In the Journals

High sensitivity troponin test helps exclude inducible myocardial ischemia

Measuring levels of high-sensitivity cardiac troponin I may be useful to determine if a patient with coronary artery disease has a low risk for myocardial ischemia, according to a study published in Annals of Internal Medicine.

“Many patients with coronary artery disease are routinely referred for surveillance stress testing despite recommendations against it,” Muhammad Hammadah, MD, from Emory University School of Medicine, and colleagues wrote.

Hammadah and colleagues conducted an observational study to determine whether individuals without inducible myocardial ischemia can be identified via low levels of resting high-sensitivity cardiac troponin I (hs-cTnI), a sensitive cardiac injury marker that indicates whether a patient has recently experienced a myocardial infarction. Approximately 700 patients with coronary artery disease were enrolled and divided into two groups: the derivation group (n = 589) and the validation group (n = 118).

The researchers used myocardial perfusion imaging with technetium-99m single-photon emission CT during either treadmill or pharmacologic stress testing to determine if inducible myocardial ischemia was present. Within 1 week of the stress test, resting plasma hs-cTnI was measured. Then, the negative predictive value (NPV) for inducible ischemia was calculated. The researchers followed the derivation group for 3 years and documented incident cardiovascular death and myocardial infarction.

Results showed that inducible myocardial ischemia (NPV = 90%; 95% CI, 83-95) was present in 10 of 101 patients in the derivation cohort with an hscTnI level below 2.5 pg/mL. Inducible ischemia involving at least 10% of the myocardium (NPV = 97%; 95% CI, 92-99) was present in three of 101 patients in the derivation cohort with an hscTnI level below 2.5 pg/mL.

Inducible ischemia (NPV = 88%; 95% CI, 71-96) was present in four of 32 patients in the validation cohort with an hs-cTnI level below 2.5 pg/mL and ischemia of 10% or greater (NPV = 94%; 95% CI, 79-99) was present in two of 32.

No adverse events were observed in patients in the derivation cohort with an hs-cTnI level below 2.5 pg/mL during the follow-up period. However, 33 (7%) cardiovascular deaths or incident MIs occurred among patients with an hs-cTnI level of 2.5 pg/mL or greater.

“A low plasma level of hs-cTnI identifies patients with coronary artery disease who have a very low risk for myocardial ischemia during stress testing and a low medium-term risk for adverse cardiovascular events,” Hammadah and colleagues concluded.

These results are critical because the troponin test may lessen the need for cardiac stress tests, as well as reduce health care costs and radiation exposures, according to the researchers.

In a related editorial, P.J. Devereaux, MD, PhD, director of the division of cardiology at McMaster University and Population Health Research Institute, Ontario, Canada, wrote that the study by Hammadah and colleagues importantly builds upon prognostication in patients with stable coronary artery disease.

“These data suggest that hs-cTn assays may be more accurate, convenient, quick and cost-effective than [myocardial perfusion single-photon emission CT] in predicting the course of stable coronary artery disease,” he wrote. “The encouraging results of Hammadah and colleagues need to be evaluated further with a large prospective, observational study that is powered to explore the optimal thresholds of, ideally, several hs-cTn assays to identify patients at low and high risk for cardiovascular death and nonfatal myocardial infarction.” – by Alaina Tedesco

Disclosures : Devereaux reports receiving grants from Abbott Diagnostics, Boehringer Ingelheim, Covidien, Philips Healthcare and Roche Diagnostics. Hammadah reports no relevant financial disclosures. Please see study for all other authors’ relevant financial disclosures.

Measuring levels of high-sensitivity cardiac troponin I may be useful to determine if a patient with coronary artery disease has a low risk for myocardial ischemia, according to a study published in Annals of Internal Medicine.

“Many patients with coronary artery disease are routinely referred for surveillance stress testing despite recommendations against it,” Muhammad Hammadah, MD, from Emory University School of Medicine, and colleagues wrote.

Hammadah and colleagues conducted an observational study to determine whether individuals without inducible myocardial ischemia can be identified via low levels of resting high-sensitivity cardiac troponin I (hs-cTnI), a sensitive cardiac injury marker that indicates whether a patient has recently experienced a myocardial infarction. Approximately 700 patients with coronary artery disease were enrolled and divided into two groups: the derivation group (n = 589) and the validation group (n = 118).

The researchers used myocardial perfusion imaging with technetium-99m single-photon emission CT during either treadmill or pharmacologic stress testing to determine if inducible myocardial ischemia was present. Within 1 week of the stress test, resting plasma hs-cTnI was measured. Then, the negative predictive value (NPV) for inducible ischemia was calculated. The researchers followed the derivation group for 3 years and documented incident cardiovascular death and myocardial infarction.

Results showed that inducible myocardial ischemia (NPV = 90%; 95% CI, 83-95) was present in 10 of 101 patients in the derivation cohort with an hscTnI level below 2.5 pg/mL. Inducible ischemia involving at least 10% of the myocardium (NPV = 97%; 95% CI, 92-99) was present in three of 101 patients in the derivation cohort with an hscTnI level below 2.5 pg/mL.

Inducible ischemia (NPV = 88%; 95% CI, 71-96) was present in four of 32 patients in the validation cohort with an hs-cTnI level below 2.5 pg/mL and ischemia of 10% or greater (NPV = 94%; 95% CI, 79-99) was present in two of 32.

No adverse events were observed in patients in the derivation cohort with an hs-cTnI level below 2.5 pg/mL during the follow-up period. However, 33 (7%) cardiovascular deaths or incident MIs occurred among patients with an hs-cTnI level of 2.5 pg/mL or greater.

“A low plasma level of hs-cTnI identifies patients with coronary artery disease who have a very low risk for myocardial ischemia during stress testing and a low medium-term risk for adverse cardiovascular events,” Hammadah and colleagues concluded.

These results are critical because the troponin test may lessen the need for cardiac stress tests, as well as reduce health care costs and radiation exposures, according to the researchers.

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In a related editorial, P.J. Devereaux, MD, PhD, director of the division of cardiology at McMaster University and Population Health Research Institute, Ontario, Canada, wrote that the study by Hammadah and colleagues importantly builds upon prognostication in patients with stable coronary artery disease.

“These data suggest that hs-cTn assays may be more accurate, convenient, quick and cost-effective than [myocardial perfusion single-photon emission CT] in predicting the course of stable coronary artery disease,” he wrote. “The encouraging results of Hammadah and colleagues need to be evaluated further with a large prospective, observational study that is powered to explore the optimal thresholds of, ideally, several hs-cTn assays to identify patients at low and high risk for cardiovascular death and nonfatal myocardial infarction.” – by Alaina Tedesco

Disclosures : Devereaux reports receiving grants from Abbott Diagnostics, Boehringer Ingelheim, Covidien, Philips Healthcare and Roche Diagnostics. Hammadah reports no relevant financial disclosures. Please see study for all other authors’ relevant financial disclosures.