Incremental Value of a Single High-sensitivity Cardiac Troponin I Measurement to Rule Out Myocardial Ischemia

Abstract

BackgroundThe aim of this study was to investigate the value of a novel high-sensitivity cardiac troponin I measurement to rule out exercise-induced myocardial ischemia in patients without known coronary artery disease. MethodsWe included 714 patients without previously known coronary artery disease who were referred for rest/stress myocardial perfusion single photon emission tomography. All clinical information available to the treating cardiologist was used to quantify the clinical judgment regarding the presence of exercise-induced myocardial ischemia using a visual analogue scale twice: once before and once after bicycle exercise stress testing. High-sensitivity cardiac troponin I measurements were obtained before stress testing in a blinded manner. The presence of exercise-induced myocardial ischemia was adjudicated on the basis of myocardial perfusion single photon emission tomography combined with coronary angiography findings. ResultsExercise-induced myocardial ischemia was detected in 167 participants (23.4%). High-sensitivity cardiac troponin I levels were significantly higher in patients with exercise-induced myocardial ischemia (4.0 ng/L [95% confidence interval, 2.8-8.6] vs 2.6 ng/L [95% confidence interval, 1.8-4.1], P < .001) and remained an independent predictor of ischemia in multivariable analysis (P < .001). Combining clinical judgment before exercise testing with high-sensitivity cardiac troponin I levels increased diagnostic accuracy as quantified by the area under the receiver operating curve from 0.64 to 0.73 (P < .001), which also tended to be superior to clinical judgment after exercise testing (0.69, P = .056). A single resting high-sensitivity cardiac troponin I measurement provided similar diagnostic accuracy as integrated clinical judgment after exercise testing including work load, as well as symptoms and electrocardiogram changes (0.70 vs 0.69, P = not significant). ConclusionsHigh-sensitivity cardiac troponin I measurements seem to complement noninvasive clinical assessment in patients with suspected coronary artery disease.