Presentation about coronary angiography describing the definition, indications, contraindications and patient preparation required for a CT coronary angiography.
2. Introduction
● Used to visualize blood flow throughout the body to determine if either fatty
deposits or calcium deposits have built up in the arteries
● Used to visualize the distribution and anatomy of the vasculature.
● CT coronary angiography using scanners with at least 64 slices should be
recommended as a test to rule out obstructive coronary stenoses in order to
avoid inappropriate invasive coronary angiography in patients with an
intermediate pretest probability of CHD.
Gorenoi V, Schönermark MP, Hagen A. CT coronary angiography vs. invasive coronary angiography in CHD. GMS Health
Technol Assess. 2012;8:Doc02. doi: 10.3205/hta000100. Epub 2012 Apr 16. PMID: 22536300; PMCID: PMC3334923.
3. Introduction
● For identifying or excluding of obstructive coronary stenosis, CT coronary
angiography was shown to be more cost-saving at a pretest probability of
CHD of 50% or lower, and invasive coronary angiography at a pretest
probability of CHD of 70% or higher.
● The percentages of uninterpretable CCT studies have gradually decreased
from 20%–40% with 4-slice systems to 15%–25% with 16-slice systems and
are now as low as 3%–10% with 64-slice systems
Gorenoi V, Schönermark MP, Hagen A. CT coronary angiography vs. invasive coronary angiography in CHD. GMS Health
Technol Assess. 2012;8:Doc02. doi: 10.3205/hta000100. Epub 2012 Apr 16. PMID: 22536300; PMCID: PMC3334923.
4. Indications
● To test the presence and severity of coronary artery stenosis, in patients
presenting with chest pain with intermediate pretest probability of having
obstructive CAD.
● As the initial test in patients without known CAD who present with possible
acute coronary syndrome (ACS) when highly sensitive troponin assay testing
and the clinical evaluation cannot confidently exclude ACS.
● Coronary anatomical abnormalities (eg- adult patients with suspected
congenital anomalous coronary arteries)
Gorenoi V, Schönermark MP, Hagen A. CT coronary angiography vs. invasive coronary angiography in CHD. GMS Health
Technol Assess. 2012;8:Doc02. doi: 10.3205/hta000100. Epub 2012 Apr 16. PMID: 22536300; PMCID: PMC3334923.
5. Indications
● As an alternative to stress testing or invasive coronary angiography in
selected patients
○ without previously known CAD (AND)
○ who are diagnosed with non-ST-elevation ACS (AND)
○ with clinically low-risk presentation (eg, absence of heart failure and
refractory ischemic symptoms), (OR)
○ when the cause for troponin elevation is uncertain.
● Cardiac masses or pericardial disease with technically limited images
from echocardiogram, MRI, or transesophageal echocardiography
Cademartiri F, Casolo G, Clemente A, Seitun S, Mantini C, Bossone E, Saba L, Sverzellati N, Nistri S, Punzo B, Cavaliere C,
La Grutta L, Gentile G, Maffei E. Coronary CT angiography: a guide to examination, interpretation, and clinical indications.
Expert Rev Cardiovasc Ther. 2021 May;19(5):413-425. doi: 10.1080/14779072.2021.1915132. Epub 2021 Apr 22. PMID:
33884942.
6. Indications
● As the initial test in patients without known CAD
○ who present with possible acute coronary syndrome
(ACS)
○ when highly sensitive troponin assay testing and the
clinical evaluation cannot confidently exclude ACS.
7. ● CCT is the primary tool in the assessment of suspected Coronary
Artery Disease (CAD) and should be followed by functional
assessment when needed to stratify disease and to plan potential
interventional or surgical therapy.
● Screening high risk patients
● Evaluation of chest pain
● Post procedural study (CABG, stent)
● Dilated cardiomyopathy
Indications
8. Absolute Contraindications
● Hypersensitivity to contrast agent
● Pregnancy
● Patients with ongoing chest pain who may have ACS (since
transporting them is unsafe and CT suites are generally not
equipped to deal with potentially unstable patients.)
9. Relative Contraindications
● Irregular heart rate
● Renal insufficiency
● Hyperthyroidism
● Inability to hold breath for more than 10 sec
● Allergy to medications/ food
● Metallic interference (pacemaker etc.)
10. Patient Preparation
● Avoid caffeine and smoking 12 hours prior to the procedure
● Nil per oral for 4 hours
● In patients with heart rate > 65/min, oral or IV beta blockers is
used
○ Tab metoprolol 50-100 mg administered around 1 hour before procedure
or
○ Inj metaprolol 5-20 mg IV administered at the time of the procedure
● Sublingual nitroglycerine: given immediately before the
procedure to dilate the coronary arteries
11. Patient Preparation
● Patient placed in supine position
● ECG leads attached to obtain an adequate ECG tracing
● IV access of 18 gauge at right antecubital vein (to
minimise streak artifact and allow rapid infusion of
contrast)
● Training of patient with repeated breath holds
12. Induction of Bradycardia and its Wisdom
● Coronary arteries fill up during diastole.
● The duration of systole remains constant and its the diastole that is
compromised in the event of an increase in heart rate.
● By inducing bradycardia we are ensuring that the window of
opportunity for taking an image that clearly captures the coronary
arteries is possible.
● Beta blockers and ivabradine are useful in this.
13.
