Lack of an association between T-wave alternans and ST-segment depression during exercise-induced ambulatory ischemia

It is known that T-wave alternans (TWA), which identify patients at risk for arrhythmic events, often occur during acute coronary occlusion in association with ST-segment elevation. To test the hypothesis that TWA is associated with a certain state/severity of myocardial infarction/ischemia, we assessed the association between TWA and ST-segment depression during exercise-induced ambulatory ischemia. Of 351 consecutive patients with coronary artery disease who underwent assessment of microvolt TWA by exercise, 23 patients with effort angina without a history of infarction with ST depression (> or =0.11 mV) during TWA test were selected. These patients were compared with 222 postinfarction patients consisting of 38 patients with, and 184 patients, without the ST depression, and 18 normal individuals. The incidence (9%) of determinate TWA in the patients with angina was significantly (P < .0001) lower than that (52%) in the postinfarction patients. There was no significant difference between the angina patients and the controls (6%). There was also no difference between the patients with (58%) and without the ST depression (51%) in the postinfarction patients. Moreover, no correlation existed between the TWA voltage and the ST-depression magnitude in both angina and postinfarction patients. We concluded that there is no association between TWA and ambulatory ischemia with ST depression.