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Three Part Question

In [patients who require exclusion of coronary artery disease] is [CT coronary angiography] comparable to [percutanous coronary angiography] for detecting/excluding clinically significant stenoses?

Clinical Scenario

You are seeing a 65 year old patient who has been referred for aortic valve replacement due to aortic stenosis. He has no symptoms of angina but smoked for 25 years, finally quitting 10 years ago. His father also died of a heart attack when he was 60 years old. You tell him that you would like to get an angiogram to check his coronary arteries. He is not that keen on the idea and asks if there are any other scans that could do the same thing without the risks of angiography. You wonder whether a CT angiogram would be as sensitive a test for this patient

Search Strategy

Medline 2000-Oct 2006 using the OVID interface.
[exp Tomography, X-Ray Computed/ OR exp Tomography, Spiral Computed/ OR computed tomography.mp] AND [ 64-slice.mp OR multislice.mp OR spiral.mp OR CVCT.mp or MSCT.mp or multidetector.mp] AND [coronary artery.mp or exp coronary vessels/] AND [exp coronary angiography/ OR angiography.mp OR exp angiography/] LIMIT to Human

Search Outcome

595 papers were found in MEDLINE. 11 were deemed to be relevant. We included 2 systematic reviews and a guideline that considered papers of all generations of CT scanners and also documented all papers describing the results of 64 slice multidetector CT scanners.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Budoff et al, 2006, USA	A review and guideline from the AHA, documenting all studies up to 2006 using Electron Beam CT, and 4-64 CLi	Systematic Review (level 1a)	Recommendation	The high negative predictive value may be useful for obviating the need for invasive coronary angiography in patients whose symptoms or abnormal stress test results make it necessary to rule out the presence of coronary artery stenoses. Especially if symptoms, age, and gender suggest a low to intermediate probability of hemodynamically relevant stenoses. CT coronary angiography is reasonable for the assessment of obstructive disease in symptomatic patients (Class IIa, Level of Evidence: B).
			Radiation	Angiogram – 2.1 – 3.3 mSv MDCT up to 18mSv , generally around 8-11mSv
Schuijf et al, 2006, Holland	Search of Medline Jan 1990 to Jan 2005, and journal hand-search, of studies documenting diagnostic accuracy of Multislice CT and MRI angiography.	Systematic Review and Meta-analysis ( level 1a)	Segment based Accuracy of CT scanning	4-Slice CT Sensitivity 80% (495/619) Specificity 94% (3482/3722) 8-Slice CT Sensitivity 80% Specificity 98% 16-Slice CT Sensitivity 88% (829/941) Specificity 96% (5179/5376)	No documentation of the 64 slice CT data.
			Accuracy of MRI	28 studies MRI versus angiography Sensitivity 72% Specificity 87% Assessable segments 83%
Stein et al, 2006, USA	A search of Pubmed from 1950 to March 2005 for studies comparing Multidetector CT with angiography.	Systematic review (level 1a)	Patient Based Accuracy of CT scanning	4-Slice CT Sensitivity 95% (61/64). Specificity 84% (21/25) 16-Slice CT Sensitivity 95% (276/292) Specificity 84% (131/156)	Only 1 64 Slice CT scanner paper found [Leschka]
			Evaluable segments	4-slice CT 78% 16-Slice CT 91% 64-Slice CT 100%
Leschka et al, 2005, Switzerland	67 patients (mean age 60.1 ± 10.5 years) awaiting CABG had PTCA followed by MDCT coronary angiography using a 64 slice CT scanner with a 0.6mm resolution. Images independently evaluated in blinded fashion B-blockers not used	Diagnostic Cohort Study (Level 2b)	Accuracy of CT scanning	sensitivity 94%, specificity 97%, PPV 87% NPV 99%	The median time between CTCA and PTCA was 13 days (range 1-55days) The patient population had a high pre-test probability for having significant stenosis and this may have resulted in an overestimation of the ability of CTCA to detect and rule out stenoses. If B-blockers had been used to reduce the heart rate maybe the errors on CTCA due to motion artefacts would have been reduced.
