Background: The objective of the study was to identify the parameter(s) of cardiopulmonary exercise testing (CPET) that can detect exercise-induced myocardial ischaemia (EIMI), and to determine its diagnostic accuracy for identifying patients with coronary artery disease (CAD).
Methods and results: We prospectively studied 202 consecutive patients (173 men, 29 women, mean age 55.7+/-10.8 years) with documented CAD. All patients underwent an incremental exercise stress testing (ECG-St) with breath-by-breath gas exchange analysis, followed by a 2-day stress/rest gated SPECT myocardial scintigraphy (GSMS) as the gold standard for ischaemia detection. ROC analysis selected a two-variable model-O(2)pulse flattening duration, calculated from the onset of myocardial ischaemia to peak exercise, and deltaVO(2)/deltawork rate slope-to predict EIMI by CPET. GSMS identified 140 patients with reversible myocardial defects, with a Summed Difference Score (SDS) of 9.7+/-2.8, and excluded EIMI in 62 (SDS 1.3+/-1.6). ECG-St had low sensitivity (46%) and specificity (66%) to diagnose EIMI as compared with CPET (87% and 74%, respectively).
Conclusions: The addition of gas exchange analysis improves the diagnostic accuracy of standard ECG stress testing in identifying EIMI. A two-variable model based on O(2)pulse flattening duration and deltaVO(2)/deltawork rate slope had the highest predictive ability to identify EIMI.