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MI probability, outcomes may be predicted with high-sensitivity troponin
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A risk assessment tool that incorporated high-sensitivity troponin I or troponin T concentrations determined which patients had an MI when presenting with symptoms at the ED in addition to outcomes at 30 days, according to a study published in The New England Journal of Medicine.
“The COMPASS-MI approach provides risk probabilities for myocardial infarction using a wide range of cutoff combinations of high-sensitivity troponin I or T concentrations, as well as thresholds that are based on either early or late serial sampling,” Johannes T. Neumann, MD, of the University Heart Center Hamburg in Germany, and colleagues wrote.
Suspected MI
Researchers analyzed data from 22,651 patients (median age, 63 years; 62% men) from 15 international cohorts who presented to the ED with symptoms that were suggestive of MI. Patients were in the derivation data set (n = 9,604) or the validation data set (n = 13,047).
High-sensitivity troponin I and high-sensitivity troponin T were measured at ED presentation and after early (> 45 minutes to 120 minutes) or late serial sampling (> 120 minutes to 210 minutes) to identify patients who were at low or high risk for MI.
The short-term prognostic endpoint was a composite of all-cause death or subsequent MI at 30 days. The long-term prognostic endpoint was a composite of all-cause death or subsequent MI at 1 year and 2 years.
Of the patients in the study, 15.3% were diagnosed with MI.
The risk assessment tool had a high negative predictive value for MI. Patients who were at low risk for MI typically had very low concentrations of high-sensitivity troponin I or high-sensitivity troponin T at presentation and small absolute changes on serial sampling.
Low-risk patients
Patients who had high-sensitivity troponin I concentrations less than 6 ng/L when presenting with symptoms at the ED and an absolute change of less than 4 ng/L after 45 to 120 minutes had a negative predictive value for MI of 99.5% (95% CI, 99.2-99.7). The risk for MI or death at 30 days in these patients was 0.2% (95% CI, 0.1-0.4). Based on this, 56.5% of the acute study population would be considered low risk (95% CI, 55.4-57.6).
Results were confirmed by the external validation data set.
“The assignment of patients to the low-risk category may allow for the discharge of patients after other life-threatening causes of chest pain have been ruled out,” Neumann and colleagues wrote. “Patients assigned to the high-risk category have a high prevalence of myocardial infarction and a high risk of death. Therefore, the majority of these patients are candidates for early invasive strategies. It would be important for all of the remaining patients (those fulfilling neither the low-risk nor high-risk criteria) to undergo detailed clinical evaluation, monitoring, further diagnostic testing and invasive strategies as appropriate.” – by Darlene Dobkowski
Disclosures: High-sensitivity troponin I and high-sensitivity troponin T assays used in the study were partially donated by Roche and Abbott. Neumann reports he received grants from the German Heart Foundation/German Foundation of Heart Research and Else Kröner Fresenius Stiftung and personal fees from Abbott Diagnostics and Siemens. Please see the study for all other authors’ relevant financial disclosures.
Perspective
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Joseph S. Alpert, MD
This is further supporting evidence for how important high-sensitivity troponin is as a prognostic factor. There’s a whole raft of areas.
There was a study from Sweden that went into a clinic with patients with CAD who were perfectly stable who had high-sensitivity troponin measured. There was a moderate group who were asymptomatic that had elevated troponin. Over the next couple of years, these patients did badly and had events. Even when you talk to someone who says they feel perfect, if they have an elevated troponin, it’s not a good sign.
We see the same thing in medical intensive care units. When patients have moderate troponin elevation along with their other illness abnormalities, it says they have a bad prognostic sign.
There are further data that say when you come to the ED and you’re having some symptoms like chest pain, if your troponin is normal, you’ll do fine and even in follow-up, you’ll do fine. There have been other reports of this as well.
Often in Europe, when a patient with chest pain comes in, clinicians will watch them for 1 hour with the troponin and if it’s negative, they send them home. We’re a little more reluctant to do it in 1 hour in the U.S. Many of our patients don’t have typical chest pain, and the European studies are done in patients with chest pain. Sometimes MIs present with shortness of breath, fainting or even confusion in elderly patients. Our EDs measure troponin left, right and center. It’s not as focused. We usually take 3 hours to decide MI or no MI, but even so, the high-sensitivity troponin is going to be very helpful as a screening test in the ED and it tells you that it’s not good to have an elevated troponin no matter what the setting is.
We need more U.S. data because the patients we’re seeing in the ED are different than what has been seen in European studies, where they only screen patients with chest pain. I expect studies conducted in the U.S. to be similar with some minor variations, but it will still say if you have an elevated troponin, it’s not good, and if you have a normal troponin, you’re pretty safe.
There are also a couple of articles with data that point out that if you combine troponin with B-type natriuretic peptide or one of the other atrial natriuretic factor measurements, you get a closer approximation as to how much trouble we’re going to have with the patient down the road when they’re admitted. It is not good to have both an elevated atrial natriuretic factor as well as troponin.
This is a very important marker. Just about a year ago, the high-sensitivity test was finally approved in the U.S. and now we have a couple of them, one that measures troponin T and one that measures troponin I.
We’re in an era of biomarkers, and troponin is one of the very best biomarkers. There are many others being offered, but the thing is with troponin is that it’s been standardized. We understand a lot about how it’s used.
I’m collaborating with one of our hospitals up in Phoenix who have an early high-sensitivity troponin program. They find the length of stay in the ED is shorter, and fewer patients are admitted to the hospital. There’s some cost saving in this, and in our current health care system, any cost saving is great.
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