Title: Diagnostic Accuracy of 320-Row Multidetector Computed Tomography Coronary Angiography in the Non-invasive Evaluation of Significant Coronary Artery Disease
Topic: Noninvasive Cardiology
Date Posted: 1/14/2010
Author(s): de Graaf FR, Schuijf JD, van Velzen J, et al.
Citation: Eur Heart J 2010;Jan 4:[Epub ahead of print].
Clinical Trial: No
Study Question: What is the accuracy and feasibility of detecting obstructive coronary artery disease (CAD) with 320-row computed tomographic coronary angiography (CTA)?
Methods: CTA, using a new 320-row multidetector system and standard coronary arteriography, was performed in 64 patients with known or suspected CAD. CTA was analyzed on a per-segment, per-vessel, and per-patient basis. Usual selection criteria for CTA, including avoidance of atrial fibrillation, renal failure, and more, were employed. Beta-blockers were used when necessary to maintain heart rate <65 bpm. The 320-row CTA encompasses a 16 cm field of view, allowing imaging of the entire cardiac anatomy within a single heart beat.
Results: On a per-segment basis, 12 of 839 segments were deemed nondiagnostic. By standard coronary arteriography, 71 lesions ≥50% diameter stenosis were noted, 62 of which were detected with CTA. On a per-segment basis, the sensitivity, specificity, and positive and negative predictive values for detecting ≥50% coronary stenosis were 87%, 97%, 75%, and 99%. Data were nondiagnostic in 2 of 177 vessels containing 48 stenoses. Sensitivity, specificity, and positive and negative predictive values were 94%, 92%, 83%, and 97%. Data were analyzable in 60 of 64 patients resulting in sensitivity, specificity, and positive and negative predictive values of 100%, 88%, 92%, and 100%, respectively on a per-patient basis. On a per-segment basis, sensitivity, specificity, and positive and negative predictive values for detecting stenoses ≥70% were 96%, 99%, 74%, and 99.9%.
Conclusions: The study shows that 320-row CTA allows an accurate identification of obstructive CAD when compared to standard coronary arteriography.
Perspective: The 320-row multidetector scanner described here represents the latest generation of multidetector CTA. Multiple studies using the currently and commonly utilized 64-slice scanners have demonstrated excellent accuracy for detecting and excluding obstructive CAD in proximal coronary arteries, and CTA has been proposed as both a screening and prognostic tool in patients with known or suspected coronary disease. The potential advantages of a 320-row scanner are that it is capable of encompassing the entire length of the left ventricle in one heartbeat, thus reducing the likelihood of motion artifact. It also results in a reduced radiation and contrast dosage and less of a need for prolonged breath-holding. It is still dependent on a relative bradycardia, and an unstable rhythm such as atrial fibrillation or frequent premature ventricular contractions may interfere with gating. This relatively small study suggests that its overall accuracy with respect to sensitivity, specificity, and positive and negative predictive values are equivalent to that seen with the more well-established 64-slice scanner. When combined with what may be a more rapid throughput with less radiation and the ability to scan the entire heart in a single heartbeat, it may provide significant clinical and practical advantages in the future. William F. Armstrong, M.D., F.A.C.C.
Title: The Association Between Plaque Characterization by CT Angiography and Post-Procedural Myocardial Infarction in Patients With Elective Stent Implantation
Topic: Noninvasive Cardiology
Date Posted: 1/12/2010
Author(s): Uetani T, Amano T, Kunimura A, et al.
Citation: JACC Cardiovasc Imaging 2009;3:19-28.
Clinical Trial: No
Study Question: What is the association between volumetric characterization of target lesions by multidetector computed tomography (MDCT) angiography and the risk of postprocedural myocardial injury after elective stent implantation?
Methods: A total of 189 consecutive patients were enrolled; they underwent elective stent implantation after volumetric plaque analysis with 64-slice MDCT. Each plaque component and lumen (filled with dye) was defined as follows: 1) low-attenuation plaque (LAP) (<50 HU); 2) moderate-attenuation plaque (MAP) (50-150 HU); 3) lumen (151-500 HU); and 4) high-attenuation plaque (HAP) (>500 HU). The volume of each plaque component in the target lesion was calculated using Color Code Plaque. Post-procedural creatine kinase-MB isoform and troponin-T (TnT) at 18 hours after percutaneous coronary intervention were also evaluated.
Results: The volumes of LAP (87.9 ± 94.8 mm3 vs. 47.4 ± 43.7 mm3, p < 0.01) and MAP (111.6 ± 77.5 mm3 vs. 89.8 ± 67.1 mm3, p < 0.05) were larger in patients with post-procedural myocardial injury (defined as positive TnT) than in those with negative TnT. The volumes of LAP and MAP and fraction of LAP in total plaque (LAP volume/total plaque volume) correlated with biomarkers; the MAP fraction was inversely correlated with biomarkers. The volume of LAP was an independent predictor of positive TnT after adjusting for patient background, conventional intravascular ultrasound parameters, and procedural factors.
Conclusions: The authors concluded that post-procedural myocardial injury was associated with the volume and fraction of LAP, as detected by MDCT.
Perspective: This pilot study suggests a significant correlation between LAP volume within target lesions, as measured by MDCT, and post-procedural elevation of cardiac biomarker levels. The LAP volume was found to be an independent predictor of myocardial injury after elective stenting. Plaque evaluation by MDCT may, therefore, provide useful information to identify high-risk patients who are expected to have a better outcome with aggressive medical treatment or bypass surgery. However, evaluation of coronary plaque by MDCT involves significant exposure to radiation as well as use of iodinated contrast medium. Further evaluations with larger multicenter studies are indicated to validate the findings of this study and assess potential clinical utility/benefits. Debabrata Mukherjee, M.D., F.A.C.C.