Cardiac CT with triple-rule-out (TRO) and late iodine enhancement (LIE) acquisition in the evaluation of patients presenting with acute troponin elevation

Purpose: To evaluate the diagnostic yield of the late iodine enhancement (LIE) acquisition added to the triple-rule-out CT (TRO-CT) performed in patients presenting with acute symptoms and troponin elevation without clinical/electrocardiography criteria for acute myocardial infarction (AMI). Methods and materials: 60 consecutive patients with acute symptoms, troponin elevation, and no diagnostic criteria for AMI underwent TRO-CT to diagnose acute aortic syndromes, obstructive coronary artery disease (CAD-RADS≥4), and pulmonary embolism (PE). Patients with a negative TRO-CT underwent LIE acquisition to evaluate the presence and pattern of LIE and to quantify the myocardial extracellular volume fraction (ECV). Obstructive CAD was confirmed by invasive coronary angiography and myocardial disease by cardiac magnetic resonance. Results: The male to female ratio was 35:25. The median age was 71 years [IQR=47-78]. Peak median troponinT (n=46) was 49.0 ng/L[IQR=20.4-195.7] and peak median troponinI (n=14) was 4.1 ng/L[IQR=1.2-11.8]. Reported symptoms were chest pain (n=31[51%]), dyspnoea (n=16[26%]), palpitations (n=6[11%]), loss of consciousness (n=5[8%]), and other (n=14[23%]). TRO-CT identified 19 (32%) obstructive CAD, 1 (1%) acute aortic syndrome, 5 (8%) PE, 1 (1%) CAD+PE, and 1 (1%) CAD+acute aortic syndrome. LIE acquisition was performed in the remaining 33 (55%) TRO-negative patients. 2 (3%) had LIE with ischemic pattern, 16 (27%) LIE with non-ischemic pattern [13 (22%) myocarditis, 3 (5%) idiopathic dilated cardiomyopathy], 3 (5%) increased ECV suggestive for amyloidosis, 2 (3%) cardiac metastasis, 2 (3%) tako-tsubo cardiomyopathy, 1 (1%) pericarditis, and 1 (1%) basal hyperdensity of myocardium suggestive for haemosiderosis. 6 (10%) patients were negative to TRO and LIE and did not report major cardiovascular adverse events after a mean follow-up of 419 days. Conclusion: LIE acquisition increases the diagnostic value of TRO-CT, finding a diagnosis in 82% of TRO-negative patients and allowing a safe discharge of TRO- and LIE-negative patients.