

We describe the case of a patient with coronary artery disease who developed transient ST-segment depression, right bundle branch block (RBBB), left anterior hemiblock, ST-segment elevation +ST), and "giant" T-waves in her electrocardiogram (ECG), an assortment of ECG patterns heretofore unreported in conjunction with exercise stress testing (EST). The amplitude of the +ST was modulated by the superimposed RBBB, as was shown by its augmentation after the abrupt disappearance of RBBB. Following recession of the latter "giant" T-waves, which usually are encountered in the hyperacute phase of myocardial infarction, developed and persisted late in the recovery period. Cardiac enzymes after EST were negative, and arteriography revealed a stenotic left anterior descending coronary artery. The present case indicates that a variety of ECG expressions of severe transmural ischemia or myocardial infarction can also be manifest in the course of EST; this also suggests a common pathophysiological mechanism in severe EST-triggered ischemia and the early phase of myocardial infarction.