Jan Vontobel

Multicentre multi-device hybrid imaging study of coronary artery disease: results from the EValuation of INtegrated Cardiac Imaging for the Detection and Characterization of Ischaemic Heart Disease (EVINCI) hybrid imaging population

AIMS Hybrid imaging provides a non-invasive assessment of coronary anatomy and myocardial perfusion. We sought to evaluate the added clinical value of hybrid imaging in a multi-centre multi-vendor setting. METHODS AND RESULTS Fourteen centres enrolled 252 patients with stable angina and intermediate (20-90%) pre-test likelihood of coronary artery disease (CAD) who underwent myocardial perfusion scintigraphy (MPS), CT coronary angiography (CTCA), and quantitative coronary angiography (QCA) with fractional flow reserve (FFR). Hybrid MPS/CTCA images were obtained by 3D image fusion. Blinded core-lab analyses were performed for CTCA, MPS, QCA and hybrid datasets. Hemodynamically significant CAD was ruled-in non-invasively in the presence of a matched finding (myocardial perfusion defect co-localized with stenosed coronary artery) and ruled-out with normal findings (both CTCA and MPS normal). Overall prevalence of significant CAD on QCA (>70% stenosis or 30-70% with FFR≤0.80) was 37%. Of 1004 pathological myocardial segments on MPS, 246 (25%) were reclassified from their standard coronary distribution to another territory by hybrid imaging. In this respect, in 45/252 (18%) patients, hybrid imaging reassigned an entire perfusion defect to another coronary territory, changing the final diagnosis in 42% of the cases. Hybrid imaging allowed non-invasive CAD rule-out in 41%, and rule-in in 24% of patients, with a negative and positive predictive value of 88% and 87%, respectively. CONCLUSION In patients at intermediate risk of CAD, hybrid imaging allows non-invasive co-localization of myocardial perfusion defects and subtending coronary arteries, impacting clinical decision-making in almost one every five subjects.

Minimized Radiation and Contrast Agent Exposure for Coronary Computed Tomography Angiography: First Clinical Experience on a Latest Generation 256-slice Scanner

RATIONALE AND OBJECTIVES The aim of the study was to evaluate the impact of the latest coronary computed tomography angiography (CCTA) techniques allowing a radiation- and contrast-sparing protocol on image quality in unselected patients referred for exclusion of suspected coronary artery disease (CAD). MATERIALS AND METHODS This prospective study was approved by the local ethics committee, and all patients provided written informed consent. Between March and June 2015, 89 consecutive patients (61% male; mean age 55 ± 11 years) referred for exclusion of CAD by 256-slice CCTA using prospective electrocardiogram triggering were included. Tube voltage (80-120 kVp), tube current (180-310 mA) as well contrast agent volume (25-45 mL) and flow rate (3.5-5 mL/s) were adapted to body mass index. Signal intensity was measured by placing a region of interest in the aortic root, the left main artery, and the proximal right coronary artery. Image noise was measured in the aortic root. Two independent blinded readers semi-quantitatively assessed the image quality regarding motion, noise, and contrast on a 4-point scale. RESULTS Median contrast agent volume and median effective radiation dose were 35 mL (interquartile range, 30-40 mL) and 0.5 mSv (interquartile range, 0.4-0.6 mSv), respectively. Mean attenuation in the aortic root was 412 ± 89 Hounsfield units. Diagnostic image quality was obtained in 1050 of 1067 (98.4%) coronary segments and, on an intention-to-diagnosis basis, in 85 of 89 (95.5%) patients. Below a cut-off heart rate of 67 beats/min, only 1 of 974 (0.1%) coronary segments was nondiagnostic. CONCLUSION A radiation- and contrast-sparing protocol for CCTA on a latest generation 256-slice computed tomography scanner yields diagnostic image quality in patients referred for CAD exclusion in daily clinical routine.

Adaptive Statistical Iterative Reconstruction-V: Impact on Image Quality in Ultralow-Dose Coronary Computed Tomography Angiography.

