Validity of exercise treadmill test in diagnosis of coronary artery disease

Abstract

Background: Exercise is commonly used as a physiological test to determine cardiovascular disorders not appearing at rest and to assess the functional status of the heart. It is a widely used non-invasive test for assessment of suspicious or proved cardiovascular disorders. It is mainly performed to clarify the prognosis and to assess the functional capacity, the possibility and severity of coronary artery disease (CAD), and the efficacy of treatment. Coronary angiograprhy is the standard method for diagnosis of coronary artery disease (CAD), and it determins the type of therapy according to severity of coronary involvement wether by medical therapy, percutanous coronary intervention (PCI), or coronary artery bypass grafting (CABG) surgery in patients with CAD. Aim: To estimate the sensitivity, specificity, positive and negative predictive values and accuracy of exercise treadmill test in diagnosis of coronary artery disease. Methods: Exercise treadmill test and coronary angiography were performed on 77 consecutive patients (men and women), age range between 30-70 years, they were evaluated at Basrah Cardiac Center (February-June-2012). Both examinations were performed primarily for diagnostic reasons. All clinical data and results of ECG and exercise treadmill test were collected before coronary angiography. Results: The total number of patients included in the study was 77; mean age was 56.9 ± 8.9 years. The mean age for men was 57.0 ± 8.7 years (n= 53), women had a mean age of 56.0 ± 9.5 years (n=24), 90.9% of patients had CAD risk factors. Hypertension was the frequent risk factor present in 72% of patients. Exercise test was positive in 75.3%, negative in 20.8%, pseudonormalization in 3.9%. The sensitivity and positive predictive value of the test were 88% and 79% respectively, while its specificity, negative predictive value and accuracy were 46%, 63% and 75% respectively. Conclusion: Exercise test is a relatively safe, non-invasive and valuable test in the diagnosis of CAD in patients with signs and symptoms of this disease, but still considered below the coronary angiography (which is the gold standard method) for the diagnosis of CAD. The sensitivity of the test increases as the number of diseased coronary arteries increases as in left main and three vessel diseases. ST depression in women with abnormal resting ECGs is probably of less diagnostic value than in men, false positive and false negative tests were more common in women than men.