Does ST-segment depression combined with R wave amplitude change improve the test accuracy of the EKG during exercise testing?

Park, Seong Mi; Ro, Young Moo; Jeong, Seong Won; Shin, Jeong Ho; Kim, Jin Seok; Lee, Ho Joon; Song, Woo Hyuk; Park, Chang Kyu; Kim, Young Hoon; Seo, Hong Seog; Shim, Wan Joo; Oh, Dong Joo

Abstract

BACKGROUND
Exercise electrocardiogram is the most widely used non-invasive test in those patients suspected of having coronary artery disease. However, sensitivity and specificity of this test are not satisfactory, especially when the exercise induced ST-segment depression is used as a single criterion of myocardial ischemia. Although many investigators have tried to improve diagnostic accuracy with R-wave amplitude change in addition to ST-segment depression, controversy exists whether this new criteria improve the test accuracy for coronary artery disease or not. The purpose of this study is to determine the test accuracy of R-wave amplitude change induced by exercise combined with the conventional ST-segment criterion for myocardial ischemia.
METHODS
We reviewed our records of patients who visited to Korea University Anam Hospital with chest pain from January, 1998 to July, 1999. We included 130 patients with chest pain who had a tredmill test followed by a coronary angiography within 2 months. Patients with change in ST-segment depression (delta STD)> or = 1.00 mm and delta STD> or = 1.00 mm with R wave amplitude decrease (-delta R)> or = 1.00 mm in the same lead in any of 12 leads and delta STD> or = 1.00 mm with R wave amplitude increase (+delta R)> or = 1.00 mm in the same lead in any of 12 leads were compared. According to the findings of coronary angiograms, patients were divided into 4 groups ; normal coronary artery group, mild coronary artery stenosis group (> or = 30% to <50%), moderate coronary artery stenosis group (> or = 50% to <70%), severe coronary artery stenosis group (> or = 70%).
RESULTS
Fifty three patients (40.7%) had normal coronary angiograms and 77 patients (59.3%) had coronary artery stenosis. There was no significant difference in gender and age. But, patients with coronary artery stenosis had more diabetes mellitus, hyperlipidemia, smoking, previous myocardial infarction history and angina during exercise testing than those without coronary artery stenosis. The sensitivity of exercise EKG is significantly decreased when combined with delta R (delta STD, 74.0%, delta STD with -delta R, 45.5%, delta STD with +delta R, 30.0%, p<0.01), but the The test accuracy is delta STD; 73.7%, delta STD with -delta R; 61.5%, delta STD with +delta R; 57.7%.
CONCLUSION
When ST-segment depression is combined with R-wave amplitude change as a marker for myocardial ischemia, the specificity is increased, but the test accuracy of exercise EKG is not improved.