Troponin-Guided Coronary Computed Tomography Angiography After Exclusion of Myocardial Infarction

Background: Patients with suspected acute coronary syndrome in whom myocardial infarction has been excluded are at risk of future adverse cardiac events. Objective: We evaluated the utility of high-sensitivity cardiac troponin I (hs-cTnI) to select patients for further investigation after myocardial infarction has been excluded. Methods: We performed a prospective cohort study of patients presenting to the Emergency Department with suspected acute coronary syndrome and hs-cTnI concentrations below the sex-specific 99th centile. Patients were recruited in a 2:1 fashion stratified by peak hs-cTnI concentration above and below the risk stratification threshold of 5 ng/L. All patients underwent coronary computed tomography angiography (CCTA) after hospital discharge. Results: Overall, 250 patients were recruited (61.4±12.2 years, 31% women) in whom 62.4% (156/250) had coronary artery disease (CAD). Patients with intermediate hs-cTnI concentrations (between 5 ng/L and the sex-specific 99th centile) were more likely to have CAD than those with hs-cTnI concentrations <5 ng/L (71.9% [120/167] versus 43.4% [36/83]; odds ratio 3.33 [95% confidence interval 1.92-5.78]). Conversely, there was no association between anginal symptoms and CAD (63.2% [67/106] versus 61.8% [89/144]; odds ratio 0.92 [0.48-1.76]). Most patients with CAD did not have a prior diagnosis (53.2%, 83/156) and were not on antiplatelet and statin therapies (63.5%, 99/156) prior to undergoing CCTA. Conclusions: In patients who had myocardial infarction excluded, CAD was three-times more likely in those with intermediate compared with low hs-cTnI concentrations. In such patients, CCTA could help to identify those with occult CAD and to target preventative treatments thereby improving clinical outcomes.