14. Medications used in coronary angiography
● Beta blocker and ivabradine are used to induce sinus bradycardia
○ Metoprolol is the ß-blocker of choice in CCTA, and it has been shown to be effective in
achieving the goal heart rate of less than 65 beats per minute for CCTA and in minimizing
variability of heart rate.
○ It is contraindicated in patients with hypotension or high degree AV block, and
○ It must be used with caution in patients with asthma or obstructive pulmonary disease, patients
with decompensated heart failure, and those with vasospastic or vaso-occlusive disease.
● Diltiazem, the CCB of choice in CCTA, is a reasonable alternative for heart rate control, particularly
in patients with asthma or bronchospastic disease, and patients with orthotopic heart transplants that
have been sympathetically denervated.
Khan M, Cummings KW, Gutierrez FR, Bhalla S, Woodard PK, Saeed IM. Contraindications and side effects of commonly used
medications in coronary CT angiography. Int J Cardiovasc Imaging. 2011 Mar;27(3):441-9. doi: 10.1007/s10554-010-9654-8. Epub
2010 Jun 23. PMID: 20571874.
15. Medications used in coronary angiography
● Nitroglycerine
○ For vasodilation and good visualization of coronary arteries and stenosis
○ Sublingual nitroglycerin is especially useful in order to dilate distal arteries to
improve stenosis visibility.
○ Contraindications:
■ Severe hypotension or use of phosphodiesterase inhibitors
■ Patients on erectile dysfunction medications and those with severe anemia.
■ It must be used cautiously in patients with aortic stenosis or other preload-
dependant cardiac pathologies.
Khan M, Cummings KW, Gutierrez FR, Bhalla S, Woodard PK, Saeed IM. Contraindications and side effects of commonly used
medications in coronary CT angiography. Int J Cardiovasc Imaging. 2011 Mar;27(3):441-9. doi: 10.1007/s10554-010-9654-8. Epub
2010 Jun 23. PMID: 20571874.
16. Breath holding
● During the test, a breath hold of 15–20 s will need to be performed.
● If the patient cannot hold still and follow breathing instructions, he or she
should not be scanned.
● Breathing during the scan significantly compromises image quality and
produces segments that cannot be evaluated.
● Before the scan, practicing breath holding helps to avoid such artifacts.
17. A: CCT image obtained from patient who was
breathing during image acquisition. Note “stair-step”
artifacts, with displacement of trajectory of coronary
vessels and chest wall (arrows)
B: 3-D volume-rendered CT image reconstruction
of whole heart. Motion artifacts (arrows) are seen
in patients who experience multiple extrasystolic
beats during image acquisition
18. ECG gating protocols
● Two different approaches:
○ Prospective ECG gating
○ Retrospective ECG gating
19. Prospective ECG gating
● Scan acquisition is triggered by the ECG signal at the prospected mid-
diastolic phase of the cardiac cycle
● Between 40% and 80% of the R-R interval
● Advantage: Smaller radiation exposure
20. Retrospective ECG gating
● Heart is scanned continuously
● Contiguous data of cardiac region is acquired, while ECG is
recorded at the same time
● Scan data with the least cardiac motion, usually the diastolic phase,
is used for image reconstruction
● Advantage: Continuous and gapless acquisition of entire volume
● Disadvantage: Higher radiation exposure
21. Pitfalls and artifacts in CCTA
● Artifacts in CCTA are discrepancies between the reconstructed Hounsfield Unit
(HU) values in the image and true attenuation coefficients of the object that can
cause a clinically significant difference in diagnosis.
● Artifacts can be broadly classified as those that may be related to patient,
procedure, contrast, technique or reconstruction, although several artifacts result
from a combination of these causes.
● Elevated heart rate:
○ Higher or variable heart rates increase motion artifacts.
○ Image quality is often suboptimal in patients with irregular heart rates.
○ Scanning patients during atrial fibrillation should be avoided unless there are
relatively stable R-R intervals.
○ Similarly, strong consideration should be given to aborting a scan if frequent
ventricular ectopy is present.
Tridandapani S, Banait-Deshmane S, Aziz MU, Bhatti P, Singh SP. Coronary computed tomographic angiography: A review of
the techniques, protocols, pitfalls, and radiation dose. J Med Imaging Radiat Sci. 2021 Nov;52(3S):S1-S11. doi:
10.1016/j.jmir.2021.08.014. Epub 2021 Sep 24. PMID: 34565701.
22. ● Evaluating coronary artery stenosis in patients with extensive coronary artery
calcifications may be difficult and represents a major limiting factor.
● Reconstructions involving calcified structures tend to overestimate the volume set
representing calcium (“blooming”) because of partial-volume averaging effects,
which suggest that much of the coronary lumen is apparently occupied by
calcified plaque.
● In addition, the true lumen results in a low-density area because of beam-
hardening artifacts.
● In some situations, it can be difficult to distinguish these artifacts from noncalcified
coronary plaque.
● Because symptomatic patients with very high calcium scores have a very high
probability of having obstructive CAD, it is reasonable to avoid CCT coronary
angiography and proceed directly to invasive catheterization in these patients
Pitfalls and artifacts in CCTA
Cardiac CT: Indications and Limitations Susanna Prat-Gonzalez, Javier Sanz and Mario J. Garcia Journal of Nuclear
Medicine Technology March 2008, 36 (1) 18-24; DOI: https://doi.org/10.2967/jnmt.107.042424
