Used Together, Troponin and Coronary Calcium Improve CV Risk Assessment

Ted Bosworth

July 21, 2020

If either high sensitivity cardiac troponin (hs-cTnT) or coronary artery calcium (CAC) are elevated, the 10-year risk of atherosclerotic cardiovascular disease (ASCVD) climbs substantially, which suggests these biomarkers yield more prognostic information when they are used together, according to a cohort study with a median 15 years of follow-up.

Among those with a double negative result, meaning hs-cTnT was less than the limit of detection (<3 ng/L) and the CAC score was zero, only 2.8% developed ASCVD within 10 years, but the rates climbed to 4.6% if hs-cTnT was detectable and to 9.8% if the CAC score exceeded zero even when the other biomarker was negative.

"The increased risk for ASCVD among those with discordant results indicate that their prognostic information is complementary, favoring their conjoined use for risk prediction," reported a multicenter team of investigators led by Allan S. Jaffe, MD, professor of laboratory medicine and pathology, Mayo Clinic, Rochester, Minn.

The study was performed with data from 6,749 participants in the Multi-Ethnic Study of Atherosclerosis (MESA), which is a longitudinal, community-based study funded by the National Heart, Lung, and Blood Institute. Over the course of long-term follow-up in a patient population that was about half female, 39% non-Hispanic white, 28% Black, 22% Hispanic American, and 12% Asian, ASCVD events were evaluated in relation to both biomarkers measured at baseline.

At baseline, both biomarkers were negative in 22%, both positive in 40%, and discordant in 38%.

After a median follow-up of 15 years, when 1,002 ASCVD events had occurred, the crude rate of ASCVD was 2.8 per 1,000 person-years in the double-negative group. When compared with this, the adjusted hazard ratio for ASCVD among those with double positive biomarkers was 3.5 (P < .00001). Increased risk was also highly significant if just hs-cTnT was positive (HR, 1.59; P = .003) or if just CAC was positive (HR, 2.74; P < .00001).

The added value of using both biomarkers to identify individuals at very low risk of ASCVD makes sense, according to the authors of an accompanying editorial. Written by a team led by John W. McEvoy, MB, BCh, National University of Ireland, Galway, the editorial explained why the information is complementary.

"CAC indicates subclinical atherosclerosis, whereas hs-cTnT indicates myocardial ischemia or damage, not just from coronary stenosis but also due to other conditions like hypertensive heart and left ventricular hypertrophy," the authors stated.

Although they maintained that adding N-terminal pro-brain natriuretic peptide, which could be drawn from the same blood sample as hs-cTnT, might prove to be an even better but still simple strategy to identify low-risk patients, they praised the concept of combining biomarkers.

"If one's wish is to identify truly low-risk individuals, then it appears that it takes two negative ASCVD biomarkers to make that wish come true," the authors of the editorial concluded.

Relative to alternative methods of ASCVD risk assessment, measurement of these biomarkers might be useful for sparing patients from interventions, such as lipid lowering with statin therapy, being considered on the basis of conventional risk factors alone.

Dr. Jaffe said in an interview that he considers the two-biomarker assessment to be a useful tool in the low-risk population that he studied, but he does not consider this strategy as a substitute for other methods, such as those outlined in the 2019 ACC/AHA guidelines that address the entire spectrum of risk, although work is planned to see if this approach can be extended to this broader group.*

"The data we have presented now is a good start and suggests that these two objective measures can identify those who are at very low risk and avoid adding individuals who may not be at as low risk if only one of the two tests is used," Dr. Jaffe explained.

"Given there are now techniques to measure coronary calcium from any chest CT study, and that high sensitivity cardiac troponin is a relatively inexpensive test, putting them together should really help risk stratify patients," he added.

When asked whether this approach will eventually replace conventional methods of ASCVD risk assessment, such as those proposed in the 2019 American College of Cardiology/American Heart Association guidelines for the primary prevention of cardiovascular disease (Circulation. 2019;140:e596-e646), he said maybe.

"The answer is that we will probe that question in our ongoing studies using continuous data in an attempt to evaluate how to use this approach to risk stratify larger numbers of individuals," Dr. Jaffe replied.

The senior investigator, Dr. Jaffe, has consulting relationships with many pharmaceutical companies. The editorial authors had no relevant disclosures.

J Am Coll Cardiol. 2020;76:357-370. Abstract

This article originally appeared on MDEdge.com *Correction, 7/27/20: An earlier version of this article mischaracterized Dr. Jaffe's statement.

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