			Unable to assess by CT	11/176 (6.25%) stenosis were missed due to motion artefact or severe calcification.
Ropers et al, 2006, Germany	84 consecutive patients with suspected CAD had ICA and then subsequent CTCA (within 1-3 days) using a 64 slice CT scanner with 0.6mm resolution Blinded interpretation of results	Diagnostic Cohort Study (level 2b)	CT ability to diagnose significant stenoses	Sensitivity 95%, Specificity 93% NPV 100%	Only one blinded observer assessed the CTCA data. The incidence of significant coronary artery disease in the study population was relatively low at 31%
			Unable to assess by CT	Of the 1128 coronary segments included in the analysis, 45 (4%) were unevaluable on CTCA due to the presence of severe calcium or due to motion artefact
Raff et al, 2005, USA	70 consecutive patients undergoing 64-slice 0.4mm resolution 330ms rotation scanning, compared to angiography. Stenoses over 50% sought. Patients received Beta-blockers to keep pulse <60bpm	Diagnostic Cohort Study (level 2b)	Accuracy of CT scanning by segment.	Sensitivity 86% (79/92) Specificity 95% (802/843) PPV 66% (79/120) NPV 98% (802/815)	14 patients were excluded due to atrial fibrillation, extrasystoles or sinus node dysfunction) Accuracy significantly declined if patient had a heart rate over 70bpm 54% of patients had true disease. High NPV makes MDCT suitable for elimination of coronary arterial disease
			Radiation dose	13mSv men 18mSv women
			Evaluable segments	88% (935/1065)
Leber et al, 2005, Germany	59 patients who were undergoing angiography for stable angina. 64-Slice CT the day after . 9 second acquisition, 0.6mm collimation, 330ms per rotation Beta-blockers given (50mg of metoprolol) IVUS correlation also performed in a subset	Diagnostic Cohort study (level 2b)	Accuracy of CT scanning to detect >50% stenosis by segment	Sensitivity 73% (29/40) Specificity 97% (638/657)	10 patients had previous stenting. Poor ability of the CT scanner to quantify the degree of stenosis. 4 patients had poor quality CT scans due to motion artefact.
			Radiation dose	10-14mSv
Mollet et al, 2005, Holland	52 patients with atypical chest pain, stable or unstable angina or NSTEMI scheduled for diagnostic conventional coronary angiography. 64-Slice CT scan, 0.6mm slices, 8 second acquisition. 330ms rotation	Diagnostic Cohort study (level 2b)	Accuracy of CT scanning per segment	Sensitivity 99% (93/94) Specificity 95% (601/631) PPV 76% 93/123) NPV 99% (601/602)	1 CT scan failed due to ventricular bigeminy
			Radiation dose	15.4mSv to 21.4mSv
Fine et al, 2006, USA	66 sequential patients who underwent angiography and 64 slice CT scanning. 0.2mm slices Metoprolol given to reduce heart rate.	Diagnostic Cohort study (level 2b)	Accuracy of CT scanning per patient	Sensitivity 100% Specificity 80% PPV 55% NPV 100%	8 patients were excluded due to irregular heart rate (n=4), contraindication to contract, (n=1) or renal insufficiency, (n=4). Prevalence of coronary arterial disease was 20%.
			Angiograms potentially avoided	35 patients would not have needed an angiogram after exclusion of disease by CT
			Radiation	4-12mSv
Ong et al, 2006, Malaysia	134 symptomatic patients undergoing angiography, underwent 64 slice MDCT within 3 months.		Accuracy of CT scanning by segment ( Low calcium group)	Sensitivity 85% Specificity 98% PPV 76.7% NPV 99.2%	Sensitivity limited by presence of calcium in the coronary arteries.
			Accuracy of CT scanning by segment ( High calcium group)	Sensitivity 80% Specificity 93% PPV 79% NPV 94%
			Evaluable segments	97.3%
Plass et al, 2006, Switzerland	54 patients undergoing an angiogram and a 64-Slice CT scan with a 370ms rotation, Evaluation of the CT scans by 2 cardiovascular surgeons. Beta blockers used and people with pulse >80 cancelled and scan rebooked. 12 second breath hold for full acquisition		Accuracy of CT scanning by segment in low calcium group	Sensitivity 93% (106/114) Specificity 97% (381/392) PPV 91% (106/117) NPV 98% (381/389)
			Agreement between surgeons	Kappa of 0.93 indicating very good agreement.
			Evaluable segments	92% (506 of 550)

