Computed tomography coronary angiography after excluding myocardial infarction: high-sensitivity troponin versus risk score-guided approach

BACKGROUND: Patients with suspected acute coronary syndrome (ACS) in whom myocardial infarction has been ruled out are still at risk of having obstructive coronary artery disease (CAD). This rate is higher among patients with intermediate high-sensitivity troponin I (hsTnI) concentrations (5 ng/L to 99(th) percentile) than low concentrations (<5 ng/L). Therefore, an intermediate concentration has been suggested as a candidate for downstream investigation with computed tomography coronary angiography (CTCA). We tried to compare the HEART score-guided vs. hsTnI-guided approach for identifying obstructive CAD.METHODS: From a prospective cohort study of patients presenting to the emergency department with suspected ACS, 433 patients without elevated hsTnI who also underwent CTCA were selected and analyzed. The performances of hsTnI concentration and HEART score were compared using sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV).RESULTS: Overall, 120 (27.7%) patients had obstructive CAD. Patients with intermediate hsTnI concentrations were more likely to have obstructive CAD than those with low hsTnI concentrations (40.0% vs. 18.1%); patients with non-low-risk HEART scores (>= 4 points) were also more likely to have obstructive CAD than those with low-risk scores (0 to 3 points) (41.0% vs. 7.6%). The HEART score had higher sensitivity and NPV for detecting obstructive CAD in each classification than hsTnI concentration (sensitivity: 89.2% vs. 63.3%; NPV: 92.4% vs. 81.9%, respectively).CONCLUSION: After excluding myocardial infarction in patients with suspected ACS, adding the HEART score for selecting candidates for CTCA could improve patient risk stratification more accurately than relying on hsTnI concentration.