A low-dose comprehensive cardiac CT protocol assessing anatomy, function, perfusion, and viability

AbstractRadiation exposure in cardiac imaging is a major healthcare concern and low-dose cardiac imaging has important implications for patients. We describe the application of a low-dose comprehensive cardiac computed tomography protocol that assesses anatomy, function, perfusion and viability with correlations to invasive coronary angiography and magnetic resonance imaging

Delayed recovery of coronary resistive vessel function after coronary angioplasty

AbstractObjectives. The aim of this study was to use Doppler catheterization and sequential dynamic positron emission tomography (PET) to investigate the role and time course of abnormal coronary resistive vessel function in the impairment of the coronary vasodilator response (maximal/basal coronary blood flow) after successful coronary angioplasty.Background. The coronary vasodilator response may be impaired immediately after coronary angioplasty, despite successful dilation of a flow-limiting stenosis.Methods. Twelve men (mean age 52 ± 10 years) with singlevessel coronary artery disease and normal left ventricular function were studied. The coronary vasodilator response to intravenous dipyridamole (0.5 mg·kg−1over 4 min) was determined from intracoronary Doppler measurement of coronary How velocity, before and after successful angioplasty. Basal and maximal myocardial blood flow in the angioplasty region and a normal region were determined in nine patients with positron emission tomography with H215O at 1 day (PET1), 7 days (PET2) and 3 months (PET3) after angioplasty.Results. The coronary vasodilator response, measured by Doppler catheterization, was similar before and immediately after angioplasty, 1.63 ± 0.41 and 1.62 ± 0.55, respectively (p = NS). After angioplasty, in seven of nine patients without restenosis, basal myocardial blood flow at PET1, PET2and PET3was 0.98 ± 0.16, 0.94 ± 0.09 and 0.99 ± 0.13 ml·min−1·g−1, respectively, in the remote region and 1.19 ± 0.23 (p < 0.01 vs. remote region), 1.17 ± 0.19 (p < 0.01 vs. remote region) and 1.10 ± 0.08 ml·min-1·g−1(p = NS vs. remote region), respectively, in the angioplasty region. Myocardial blood flow after dipyridamole at PET1, PET2and PET3was 3.04 ± 0.68, 3.00 ± 0.71 and 3.00 ± 0.60 ml·ml·min−1g−1, respectively, in the remote region and 2.11 ± 0.80 (p < 0.01 vs. remote region), 2.28 ± 0.73 (p = NS vs. remote region) and 3.06 ± 0.86 ml · min−1· g−1(p = NS vs. remote region), respectively, in the angioplasty region. The coronary vasodilator response at PET1, PET2and PET3was 3.15 ± 0.85, 3.18 ± 0.68 and 3.08 ± 0.75, respectively, in the remote region and 1.80 ± 0.68 (p < 0.01 vs. remote region), 1.94 ± 0.49 (p < 0.01 vs. remote region) and 2.77 ± 0.74 (p = NS vs. remote region), respectively, in the angioplasty region.Conclusions. After successful angioplasty, basal myocardial blood flow is increased for ≥7 days in the angioplasty region, with a reduction in the dipyridamole · induced increase in maximal myocardial blood flow for ≥24 h after the procedure. Thus, the coronary vasodilator response is impaired for ≥7 days after angioplasty, indicating that there is abnormal resistive vessel function in the coronary vascular bed distal to a coronary artery stenosis that persists for 7 days to 3 months

Optical coherence tomography versus intravascular ultrasound to evaluate stent implantation in patients with calcific coronary artery disease

AIMS: Stent underexpansion and malapposition are associated with adverse outcomes following percutaneous coronary intervention, but detection and treatment can be challenging in the presence of extensive coronary artery calcification. Frequency domain optical coherence tomography (FD-OCT) is a novel intravascular imaging technique with greater spatial resolution than intravascular ultrasound (IVUS) but its role in the presence of extensive coronary calcification remains unclear. We sought to determine the utility of FD-OCT compared to IVUS imaging to guide percutaneous coronary intervention in patients with severe calcific coronary artery disease. METHODS: 18 matched IVUS and FD-OCT examinations were evaluated following coronary stent implantation in 12 patients (10 male; mean age 70±7 years) undergoing rotational atherectomy for symptomatic calcific coronary artery disease. RESULTS: In-stent luminal areas were smaller (minimum in-stent area 6.77±2.18 vs 7.19±2.62 mm(2), p<0.05), while reference lumen dimensions were similar with FD-OCT compared with IVUS. Stent malapposition was detected in all patients by FD-OCT and in 10 patients by IVUS. The extent of stent malapposition detected was greater (20% vs 6%, p<0.001) with FD-OCT compared to IVUS. Postdilation increased the in-stent luminal area (minimum in-stent area: 8.15±1.90 vs 7.30±1.62 mm(2), p<0.05) and reduced the extent of stent malapposition (19% vs 34%, p<0.005) when assessed by FD-OCT, but not IVUS. CONCLUSIONS: Acute stent malapposition occurs frequently in patients with calcific coronary disease undergoing rotational atherectomy and stent implantation. In the presence of extensive coronary artery calcification, FD-OCT affords enhanced stent visualisation and detection of malapposition, facilitating improved postdilation stent apposition and minimal luminal areas. TRIAL REGISTRATION NUMBER: NCT02065102

Observer variability in the assessment of CT coronary angiography and coronary artery calcium score:substudy of the Scottish COmputed Tomography of the HEART (SCOT-HEART) trial

