Fractional Flow Reserve to Guide Treatment of Patients With Multivessel Coronary Artery Disease.

BACKGROUND: There is limited evidence that fractional flow reserve (FFR) is effective in guiding therapeutic strategy in multivessel coronary artery disease (CAD) beyond prespecified percutaneous coronary intervention or coronary graft surgery candidates. OBJECTIVES: The FUTURE (FUnctional Testing Underlying coronary REvascularization) trial aimed to evaluate whether a treatment strategy based on FFR was superior to a traditional strategy without FFR in the treatment of multivessel CAD. METHODS: The FUTURE trial is a prospective, randomized, open-label superiority trial. Multivessel CAD candidates were randomly assigned (1:1) to treatment strategy based on FFR in all stenotic (≥50%) coronary arteries or to a traditional strategy without FFR. In the FFR group, revascularization (percutaneous coronary intervention or surgery) was indicated for FFR ≤0.80 lesions. The primary endpoint was a composite of major adverse cardiac or cerebrovascular events at 1 year. RESULTS: The trial was stopped prematurely by the data safety and monitoring board after a safety analysis and 927 patients were enrolled. At 1-year follow-up, by intention to treat, there were no significant differences in major adverse cardiac or cerebrovascular events rates between groups (14.6% in the FFR group vs 14.4% in the control group; hazard ratio: 0.97; 95% confidence interval: 0.69-1.36; P = 0.85). The difference in all-cause mortality was nonsignificant, 3.7% in the FFR group versus 1.5% in the control group (hazard ratio: 2.34; 95% confidence interval: 0.97-5.18; P = 0.06), and this was confirmed with a 24 months' extended follow-up. FFR significantly reduced the proportion of revascularized patients, with more patients referred to exclusively medical treatment (P = 0.02). CONCLUSIONS: In patients with multivessel CAD, we did not find evidence that an FFR-guided treatment strategy reduced the risk of ischemic cardiovascular events or death at 1-year follow-up. (Functional Testing Underlying Coronary Revascularisation; NCT01881555).

Radial versus femoral access for coronary angiography and intervention is associated with lower patient radiation exposure in high-radial-volume centres: Insights from the RAY'ACT-1 study.

BACKGROUND: Literature suggests that radial access is associated with higher radiation doses than femoral access. AIMS: To compare patient radiation exposure during coronary angiography (CA) and percutaneous coronary intervention (PCI) with radial versus femoral access. METHODS: RAY'ACT is a nationwide, multicentre, French survey evaluating patient radiation in interventional cardiology. Variables of patient exposure from 21,675 CAs and 17,109 PCIs performed at 44 centres during 2010 were analysed retrospectively. RESULTS: Radial access was used in 71% of CAs and 69% of PCIs. Although median fluoroscopy times were longer for radial versus femoral access (CA, 3.8 vs 3.5minutes [P<0.001]; PCI, 10.4 vs 10.1minutes [P=0.001]), the Kerma-area product (KAP) was lower with radial access (CA, 26.8 vs 28.1Gy·cm2; PCI, 55.6 vs 59.4Gy·cm2; both P=0.001). Differences in KAP remained significant in the multivariable analysis (P<0.01), and in a propensity score-matched analysis (P=0.01). A significant interaction was found between KAP and the percentage of procedures with radial access by centre (P<0.001). KAP was higher by radial versus femoral access in low-radial-volume centres, and lower in high-radial-volume centres. Radiation protection techniques, such as the use of low frame rates (7.5 frame/s), were used more frequently in high-radial-volume radial centres. CONCLUSIONS: In this multicentre study, radial access was associated with lower radiation doses to patient than femoral access in high-radial-volume centres. Provided that radioprotection methods are implemented, radial access could be associated with lower patient radiation exposure.

Dual-Gated Motion-Frozen Cardiac PET with Flurpiridaz F 18.

