Does the Exercise Induced QRS Score Improve the Diagnostic Accuracy for Coronary Artery Disease?

ABSTRACT

BACKGROUND: In an effort to improve the diagnostic accuracy of the exercise electrocardiography (ECG) to detect coronary artery disease, exercise-induced changes in Q, R and S wave amplitudes has been evaluated in conjunction with or without ST segment changes. We measured the exercise-induced changes in Q, R and S wave amplitudes, and calculated the Athens QRS score to assess its diagnostic value. MATERIALS AND METHOD: Fifty patients who underwent the exercise test and MIBI myocardial scan and were proved to have coronary artery diameter stenosis > or =50% in coronary angiography were included in the patient group. Data of forty-nine persons showing negative findings in the exercise test and MIBI scan were used as control. The exercise test was performed according to the modified Bruce protocol using Marquette case 16. Exercise ECG was positive in 58% (29/50) of the patient group. The Q, R and S wave amplitudes at peak exercise were subtracted from the values of standing position at rest to obtain Athens QRS score. RESULTS: The mean age of patients and control were 54.5+/-9.4 years and 49.8+/-11.4 years respectively (p=NS), and their exercise capacity was 8.5+/-3.1 mets and 9.8+/-1.9 mets respectively (p=NS). The values of delta(R-Q-S)V5 + delta(R-Q-S)aVF and delta(R-Q-S)aVF were significantly lower in patients than the control (0.85+/-6.60 mm vs 3.72+/-5.09 mm, p=0.017, -0.60+/-4.76 mm vs 1.00+/-2.72 mm, p=0.030), and the values of deltaQV5 and deltaSaVF were significantly higher in patients than the control (-0.045+/-0.65 mm vs -0.41+/-0.78 mm, p=0.012, -0.84+/-1.90 mm vs -1.62+/-1.60 mm, p=0.009). However, the values were too widely overlaped between the patients and the control to give diagnostic cutoff points. CONCLUSION: It seems that exercise QRS scores do not have additive diagnostic value for coronary artery disease.