Intermediate hs-cTn associated with higher risk of CAD on CCTA in those with suspected ACS without MI
Troponin-Guided Coronary Computed Tomographic Angiography After Exclusion of Myocardial InfarctionLiterature - Lee KK, Bularga A, O’Brien R., et al. - J Am Coll Cardiol 2021, 78:1407-1417, doi.org/10.1016/j.jacc.2021.07.055
Introduction and methods
Aim of the study
Bedside clinical assessment, electrocardiography and serial cardiac troponin testing are strategies to rule in or rule out acute myocardial infarction (MI) . After ruling out MI though, there is a substantial proportion of patients with underlying coronary artery disease (CAD) and an increased risk of future cardiac events. It is not clear what the optimal strategy is to identify these patients. In this study, in patients with suspected acute coronary syndrome (ACS) in whom MI was ruled out, it was examined whether those with intermediate troponine have a higher prevalence of CAD and whether troponin can be used to select patients for coronary computed tomography angiography (CCTA).
PRECISE-CTCA (Troponin to Risk Stratify Patients with Acute Chest Pain for Computed Tomography Coronary Angiography) was a prospective cohort study of 250 patients who presented with suspected ACS to the emergency department at the Royal Infirmary of Edinburgh, UK and in whom acute MI was ruled out. Peak high-sensitivity cardiac troponin (hs-cTn) was within the normal range. Patients were recruited in a 2:1 ratio stratified by peak hs-cTn above and below the risk stratification threshold of 5 ng/L [2,3]. All patients underwent CCTA as an outpatient procedure.
Luminal cross-sectional area stenoses were classified as normal (<10%), mild non-obstructive (10-49%), moderate nonobstructive (50-70%), or obstructive (>70% in ≥1 major epicardial artery or >50% in the left main stem). Patients were classified according to the most significant stenosis identified on the CCTA. Atherosclerotic plaque burden was quantified using the segment involvement , segment stenosis and computed tomography (CT)-adapted Leaman scores .
- There were 167 patients with intermediate troponine concentrations (between 5 ng/L and the sex-specific 99th percentile threshold) and 83 patients had low troponin concentrations (<5 ng/L).
- 42.4% Of patients had anginal symptoms and the rest had nonanginal chest pain.
- Overall, 37.6% (94 of 250 patients) had normal coronary arteries on CCTA, 36.0% had nonobstructive disease and 26.4% had obstructive disease.
- Patients with intermediate troponin had higher risk of CAD than those with lower troponin (OD 3.33, 95%CI:1.92-5.78 for any CAD and OD 1.79, 95%CI:0.95-3.39 for obstructive disease).
- Patients with intermediate troponin also had more atherosclerotic plaque burden (for all scores P<0.001).
- As troponin increased within the normal range, the cumulative proportion of patients with any CAD increased from 32.3% in patients with troponin below detection limit (1.2 ng/L) to 62.2% in those with troponin of ≤16 ng/L. Across this troponin range, the cumulative proportion of obstructive CAD increased from 3.2% to 26.5%.
- There was no difference in prevalence of CAD or atherosclerotic plaque burden between those with and without anginal symptoms. Patients with intermediate troponin had a higher prevalence of CAD compared to those with low troponin in both with and without anginal symptoms.
- Most patients with CAD identified by CCTA did not have a history of CAD (50.8% of patients with intermediate troponin and 61.0% of patients with low troponin). Most were not on optimal medical therapy for CAD.
In patients presenting with suspected ACS and in whom MI was ruled out, intermediate troponin concentration was associated with increased risk of CAD on CCTA (3 fold higher risk compared to those with low troponin concentration). Using cardiac troponin to select patients for downstream investigation after rule out of MI has major potential for improvement of outcomes, the authors concluded.