Very Low High-Sensitivity Cardiac Troponin Levels May Exclude Inducible Myocardial Ischemia

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Low hs-cTnI levels may identify patients with CAD who have a low medium-term risk for adverse cardiovascular events.
Low hs-cTnI levels may identify patients with CAD who have a low medium-term risk for adverse cardiovascular events.

Very low resting plasma high-sensitivity cardiac troponin levels may help exclude inducible myocardial ischemia in individuals with coronary artery disease (CAD), according to a study published in the Annals of Internal Medicine.

The study authors pooled 589 patients with stable CAD and placed them into 2 groups: 118 individuals in the validation group and the remainder in the derivation group. These participants were followed for 3 years.

CAD in the derivation group was based on abnormal coronary angiogram with evidence of atherosclerosis with luminal irregularities, prior percutaneous or coronary revascularization, myocardial infarction, or positive results on the stress test.

The validation group consisted of individuals who had had a myocardial infarction within 6 months of study onset. Myocardial ischemia was diagnosed based on myocardial infusion during treadmill exercise or pharma stress testing. Within the same week, resting high-sensitivity cardiac troponin levels were measured, and authors calculated the negative predictive value (NPV) for inducible myocardial ischemia. 

In the validation group, 4 out of 32 participants with a resting high-sensitivity cardiac troponin level below 2.5 pg/mL had inducible ischemia (NPV 88%; CI, 71%-96%), and 2 of 32 had ischemia of 10% or greater (NPV 94%; CI, 79%-99%).

In the derivation group, 10 out of 101 participants who showed a resting high-sensitivity cardiac troponin level below 2.5 pg/mL had inducible myocardial ischemia (NPV 90%; 95% CI, 83%-95%), and 3 out of 101 participants in the same group had inducible ischemia relating to 10% of the myocardium (NPV 97%; CI, 92%-99%).

At 3-year follow-up, members of the derivation group with a resting high-sensitivity cardiac troponin below 2.5 pg/mL demonstrated no adverse events compared with 33 cardiovascular deaths or myocardial infarctions in participants with levels at 2.5 pg/mL or greater.

Study authors concluded that low circulating levels of resting high-sensitivity cardiac troponin in patients with established CAD may have a high NPV "for excluding myocardial ischemia during stress testing."

Reference

Hammadah M, Kim JH, Tahhan AS, et al. Use of high-sensitivity cardiac troponin for the exclusion of inducible myocardial ischemia: a cohort study [published online November 6, 2018]. Ann Intern Med. doi: 10.7326/M18-0670

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