Objective The clinical utility of a latest generation iterative reconstruction algorithm (adaptive statistical iterative reconstruction [ASiR-V]) has yet to be elucidated for coronary computed tomography angiography (CCTA). This study evaluates the impact of ASiR-V on signal, noise and image quality in CCTA. Methods Sixty-five patients underwent clinically indicated CCTA on a 256-slice CT scanner using an ultralow-dose protocol. Data sets from each patient were reconstructed at 6 different levels of ASiR-V. Signal intensity was measured by placing a region of interest in the aortic root, LMA, and RCA. Similarly, noise was measured in the aortic root. Image quality was visually assessed by 2 readers. Results Median radiation dose was 0.49 mSv. Image noise decreased with increasing levels of ASiR-V resulting in a significant increase in signal-to-noise ratio in the RCA and LMA (P < 0.001). Correspondingly, image quality significantly increased with higher levels of ASiR-V (P < 0.001). Conclusions ASiR-V yields substantial noise reduction and improved image quality enabling introduction of ultralow-dose CCTA.

Prevalence and characteristics of coronary artery anomalies detected by coronary computed tomography angiography in 5 634 consecutive patients in a single centre in Switzerland.

STUDY PRINCIPLES Coronary computed tomography angiography (CCTA) allows three-dimensional visualisation of the origin, course and ending of the coronary vessels with high spatial resolution, yielding an accurate depiction of coronary artery anomalies (CAAs). This study sought to determine the prevalence, incidence and characteristics of CAAs detected with CCTA in a single centre in Switzerland. METHODS CAAs were retrospectively identified in 5 634 consecutive patients referred for CCTA between March 2007 and July 2015. Single coronary arteries, Bland-White-Garland syndrome, anomalous coronary arteries originating from the opposite site of the sinus of Valsalva (ACAOS) with an interarterial course and coronary artery fistulas were classified as potentially malignant CAAs. RESULTS We identified 145 patients with CAAs, resulting in an overall prevalence of 2.6% and cumulative incidence of 2.1% in all patients referred for CCTA in the observation period. Forty-nine (33.8%) patients showed malignant CAAs including 1 (0.7%) patient with Bland-White-Garland syndrome, 7 (4.8%) with single coronary arteries, 36 (24.8%) with ACAOS and an interarterial course, and 5 (3.5%) with coronary artery fistulas. The remaining 96 (66.2%) patients were classified as having benign variants. CONCLUSIONS The prevalence of CAA detected by CCTA is not negligible. Because of its noninvasive nature, relatively low cost and low radiation exposure, a further increase in the utilisation of CCTA may be expected, which may consequently be paralleled by an increasing absolute number of incidentally detected CAAs. Hence, awareness of the main issues and possible management strategies regarding CAAs is of importance for every treating physician.

Real-time respiratory triggered SPECT myocardial perfusion imaging using CZT technology: impact of respiratory phase matching between SPECT and low-dose CT for attenuation correction

Aims To assess the impact of respiratory phase matching between single-photon-emission computed tomography myocardial perfusion imaging (SPECT-MPI) and low-dose computed tomography (CT) for attenuation correction (AC). Methods and results Forty patients underwent 1-day 99mTc-tetrofosmin pharmacological stress/rest SPECT-MPI using a cadmium–zinc–telluride gamma camera. Low-dose CT for AC was performed at deep-inspiration breath-hold. SPECT-MPI was acquired once with free-breathing (FB) and repeated at deep-inspiration breath-hold (BH) to match the respiratory phase of AC. From these acquisitions we reconstructed four data sets: free-breathing SPECT-MPI without AC (non-corrected; FB-NC), breath-hold SPECT-MPI without AC (non-corrected; BH-NC), free-breathing SPECT-MPI with AC (FB-AC), and breath-hold SPECT-MPI with AC (BH-AC), the latter representing respiratory-phase-matched AC SPECT-MPI. We compared semi-quantitative segmental tracer uptake, visual diagnosis, inter-observer agreement, and image quality. Compared with FB-NC, deep-inspiration BH-NC increases inferior and lateral uptake, but decreases septal uptake. Addition of AC to FB increases inferior and septal uptake, but decreases anterolateral uptake. Combining breath-hold MPI with breath-hold CT AC (BH-AC) increases inferior, inferolateral, and septal uptake, but reduces apical uptake, without affecting anterolateral uptake, with significant differences to all other protocols. Frequency of normal scans increases across protocols: 10% with FB-NC, 21% with BH-NC, 38% with FB-AC, and 51% with BH-AC. Image quality and inter-observer agreement were highest for BH-AC among all protocols. Conclusion Compared with non-corrected breath-hold SPECT-MPI and with free-breathing AC SPECT-MPI, respiratory-phase-matched AC SPECT-MPI significantly affects segmental semi-quantitative uptake, increases the frequency of normal scans, yields the best inter-observer agreement, and significantly improves image quality. These findings suggest a potential role of respiratory triggered SPECT-MPI in clinical routine.

