Effect of exercise protocol and lead selection on the accuracy of heart rate-adjusted indices of ST-segment depression for detection of three-vessel coronary artery disease.
Academic Article
Overview
abstract
To assess the effect of exercise protocol and number of monitoring leads on the ability of the ST/HR slope and delta ST/HR index to identify three-vessel coronary artery disease, the exercise ECGs of 50 patients who had coronary arteriography were reviewed. Test performance of the ST/HR slope using the Cornell exercise protocol with 13 leads was compared with performance obtained from the standard 12 leads and from sets of only 3 leads, as well as with test outcome using Bruce protocol equivalent stages with multiple-lead sets. ST/HR slopes could be calculated in 100% of patients using data from the Cornell protocol, but in only 80% of patients using the Bruce protocol with 13 leads (chi 2 = 8.1, p less than 0.005) and 54% of patients using the Bruce protocol with 3 leads (chi 2 = 21.0, p less than 0.001). With the Cornell protocol and 13 leads, an ST/HR slope partition of 6.0 microV/bpm identified three-vessel disease with a sensitivity of 96%, specificity of 58%, and overall test accuracy of 76%. At matched specificity, the Bruce protocol 13-lead ST/HR slope partition of 5.0 microV/bpm had a sensitivity of only 48% and overall test accuracy of 53% for three-vessel disease in those patients with calculable test outcomes (each p less than 0.01). Receiver operating characteristic curve analysis confirmed the superior performance of data acquired with the Cornell protocol and demonstrated no significant loss of Cornell ST/HR slope performance calculated from fewer monitored leads. Performance of the delta ST/HR index was similar with 3 leads and with 13 leads.(ABSTRACT TRUNCATED AT 250 WORDS)
