Elsevier

American Heart Journal

Volume 173, March 2016, Pages 8-17
American Heart Journal

Clinical Investigation
Clinical benefit of high-sensitivity cardiac troponin I in the detection of exercise-induced myocardial ischemia

https://doi.org/10.1016/j.ahj.2015.11.010Get rights and content

Background

A pilot study using a novel high-sensitivity cardiac troponin I (hs-cTnI) assay suggested that cTnI might be released into blood during exercise-induced myocardial ischemia. We investigated the potential clinical value of this signal.

Methods

We included 819 patients with suspected exercise-induced myocardial ischemia referred for rest/bicycle myocardial perfusion single-photon emission computed tomography. The treating cardiologist used all available clinical information to quantify clinical judgment regarding the presence of myocardial ischemia using a visual analog scale twice: prior and after stress testing. High-sensitivity cTnI measurements were obtained before, immediately after peak stress, and 2 hours after stress testing in a blinded manner. Myocardial ischemia was adjudicated using perfusion single-photon emission computed tomography and coronary angiography findings.

Results

Exercise-induced myocardial ischemia was detected in 278 (34%) patients. High-sensitivity cTnI levels were significantly higher at all time points in patients with myocardial ischemia as compared with those without (P < .001 for all). Combining clinical judgment prior exercise testing with baseline hs-cTnI levels increased diagnostic accuracy as quantified by the area under the receiver operating characteristics curve (AUC) from 0.672 to 0.757 (P < .001). Combining clinical judgment after exercise testing (AUC 0.704) with baseline or poststress hs-cTnI levels also increased the diagnostic accuracy (AUC 0.761-0.771, P < .001 for all). In contrast, exercise-induced changes in hs-cTnI during exercise did not seem useful, as they were small and similar in patients with or without myocardial ischemia.

Conclusions

High-sensitivity cTnI concentrations at rest and after exercise, but not its exercise-induced changes, provide substantial incremental value to clinical judgment including exercise electrocardiography regarding the presence of myocardial ischemia.

Section snippets

Patient population

From January 2010 to July 2012, consecutive patients referred to the University Hospital Basel for CAD evaluation by rest/bicycle myocardial perfusion SPECT were recruited for the “Biomarkers and ECG signals in exercise-induced myocardial ischemia” (BASEL VIII) study. We took advantage of a unique setting in which myocardial perfusion SPECT is the cardiac stress test of choice for patients with a wide range of pretest probability for CAD.

For this analysis, we only included patients who

Patient characteristics

The baseline characteristics of the 819 patients are shown in Table I. Exercise-induced myocardial ischemia was present in 278 (34%) patients. Patients with exercise-induced myocardial ischemia were more often male and had more cardiovascular risk factors.

Hs-cTnI measurements before and after exercise testing

High-sensitivity cTnI levels before and after exercise testing are shown in Table II and Figure 1. Baseline hs-cTnI levels above the assay's limit of detection of 0.1 ng/L were measured in 813 patients (99%). High-sensitivity cTnI levels

Discussion

This large diagnostic study was designed to investigate whether hs-cTnI measurements before and after stress testing to assess exercise-induced changes provide clinical benefit in the detection of exercise-induced myocardial ischemia, which may go beyond that observed for resting concentrations of hs-cTnI.9 We report 5 major findings. First, baseline, peak exercise, and 2-hour hs-cTnI levels were significantly higher in patients with exercise-induced myocardial ischemia as compared with

Disclosures

Professor Mueller has received research grants from the Swiss National Science Foundation, the Swiss Commission for technology and innovation, the European Union, the Swiss Heart Foundation, the Cardiovascular Research Foundation Basel, 8sense, Abbott, ALERE, Astra Zeneca, Biomerieux, Brahms, Critical Diagnostics, Nanosphere, Roche, Siemens, Singulex, Sphingotec, and the University Hospital Basel, as well as speaker/consultancy honoraria from Abbott, ALERE, Astra Zeneca, Biomerieux,

Acknowledgments

We thank the patients who participated in the study, the staff of the nuclear medicine department, and the laboratory technicians (particularly Melanie Wieland, Kathrin Meissner, Irina Klimmeck, and Fausta Chiaverio) for their most valuable efforts.

References (34)

Cited by (54)

View all citing articles on Scopus

All authors take responsibility for all aspects of the reliability and freedom from bias of the data presented and their interpretation.

View full text