Outcome in middle-aged individuals with anomalous origin of the coronary artery from the opposite sinus: a matched cohort study

Aims Anomalous origin of a coronary artery from the opposite sinus (ACAOS) has been associated with adverse cardiac events in the young. It remains unknown whether this holds true for middle-aged patients with uncorrected ACAOS as well. We assessed the outcome in middle-aged patients with newly diagnosed ACAOS by coronary computed tomography angiography (CCTA) compared with a matched cohort. Methods and results We retrospectively identified 68 consecutive patients with ACAOS documented by CCTA. ACAOS with a course of the anomalous vessel between the aorta and pulmonary artery were classified as interarterial course (IAC). Each patient with ACAOS was matched to two controls without ACAOS. Major adverse cardiac events (i.e. myocardial infarction, revascularization and cardiac death) were recorded for all patients and controls. Two (3%) patients were lost to follow-up. Thus, 66 patients with ACAOS were included in the final analysis and matched with 132 controls. Mean age of patients was 56 ± 11 years, 73% were male and the mean follow-up was 49 months. Forty (65%) patients were classified as having ACAOS with IAC. The annual event rate of ACAOS vs. controls was 4.9 and 4.8%, the hazard ratio (HR) 0.94 (0.39-2.28, P = 0.89). The annual event rate of ACAOS with IAC compared with their matched controls was 5.2 and 4.3%, and the HR 1.01 (95% CI 0.39-2.58, P = 0.99). Conclusions In middle-aged individuals with newly diagnosed ACAOS mid-term outcome is not statistically different to a matched control cohort without coronary artery anomalies, regardless of whether ACAOS with or without IAC variants are present.

Prognostic value of aortic regurgitation after TAVI in patients with chronic kidney disease

BACKGROUND Aortic regurgitation (AR) after transcatheter aortic valve implantation (TAVI) for severe aortic valve stenosis results in major haemodynamic changes. Influence of post-implant AR and aortic valve calcification on outcome in patients with chronic kidney disease (CKD) is unclear. METHODS Short-term outcome was defined as a combined 30-day endpoint, long-term outcome as survival. Post-implant AR was classified as none/mild or moderate/severe using transthoracic echocardiography. Aortic valve calcification was calculated by computed tomography. Logistic regression analyses were performed in patients with none/mild (estimated glomerular filtration rate [eGFR]≥30ml/min/1.73m(2)) and advanced (eGFR<30ml/min/1.73m(2)) CKD to evaluate predictors of outcome and post-implant AR. RESULTS TAVI was performed in 546 consecutive patients. Moderate/severe post-implant AR was the only independent predictor of the 30-day endpoint in patients with advanced (OR 7.091, 95% CI 1.144-43.962, p=0.035), but not in patients with none/mild CKD. Similarly, moderate/severe AR predicted impaired survival only in patients with advanced CKD (p<0.001). NT-proBNP (OR 1.023 per 500ng/l increase, 95% CI 1.003-1.043; p=0.026) before intervention was the only independent predictor of the 30-day endpoint in patients with none/mild CKD. Aortic valve calcification was comparable in patients with none/mild versus advanced CKD and was an independent predictor of moderate/severe post-implant AR in the overall population as well as in the subgroups with none/mild or advanced CKD. CONCLUSIONS Moderate/severe AR after TAVI predicts outcome in patients with advanced CKD, but not in patients with none/mild CKD. Aortic valve calcification is an important predictor of post-implant AR independent of kidney function.

Ultra-low-dose coronary artery calcium scoring using novel scoring thresholds for low tube voltage protocols—a pilot study

