The Role of Computed Tomography

in the Diagnosis of Coronary Atherosclerosis

Saurabh Rajpal, MBBS, MD

Assistant Professor

Department of Internal Medicine

Division of Cardiology

The Ohio State University

PLAN

• Discuss Current Guidelines

• Recent Literature – Use of Cardiac CT as an Initial Test for Chest Pain

• Use of Cardiac CT for evaluation of patients with Stents and Bypass Grafts

• Coronary Artery Calcium (CAC)

• Limitations of Cardiac CT

• Future of Cardiac CT

JOURNEY FROM FROM RULING IN TO RULING OUT

• In the 90s pre-requisite for non-invasive CAD evaluation

• High pre-test probability of angina

• Clear history of anginal chest pain

• EKG

• Non-invasive testing - Predominantly exercise-EKG

Braunwald E, Jones RH, Mark DB, Brown J, Brown L, Cheitlin MD, et al. Diagnosing and managing unstable angina. Circulation. 1994;90:613–622

Circa 2018..

• Exercise EKG

• Stress Echocardiogram • High sensitive troponin

• Nuclear Stress Test (Exercise and Pharmacological)

• Stress Cardiac MR (Exercise and Pharmacological)

• Cardiac CT- Coronary CT Angiography (CCTA)

CARDIAC CT

• Rapid

• Gives high quality anatomic information

• High negative predictive value

• High sensitivity and specificity

Why would you not order CCTA as initial test for investigating suspected angina?

• Its expensive

• I think nuclear test is better

• We do not have the expertise

• It’s a lot of radiation

• Not comfortable with new technology

• Habit

• Its not a functional test

• Don’t know what to do with the results

GUIDELINES

AHA/ACC 2014 Non-ST-Elevation ACS

Class II a :

In patients with possible ACS and a normal ECG, normal cardiac troponins, and no history of CAD, it is reasonable to initially perform (without serial ECGs and troponins) CCTA (Level of Evidence: A) to assess coronary anatomy or rest myocardial perfusion imaging (Level of Evidence B) with a technetium-99m radiopharmaceutical to exclude myocardial ischemia

• high negative predictive value

• decreased length of stay

• reduced costs

Amsterdam E et all. AHA/ACC Guideline for the Management of Patients With Non-ST-Elevation Acute Coronary Syndromes A Report of the American College of Cardiology/American Heart

Association Task Force on Practice Guidelines. Circulation 2014

CCTA More Efficient for Triage in the ED- ROMICAT II

• MultiCtr RCT l-501 to CCTA and 499 SOC

• Decreased LOS

• ↑ D/C from ED

• ↑ downstream test. ↑revascularization

• ↓ negative ICA and ↑ CAD detection

• ↔ undetected ACS

• ↑ radiation exposure • CCTA - 11.3±5.3 mSv

• SPECT- 14.1±4.8 mSv, P<0.001

• ↔Cost

Hoffmann U, Truong QA, Schoenfeld DA, et al (ROMICAT II Investigators). Coronary CT angiography versus standard evaluation in acute chest pain. N Engl J Med 2012;367:299–308

CCTA in The Era of hs Troponin (BEACON)

• Multicenter RCT 250 CCTA and 250 SOC

• CCTA is • safe

• associated with less outpatient testing

• lower costs

• Identifies patients with Non-Obs CAD

• CCTA does not • Identify more patients with significant CAD requiring

coronary revascularization

• Shorten hospital stay

• Allow for more direct discharge from the ED

Dedic A et al. Coronary CT Angiography for Suspected ACS in the Era of High-Sensitivity Troponins: Randomized Multicenter Study. JACC 2016 Litt H et al. CT Angiography for Safe Discharge of Patients with Possible Acute Coronary Syndromes. NEJM 2012

Summary- Use of CCTA in the ED

Pros

• Lowers cost and shortens hospital stay

• High negative predictive value

• Identifies more sig CAD req revasc

• Identifies non-obs CAD

• Diagnose PE and Aortic Dissection

Cons

• Radiation exposure

• Maybe more downstream test

• Role may need to be redefined in the era of hsTn

• 24 X 7 expertise ?