Introduction Observer variability can influence the assessment of CT coronary angiography (CTCA) and the subsequent diagnosis of angina pectoris due to coronary heart disease. Methods We assessed 210 CTCAs from the Scottish COmputed Tomography of the HEART (SCOT-HEART) trial for intraobserver and interobserver variability. Calcium score, coronary angiography and image quality were evaluated. Coronary artery disease was defined as none (70%) luminal stenosis and classified as no (70%) coronary artery disease. Post-CTCA diagnosis of angina pectoris due to coronary heart disease was classified as yes, probable, unlikely or no. Results Patients had a mean body mass index of 29 (28, 30) kg/m2, heart rate of 58 (57, 60)/min and 62% were men. Intraobserver and interobserver agreements for the presence or absence of coronary artery disease were excellent (95% agreement, κ 0.884 (0.817 to 0.951) and good (91%, 0.791 (0.703 to 0.879)). Intraobserver and interobserver agreement for the presence or absence of angina pectoris due to coronary heart disease were excellent (93%, 0.842 (0.918 to 0.755) and good (86%, 0.701 (0.799 to 0.603)), respectively. Observer variability of calcium score was excellent for calcium scores below 1000. More segments were categorised as uninterpretable with 64-multidetector compared to 320-multidetector CTCA (10.1% vs 2.6%, p<0.001) but there was no difference in observer variability. Conclusions Multicentre multidetector CTCA has excellent agreement in patients under investigation for suspected angina due to coronary heart disease. Trial registration number NCT01149590

Non-invasive assessment of coronary artery bypass graft patency using 16-slice computed tomography angiography

<p>Abstract</p> <p>Background</p> <p>Invasive coronary angiography is the gold standard means of imaging bypass vessels and carries a small but potentially serious risk of local vascular complications, including myocardial infarction, stroke and death. We evaluated computed tomography as a non-invasive means of assessing graft patency.</p> <p>Methods</p> <p>Fifty patients with previous coronary artery bypass surgery who were listed for diagnostic coronary angiography underwent contrast enhanced computed tomography angiography using a 16-slice computed tomography scanner. Images were retrospectively gated to the electrocardiogram and two dimensional axial, multiplanar and three dimensional reconstructions acquired. Sensitivity, specificity, positive and negative predictive value, accuracy and level of agreement for detection of graft patency by multidetector computed tomography.</p> <p>Results</p> <p>A total of 116 grafts were suitable for analysis. The specificity of CT for the detection of graft patency was 100%, with a sensitivity of 92.8%, positive predictive value 100%, negative predictive value 85.8% and an accuracy of 94.8%. The kappa value of agreement between the two means of measuring graft patency was 0.9. Mean radiation dose was 9.0 ± 7.2 mSv for coronary angiography and 18.5 ± 4 mSv for computed tomography. Pooled analysis of eight studies, incorporating 932 grafts, confirmed a 97% accuracy for the detection of graft patency by multidetector computed tomography.</p> <p>Conclusion</p> <p>Computed tomography is an accurate, rapid and non-invasive method of assessing coronary artery bypass graft patency. However, this was achieved at the expense of an increase in radiation dose.</p

Systemic Atherosclerotic Inflammation Following Acute Myocardial Infarction:Myocardial Infarction Begets Myocardial Infarction

BACKGROUND: Preclinical data suggest that an acute inflammatory response following myocardial infarction (MI) accelerates systemic atherosclerosis. Using combined positron emission and computed tomography, we investigated whether this phenomenon occurs in humans. METHODS AND RESULTS: Overall, 40 patients with MI and 40 with stable angina underwent thoracic 18F-fluorodeoxyglucose combined positron emission and computed tomography scan. Radiotracer uptake was measured in aortic atheroma and nonvascular tissue (paraspinal muscle). In 1003 patients enrolled in the Global Registry of Acute Coronary Events, we assessed whether infarct size predicted early (≤30 days) and late (>30 days) recurrent coronary events. Compared with patients with stable angina, patients with MI had higher aortic 18F-fluorodeoxyglucose uptake (tissue-to-background ratio 2.15±0.30 versus 1.84±0.18, P<0.0001) and plasma C-reactive protein concentrations (6.50 [2.00 to 12.75] versus 2.00 [0.50 to 4.00] mg/dL, P=0.0005) despite having similar aortic (P=0.12) and less coronary (P=0.006) atherosclerotic burden and similar paraspinal muscular 18F-fluorodeoxyglucose uptake (P=0.52). Patients with ST-segment elevation MI had larger infarcts (peak plasma troponin 32 300 [10 200 to >50 000] versus 3800 [1000 to 9200] ng/L, P<0.0001) and greater aortic 18F-fluorodeoxyglucose uptake (2.24±0.32 versus 2.02±0.21, P=0.03) than those with non–ST-segment elevation MI. Peak plasma troponin concentrations correlated with aortic 18F-fluorodeoxyglucose uptake (r=0.43, P=0.01) and, on multivariate analysis, independently predicted early (tertile 3 versus tertile 1: relative risk 4.40 [95% CI 1.90 to 10.19], P=0.001), but not late, recurrent MI. CONCLUSIONS: The presence and extent of MI is associated with increased aortic atherosclerotic inflammation and early recurrent MI. This finding supports the hypothesis that acute MI exacerbates systemic atherosclerotic inflammation and remote plaque destabilization: MI begets MI. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01749254