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