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New High Sensitivity Troponin Assay - A Potential Game Changer In Heart Attack Diagnosis

New High Sensitivity Troponin Assay - A Potential Game Changer In Heart Attack Diagnosis

by Dr. Lakshmi Venkataraman on Jan 17 2018 6:11 PM
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Highlights:

  • New high sensitivity troponin assay can accurately measure elevated troponin levels in less than six hours of onset of symptoms
  • Faster (earlier) and accurate diagnosis of heart attack is extremely critical and can be life-saving
  • Existing assays less accurate in the initial hours of heart attack, a crucial period.
New high sensitivity troponin assay can diagnose heart attacks accurately in the first six hours of symptom onset and could prove to be paradigm shifting in acute coronary care according to Frederick Korley, MD,PhD, an assistant professor of emergency medicine at the University of Michigan Medical School.

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Superiority of the New High Sensitivity Troponin Assay

The new high sensitivity troponin assay could be a game changer in the diagnosis and treatment of heart attacks and be a boon to emergency care physicians, not to mention the patients and their families.
  • The new test can measure ten times lower levels of troponin and is able to diagnose a heart attack accurately much earlier than current tests.
  • The new test can accurately measure troponin levels in the blood soon after symptom onset and in less than six hours.
  • If the assay was to be repeated in the same sample the values remain constant, unlike older assays where there is a huge degree of analytical variation. The values are thus much more reliable.
  • With current tests, the first measurement diagnoses heart attacks accurately in about 70 percent of cases. It may miss persons having a small heart attack; the new assay picks up 82 percent of cases accurately, a significant difference.
  • Troponin assays may one day become useful in preventing cardiac disease. A recent study in JAMA Cardiology has found that asymptomatic persons with higher levels of troponin are at an increased risk of heart attack and would benefit from close monitoring and repeat testing at regular intervals. A sudden spike may indicate something more serious.
Currently available tests are less reliable in the early hours of symptoms and a second repeat blood test after about three hours or so may be necessary to accurately confirm the diagnosis. A negative first test in symptomatic patients does not rule out heart attack.
This delay may prove crucial in some patients as well as clog up waiting room space in the Emergency Department thus affecting the treatment of other acutely ill patients.

If it’s positive, you’re done; it’s easy. But if it’s negative, we have to wait anywhere between three to six hours and then repeat the test — depending on when a patient’s symptoms started — before we can confidently say we don’t see signs of a heart attack.

“Now, we can give you that answer in a shorter time span,” says Korley, an assistant professor of emergency medicine at the University of Michigan Medical School.

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New Troponin Assay – Caution Needed In Interpreting Results

  • With improved sensitivity of the new assay, extremely low levels of troponin can be detected. In fact, troponin levels may be detectable in healthy individuals as well since most persons have small amounts of circulating troponin.
  • It is important to realize that elevations in troponin levels can be acute (eg heart attack) or chronic.
  • For instance, in someone with uncontrolled blood pressure for a long time, this could cause damage to the heart. If troponin levels are elevated in such a person, they might not require hospitalization but need regular monitoring. They need a good primary care physician to effectively control their blood pressure. Similarly, stress from an infection or injury to the brain can damage the heart as well.
Thus not all elevated troponin levels may indicate a heart attack and clinicians must be cautious as well as think quickly in interpreting troponin levels.

According to Korley, the new troponin assay, not widely available clinically is not perfect. In fact, he has written a JAMA Cardiology editorial about its’ benefits and drawbacks. A higher degree of accuracy, he notes, also could lead to over-diagnosis and unnecessary hospitalization. Nevertheless, “it is a big deal, and it is going to be paradigm-shifting.” says Korley.

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About Troponins – In Brief

Troponins are a family of proteins (troponin C, T and I) found in heart (cardiac) muscle fibers that are necessary for muscle contraction. Troponin tests measure the level of cardiac-specific troponin in the blood to help detect heart injury.

They are done to confirm or rule out a heart attack; either troponin T or troponin I may be measured. Although there are other biomarkers (CK-MB, myoglobin) that detect heart injury, troponin is preferred since it is specific to heart and remains elevated for longer periods.

References:
  1. New Blood Test for Diagnosing Heart Attacks: A ‘Big Deal,’ with Caveats - (http://www.newswise.com/articles/new-blood-test-for-diagnosing-heart-attacks%3A-a-%E2%80%98big-deal%2C%E2%80%99-with-caveats)
  2. Troponin - (https://labtestsonline.org/tests/troponin)

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