Cycle-ergometry stress testing and use of chronotropic reserve adjustment of ST depression for identification of significant coronary artery disease in clincal practice

Abstract Diagnostic reliability of indexations of peak exercise ST segment depression (ΔST) for heart rate reserve (HRi) or chronotropic reserve (CR) to identify significant coronary artery disease (CAD) by cycle-ergometer exercise testing has not been evaluated previously. Exercise testing by upright cycle-ergometer (25 W/3 min) were performed in consecutive patients in primary prevention with history of exercise-related chest discomfort and cardiovascular risk factors, or with overt peripheral artery disease, with or type-2 diabetes associated with two or more additional cardiovascular risk factors. Coronary angiography was performed after the test to assess significant CAD. Three different criteria for definition of inducible myocardial ischemia were tested versus significant CAD: peak ΔST≥100 μV, ST/HRi>1.69 μV/bpm or ST/CR>1.76 μV/%. Diagnostic accuracy vs. CAD of ΔST≥100 μV, of ST/HRi>1.69 μV/bpm, and of ST/CR>1.76 μV/% were 78%, 72%, and 89% respectively; sensitivity and specificity of the three criteria were 91% and 50%, 84% and 43%, 88% and 93%, respectively. Abnormal ST/CR predicted CAD independent of risk factors, pre-test probability, and more strongly than ΔST. Combination of ST/HRi and ST/CR criteria did not improve CAD prediction. In conclusions, in clinical setting in patients in primary prevention but with moderate-to-high pre-test probability of CAD, exercise testing by cycle-ergometry and use of ST/CR>1.76 μV/% showed elevated sensitivity and specificity, and the best accuracy for diagnosis of significant CAD.