Invasive versus noninvasive evaluation of coronary artery disease

We sought to compare the diagnostic information obtained from noninvasive characterization of coronary artery disease by using multidetector computed tomography (MDCT) and myocardial perfusion imaging (MPI) and to compare findings with the use of invasive coronary angiography and intravascular ultrasound (IVUS).

Preliminary comparisons have suggested that abnormal myocardial perfusion studies correlate well with significant luminal stenosis on MDCT coronary angiography. However, atherosclerotic coronary lesions may be detectable with the use of MDCT even in the presence of normal myocardial perfusion

We performed MDCT, MPI, and conventional coronary angiography in 70 patients. In addition, IVUS was performed in 53 patients. Quantitative information was obtained from quantitative coronary angiography (QCA) and IVUS assessment of plaque burden and minimal luminal area.

Of 26 patients with an abnormal MPI study, 23 (88%) showed significant stenosis on MDCT. As compared with QCA, MDCT showed a sensitivity of 96% and specificity of 67% for the detection of stenoses > or =50% diameter narrowing in these patients. Mean diameter stenosis on QCA was 76% and mean minimal lumen area in IVUS was 3.3 mm(2). On the other hand, 27 (84%) of 44 patients with normal MPI had evidence of coronary atherosclerosis on MDCT (luminal stenosis > or =50%: n = 15, luminal stenosis <50%: n = 12, sensitivity of 100% and specificity of 83% as compared with QCA). Using IVUS, we found substantial plaque burden (mean 58.9 +/- 18.1% of cross-sectional area), but presence of a stenosis (minimal lumen area <4.0 mm(2)) in only 14 patients (mean minimal lumen area, 5.8 +/- 3.3 mm(2)). Only 7 patients with normal myocardial perfusion scans demonstrated absence of coronary atherosclerosis by MDCT.

Considerable plaque burden can be observed with MDCT even in the absence of myocardial perfusion abnormalities. This finding does not constitute a false-positive MDCT result, but rather reflects the fact that MDCT can detect atherosclerotic lesions that are not flow-limiting.