Case presentation: A 55-year-old

Size: px

Start display at page:

Download "Case presentation: A 55-year-old"

Darcy Owens
5 years ago
Views:

1 Clinician Update Coronary Computed Tomographic Angiography Its Role in Emergency Department Triage Michael K. Cheezum, MD; Ron Blankstein, MD Case presentation: A 55-year-old man presents to the emergency department (ED) after an episode of substernal chest discomfort that lasted 2 hours. His pain occurred at rest and was not positional, pleuritic, or postprandial. He has a history of hypertension and no known coronary artery disease (CAD). Vital signs and physical examination are unremarkable. His initial ECG, troponin, and serum creatinine are normal. How should this patient be evaluated? The Challenge of Evaluating Acute Chest Pain Chest pain is a common complaint in the ED, accounting for 10% to 15% of visits at an annual cost of $8 billion in the United States. 1 However, missed myocardial infarctions occur in up to 2% of patients with acute chest pain 2 and represent a leading cause of malpractice litigation. Because history alone is often inadequate to identify patients who may be safely discharged, 3 it is common practice to use observation and serial cardiac biomarkers for patient evaluation. Additionally, exercise testing and vasodilator stress testing are commonly used, although such testing can be performed only after an observation period, which includes serial cardiac biomarkers. With increasing use of cardiac testing in an era of cost containment, a growing need exists to improve the efficiency and cost associated with the evaluation of acute chest pain. Coronary Computed Tomographic Angiography: A Rapid Alternative to Usual Care Coronary computed tomographic (CT) angiography (CTA) is a high-resolution, noninvasive technique to image the coronary arteries and to detect the presence, severity, and extent of CAD. 4 The greatest utility of CTA lies in its high negative predictive value ( 95%) to exclude obstructive CAD and thus to identify patients who can be safely discharged without further diagnostic testing. 5 In addition, this test can be performed rapidly because only 1 set of negative biomarkers is needed. Consequently, 4 randomized, controlled trials in the ED have compared CTA with usual care 6 8 and single-photon emission CT, 9 demonstrating a consistent ability of CTA to expedite discharge. 10 Reassuringly, patients with a normal CTA or minimal CAD had very low downstream adverse cardiac events (<1%/y). Strengths and Limitations Although CTA avoids the inherent risks of stress testing in patients with suspected acute coronary syndrome (ACS), there are several strengths and limitations to consider (Table 1). Contrast and radiation remain potential concerns, but advances in CT hardware and software have improved overall patient safety. For instance, with prospective gated ECG triggering, the average effective dose is 3 to 4 msv, equivalent to the annual level of background radiation from natural sources. Despite these advances, alternative tests (eg, treadmill testing, stress echocardiography) remain reasonable options in selected patients. Patient Selection The initial evaluation of acute chest pain requires an ECG and cardiac biomarkers (Figure 1A). 11 Patients at very low risk for CAD and those with an alternative explanation for their symptoms require no further testing. Conversely, those with a high pretest probability for CAD may benefit from From the Departments of Medicine (Cardiovascular Division) and Radiology, Brigham and Women s Hospital, Boston MA. Correspondence to Ron Blankstein, MD, FACC, Brigham and Women s Hospital, Non-Invasive Cardiovascular Imaging Program, Departments of Medicine (Cardiovascular Division) and Radiology, 75 Francis St, Boston MA rblankstein@partners.org (Circulation. 2014;130: ) 2014 American Heart Association, Inc. Circulation is available at DOI: /CIRCULATIONAHA

Cheezum and Blankstein Role of CTA in ED Triage 2053 Table 1.

diagnosis and length of stay Evaluates other causes of chest pain Limitations Significance of anatomic lesions may be unknown Incidental findings may require further workup Intravenous contrast

tomographic angiography; and ED, emergency department. administration. Unless contraindicated, all patients receive nitroglycerin before scanning.

A Nonobstructive CAD In patients with nonobstructive CAD, a small potential for ACS remains despite the absence of significant stenosis.