• Less useful with known CAD

Stable Ischemic Heart Disease

• ACCF/ACR/AHA/NASCI/SAIP/SCAI/SCCT 2010 Expert Consensus Document on Coronary Computed Tomographic Angiography

• ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 Appropriate Use Criteria for Cardiac Computed Tomography

• 2014 ACC/AHA/AATS/PCNA/SCAI/STS Focused Update of the Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease

• 2012 ACCF/AHA/ACP/AATS/PCNA/SCAI/STS Guideline for the Diagnosis and Management of Patients With Stable Ischemic Heart Disease

• NICE Guidelines 2016

Approved (Endorsed) Indications of Cardiac CT for Non-Acute Presentation with Angina

• Low to intermediate pretest probability

• Prior revascularization – Non-acute presentation • For assessment of bypass graft and

• Left main stents > 3mm

• New onset heart failure with low to intermediate probability of CAD

• Intermediate probability CAD in patients undergoing non-coronary cardiac surgery

Anatomical Vs Functional Testing- PROMISE TRIAL

• Multicenter RCT- 10,003 patients

• Primary outcome - Death, MI, hospitalization for unstable angina, or major procedural complication

• No improvement in clinical outcomes over a median follow-up of 2 years

• CCTA - ↓ ICA showing no obstructive CAD 90 days after randomization- a prespecified secondary end point

• CCTA group had higher radiation exposure

Douglas PS, Hoffmann U, Patel MR, Mark DB, Al-Khalidi HR, Cavanaugh B, Cole J, Dolor RJ, Fordyce CB, Huang M, Khan MA, Kosinski AS, Krucoff MW, Malhotra V, Picard MH, Udelson JE, Velazquez EJ, Yow E, Cooper LS, Lee KL; PROMISE Investigators. Outcomes of anatomical versus functional testing for coronary artery disease. N Engl J Med. 2015 Apr 2;372(14):1291-300

Anatomical Vs Functional Testing- PROMISE TRIAL- A Deeper Dig…….

• Primary event rate of 3.1%

• More patients in the CCTA group underwent revascularization overall (6.2% vs. 3.2%)

• If comparison between CCTA and SPECT the median cumulative exposure was 2.5 mSv lower and the mean exposure 2.1 mSv lower in the CTA group

Douglas PS, Hoffmann U, Patel MR, Mark DB, Al-Khalidi HR, Cavanaugh B, Cole J, Dolor RJ, Fordyce CB, Huang M, Khan MA, Kosinski AS, Krucoff MW, Malhotra V, Picard MH, Udelson JE, Velazquez EJ, Yow E, Cooper LS, Lee KL; PROMISE Investigators. Outcomes of anatomical versus functional testing for coronary artery disease. N Engl J Med. 2015 Apr 2;372(14):1291-300

Certainty- The Power of CT SCOT HEART TRIAL

• RCT 1:1, 4146 patients, 12 cardiology chest pain clinics across Scotland

• SOC or SOC+ CTCA

• Clinicians were asked to diagnose both coronary heart disease, and angina due to coronary heart disease, in view of all available information at baseline and at 6 weeks after all information was available

• Clinicians were asked to categorize this according to the level of confidence in their diagnosis (yes, probable, unlikely, or no)

• Certainty of the diagnosis was assessed by comparing yes/no with probable/unlikely

SCOT-HEART investigators. CT coronary angiography in patients with suspected angina due to coronary heart disease (SCOT-HEART): an open-label, parallel-group, multicentre trial. Lancet. 2015

Certainty- The Power of CT SCOT HEART TRIAL

• 6 wks,- CTCA reclassified the diagnosis of CAD in 558 (27%) patients and the diagnosis of angina due to CAD in 481 (23%) patients

• Changed planned investigations (15% vs 1%; p<0·0001) and treatments (23% vs 5%; p<0·0001) but did not affect 6-week symptom severity or subsequent admittances to hospital for chest pain

• 1·7 years, CTCA was associated with a 38% reduction in fatal and non-fatal myocardial infarction

Post Hoc Analysis- SCOT HEART tRIAL

• CCTA was associated with a higher rate of cancellation and request for new ICA

• Compared with SOC, clinicians were more likely to recommend preventive therapies after CCTA

• Compared with standard care, the rates of fatal and nonfatal MI appeared to be reduced in patients undergoing CCTA (26 vs. 42; HR: 0.62 [95% CI: 0.38 to 1.01]; p = 0.0527

SCOT-HEART investigators. CT coronary angiography in patients with suspected angina due to coronary heart disease (SCOT-HEART): an open-label, parallel-group, multicentre trial. Lancet. 2015

Non-obstructive Coronary Artery Disease and Risk of Myocardial Infarction

• Retrospective cohort study of all

US veterans undergoing elective coronary angiography for CAD between October 2007 and September 2012

• Nonobstructive CAD, compared with no apparent CAD, was associated with a significantly greater 1-year risk of MI and all-cause mortality.

