Relationship of Resting Ejection Fraction and Extent of Coronary Arterial Disease with Changes of QRS Amplitude During Exercise Stress Testing

To further elucidate the value of the R wave criteria during the exercise stress test (EST), we studied the direction and magnitude of the changes of the QRS amplitude (delta R) as well as the extent of ST segment depression in 75 patients with coronary artery disease (CAD) and 26 normal subjects (NLS). Results were analyzed in relation to severity of the disease (number of vessels involved) and left ventricular EF. In NLS, there was an average decrease of the QRS amplitude of --1.9 +/- 0.6 mm (mean +/- SE) compared to an average increase of 0.6 +/- 0.35 mm for CAD patients. Mean delta R for 1VD was --0.28 +/- 0.75 mm; for 2VD, it was 0.27 +/- 0.54 mm, and for 3VD, it was 1.37 +/- 0.55 mm. Mean delta R for NLS was significantly different (Duncan's multiple range test, p less than 0.05) from 2VD and 3VD but not from 1VD. Although there was no statistically significant difference of mean delta R among CAD groups, a significant linear trend was observed (p less than 0.008). Resting EF did not correlate either with extent of ST segment depression or with the direction or magnitude of delta R induced by exercise. We conclude that the direction of changes in delta R during exercise is related to the presence or absence of CAD. The magnitude of delta R appears to correlate with the severity of coronary arterial involvement. We did not detect any relationship between R wave changes and left ventricular function. The use of R wave criteria may slightly improve the sensitivity of EST but detracts from specificity.