2 Cheezum and Blankstein Role of CTA in ED Triage 2053 Table 1. Strengths and Limitations of CTA for Acute Chest Pain Strengths Is noninvasive Detects the full spectrum of CAD May affect preventive therapies Lowers ED cost relative to usual care Decreases time to diagnosis and length of stay Evaluates other causes of chest pain Limitations Significance of anatomic lesions may be unknown Incidental findings may require further workup Intravenous contrast Radiation May increase downstream costs and revascularizations Limited quality if elevated heart rate, arrhythmias, or morbid obesity is present CAD indicates coronary artery disease; CTA, computed tomographic angiography; and ED, emergency department. administration. Unless contraindicated, all patients receive nitroglycerin before scanning. Management of CTA Findings Normal CTA: No Plaque or Stenosis Patients with normal CTA may be safely discharged and have an extremely low cardiac event rate (Figure 1B). A Nonobstructive CAD In patients with nonobstructive CAD, a small potential for ACS remains despite the absence of significant stenosis. In the Rule Out Myocardial Infarction Using Computer Assisted Tomography (ROMICAT) I trial, in which providers were blinded to all CTA results, 6% of patients with nonobstructive CAD were ultimately categorized as having ACS, including 3 patients with myocardial infarction a functional strategy (eg, myocardial perfusion imaging or stress echocardiography) because CTA has reduced specificity to detect ischemia. 12 Thus, ideal candidates for CTA are patients at low to intermediate risk of obstructive CAD (Figure 2). 5 In addition, the use of CTA in the ED requires careful consideration of several key clinical, patient, and institutional factors (Table 2). Beyond risk prediction for obstructive CAD, several scores are available to stratify patients for ACS risk and potential complications but have limited sensitivity to exclude ACS. Among available ED studies, 2 have used a Thrombolysis in Myocardial Infarction (TIMI) risk score of 2 or 4 among clinical features (eg, history, ECG, biomarkers) to select potential candidates for CTA. 8,9 Patient Preparation In patients selected to undergo CTA, preparation with β-blockers and breathing instructions are paramount for achieving high image quality, although some scanners now permit rapid image acquisition, obviating the need for aggressive heart rate control. Largebore ( 18 gauge) intravenous access is preferred for high-flow contrast B Figure 1. A, Proposed testing strategy in patients with possible acute coronary syndrome (ACS). *Contraindications to computed tomographic angiography (CTA) include renal disease, severe allergy to iodine contrast, inability to follow breath-hold instructions, and pregnancy. Also consider factors that may impair image quality: body mass index >40 kg/m 2, arrhythmias, high heart rate despite β-blockers, extensive coronary calcifications, and intolerance or contraindication to β-blockers or nitroglycerin. Adapted from Cheezum et al 11 with permission from the publisher. Copyright 2014 Informa Plc. Authorization for this adaptation has been obtained both from the owner of the copyright in the original work and from the owner of copyright in the translation or adaptation. B, Early imaging strategy implementing coronary CTA. CAD indicates coronary artery disease. Adapted from Cheezum et al 11 with permission from the publisher. Copyright 2014 Informa Plc. Authorization for this adaptation has been obtained both from the owner of the copyright in the original work and from the owner of copyright in the translation or adaptation.