Aims To determine if tube-adapted thresholds for coronary artery calcium (CAC) scoring by computed tomography at 80 kilovolt-peak (kVp) tube voltage and 70-kVp yield comparable results to the standard 120-kVp protocol. Methods and results We prospectively included 103 patients who underwent standard scanning with 120-kVp tube voltage and additional scans with 80 kVp and 70 kVp. Mean body mass index (BMI) was 27.9 ± 5.1 kg/m2. For the lowered tube voltages, we applied novel kVp-adapted thresholds for calculation of CAC scores and compared them with standard 120-kVp scans using intraclass correlation and Bland-Altman (BA) analysis. Furthermore, risk-class (CAC score 0/1-10/11-100/101-400/>400) changes were assessed. Median CAC score from 120-kVp scans was 212 (interquartile range 25-901). Thirteen (12.6%) patients had zero CAC. Using the novel kVp-adapted thresholds, CAC scores derived from 80-kVp scans showed excellent correlation (r = 0.994, P < 0.001) with standard 120-kVp scans with BA limits of agreement of -235 (-39.5%) to 172 (28.9%). Similarly, for 70-kVp scans, correlation was excellent (r = 0.972, P < 0.001) but with broader limits of agreement of -476 (-85.0%) to 270 (48.2%). Only 2 (2.8%) reclassifications were observed for the 80-kVp scans in patients with a BMI <30 kg/m2 (n = 71), and 2 (6.1%) for the 70-kVp scans in patients with a BMI <25 kg/m2 (n = 33). Mean effective radiation dose was 0.60 ± 0.07 millisieverts (mSv), 0.19 ± 0.02 mSv, and 0.12 ± 0.01 mSv for the 120-kVp, 80-kVp, and 70-kVp scans, respectively. Conclusion The present study suggests that CAC scoring with reduced peak tube voltage is accurate if kVp-adapted thresholds for calculation of CAC scores are applied while offering a substantial further radiation dose reduction.

A low-dose and an ultra-low-dose contrast agent protocol for coronary CT angiography in a clinical setting: quantitative and qualitative comparison to a standard dose protocol

OBJECTIVE To evaluate the impact of a low-dose (LD) and an ultra-LD (ULD) contrast protocol for coronary CT angiography on qualitative and quantitative image parameters in a clinical setting. METHODS We scanned 120 consecutive patients with a 256-slice CT scanner applying a LD (60 patients, 35-55 ml) or ULD (60 patients, 25-45 ml) contrast protocol adapted to the body mass index. Visually assessed image quality and attenuation measured in each coronary segment were retrospectively compared in 20 consecutive patients scanned with a normal-dose (ND, 40-105 ml) contrast protocol. RESULTS Visually assessed image quality did not differ significantly among protocols. By contrast, attenuation obtained from the ULD protocol (median contrast volume 35 ml) differed significantly from the LD (median 45 ml) and ND (median 70 ml) protocols in the coronary segments (316 ± 52 vs 363 ± 60 and 359 ± 52 HU, p < 0.001). Attenuation did not differ significantly between the LD and ND protocol. The proportion of patients with inadequate coronary vessel attenuation was significantly higher (p < 0.001) in the ULD protocol (37%) than in the ND (5%) and LD (10%) protocols but did not differ significantly between the ND and LD protocols. CONCLUSION In a clinical setting, a LD contrast protocol with a median volume of 45 ml is feasible for the latest generation 256-slice coronary CT angiography as it yields attenuation comparable to a ND protocol. By contrast, the implementation of an ULD protocol remains challenging. Advances in knowledge: Although not perceived by the naked eye, an ULD contrast protocol in a clinical setting yields attenuation below a threshold for diagnostic image quality.

Quantification of epicardial and intrathoracic fat volume does not provide an added prognostic value as an adjunct to coronary artery calcium score and myocardial perfusion single-photon emission computed tomography

AIMS To compare the predictive value of epicardial and intrathoracic fat volume (EFV, IFV), coronary artery calcium (CAC) score, and single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) for major adverse cardiac events (MACE). METHODS AND RESULTS Follow-up was obtained in 275 patients with known or suspected coronary artery disease (CAD), who underwent SPECT-MPI including non-contrast cardiac computed tomography (CT) for attenuation correction to evaluate ischaemic heart disease and in whom EFV, IFV, and CAC score were calculated from non-contrast CT. Associations between fat volume, traditional cardiovascular risk factors, CAC score, and SPECT-MPI results were assessed and MACE predictors identified by Cox proportional hazard regression and global χ(2) statistics. After a median follow-up of 2.9 years, MACE were recorded in 38 patients. In univariate Cox regression analysis, EFV and IFV were predictors of MACE (P = 0.013 and P = 0.004, respectively). In multivariate analysis, EFV and IFV provided incremental predictive value beyond traditional cardiovascular risk factors (P < 0.05 and P < 0.01). However, after adjustment for CAC score and SPECT-MPI results, EFV and IFV fell short of statistical significance as independent outcome predictors. CONCLUSION Quantification of EFV and IFV is associated with MACE and may improve risk stratification beyond traditional cardiovascular risk factors. However, once CAC score and/or SPECT-MPI results are known, EFV and IFV do not provide any added clinically relevant prognostic value. Further studies may identify the subpopulation with the largest relative merit of EFV and IFV as an adjunct to SPECT-MPI and CAC score.