Master the evaluation of acute and chronic chest pain with coronary CT angiography (CCTA). We deconstruct this game changing technology w/experts from the Society for Cardiovascular Computed Tomography (SCCT), Dr. Todd Villines and Dr. Ahmad Slim. We’ve got answers on what to do when a patient with chest pain has a prior CAC score of zero, and/or a CCTA with non-obstructive disease. Plus: how to select, prepare, and counsel patients; how to interpret reports; choosing between myocardial perfusion study and CCTA, and more!
Special thanks to Dr. Emilio Fentanes from SCCT for setting up this interview.
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Case: 45 yo F active duty Colonel with chronic chest pain syndrome despite negative conventional stress test and CAC score of zero.
- “Conventional testing” or “functional testing for chest pain includes exercise electrocardiography (EKG), exercise or pharmacologic nuclear stress testing, and stress echocardiography (PROMISE NEJM 2015)
- Coronary artery calcium (CAC) scoring: Non-contrast CT scanned that assesses overall coronary plaque burden, NOT stenosis. Use in asymptomatic patients to determine strategy for prevention. Radiation dose is 1 mSV or less.
- Coronary CT angiography (CCTA): Non-invasive CT of the coronary arteries w/IV contrast to assess stenosis and plaque characteristics. Modern scanner w/radiation dose 3 mSV or less (versus 3.6 mSV from solar radiation annually and over 15 mSV w/nuclear stress imaging). Has ability to identify non-obstructive coronary disease missed on conventional stress testing, and nuclear imaging. Evidence suggests CCTA may be able to prevent acute coronary syndrome (SCOT-HEART).
- Patient counseling: Avoid phosphodiesterase inhibitors (e.g. viagra, levitra, cialis) because nitroglycerin given during scan. Must be fasting for 4 hours. Beta blocker (e.g. metoprolol 50-100 mg) given 1 hour prior to test. Incidental findings e.g. nodules and incidentalomas w/about 7% of scans. Avoid CCTA if acute kidney injury, or CKD 3-4 (Cr and eGFR cut-off is institution dependent). Average radiation dose w/CCTA slightly less than annual solar radiation.
- Controversy w/CCTA: May lead to more revascularization…BUT less patients sent for left heart cath inappropriately [i.e. have non-obstructive coronary artery disease (CAD)].
- CCTA for acute chest pain syndrome: Patient in ER with negative troponin (or low level/equivocal troponin) and non-ischemic EKG with low to intermediate risk for acute coronary syndrome (ACS). NOT for high risk presentations with high suspicion for ACS.
- CCTA for chronic chest pain syndrome: Consider for low to intermediate risk patients with a chest pain syndrome w/o known CAD. Consider CCTA if unreadable EKG, or equivocal results on previous “conventional testing”. Leads to reduction in myocardial infarction (MI) by identification of non-obstructive disease.
- Clinical scenario: CAC of zero in patient w/acute chest pain syndrome: Controversial area because CAC score of zero means less than 5% risk for obstructive CAD as cause of chest pain. Consider further risk stratification (e.g. CCTA or functional testing) if multiple CV risk factors, or if patient tells a “good” story. Consider performing CCTA on these patients if not previously performed.
- Clinical scenario: CAC of zero and CCTA w/non-obstructive CAD in patient w/acute chest pain syndrome: For patients w/ “non-obstructive” CAD must consider number of segments involved (e.g. more than 4-5 means higher risk), plaque characteristics, and traditional CV risk factors. Consider a “functional” treadmill test if concerned. If stenosis less than 50%, then risk of ACS is very low. If stenosis 50% or more and “high risk” plaque features, then admit patient rule out ACS and perform functional testing.
- CAD RADS: Score 0 = warranty 2-5 years; Score 1-2 = non-obstructive disease; Score 3 = moderate 50-69% obstruction; Score 4-5 = 70% or above. Consider left heart catheterization if score 3 or above (see Table 2 in SCCT/ACR/ACC Guideline 2016) .
- Cardiac risk categories by annual event rate for myocardial infarction (MI) or cardiac death: Low risk = less than 1%. Intermediate risk = 1-3%. High risk = above 3%.
- Annual event rate for MI or cardiac death w/a negative CCTA is 0.02% versus 0.8% w/exercise stress test versus 0.65% with nuclear exercise stress test versus 1.8% w/chemical stress test.
- Annual event rate for MI or cardiac death with a positive CCTA is ~3% versus 2% w/exercise stress test.
- High risk occupations: Risk for sudden cardiac death is 3 fold higher in high risk occupations (e.g. military, police, firefighters, pilots, etc.) after age 45. Reasonable to screen age 45 years and above w/CAC scoring followed by CCTA, or functional testing if CAC score suggests risk for obstructive CAD.
- Nuclear medicine myocardial perfusion study: Good test if known CAD w/prior stents, or grafts.
Goal: Listeners will appropriately utilize CCTA to evaluate acute and chronic chest pain syndromes.
By the end of this podcast listeners will:
- Define CAC and CCTA
- Differentiate between CAC and CCTA
- Counsel patients about CCTA and preparation for testing
- Correctly identify appropriate patients for CCTA
- Utilize CCTA to evaluate acute chest pain
- Utilize CCTA to evaluate chronic chest pain
- Interpret CCTA reports
- Choose between CCTA and myocardial perfusion study
Dr. Slim is Chairman of Advocacy for SCCT. He has no relevant financial disclosures. Dr. Villines is President-Elect of SCCT. He has no relevant financial disclosures.
04:00 Rapid fire questions
08:23 Book recommendations
10:14 Defining terms CCTA vs CAC
12:47 Script for counseling patient about CCTA
14:34 Prep for CCTA
16:40 Why is CCTA controversial?
19:37 Patient selection for CCTA both acute and chronic
25:20 Chronic chest pain and CCTA
27:58 CAC and CCTA in high risk occupations
33:25 Clinical case
36:10 Acute chest pain in patient w/CAC score zero
39:18 Acute chest pain in patient w/CAC score zero and previous CCTA w/non-obstructive CAD
41:22 How to read a CCTA report
45:48 CCTA versus conventional testing and risk MI, death
49:18 Use of CCTA in outpatients
52:16 Plaque characteristics and risk ACS
55:51 CCTA w/non-obstructive disease in patients with acute chest pain
58:14 When is myocardial perfusion scanning better?
61:00 Listener question on small vessel disease
62:09 Take home points
65:00 Curbsiders recap
Links from the show:
- The Prince (book) by Niccolo Machiavelli
- Team of Teams (book) by Stanley McChrystal
- TED Talk Stanley McChrystal
- The Tim Ferriss Show podcast interview w/Stanley McChrystal
- SCCT Advocacy Website
- Appropriate Use of Cardiac Imaging in Emergency Department Patients With Chest Pain JACC 2016
- SCCT Appropriateness criteria for CCTA 2010
- CAD RAS practice guidelines 2016 SCCT/ACC/ACR
- Diamond and Forrester score NEJM 1979
- Job stress and risk sudden cardiac death BMJ 2014
- Underlying coronary lesion in MI. Often stenosis is under 50% Clin Cardiol 1991
- Promise trial NEJM 2015
- CONFIRM Registry JACC 2013
- SCOT-HEART Lancet 2015
- MESA Trial for calcium scoring JACC 2009
- COURAGE Trial NEJM 2007