Maddox et al. Nonobstructive coronary artery disease and risk of myocardial infarction JAMA. 2014 Nov 5; 312(17): 1754–1763.

Concerns About Guidelines

• Reduction in CAD prevalence → traditional risk models overestimate disease likelihood

• Concern about the minimal use of anatomical assessment of CAD

• CTCA assessment was likely to be beneficial in those with both low and intermediate PTL

• Functional imaging for all intermediate pre test likelihood would undoubtedly lead to both false-positive and false-negative results based on sensitivity and specificity of these techniques

NICE Guidelines 2016 Stable Angina

• Removal of the pre-test probability model and the use of CTCA as the

first-line investigation in all patients with atypical or typical angina symptoms or those who are asymptomatic with suggested EKG changes for ischemia.

• cost-efficacy in a testing strategy that is most applicable to the low-

intermediate likelihood group of patients - majority of patients presenting to chest

• a test with a high negative predictive value has great merit in the assessment of patients with suspected angina due to CAD.

www.nice.org.uk

www.nice.org.uk

NICE GUIDELINES 2016

• Offer 64 slice (or above) CT coronary angiography if:

• clinical assessment indicates typical or atypical angina or

• clinical assessment indicates non-anginal chest pain but 12 lead resting ECG has been

done and indicates ST T changes or Q waves.

• For people with confirmed CAD (for example, previous MI, revascularisation, previous angiography), offer non-invasive functional testing when there is uncertainty about whether chest pain is caused by myocardial ischemia. testing. An exercise ECG may be used instead of functional imaging.

www.nice.org.uk

Estimated Cost Savings with CTCA

NICE has calculated that the use of CTCA as a first-line investigation will generate annual savings of £16 million in England alone, by prompt exclusion of significant CAD and more effectively use of NHS resources.

www.nice.org.uk

CCTA- When is it Inappropriate

• New atrial fibrillation

• Syncope

• Low probability CAD asymptomatic without family history

• High probability of CAD SIHD

• Unstable IHD high probability

ACCF/SCCT/ACR/AHA/ASE/ASNC/NASCI/SCAI/SCMR 2010 Appropriate Use Criteria for Cardiac Computed Tomography

Limitations of Cardiac CT

• Overestimates disease burden if severe calcifications

• Elevated or irregular heart rate - Difficult to get a good quality test

• 24 X 7 expertise

• Use in the acute setting in patients with stents or previous CABG has not been validated in large trials

• Contrast use in patients with renal disease

• Contrast use in patients with contrast allergy

Coronary Artery Calcium (CAC)

• Performing CAC is a IIb recommendation among individuals for whom a risk-based treatment decision is uncertain after formal risk estimation

Goff et al. 2013 ACC/AHA Guidelines on assessment of Cardiovascular Risk

CCTA in Patients with Coronary Stents

Kubo et al. JACC Cardiovasc Img 2011 Cademartiri JACC 2011

FAKE NEWS !!

CCTA for Bypass Grafts

Barbero U, et al. 64 slice-coronary computed tomography sensitivity and specificity in the evaluation of coronary artery bypass graft stenosis: A meta-analysis. Int J Cardiol2016; Ropers D, et al. Diagnostic accuracy of noninvasive coronary angiography in patients after bypass surgery using 64-slice spiral computed tomography with 330-ms gantry rotation.

Circulation 2006

For Bypass Graft Occlusion Sensitivity 99% Specificity 99% For Bypass Graft Stenosis> 50% Sensitivity 98 Specificity 98 For >50% stenosis

Why would you not order CT as initial test for investigating suspected angina?

• Its expensive – Definitely reduces cost in the acute setting and most likely reduces cost if you believe the UK’s NHS projections

• I think nuclear test is better- I am not sure. High NPV, certainty of diagnosis, more appropriate use of ICA and a greater chance of patient being started on preventive therapies

• We do not have the expertise- We certainly do

• It’s a lot of radiation – Yes, but less than a nuclear scan

• Not comfortable with new technology- Get over it!!

• Habit- Hmm…..

• Its not a functional test - Yes its not, but be sure that you need a functional test

• Don’t know what to do with the results- That’s on me. We as imagers have to learn from our interventional colleagues.

Future of Cardiac CT

• Plaque morphology (composition, calcification, remodeling)

• Imaging patients with tachycardia and atrial fibrillation

• Lowering radiation dose

• CT Imaging of stents

• Ischemia- CT FFR

• CT Perfusion

THANK YOU THANK YOU