Use of High-Sensitivity Cardiac Troponin for the Exclusion of Inducible Myocardial Ischemia A Cohort Study

Background:

Many patients with coronary artery disease (CAD) are routinely referred for surveillance stress testing despite recommendations against it.

Objective:

To determine whether low levels of resting high-sensitivity cardiac troponin I (hs-cTnI) can identify persons without inducible myocardial ischemia.

Design:

Observational study.

Setting:

A university-affiliated hospital network.

Patients:

Persons with stable CAD: 589 in the derivation group and 118 in the validation cohort.

Measurements:

Presence of inducible myocardial ischemia was determined by myocardial perfusion imaging with technetium-99m single-photon emission computed tomography during either treadmill or pharmacologic stress testing. Resting plasma hs-cTnI was measured within 1 week of the stress test, and the negative predictive value (NPV) for inducible ischemia was calculated. The derivation cohort was followed for 3 years for incident cardiovascular death and myocardial infarction.

Results:

In the derivation cohort, 10 of 101 patients with an hs-cTnI level below 2.5 pg/mL had inducible myocardial ischemia (NPV, 90% [95% CI, 83% to 95%]) and 3 of 101 had inducible ischemia involving at least 10% of the myocardium (NPV, 97% [CI, 92% to 99%]). In the validation cohort, 4 of 32 patients with an hs-cTnI level below 2.5 pg/mL had inducible ischemia (NPV, 88% [CI, 71% to 96%]) and 2 of 32 had ischemia of 10% or greater (NPV, 94% [CI, 79% to 99%]). After a median follow-up of 3 years in the derivation cohort, no adverse events occurred in patients with an hs-cTnI level below 2.5 pg/mL, compared with 33 (7%) cardiovascular deaths or incident myocardial infarctions among those with an hs-cTnI level of 2.5 pg/mL or greater.

Limitation:

The data may not be applicable to a population without known CAD or to persons with unstable angina, and the modest sample sizes warrant further validation in a larger cohort.

Conclusion:

Very low hs-cTnI levels may be useful in excluding inducible myocardial ischemia in patients with stable CAD.

Primary Funding Source:

National Institutes of Health.

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