Role of Non-Invasive Coronary Computed Tomogram Angiography in Improving Risk Stratification for Patients with Coronary Artery Disease in IbnAl-Nafees Cardiac Center

Abstract

Background
From a worldwide perspective, the rate of change in the global burden of CVD is accelerating, reflecting the changes in the low- and middle-income economies, which represent 85% of the world’s population (1,3). This fact triggered a great demand for improving risk stratification for CVD (IHD on top of the list), PCI angiography being the golden standard in IHD, nevertheless, non-invasive imaging fell in trail at this target as a very attractive non-invasive alternative tool (1.2.). This has yielded the rapidly growing field of Non-Invasive Cardiac Imaging using different techniques such as CCTA and MRCA among many others(1.4). Methods:
We have retrieved previous CCTA studies, of which we have excluded evidence-lacking or ambiguous results, and chose the best results in 40 patients who had conventional PCI angiography within 4-10 days after CCTA. We traced the hospital records for these patients, according to which, 27 patients were diagnosed to have ACS (UA or NSTMI) and the remaining 13 had SA (2.1). Results: We re-evaluated 40 lesions (one lesion from each patient-the most significant and most assessable) with high image quality (obtained by Toshiba Aquilione 64-slice CT machine at Ibn Al-Nafees Cardiac Center), in 27 patients with ACS and 13 patients with SA. Culprit lesions in patients with ACS (n=14) had greater plaque area and a higher remodeling index (RI) - on cross section vessel analysis – than both stable culprit lesions in patients with ACS (n=13) and in patients with SA (n=13), showing Plaque Area (PA) as follows; (15.2 ± 2.2 mm2 VS. 7.8 ± 1.3 mm2 VS. 13.7 ± 4.8 mm2, p = 0.01; and RI (1.5 ± 0.2, 0.9 ± 0.1, 1.2 ± 0.08) p = 0.01, respectively. The prevalence of non-calcified plaque was 100%, 62%, and 77%, respectively, and the prevalence of calcified plaque was 71%, 92%, and 85%, respectively, in culprit lesions in patients with ACS and in stable lesions in patients with ACS or stable angina. Conclusion: In this study, we introduce the concept of noninvasive detection and characterization of atherosclerotic lesion and plaque characteristics (morphology and composition) in patients with CAD, so both qualitative and quantitave analysis is achieved. We demonstrate (comparing to standard IVUS methodology, i.e., cross-sectional measurements of stenosis degree, lumen and plaque area) that CCTA can noninvasively detect differences in lesion composition and morphology between culprit lesions in patients with ACS, stable lesions in patients with ACS, and stable lesions in patients with stable angina. These data suggest that noninvasive visualization of coronary atherosclerotic plaque by CCTA might improve risk stratification of patients with suspected CAD.
Coronary Computed Tomogram Angiography (CCTA) now permits nearly motion-free visualization of the coronary arteries and accurate detection of significant stenosis as compared with selective X-ray coronary angiography at low heart rates. Initial data on the detection and characterization of coronary atherosclerotic plaque indicate that CCTA can measure plaque area, remodeling index (RI), and the degree of stenosis with good correlation to intravascular ultrasound (IVUS) (5.1) and coronary angiography (5.2), respectively, in selected patients with high image quality.