Prognostic value of Duke treadmill score in unstable angina patients

Abstract

Objectives: Exercise electrocardiography still remains the corner-stone of non-invasive evaluation of functional state of cardiac patients. The purpose of this study was to evaluate prognostic value of Duce treadmill score in a very early symptom-limited exercise testing in patients admitted to hospital for a suspected unstable angina. Design and Methods: The treadmill exercise testing (TET) using a modified Bruce protocol was performed on 40 low-risk patients (group I) during 48 h after admission as early as possible but not before 24 h after stabilization of their clinical condition. The low-risk group consisted of patients with no prior history of coronary disease, no abnormal creatine kinase, and the ECG was either normal or had minor non-specific ST-segment and T-wave changes. We compared the data with the results of 167 unstable angina patients with medium or high risk after clinical stabilization (group II). Time from hospital admission to TET was more than 48 h in group II patients. Results: Mean stress duration showed no significant differences between groups: 7.87 ± 4.7 min in group I and 5.93 ± 3.1 min in group II, but exercise test responses were respectively: heart rate >75% max predicted: 63.0% and 24%, diagnostic ST depression: 27.5% and 44.3%, angina: 30% and 28%, limiting angina: 12.5% and 15.0%, no ischemia: 15.0% and 7.8%. Mean Duke treadmill score was +5.5 in group I and +2.5 in group II. Mean predictive 5 years overall survival was respectively 95% and 90%. The patients of group I had better exercise capacity and ST depression was registered only in 27% of patients as compared with 44.3% of patients of gr. II (p < 0.01). However, there were noted ST elevation episodes with ventricular tachycardia in the patients of group I during further ECG monitoring in hospital. Conclusion: Duke treadmill score is not predictive in a very early exercise test among low-risk patients with unstable angina.