16-Detector row computed tomographic coronary angiography in patients undergoing evaluation for aortic valve replacement: comparison with catheter angiography

Aim

To evaluate the diagnostic accuracy of 16-detector row computed tomography (CT) in assessing haemodynamically significant coronary artery stenoses in patients under evaluation for aortic stenosis pre-aortic valve replacement.

Subjects and methods

Forty consecutive patients under evaluation for severe aortic stenosis and listed for cardiac catheterization before potential aortic valve replacement underwent coronary artery calcium (CAC) scoring and retrospective electrocardiogram (ECG)-gated multi-detector row computed tomographic coronary angiography (MDCTA) using a GE Lightspeed 16-detector row CT within 1 month of invasive coronary angiography (ICA) for comparative purposes. All 13 major coronary artery segments of the American Heart Association model were evaluated for the presence of ≥50% stenosis and compared to the reference standard. Data were analysed on a segment-by-segment basis and also in “whole patient” terms.

Results

A total of 412/450 segments from 35 patients were suitable for analysis. The overall accuracy of MDCTA for detection of segments with ≥50% stenosis was high, with a sensitivity of 81.3%, specificity 95.0%, positive predictive value (PPV) 57.8%, and negative predictive value (NPV) 98.4%. On a “whole-patient” basis, 100% (19/19) of patients with significant coronary disease were correctly identified and there were no false-negatives. Excluding patients with CAC >1000 from the analysis improved the accuracy of MDCTA to: sensitivity 90%, specificity 98.1%, PPV 60%, NPV 99.7%.

Conclusion

Non-invasive 16-detector row MDCTA accurately excludes significant coronary disease in patients with severe aortic stenosis undergoing evaluation before aortic valve replacement and in whom ICA can therefore be avoided. Its segment-by-segment accuracy is improved further if CAC>1000 is used as a gatekeeper to MDCTA.