From the Journals

Troponins touted as ‘ally’ in COVID-19 triage, but message is nuanced


 

Cardiac troponins by high-sensitivity assays (hs-cTn) should be considered “an ally and a crucial diagnostic and prognostic aid” during the COVID-19 pandemic, cardiologists in the United Kingdom advise in a recently published viewpoint.

The tests can be used to “inform the triage of patients to critical care, guide the use of supportive treatments, and facilitate targeted cardiac investigations in those most likely to benefit,” Nicholas Mills, MD, PhD, University of Edinburgh, United Kingdom, told theheart.org | Medscape Cardiology. He is senior author on the viewpoint published online April 6 in the journal Circulation.

Older adults and those with a history of underlying cardiovascular disease appear to be at greatest risk of dying from COVID-19. “From early reports it is clear that elevated cardiac troponin concentrations predict in-hospital mortality,” said Mills.

In a recent report on hospitalized patients with COVID-19 in Wuhan, China, for example, cardiac injury (hs-cTn above the 99th-percentile upper reference limit) was seen in 1 in 5 patients and was an independent predictor of dying in the hospital. Mortality was 10-fold higher in those with cardiac injury on presentation.

Elevated cardiac troponin in the setting of COVID-19, Mills said, “may reflect illness severity with myocardial injury arising due to myocardial oxygen supply–demand imbalance. Or it may be due to direct cardiac involvement through viral myocarditis or stress cardiomyopathy, or where the prothrombotic and proinflammatory state is precipitating acute coronary syndromes.”

In their viewpoint, the authors note that circulating cTn is a marker of myocardial injury, “including but not limited to myocardial infarction or myocarditis, and the clinical relevance of this distinction has never been so clear.”

Therefore, the consequence of not measuring cardiac troponin may be to “ignore the plethora of ischemic and nonischemic causes” of myocardial injury related to COVID-19. “Clinicians who have used troponin measurement as a binary test for myocardial infarction independent of clinical context and those who consider an elevated cardiac troponin concentration to be a mandate for invasive coronary angiography must recalibrate,” they write.

“Rather than encouraging avoidance of troponin testing, we must harness the unheralded engagement from the cardiovascular community due to COVID-19 to better understand the utility of this essential biomarker and to educate clinicians on its interpretation and implications for prognosis and clinical decision making.”

Based on “same logic” as recent ACC guidance

The viewpoint was to some extent a response to a recent informal guidance from the American College of Cardiology (ACC) that advised caution in use of troponin and natriuretic peptide tests in patients with COVID-19.

Even so, that ACC guidance and the new viewpoint in Circulation are based on the “same logic,” James Januzzi Jr, MD, Massachusetts General Hospital, Boston, told theheart.org | Medscape Cardiology. Both documents:

  • Point out that troponins are frequently abnormal in patients with severe cases of COVID-19
  • Caution that clinicians should not equate an abnormal hs-cTn with acute myocardial infarction
  • Note that, in most cases, hs-cTn elevations are a result of noncoronary mechanisms
  • Recognize the potential risk to caregivers and the continued unchecked spread of SARS-CoV-2 related to downstream testing that might not be needed

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