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Three Part Question

In [patients with suspected coronary artery disease] is [64-slice CT] accurate enough to [rule out clinically significant disease]?

Clinical Scenario

A 60 year old male presents to the emergency department with substernal chest pain. He is a smoker, has hypertension and has never been diagnosed with coronary artery disease. EKG does not show an acute myocardial infarction and initial cardiac enzymes are negative. Aspirin and sublingual nitroglycerin have relieved his pain.

Search Strategy

Medline 1996 – April 4, 2006 using the OVID interface, Cochrane Library Clinical Queries
[(exp Coronary Angiography/ or Coronary Angiography.mp) AND (exp Tomography, X-Ray Computed OR exp Tomography, Spiral Computed) AND (64-slice.mp)]. LIMIT to human AND English.

Search Outcome

12 papers found, of which 5 were relevant.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Leber, A. et al. 2005 Germany	59 patients scheduled for coronary angiography due to stable angina.	Prospective, blinded. Level 2b	Detection of stenosis < 50%, > 50%, and > 75%. All vessels included regardless of size.	Sensitivity 94% (17/18) for detecting patients with lesions requiring angioplasty or bypass.	4 patients dropped from analysis due to poor image quality. High incidence of disease in study population.
Leschka, S. et al. 2005 Switzerland	67 consecutive patients referred for suspected CAD or prior to bypass surgery.	Prospective, Blinded. Level 2b	Vessels > 1.5mm evaluated and compared with conventional angiography.	Sensitivity 94%, Specificity 97%, PPV 87%, NPV 99%.	High incidence of disease in study population. 64% of patients were referred to study prior to bypass surgery.
Raff, G. et al. 2005 USA	70 consecutive patients with suspected CAD scheduled for invasive angiography.	Prospective, blinded. Level 2b	All vessels analyzed including < 1.5mm diameter, and compared to conventional angiography. Significant stenosis defined as > 50%.	For detection of significant stenosis, per-patient Sensitivity 95%, Specificity 90%, Positive Predictive Value and Negative Predictive Value both 93%. Sub-group analysis shows decreased sensitivity for heart rate > 70 and body mass index > 30.	Excluded patients suspected of acute coronary syndromes High incidence of disease in study population
Mollet, N. et. al. 2005 Netherlands	52 patients enrolled after exclusion criteria. Patients included with atypical chest pain, stable or unstable angina or Non-ST-segment elevation myocardial infarction.	Prospective, blinded. Level 2b	All vessels included regardless of size. Significant stenosis defined as > 50%.	For detection of significant stenosis, Sensitivity 99% (94-99), Specificity 95%(93-96), PPV 76% (67-89), NPV 99% (99-100).	High prevalence of disease in study population.
Fine, J. et. al. 2006 USA	66 sequential patients referred for conventional coronary angiography by their doctor.	Prospective, blinded, level 2b	Vessels > 1.5mm evaluated and compared with conventional angiography.	For detection of significant stenosis, Sensitivity 95%, Specificity 96%, PPV 97%, NPV 92%.	Patient inclusion and exclusion criteria not clearly defined. 4 subjects had poor quality scans which precluded diagnosis and it is unclear whether or not these patients were excluded from the final sensitivity and specificity calculations.

Comment(s)

All five studies found similar results and they have similar study design and patient population. The importance of CT coronary angiography for emergency department uses is to rule out clinically significant CAD. Leber and Mollet report a patient based analysis for the detection of clinically significant stenosis of 94% and 100%, respectively. Taken together this would be 55 of 56 patients for an excellent total sensitivity of 98%. Leschka also reports a patient based sensitivity of 100%, but does not give the total number of patients in the calculation, making further meta-analysis impossible. It is also clear from these studies that fast (>70 bpm) or irregular heart rates, stents, calcified arteries, and a body mass index > 30 impair accuracy. Furthermore, these studies were all done in a population of patients with a high prevalence of disease, which does not necessarily reflect an ED population.

Clinical Bottom Line

64-slice CT coronary angiography shows promise regarding the ability to rule out clinically significant coronary artery disease. A large, multi-center study is needed to prove its accuracy in an emergency department setting with a carefully defined patient population geared to increase sensitivity before it can be used in clinical practice.

References

1. Leber AW et. al. Quantification of obstructive and nonobstructive coronary lesions by 64-slice computed tomography: a comparative study with quantitative coronary angiography and intravascular ultrasound. Journal of the American College of Cardiology. 46(1):147-54, 2005 Jul 5
2. Leschka, S. et al. Accuracy of MSCT coronary angiography with 64-slice technology: first experience. European Heart Journal 26(15):1482-7, 2005 Aug.
3. Raff, G. et al. Diagnostic accuracy of noninvasive coronary angiography using 64-slice spiral computed tomography. Journal of the American College of Cardiology 46(3):552-7, 2005 Aug 2.
4. Mollet, N. et. al. High-resolution spiral computed tomography coronary angiography in patients referred for diagnostic conventional coronary angiography. Circulation 112(15):2318-23, 2005 Oct 11.
5. Fine, J. et. al. Comparison of accuracy of 64-slice cardiovascular computed tomography with coronary angiography in patients with suspected coronary artery disease. American Journal of Cardiology 97(2):173-4, 2006 Jan 15.