Non-invasive evaluation of coronary artery bypass grafts using 16-row multi-slice computed tomography with 188 ms temporal resolution.
ABSTRACT Cardiac multi-slice computed tomography (MSCT) scanners permit visualization of the coronary arteries and coronary artery bypass grafts. The latest MSCT generation with true 16-detector slices (Sensation 16 Speed 4 D, Siemens, Forchheim, Germany) provides improved temporal and spatial resolution, as well as significantly reduced scan time. To assess, whether this technical improvement has also an impact on image quality and accuracy of MSCT diagnosis in patients with previous coronary artery bypass graft (CABG) surgery the following study was conducted.
Thirteen consecutive patients (pts) (10 male, 3 female, mean age 62 +/- 6.4 [55-73] years, heart rate 68 +/- 11 [52-88] bpm) and a total number of 43 coronary bypass grafts (11 arterial, 32 venous grafts) were examined by MSCT (gantry rotation time 375 ms). In addition to the analysis of coronary bypass grafts, 13 coronary segments (sgts) were evaluated in each patient (n = 169 sgts). MSCT results were compared with coronary angiography.
Forty-one of 43 bypass grafts (95%) were analyzable by MSCT. In conventional angiography 16 of 43 (37%) grafts were occluded. Sixteen of them were correctly diagnosed by MSCT (sensitivity 100%). One graft showed a 50% anastomosis stenosis which was also detected. Twenty-five of 27 grafts without severe lesion showed no significant stenosis in MSCT (specificity 93%, positive predictive value (PPV) 89%, negative predictive value (NPV) 100%). Ninety of 108 (83%) high-grade stenosis (>70%) of the native coronary vessels were correctly detected (sensitivity 83%, PPV 78%). From the 61 sgts without high grade stenosis 36 were correctly classified (specificity 59%, NPV 67%). If sgts number 8, 9 and 10, which are normally not target for revascularization, are excluded sensitivity rises to 89%, specificity to 71%, PPV to 87% and NPV to 75%. The correct clinical diagnosis (absence or presence of a high grade stenosis of at least one bypass graft) was achieved in all patients.
True 16-slice MSCT with faster gantry rotation time allows detection of lesions in coronary artery bypass grafts with high sensitivity and specificity. The evaluation of native vessels in pts with known CAD remains a diagnostic challenge. However, the correct clinical diagnosis was achieved in all pts. MSCT is a non-invasive tool to assess coronary artery bypass grafts.
Article: Noninvasive Follow-Up of Coronary Artery Bypass Graft Patency Using Multi-Slice Computed Tomography1[show abstract] [hide abstract]
ABSTRACT: Purpose: We wanted to evaluate the utility of multi-slice computerized tomography (MSCT) for assessing coronary artery bypass graft patency and/or occlusion. Materials and Methods: For 24 patients, both conventional angiography and CT an-giography with 4-MSCT were performed within seven days of one another in order to evaluate the accuracy of MSCT with regard to graft patency and/or occlusion. A fol-low-up CT angiogram was performed in patients with and without symptoms (n=11, n=34, respectively) with 4-or 16-MSCT. We retrospectively compared the results of MSCT to those of conventional coronary graft angiography. Results: Sixty-five grafts were evaluated for the accuracy of MSCT. Six of those 65 were occluded. The sensitivity, specificity, positive predictive value and negative pre-dictive values of MSCT for the diagnosis of graft occlusion were 100% (6/6), 98% (58/59), 86% (6/7) and 100% (58/58), respectively. Patency could not be determined by angiography in two grafts; however, the grafts proved to be patent on MSCT. On fol-low-up, new graft occlusions in the asymptomatic patients were detected by MSCT in 8.2% of the previously patent grafts at the two years post-op, and in 15.2% at the three years post-op. Conclusion: MSCT is a practical and accurate noninvasive diagnostic tool for follow-ing up coronary artery bypass grafts.
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ABSTRACT: There is a need to define the current indications for coronary CT angiography (CCTA) even as technology continuously evolves. CCTA using 64 MDCT units has shown to be highly accurate for diagnosis of sténoses ≥ 50% on selected populations. It is currently used for its negative predictive value (96-98%). Stenosis quantification remains inferior to conventional coronary angiography with tendency to overestimate stenoses <70%.For diagnosis of coronary artery disease, CCTA is considered based on clinical findings (pre-test probability of coronary artery disease) and présence of myocardial ischemia on other functional studies.The main appropriate indications include:●In the setting of acute coronary syndrome, CCTA excludes coronary artery disease with excellent NPV and good negative likelihood ratio (0.05) when ECG is non-contributory, 2 consecutive troponin levels at 6 hours are negative in a patient with low risk of coronary artery disease.●In the setting of stable angina or atypical precordial chest pain, CCTA is indicated in patients with low to moderate risk when functional tests are non-contributory or unavailable, or ECG is non-interpretable.●CCTA is a complement to coronary angiography for morphological évaluation of some lésions prior to angioplasty and stent placement (long segment occlusion, proximal lésions involving LAD and circumflex arteries).In selected patients, CCTA may replace coronary angiography prior to valvular surgery.Archives of Cardiovascular Diseases Supplements.