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 fo r arrhythmic events, often occur during acute coronary occlusion in associa tion with ST-segment elevation. To test the hypothesis that TWA is associat ed with a certain state/severity of myocardial infarction/ischemia, we asse ssed the association between TWA and ST-segment depression during exercise- induced ambulatory ischemia. Of 351 consecutive patients with coronary arte ry disease who underwent assessment of microvolt TWA by exercise, 23 patien ts with effort angina without a history of infarction with ST depression (g reater than or equal to 0.1 mV) during TWA test were selected. These patien ts were compared with 222 postinfarction patients consisting of 38 patients with, and 184 patients, without the ST depression, and 18 normal individua ls. The incidence (9%) of determinate TWA in the patients with angina was s ignificantly (P < .0001) lower than that (52%) in the postinfarction patien ts. 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. Moreo ver, no correlation existed between the TWA voltage and the ST-depression m agnitude in both angina and postinfarction patients. We concluded that ther e is no association between TWA and ambulatory ischemia with ST depression.