UNRELIABILITY OF EXERCISE-INDUCED R-WAVE CHANGES AS INDEXES OF CORONARY-ARTERY DISEASE

To investigate the diagnostic value of exercise-related QRS amplitude changes, the responses of 40 young normal subjects and 28 patients with chest pain and no significant coronary arterial obstruction were compared with those of 73 patients with coronary arterial narrowing of various degrees of severity. All underwent submaximal, multiple lead multistaged treadmill exercise testing. The combined normal group showed an average decrease in R wave amplitude between rest and exercise of 1.1 ± 2.8 mm (mean ± standard deviation) in lead V5; those with coronary artery disease had an increase of 0.6 ± 3.4 mm (P = 0.001). Similar but less pronounced differences were observed in lead II (a decrease of 1.9 ± 2.3 mm in normal subjects versus a decrease of 0.5 ± 3.1 mm in those with coronary disease, P = 0.01). When derived R wave criteria were used, the test sensitivity averaged 52 percent and the specificity 63 percent; these values were inferior to the sensitivity of 88 percent and specificity of 72 percent of S-T segment criteria in the same group of patients. No significant relation was found between the extent of coronary artery disease and R wave changes, and an analysis of multiple variables suggested possible correlations with factors not directly related to ischemia. It is concluded that exercise-induced QRS amplitude changes are unreliable predictors of the presence, absence or severity of coronary artery disease. © 1979.