Usefulness of the QTc interval in predicting myocardial ischemia in patients undergoing exercise stress testing.

Prolongation of the QTc interval during stress testing predicts myocardial ischemia with a sensitivity of 88% and a specificity of 93%. Measurement of the QTc segment should be considered as an adjunctive electrocardiographic variable in the interpretation of stress tests and is even useful in patients who are not able to achieve the age-predicted target heart rate level.