3 2054 Circulation December 2, 2014 Figure 2. The 2010 computed tomographic angiography (CTA) appropriate use criteria in patients with acute chest pain. CAD indicates coronary artery disease; and MI, myocardial infarction. Adapted from Taylor et al. 5 who had a positive second set of cardiac biomarkers. 13 Nevertheless, 2 subsequent randomized, controlled trials have demonstrated a very low event rate when patients with nonobstructive CTA findings were immediately discharged. On the basis of the available data, a conservative approach among patients who are found to have nonobstructive plaque is to check a second Table 2. Factors Influencing Testing Strategy Examples set of biomarkers. If negative, such patients can be discharged but require outpatient follow-up for preventive care (Figure 1B). Obstructive CAD In patients with obstructive CAD, admission and further workup are recommended to guide management. For the majority of these patients, particularly those with moderate stenosis (ie, 50% 70%), functional testing for ischemia (noninvasive or invasive) is recommended because it may reduce unnecessary coronary revascularizations (Figure 1B). CTA to Guide Preventive Therapy Patients with both nonobstructive and obstructive CAD have increased risk for long-term major adverse cardiac events relative to patients with no CAD. For example, among patients with nonobstructive plaque, the 2-year Favors CTA Favors Functional Testing Clinical factors What is the clinical Exclude CAD question? Exclude ischemia Identify future risk of adverse cardiac events... To guide preventive therapies To guide revascularization Evaluate physiological response to exercise Is there an alternative diagnosis that may account Hiatal hernia, aortopathy, lung disease, pulmonary embolism for patient symptoms? Valvular disease, pericarditis * Patient factors Pretest probability of CAD Low to intermediate risk High risk, known CAD, prior PCI/CABG Ability to obtain diagnostic High heart rate, arrhythmias, extensive CTA image quality coronary calcification, inability to hold breath, morbid obesity Contraindications to CTA Kidney dysfunction, iodine allergy, pregnancy Institutional factors (experience, availability, local reimbursement policy) ACS indicates acute coronary syndrome; CABG, coronary artery bypass grafting; CAD, coronary artery disease; CTA, computed tomographic angiography; and PCI, percutaneous coronary intervention. *Depending on the type of functional testing performed (eg, magnetic resonance imaging is best for evaluating pericardial disease; echocardiography may be useful when valvular disease is suspected). cardiac event rate in ROMICAT I was 4.6% (1.2% after excluding early [<30 day] major adverse cardiac events) versus 0% for patients with no CAD. 14 Similarly, other studies have demonstrated that nonobstructive plaque on CTA, especially when multiple segments are involved, is associated with a higher rate of hard cardiovascular events compared with no plaque on CTA. 4 Supporting the growing recognition that coronary plaque on CTA is associated with an increased event rate, multiple observational studies have shown that CTA is associated with intensification in preventive therapies and modification of CVD risk factors. 15,16 Unanswered Questions What is the Long-Term Cost- Effectiveness of CTA Relative to Usual Care? Although CTA has been shown to reduce ED costs compared with usual care, available studies have shown no benefit in total hospital costs with CTA use. As a test designed to detect the anatomic presence of CAD, CTA has potential to increase downstream costs by unnecessarily triggering invasive angiography and coronary revascularization procedures. Although further research is needed to clarify the cost benefit of CTA, data suggest that when the prevalence or inability to exclude obstructive CAD is <30%, CTA offers cost savings relative to usual care for acute chest pain. 17 Can Coronary Artery Calcification Testing Alone Safely Exclude ACS in Low-Risk Patients? Coronary artery calcification (CAC) testing alone has been proposed as a rapid, inexpensive test that is easy to perform and can exclude ACS in a majority of low-risk symptomatic patients. 18 National Institute for Health and Clinical Excellence guidelines have adopted this strategy on the basis of estimates of the cost-effectiveness of this approach, 19

Cheezum and Blankstein Role of CTA in ED Triage 2055 Case Resolution Given the intermediate pretest probability of obstructive CAD and the absence of contraindications, the patient underwent CTA,