Comment(s)

The American Heart Association have published guidelines in this area in 2006. They documented studies up to 2006 and conclude that 64 slice multi-detector CT (MDCT) has a very high negative predictive value, thereby being able to rule out coronary artery disease in lower risk patients. They state that an MDCT to rule out coronary disease is a reasonable strategy compared to angiography (Class IIa, Level of Evidence B). 2 meta-analyses have been performed. Schuijf et al summarized 24 studies with 1300 patients using 4 to 16 slice CT scanners compared to coronary angiography. They reported an overall per-segment sensitivity of 85%(1396/1650) and specificity of 95%(9064/9511) with an 87% rate of assessable coronary segments. The second meta-analysis was by Stein et al[4], and they documented the per-patient sensitivity of 95% for 4-16 slice CT and specificity of 84% for 4-16 slice CT. They also documented that the number of evaluable segments increased from 78% for 4-slice scanners to 100% for the 64-slice study that they found. Both meta-analyses endorsed multislice CT scanning for exclusion of coronary disease in low risk patients. We identified 8 studies documenting the effectiveness of 64 Slice MDCT angiography [Leschka, Ropers, Raff, Leber, Mollet, Fine, Ong, Plass]. These studies show a sensitivity of around 95% (range 73%-100%) and a specificity of around 97% (range 93% to 100%) with a negative predictive value of 92%-100%. 88%-97% of segments were evaluable and the radiation dose was around 10-15mSv compared to a conventional angiography dose of around 2mSv. Interestingly Plass et al studied 134 patients undergoing 64-slice MDCT and an angiogram, but asked 2 cardiac surgeons to report the scans. They obtained very good agreement between them and also an excellent sensitivity of 93% and specificity of 97% compared to routine angiography. 92% of segments were evaluable, with vessels less than 1.5mm being excluded from analysis. Gilard et al performed a study specifically on 55 patients undergoing assessment prior to surgery for aortic stenosis. They used a 16 slice CT scanner, but successfully excluded coronary arterial disease in 35 patients with a negative predictive value of 100%. The weakness of the CT scan was again for patients with coronary arterial disease with calcium deposits, where quantification of stenotic lesions was difficult. 64 Slice MDCT has an excellent negative predictive ability, and thus can accurately exclude the presence of coronary arterial disease. However the presence of high levels of calcium reduce the sensitivity of the scan, as it remains difficult to assess the luminal narrowing in the presence of calcium. The number of segments that cannot be excluded are now markedly reduced, mainly only being vessels under 1.5mm in diameter. The radiation dose is around 5 times that of an angiogram. A significant limitation is the inability to perform a scan on any patient who is not in sinus rhythm with a slow rate.

Clinical Bottom Line

Angiography with 64-slice multi-detector CT scanner may provide reliable non-invasive imaging to exclude significant coronary artery stenoses prior to valve surgery. The negative predictive value of a normal CT scan is around 97% thus providing a good alternative to conventional angiography in lower atherosclerotic risk patients. The ability of CT angiography to assess the reduction in luminal diameter is reduced in the presence of calcium deposits, and is also reduced in vessels under 1.5mm. Further disadvantages include an inability to perform scans in patients with arrhythmias or atrial fibrillation, and a 5 times increased radiation dose compared to conventional angiography.

