1 Answer B. The curved multiplanar reformat of the RCA (right-dominant system) demonstrates mixed plaque within the proximal vessel resulting in severe (roughly 80%) stenosis. A more proximal lesion consisting of noncalcified plaque causes 40% to 50% stenosis. A lesion is considered hemodynamically significant if it causes >70% stenosis. This is based on myocardial blood flow studies. The lateral wall is perfused by the circumflex, not the RCA. Contrast is noted throughout the lumen indicating partial patency. STEMI is caused by acute plaque rupture and acute total occlusion.

Reference: Uren NG, Melin JA, De Bruyne B, et al. Relation between myocardial blood flow and severity of coronary-artery stenosis. N Engl J Med 1994;330(25):1782-1788.

2 Answer B. During coronary CTA, sublingual nitroglycerin (SL NTG) is given for coronary artery dilation. Use of phosphodiesterase inhibitors serves as a contraindication for SL NTG administration because of possible hypotension. A review of the patient’s medication list is mandatory prior to performing coronary CTA.

Reference: http://www.ctisus.com/learning/pearls/cardiac/patient-prep:-beta-blockers,-iv-contrast,-etc

3 Answer D. The curved multiplanar reformat of the LAD shows a long-segment intramyocardial bridge in the mid LAD. This is the most common site for bridging. Studies show that there is increased likelihood of ischemia with increasing depth and length of the bridge. Initial treatment is with beta blockers to unload the left ventricle. Refractory cases may be referred to surgery for unroofing.

References: Nakanishi R, et al. Myocardial bridging on coronary CTA: an innocent bystander or a culprit in myocardial infarction? JCCT 2012;6:3-13.

Vliegen HW, Jukema JW, Bruschke AVG. Congenital coronary artery anomalies. Anatomy, diagnosis, and management. Leiden, The Netherlands: TTMA B.V., 2012.

4 Answer C. The image shows a “nubbin” from an occluded vein graft arising from the aorta. Additionally, the left internal mammary artery (LIMA) is not along the chest wall like the right one, indicating that the LIMA has been used as a graft to (most likely) the LAD.

Reference: Frazier A, et al. Coronary artery bypass grafts: assessment “with multidetector CT in the early and late postoperative settings. Radiographics 2005;25:881-896.

5 Answer A. Graft at 10 years was 61% for saphenous vein grafts compared with 85% for internal mammary artery grafts (p < 0.001).

Reference: Goldman, et al. J Am Coll Cardiol 2004;44(11):2149-2156.

6 Answer A. Coronary artery calcification occurs in proportion to underlying plaque burden but not degree of stenosis. While it has been shown that a calcium score of >100 AU carries a 5× increased risk of a coronary event than a score <100, the presence of high-grade stenosis cannot be accurately determined on a calcium score image alone, as this does not account for occult noncalcified plaque. Additionally, it is possible that calcium is mostly intramural and does not cause significant luminal narrowing.

References: Guerci AD, et al. Relation of coronary calcium score by electron beam computed tomography to arteriographic findings in asymptomatic and symptomatic adults. Am J Cardiol 1997;79:128-133.

Yadon, et al. J Am Coll Cardiol 2005;46(1):158-165.

7 Answer B. All scan parameters listed above are within reasonable protocol limits. The body habitus in this patient, however, is causing significant attenuation of the x-ray and increased image noise. BMI > 39 can potentially lead to nondiagnostic studies and is a relative contraindication.

Reference: Raff, et al. SCCT guidelines on the use of coronary computed tomographic angiography for patients presenting with acute chest pain to the emergency department: A Report of the Society of Cardiovascular Computed Tomography Guidelines Committee. J Cardiovas Comput Tomogr 2014;8:254 e271.

8 Answer B. Infarcted tissue demonstrates subendocardial enhancement or (when extensive) transmural enhancement. If less than 50% of the affected wall demonstrates scarring/enhancement, it is deemed viable, and revascularization has been shown to improve postinfarction ejection fraction and clinical outcome.

