Ignore elevated cardiac troponin in patients without
a specific diagnosis at your own peril, cautions a new retrospective
registry-based cohort study of more than 45,000 patients in the SWEDEHEART
(Swedish Web-system for Enhancement and Development of Evidence-based care in
Heart disease Evaluated According to Recommended Therapies) registry.
The study is published online Jan. 7, 2019 in the Journal
of the American College of Cardiology.
Most patients included in the study had been hospitalized
for chest pain with clinically suspected acute coronary syndrome (ACS). Fifteen
percent of patients developed a major adverse event (MAE; mortality, ACS, heart
failure, or stroke) during a median follow-up of 4.9 years. The risk for MAE
was associated with higher cardiac troponin (cTn). The hazard ratio for highest
assay-specific cTn tertile was 2.59.
Notably, in patients without cardiovascular
comorbidities, renal dysfunction, left ventricular dysfunction, or significant
coronary stenosis the hazard ratio was 3.57.
The study concluded that raised cardiac troponin is a
predictor for an impending MAE even in patients with no evidence of coronary
artery disease, heart failure, or kidney dysfunction and hence should not be
ignored. It is not just enough to rule out an acute ischemic event.
These patients should be investigated carefully with
modalities such as echocardiography and angiography. And, even if the
tests do not conclusively establish coronary disease, they should still be closely monitored and be given cardioprotective
medications such as statins, ACEIs.
The Fourth universal definition of myocardial infarction
(2018) has for the first time differentiated myocardial injury from myocardial
infarction (Eur Heart J. 2019;40:237-69). It also recognizes myocardial injury
as an entity in itself even though it is essential for the diagnosis of acute
myocardial infarction. It states: “The term myocardial injury should be
used when there is evidence of elevated cardiac troponin values (cTn) with
at least one value above the 99th percentile upper reference limit (URL). The
myocardial injury is considered acute if there is a rise and/or fall of cTn
values.”
“The term acute myocardial infarction should be used
when there is acute myocardial injury with clinical evidence of acute
myocardial ischaemia and with detection of a rise and/or fall of cTn values
with at least one value above the 99th percentile URL and at least one of the
following:
·
Symptoms of myocardial ischaemia
·
New ischaemic ECG changes
·
Development of pathological Q waves
· Imaging evidence of new loss of viable myocardium or new
regional wall motion abnormality in a pattern consistent with an ischaemic
aetiology
·
Identification of a coronary thrombus by angiography or
autopsy (not for types 2 or 3 MIs)”
(Source: Medscape, JACC, European Heart Journal)
Dr KK Aggarwal
Padma Shri Awardee
President Elect Confederation of Medical
Associations in Asia and Oceania
(CMAAO)
Group Editor-in-Chief IJCP Publications
President Heart Care Foundation of India
Past National President IMA
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