Coronary CT angiography for myocardial infarction: case studies of the Massachusetts General Hospital.

Abstract

A 63-year-old man with no significant past medical history presented to the emergency department (ED) on a cold February morning with several hours of nonradiating substernal 6/10 chest heaviness since waking. He reported shoveling large amounts of snow during the ‘Boston Blizzard of 2015’ 7 days before presentation but denied subsequent dizziness, dyspnea, diaphoresis, nausea, or vomiting. Initial serum troponin-T testing was negative (<0.01 ng/ml), and ECG demonstrated sinus bradycardia without ischemic changes. The patient was administered full-dose aspirin and one spray of sublingual nitroglycerin with a reduction in his discomfort to 3/10. Coronary computed tomography angiography (CTA) was requested by the ED physician as the patient met institutional guidelines including low to intermediate risk (TIMI score≤4 at the time of scan), symptoms suspicious for acute coronary syndrome, unimpaired renal function, one set of negative serum biomarkers, and absence of ischemic ECG changes. Given the TIMI score of 1, the patient underwent coronary CTA monitored by a cardiac radiologist. A standard ED coronary CTA protocol was utilized, with prospective ECG–triggered acquisition in systole and a widened acquisition window to allow simultaneous evaluation of ventricular function. Coronary CTA demonstrated right coronary artery (RCA) dominance with short-segment focal subtotal occlusion of the distal RCA and adjacent fat stranding suspicious for acute plaque rupture. Multiphase cine images demonstrated regional hypokinesis of the basal and mid-inferior and inferoseptal left ventricle, consistent with an RCA territory ischemic event (Fig. 1; Supplemental video file 1, Supplemental digital content 1, https://links.lww.com/MCA/A58 and Supplemental video file 2, Supplemental digital content 2, https://links.lww.com/MCA/A59). Cardiology consultation led to a plan for admission and early elective invasive coronary angiography. Repeat serum troponin-T evaluations several hours after the scan showed elevations in troponin-T levels to 0.05 ng/ml, followed by 0.84 ng/ml.Fig. 1: Maximal-intensity projection coronary CTA image of the RCA demonstrating focal subtotal distal RCA occlusion (arrows) with adjacent fat stranding suspicious for acute plaque rupture. CTA, computed tomography angiography; RCA, right coronary artery.Coronary angiography confirmed distal RCA subtotal occlusion and demonstrated left-to-right collaterals. Percutaneous coronary intervention was performed with angioplasty, followed by placement of a 2.5×24 mm drug-eluting stent and postdilation (Fig. 2). Final postintervention stenosis was 0%. The patient was discharged home 2 days later on aspirin, atorvastatin, lisinopril, and clopidogrel. At the 2-month follow-up, he reported complete resolution of symptoms and had returned to work and his normal active baseline state of health.Fig. 2: (Left) Invasive coronary angiography confirms focal subtotal distal RCA occlusion (arrows). (Right) Post-PCI image shows 0% residual stenosis of the distal RCA after angioplasty, drug-eluting stent placement, and postdilatation. PCI, percutaneous coronary intervention; RCA, right coronary artery.Coronary CTA has been demonstrated by multiple large randomized controlled trials to improve the efficiency of care for low-to-intermediate risk patients with acute chest pain presenting to the ED, and it has an excellent negative predictive value for obstructive coronary artery disease (CAD) 1–3. In the largest published trials and in our own clinical experience, ∼85% of appropriately selected patients have no plaque or only nonobstructive CAD, defined as less than 50% luminal narrowing, and thus can be safely discharged home. In a minority of patients, potentially obstructive CAD is identified more rapidly than by the standard of care. At our institution, management for moderate stenoses (50–69% luminal narrowing) detected by CTA includes consideration of functional testing and complete 24-h serum biomarker and ECG evaluation, whereas management of severe stenoses (>70%) includes immediate cardiology consultation for consideration of invasive coronary angiography. This case demonstrates the utility of coronary CTA in rapidly and definitively identifying acute coronary syndrome in a low-risk patient with acute chest pain, resulting in immediate catheterization and revascularization. In addition, a coronary CTA protocol including multiphase images allows evaluation of ventricular function, which in this case demonstrated a regional wall-motion abnormality corresponding to the culprit ischemic lesion. Acknowledgements Conflicts of interest There are no conflicts of interest.