4 Cheezum and Blankstein Role of CTA in ED Triage 2055 Case Resolution Given the intermediate pretest probability of obstructive CAD and the absence of contraindications, the patient underwent CTA, demonstrating mild nonobstructive CAD (Figure 3). A second set of cardiac biomarkers was normal. He was discharged with follow-up for risk factor management and has remained free of adverse cardiac events. Disclosures None. The views expressed here are those of the authors only. Figure 3. Coronary computed tomographic angiography (CTA) demonstrating nonobstructive coronary artery disease. Top row, Three-dimensional and curved multiplanar views of the left anterior descending artery (LAD), left circumflex artery (LCX), and right coronary artery (RCA). There is noncalcified and calcified plaque in the proximal and mid-lad, resulting in mild (25% 49%) stenosis. Bottom row, Orthogonal and shortaxis views of mid-lad demonstrating (b) predominant calcified plaque in the mid-lad, resulting in mild (25% 49%) stenosis relative to (a) proximal and (c) distal reference vessels. yet research and widespread use of CAC alone in symptomatic patients remain limited. Although data support favorable prognosis among patients with CAC of zero, 20 further studies are needed to examine the safety of CAC for ruling out ACS and potentially to guide the need and type of further testing (eg, discharge when CAC=0, CTA when CAC=1 99, and perfusion imaging for patients with CAC >100). Is There a Role for Triple Rule- Out Scanning? Of relevance to the ED setting is the potential for CTA use as a triple ruleout (TRO) test to simultaneously exclude ACS, aortic dissection, and pulmonary embolism. Challenges to TRO use have limited its widespread application, with data suggesting that the rate of pulmonary embolism and aortic dissection detected by TRO testing is very low ( 1% of scans). 21 Additionally, TRO scans require more contrast to opacify all 3 vascular beds with higher radiation doses compared with CTA. Although newer scanners and techniques should improve the riskto-benefit ratio of TRO, appropriate use of TRO scanning remains uncertain. 5 What Is the Role of High- Sensitivity Troponin Among Testing Strategies? Initial studies have demonstrated a high accuracy for high-sensitivity troponin (c statistic=0.94) to exclude ACS in the first hour of presentation, with an ability to predict ischemia and CAD burden among patients with normal initial standard troponin levels. 22 Although studies have shown that high-sensitivity troponin may offer prognostic value independently of CTA findings, its specificity for ACS appears to be more limited. 23 Further research is needed to define the role of high-sensitivity troponin among available strategies. Conclusions Coronary CTA is now an established, noninvasive technique that can rapidly exclude obstructive CAD and identify patients who can be safely discharged from the ED. Although CTA appears to lower ED costs and may lead to intensification in preventive therapies, concern remains about the potential for this test to increase invasive angiography and coronary revascularizations. Ultimately, appropriate patient selection will remain essential for ensuring optimal test use and patient management. References 1. Bhuiya FA, Pitts SR, McCaig LF. Emergency department visits for chest pain and abdominal pain: United states, NCHS Data Brief. 2010: Pope JH, Aufderheide TP, Ruthazer R, Woolard RH, Feldman JA, Beshansky JR, Griffith JL, Selker HP. Missed diagnoses of acute cardiac ischemia in the emergency department. N Engl J Med. 2000;342: Swap CJ, Nagurney JT. Value and limitations of chest pain history in the evaluation of patients with suspected acute coronary syndromes. JAMA. 2005;294: Bittencourt MS, Hulten E, Ghoshhajra B, O Leary D, Christman MP, Montana P, Truong QA, Steigner M, Murthy VL, Rybicki FJ, Nasir K, Gowdak LH, Hainer J, Brady TJ, Di Carli MF, Hoffmann U, Abbara S, Blankstein R. Prognostic value of nonobstructive and obstructive coronary artery disease detected by coronary computed tomography angiography to identify cardiovascular events. Circ Cardiovasc Imaging. 2014;7: Taylor AJ, Cerqueira M, Hodgson JM, Mark D, Min J, O Gara P, Rubin GD. ACCF/ SCCT/ACR/AHA/ASE/ASNC/NASCI/ SCAI/SCMR 2010 appropriate use criteria for cardiac computed tomography: a report of the American College of Cardiology Foundation Appropriate Use Criteria Task Force, the Society of Cardiovascular Computed Tomography, the American College of Radiology, the American Heart Association, the American Society of Echocardiography, the American Society of Nuclear Cardiology, the North American Society for Cardiovascular Imaging, the Society for Cardiovascular Angiography and Interventions, and the Society for Cardiovascular Magnetic Resonance. Circulation. 2010;122:e525 e Goldstein JA, Gallagher MJ, O Neill WW, Ross MA, O Neil BJ, Raff GL. A randomized controlled trial of multi-slice coronary computed tomography for evaluation of acute chest pain. J Am Coll Cardiol. 2007;49:

