Event-free survival in patients after an acute coronary event with exercise-induced normalization of the T-wave

Abstract

Background: Risk stratification of patients with unstable angina or non-Q-wave myocardial infarction (MI) is an unresolved clinical problem. The prognostic value of T-wave normalization (TWN) during exercise has not been studied in this group of patients. Hypothesis: Event-free survival in clinically stable patients after an acute coronary event without ST-segment elevation can be predicted by the presence of exercise-induced TWN. Methods: Sixty-five patients (43 men and 22 women, mean age 62 ± 10 years) entered the study. The diagnosis of unstable angina and non-Q-wave MI was made in 40 and 25 patients, respectively. A treadmill exercise test was performed in all patients after clinical stabilization. The patients were divided into three groups: Those with negative baseline T waves and exercise-induced TWN (Group 1); those with negative baseline T waves, but without TWN (Group 2); and those with positive baseline T waves (Group 3). The patients were followed up for 6 months. Results: During follow-up, serious cardiovascular complications occurred in 15 (23%) patients. These included exacerbation of ischemic heart disease (14 patients) and acute MI (1 patient). Event-free survival was greater in patients in Group 1 (95%) than in those in Group 2 (68%, p < 0.034) or Group 3 (71%, NS). Among all patients studied, exercise-induced TWN was predictive of event-free survival with a sensitivity of 38% and a specificity of 93%. Conclusions: In clinically stable patients after an acute coronary event without ST-segment elevation, exercise-induced TWN is a specific but not sensitive predictor of event-free survival after 6 months.