A blood test now available at Vanderbilt University Hospital and Monroe Carell Jr. Children’s Hospital at Vanderbilt will lead to earlier treatment for individuals experiencing a heart attack, also known as myocardial infarction (MI), and can reduce time spent in the emergency room and unnecessary hospital admissions for those with signs or symptoms of a heart attack but who do not have this diagnosis.
The new high-sensitivity cardiac troponin T (hs-cTnT) test is more precise than the conventional troponin test previously used. It also provides results in less time, which means an MI can be confirmed or ruled out earlier so appropriate treatment can begin.
“When it comes to the evaluation of chest pain, which should always be taken very seriously, every second counts,” said Henry “Gerad” Colmer IV, MD, assistant professor of Emergency Medicine and associate medical director of VUH Clinical Operations. “This newer test is approximately three times faster to run and costs the same. And the higher sensitivity cardiac troponin tests have been shown to improve and accelerate the early management of patients presenting with suspected MI.”
The hs-cTnT test detects troponin, a protein involved in muscle contraction. Troponin is released when the heart is damaged, such as when a person has an acute MI or heart attack. For children, testing for elevated cardiac troponin may help detect heart failure due to an unknown cardiac disorder or worsening heart failure.
Troponin levels typically begin to elevate in the blood within two to three hours of the onset of symptoms of a possible heart attack, including chest pain and shortness of breath.
“The hs-cTnT assay can be run in under 15 minutes after a patient test sample is received by our Vanderbilt Medical Laboratories,” said Andrew DeFilippis, MD, medical director of the Cardiovascular Intensive Care Unit. “This is essential in establishing the diagnosis of MI as soon as possible to implement therapies that halt any potential, ongoing heart damage.
“A negative test is also time sensitive, allowing the medical team to focus on other diagnoses that may explain a patient’s symptoms or to safely discharge patients home as soon as possible.”
At Vanderbilt University Hospital, there are approximately 75,000 adult emergency department (ED) visits a year, and approximately 20% of all ED patients receive a cardiac troponin test as part of their initial evaluation, said Joy Crook, MD, executive medical director for Emergency Medicine. Over the past 12 months, 45,000 cardiac troponin tests were ordered in the VUH Emergency Department and for hospitalized patients, said Joe Wiencek, PhD, associate professor of Pathology, Microbiology and Immunology and Vanderbilt Medical Laboratories Core Laboratory service line medical director.
“To safely exclude MI, three cardiac troponin measurements using the conventional troponin test at zero hours, three hours and six hours have been used,” said Wiencek. “Evidence-based literature shows the same performance can be obtained within two to three hours of the onset of symptoms using only two hs-cTnT measurements taken at zero and three hours if cardiac troponin concentrations are below sex-specific 99th percentiles, in combination with a normal ECG.
“Conversely, if at least one cardiac troponin measurement using the hs-cTnT test is above the 99th percentile, further evaluation and pathophysiologic etiologies including type 1 and type 2 MI and myocardial injury are considered.”
Another benefit of the hs-cTnT test is that it can also more accurately predict a patient’s future cardiac risk, Wiencek said.
While the new test can rule in or rule out an MI, it does not diagnose the underlying cause of an MI. This requires additional clinical evaluation, DeFilippis said.
“While type 1 MI, plaque disruption resulting in coronary atherothrombosis, is a major cause of myocardial injury, it is not the only cause,” he said. “Other causes include sepsis, pulmonary embolism, acidosis, renal failure and chemotoxicity. When an abnormal troponin is present, careful clinical assessment is necessary to determine the cause so the appropriate care can be provided.”
VUMC clinicians should refer to the new Vanderbilt Suspected Acute Coronary Syndrome Evaluation Pathway and the Vanderbilt Medical Laboratories Test Directory for more information.