5 2056 Circulation December 2, Hoffmann U, Truong QA, Schoenfeld DA, Chou ET, Woodard PK, Nagurney JT, Pope JH, Hauser TH, White CS, Weiner SG, Kalanjian S, Mullins ME, Mikati I, Peacock WF, Zakroysky P, Hayden D, Goehler A, Lee H, Gazelle GS, Wiviott SD, Fleg JL, Udelson JE; ROMICAT-II Investigators. Coronary CT angiography versus standard evaluation in acute chest pain. N Engl J Med. 2012;367: Litt HI, Gatsonis C, Snyder B, Singh H, Miller CD, Entrikin DW, Leaming JM, Gavin LJ, Pacella CB, Hollander JE. CT angiography for safe discharge of patients with possible acute coronary syndromes. N Engl J Med. 2012;366: Goldstein JA, Chinnaiyan KM, Abidov A, Achenbach S, Berman DS, Hayes SW, Hoffmann U, Lesser JR, Mikati IA, O Neil BJ, Shaw LJ, Shen MY, Valeti US, Raff GL; CT-STAT Investigators. The CT-STAT (Coronary Computed Tomographic Angiography for Systematic Triage of Acute Chest Pain Patients to Treatment) trial. J Am Coll Cardiol. 2011;58: Hulten E, Pickett C, Bittencourt MS, Villines TC, Petrillo S, Di Carli MF, Blankstein R. Outcomes after coronary computed tomography angiography in the emergency department: a systematic review and meta-analysis of randomized, controlled trials. J Am Coll Cardiol. 2013;61: Cheezum MK, Bittencourt MS, Hulten EA, Scirica BM, Villines TC, Blankstein R. Coronary computed tomographic angiography in the emergency room: state of the art. Expert Rev Cardiovasc Ther. 2014;12: Blankstein R, Di Carli MF. Integration of coronary anatomy and myocardial perfusion imaging. Nat Rev Cardiol. 2010;7: Hoffmann U, Bamberg F, Chae CU, Nichols JH, Rogers IS, Seneviratne SK, Truong QA, Cury RC, Abbara S, Shapiro MD, Moloo J, Butler J, Ferencik M, Lee H, Jang IK, Parry BA, Brown DF, Udelson JE, Achenbach S, Brady TJ, Nagurney JT. Coronary computed tomography angiography for early triage of patients with acute chest pain: the ROMICAT (Rule Out Myocardial Infarction Using Computer Assisted Tomography) trial. J Am Coll Cardiol. 2009;53: Schlett CL, Banerji D, Siegel E, Bamberg F, Lehman SJ, Ferencik M, Brady TJ, Nagurney JT, Hoffmann U, Truong QA. Prognostic value of CT angiography for major adverse cardiac events in patients with acute chest pain from the emergency department: 2-year outcomes of the ROMICAT trial. JACC Cardiovasc Imaging. 2011;4: Cheezum MK, Hulten EA, Smith RM, Taylor AJ, Kircher J, Surry L, York M, Villines TC. Changes in preventive medical therapies and CV risk factors after CT angiography. JACC Cardiovasc Imaging. 2013;6: Hulten E, Bittencourt MS, Singh A, O Leary D, Christman MP, Osmani W, Abbara S, Steigner M, Truong QA, Nasir K, Rybicki F, Klein J, Hainer J, Brady TJ, Hoffmann U, Ghoshhajra B, Hachamovitch R, Di Carli MF, Blankstein R. Coronary artery disease detected by coronary CT angiography is associated with intensification of preventive medical therapy and lower LDL cholesterol. Circ Cardiovasc Imaging. 2014;7: Hulten E, Goehler A, Bittencourt MS, Bamberg F, Schlett CL, Truong QA, Nichols J, Nasir K, Rogers IS, Gazelle SG, Nagurney JT, Hoffmann U, Blankstein R. Cost and resource utilization associated with use of computed tomography to evaluate chest pain in the emergency department: the Rule Out Myocardial Infarction using Computer Assisted Tomography (ROMICAT) study. Circ Cardiovasc Qual Outcomes. 2013;6: Sarwar A, Shaw LJ, Shapiro MD, Blankstein R, Hoffmann U, Hoffman U, Cury RC, Abbara S, Brady TJ, Budoff MJ, Blumenthal RS, Nasir K. Diagnostic and prognostic value of absence of coronary artery calcification. JACC Cardiovasc Imaging. 2009;2: Skinner JS, Smeeth L, Kendall JM, Adams PC, Timmis A; Chest Pain Guideline Development Group. NICE guidance: chest pain of recent onset: assessment and diagnosis of recent onset chest pain or discomfort of suspected cardiac origin. Heart. 2010;96: Hulten E, Bittencourt MS, Ghoshhajra B, O Leary D, Christman MP, Blaha MJ, Truong Q, Nelson K, Montana P, Steigner M, Rybicki F, Hainer J, Brady TJ, Hoffmann U, Di Carli MF, Nasir K, Abbara S, Blankstein R. Incremental prognostic value of coronary artery calcium score versus CT angiography among symptomatic patients without known coronary artery disease. Atherosclerosis. 2014;233: Madder RD, Raff GL, Hickman L, Foster NJ, McMurray MD, Carlyle LM, Boura JA, Chinnaiyan KM. Comparative diagnostic yield and 3-month outcomes of triple rule-out and standard protocol coronary CT angiography in the evaluation of acute chest pain. J Cardiovasc Comput Tomogr. 2011;5: Ahmed W, Schlett CL, Uthamalingam S, Truong QA, Koenig W, Rogers IS, Blankstein R, Nagurney JT, Tawakol A, Januzzi JL, Hoffmann U. Single resting hstnt level predicts abnormal myocardial stress test in acute chest pain patients with normal initial standard troponin. JACC Cardiovasc Imaging. 2013;6: Laufer EM, Mingels AM, Winkens MH, Joosen IA, Schellings MW, Leiner T, Wildberger JE, Narula J, Van Dieijen-Visser MP, Hofstra L. The extent of coronary atherosclerosis is associated with increasing circulating levels of high sensitive cardiac troponin T. Arterioscler Thromb Vasc Biol. 2010;30:

Coronary Artery Disease - Reporting and Data System (CAD-RADS)

A joint publication of the Department of Radiology and Corrigan Minehan Heart Center November 2016 Issue 66 Coronary Artery Disease - Reporting and Data System (CAD-RADS) Sandeep S. Hedgire, MD; Udo Hoffmann,