Physicians' Academy for Cardiovascular Education

Elevated cTn levels of unknown etiology can predict major adverse outcomes in suspected ACS

Cardiac Troponin Elevation in Patients Without a Specific Diagnosis

Literature - Eggers KM, Jernberg T, Lindahl B et al. - JACC 2019;73(1):1-9

Introduction and methods

Elevated cardiac troponin (cTn) levels predict adverse outcomes, both cardiac and noncardiac conditions. However, since not all elevated cTn levels are associated with adverse outcomes [1-2], a higher cTn level warrants the search for the underlying cause. In some patients, etiology of elevated cTn levels remains unknown. It has been reported that 31% of patients discharged from the emergency department have no specified diagnosis but do have cTn levels above the 99th percentile are [3] and this may be similarly high in those who are admitted [4]. This scenario has been named troponinemia. Scientific studies investigating this condition are, however, largely lacking.

This retrospective registry-based cohort study therefore investigated clinical characteristics of patients with elevated cTn levels of unknown etiology and their long-term risk of fatal and non-fatal events. This study is part of the Tailoring Of Treatment in All comers with Acute Myocardial Infarction (TOTAL-AMI) project, which used data from the SWEDEHEART registry, a nationwide registry including consecutive patients admitted to Swedish coronary units or other specialized facilities because of suspected acute coronary syndrome (ACS).

This study included all patients acutely admitted between January 2005 and August 2013, who had been discharged without a specified diagnosis. 48.872 Participants were divided into four groups based on cTn levels: those with cTn levels ≤99th percentile and the remaining patients stratified by tertiles calculated separately for each assay. Three clinically relevant subcohorts were separately evaluated to investigate the association of higher cTn groups with adverse events. Subcohort 1 consisted of patients without previous MI, previous coronary revascularization, previous stroke, and known congestive heart failure (HF). In subcohort 2 patients with an eGFR <60 ml/min/1.73 m2 were further excluded and subcohort 3 also excluded patients who had a left ventricular ejection fraction (LVEF) ≤0.50% or significant coronary artery disease (CAD), defined as ≥50% coronary stenosis according to invasive angiography. Outcomes for this analysis were all-cause mortality, MI, CV mortality, non-CV mortality, and hospitalization for HF and ischemic stroke. Major adverse events (MAE) were also assessed, defined as the composite of all-cause mortality and all non-fatal outcomes.

Main results

Clinical characteristics and cTn levels

cTn levels and clinical outcomes

Conclusion

This retrospective registry-based cohort study demonstrated that elevated cTn levels can predict major adverse outcomes in patients acutely admitted with suspected ACS in whom no definite diagnosis can be established, even in the absence of significant CAD or left ventricular dysfunction. These data indicate that careful work-up is necessary in these patients and the term troponinemia is not useful and should be avoided.

References

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