References: Cummings, et al. A pattern based approach to assessment of delayed enhancement in nonischemic cardiomyopathy at MR imaging. Radiographics 2009;29:89-103.

Kim R, et al. The use of contrast enhanced magnetic resonance imaging to identify reversible myocardial dysfunction. NEJM 2000;343(2):1445-1453.

9 Answer C. The curved multiplanar reformat of the left main and LAD shows mixed plaque within the LM resulting in greater than 50% stenosis. A lesion is considered hemodynamically significant if it causes >50% stenosis in the left main. This is based on myocardial blood flow studies. A greater than 50% lesion in the left main is an indication for coronary artery bypass grafting.

References: Uren NG, Melin JA, De Bruyne B, et al. Relation between myocardial blood flow and severity of coronary-artery stenosis. N Engl J Med 1994;330(25):1782-1788.

Eagle KA, et al. ACC/AHA guidelines for coronary artery bypass graft surgery: executive summary and recommendations: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (Committee to revise the 1991 guidelines for coronary artery bypass graft surgery). Circulation 1999;100(13):1464-1480.

10 Answer B. Microvascular obstruction (MVO), also known as no-reflow phenomenon is a focus of infracted myocardium where obstruction of the microvasculature does not allow contrast to perfuse the tissue. Following infarction, administered contrast resides in the interstitium and creates the scar seen on delayed enhancement images. In areas where the microvasculature is obstructed, the contrast never reaches the interstitium, and this tissue appears as very dark signal surrounded by an enhancing scar on both sides. MVO is recognized as a poor prognostic indicator and marker of subsequent adverse LV remodeling.

Reference: Wu K. CMR of microvascular obstruction and hemorrhage in myocardial infarction. JCMR 2012;14:68.

11 Answer C. Coronary CTA has a negative predictive value greater than 95% and is an excellent test to exclude coronary artery disease. In particular, it has been shown to be of value when evaluating low risk patients with atypical chest pain, low risk patients with negative or equivocal stress testing an in the emergency room setting to evaluate patients with acute chest pain who are of low- to medium-risk (shown in ACRIN-PA and ROMICAT-II clinical trials).

Reference: Taylor, et al. ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 Appropriate use criteria for cardiac computed tomography. Evaluation of graft patency after CABG has an appropriateness score of 8/9 in a symptomatic patient. Circulation 2010;122:e525-e555.

12 Answer D. Long-term data is now available for patients who underwent coronary CTA in the emergency room. Current data suggests that a normal CTA in a low-risk patient presenting to the ER has a “warranty period” of up to 2 years meaning a rescan is not necessary as there has been no recorded incident of ACS within 2 years in this population.

Reference: Schlett, et al. Prognostic value of CT angiography for major adverse cardiac events in patients “with acute chest pain from the emergency department. JACC Cardiovas Img 2011;4(5):481-491.

13 Answer A. Several clinical trials such as ACRIN-PA, CT-STAT, and ROMICAT have demonstrated the utility of coronary CTA for low-risk emergency room patients presenting with chest pain. Current data supports the position that a CCTA-based strategy for low- to intermediate-risk patients presenting with a possible acute coronary syndrome allows for the safe, expedited discharge home rather than admission and continued monitoring.

Reference: Litt HI, et al. CT angiography for safe discharge of patients “with possible acute coronary syndromes. N Engl J Med 2012;366:1393-1403.

14 Answer C. Myocardial infarction carries many associated complications that include apical aneurysm formation, decreased ejection fraction, ventriculoseptal defect formation and papillary muscle infarction.

In one study, the incidence of rupture of the papillary muscle was found to be 0.9%. The clinical features usually occur during the first week after infarction. More common is slight mitral regurgitation without pulmonary edema from papillary muscle dysfunction.

Reference: Clements, et al. Ruptured papillary muscle, a complication of myocardial infarction: clinical presentation, diagnosis, and treatment. Clin Cardiol 1985;8:93-103.