References

1. Budoff MJ, Achenbach S, Blumenthal RS, Carr JJ, Goldin JG, Greenland P, Guerci AD, Lima JAC, Rader DJ, Rubin GD, Shaw LJ, Wiegers SE. Assessment of Coronary Artery Disease by Cardiac Computed Tomography: A Scientific Statement From the American Association Committee on Cardiovascular Imaging and Intervention, Council on Cardiovascular Radiology and Intervention, and Committee on Cardiac Imaging, Council on Clinical Cardiology. Circulation 2006;114:1761-91.
2. Schuijf JD, Bax JJ, Shaw LJ, de RA, Lamb HJ, van der Wall EE, Wijns W. Meta-analysis of comparative diagnostic performance of magnetic resonance imaging and multislice computed tomography for noninvasive coronary angiography. Am Heart J 2006;151(2):404-11.
3. Stein PD, Beemath A, Kayali F, Skaf E, Sanchez J, Olson RE, Stein PD, Beemath A, Kayali F, Skaf E, Sanchez J, Olson RE. Multidetector computed tomography for the diagnosis of coronary artery disease: a systematic review. Am J Med 2006;119(3):203-16.
4. Leschka S, Alkadhi H, Plass A et al. Accuracy of MSCT coronary angiography with 64-slice technology: first experience. Eur Heart J 2005;26(15):1482-7.
5. Ropers D, Rixe J, Anders K et al. Usefulness of multidetector row spiral computed tomography with 64- x 0.6-mm collimation and 330-ms rotation for the noninvasive detection of significant coronary artery stenoses. Am J Cardiol 2006;97(3):343-8.
6. Raff GL, Gallagher MJ, O'Neill WW, Goldstein JA, Raff GL, Gallagher MJ, O'Neill WW, Goldstein JA. Diagnostic accuracy of noninvasive coronary angiography using 64-slice spiral computed tomography. J Am Coll Cardiol 2005;46(3):552-7.
7. Leber AW, Knez A, von ZF, Becker A, Nikolaou K, Paul S, Wintersperger B, Reiser M, Becker CR, Steinbeck G, Boekstegers P. Quantification of obstructive and nonobstructive coronary lesions by 64-slice computed tomography: a comparative study with quantitative coronary angiography and intravascular ultrasound. J Am Coll Cardiol 2005;46(1):147-54.
8. Mollet NR, Cademartiri F, van Mieghem CA, Runza G, McFadden EP, Baks T, Serruys PW, Krestin GP, de Feyter PJ. High-resolution spiral computed tomography coronary angiography in patients referred for diagnostic conventional coronary angiography. Circulation 2005;112(15):2318-23.
9. Fine JJ, Hopkins CB, Ruff N, Newton FC, Fine JJ, Hopkins CB, Ruff N, Newton FC. Comparison of accuracy of 64-slice cardiovascular computed tomography with coronary angiography in patients with suspected coronary artery disease. Am J Cardiol 2006;97(2):173-4.
10. Ong TK, Chin SP, Liew CK, Chan WL, Seyfarth MT, Liew HB, Rapaee A, Fong YY, Ang CK, Sim KH. Accuracy of 64-row multidetector computed tomography in detecting coronary artery disease in 134 symptomatic patients: influence of calcification. Am Heart J 2006;151(6):1323-6.
11. Plass A, Grunenfelder J, Leschka S, Alkadhi H, Eberli FR, Wildermuth S, Zund G, Genoni M. Coronary artery imaging with 64-slice computed tomography from cardiac surgical perspective. Eur J Cardiothorac Surg 2006;30(1):109-16.
12. Gilard M, Cornily JC, Pennec PY, Joret C, Le GG, Mansourati J, Blanc JJ, Boschat J. Accuracy of multislice computed tomography in the preoperative assessment of coronary disease in patients with aortic valve stenosis.[see comment]. J Am Coll Cardiol 2006;47(10):2020-4.