Key result
Resting hs-cTnI levels <2.5 pg/mL identified patients without inducible myocardial ischemia with a 90% negative predictive value (95% CI 83-95%) and 0% vs 7% adverse events at 3 years.
Why the study?
Does a very low resting high-sensitivity cardiac troponin I level exclude inducible myocardial ischemia in patients with stable CAD?
Observational (n=707)
Does a very low resting high-sensitivity cardiac troponin I level exclude inducible myocardial ischemia in patients with stable CAD?
Effect estimate: NPV 90% (95% CI 83-95)
Very low resting hs-cTnI levels (<2.5 pg/mL) can effectively exclude inducible myocardial ischemia and predict a very low risk of adverse cardiovascular events over 3 years in patients with stable CAD.
Very low hs-cTnI may exclude ischemia in stable CAD; hypothesis-generating and requires prospective validation before practice change.
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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Hammadah et al. (2018) conducted an observational in stable coronary artery disease (n=707). hs-cTnI level <2.5 pg/mL vs. hs-cTnI level ≥2.5 pg/mL was evaluated on inducible myocardial ischemia (NPV 90%, 95% CI 83-95). Resting hs-cTnI levels <2.5 pg/mL identified patients without inducible myocardial ischemia with a 90% negative predictive value (95% CI 83-95%) and 0% vs 7% adverse events at 3 years.
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