UNLABELLED: A novel PET radiotracer, Flurpiridaz F 18, has undergone phase II clinical trial evaluation as a high-resolution PET cardiac perfusion imaging agent. In a subgroup of patients imaged with this agent, we assessed the feasibility and benefit of simultaneous correction of respiratory and cardiac motion. METHODS: In 16 patients, PET imaging was performed on a 4-ring scanner in dual cardiac and respiratory gating mode. Four sets of data were reconstructed with high-definition reconstruction (HD•PET): ungated and 8-bin electrocardiography-gated images using 5-min acquisition, optimal respiratory gating (ORG)-as developed for oncologic imaging-using a narrow range of breathing amplitude around end-expiration level with 35% of the counts in a 7-min acquisition, and 4-bin respiration-gated and 8-bin electrocardiography-gated images (32 bins in total) using the 7-min acquisition (dual-gating, using all data). Motion-frozen (MF) registration algorithms were applied to electrocardiography-gated and dual-gated data, creating cardiac-MF and dual-MF images. We computed wall thickness, wall/cavity contrast, and contrast-to-noise ratio for standard, ORG, cardiac-MF, and dual-MF images to assess image quality. RESULTS: The wall/cavity contrast was similar for ungated (9.3 ± 2.9) and ORG (9.5 ± 3.2) images and improved for cardiac-MF (10.8 ± 3.6) and dual-MF images (14.8 ± 8.0) (P < 0.05). The contrast-to-noise ratio was 22.2 ± 9.1 with ungated, 24.7 ± 12.2 with ORG, 35.5 ± 12.8 with cardiac-MF, and 42.1 ± 13.2 with dual-MF images (all P < 0.05). The wall thickness was significantly decreased (P < 0.05) with dual-MF (11.6 ± 1.9 mm) compared with ungated (13.9 ± 2.8 mm), ORG (13.1 ± 2.9 mm), and cardiac-MF images (12.1 ± 2.7 mm). CONCLUSION: Dual (respiratory/cardiac)-gated perfusion imaging with Flurpiridaz F 18 is feasible and improves image resolution, contrast, and contrast-to-noise ratio when MF registration methods are applied.

Comparison of clinical tools for measurements of regional stress and rest myocardial blood flow assessed with 13N-ammonia PET/CT.

UNLABELLED: Several models for the quantitative analysis of myocardial blood flow (MBF) at stress and rest and myocardial flow reserve (MFR) with (13)N-ammonia myocardial perfusion PET have been implemented for clinical use. We aimed to compare quantitative results obtained from 3 software tools (QPET, syngo MBF, and PMOD), which perform PET MBF quantification with either a 2-compartment model (QPET and syngo MBF) or a 1-compartment model (PMOD). METHODS: We considered 33 adenosine stress and rest (13)N-ammonia studies (22 men and 11 women). Average age was 54.5 ± 15 y, and average body mass index was 26 ± 4.2. Eighteen patients had a very low likelihood of disease, with no chest pain, normal relative perfusion results, and normal function. All data were obtained on a PET/CT scanner in list mode with CT attenuation maps. Sixteen dynamic frames were reconstructed (twelve 10-s, two 30-s, one 1-min, and one 6-min frames). Global and regional stress and rest MBF and MFR values were obtained with each tool. Left ventricular contours and input function region were obtained automatically in system QPET and syngo MBF and manually in PMOD. RESULTS: The flow values and MFR values were highly correlated among the 3 packages (R(2) ranging from 0.88 to 0.92 for global values and from 0.78 to 0.94 for regional values. Mean reference MFR values were similar for QPET, syngo MBF, and PMOD (3.39 ± 1.22, 3.41 ± 0.76, and 3.66 ± 1.19, respectively) by 1-way ANOVA (P = 0.74). The lowest MFR in very low likelihood patients in any given vascular territory was 2.25 for QPET, 2.13 for syngo MBF, and 2.23 for PMOD. CONCLUSION: Different implementations of 1- and 2-compartment models demonstrate an excellent correlation in MFR for each vascular territory, with similar mean MFR values.

Coronary artery calcium scoring using a reduced tube voltage and radiation dose protocol with dual-source computed tomography.

BACKGROUND: Technical advances to minimize radiation exposure because of imaging are in accord with the "as low as reasonably achievable" principle. OBJECTIVE: We aimed to determine whether coronary calcium scoring (CCS) by multidetector CT at a tube voltage of 100 kVp yields comparable results to the standard 120-kVp protocol while reducing radiation dose. METHODS: Sixty consecutive outpatients were scanned with a dual-source CT scanner with both the120- and 100-kVp protocols. The calcium threshold was 130 Hounsfield units (HUs) for 120 kVp and 147 HU for 100 kVp, as determined from phantom data. All 100-kVp scans were scored by an experienced reader blinded to 120-kVp data. RESULTS: Image quality was comparable for 100- and 120- kVp scans. Mean Agatston scores for 100 and 120 kVp were 189 +/- 484 and 189 +/- 498 (P = 0.92), with perfect correlation (r = 1.0; P < 0.0001; 95% limits of agreement, -36 to 37; bias, 0.6). Mean coronary calcium volume scores for 100 and 120 kVp were 143 +/- 370 mm(3) and 149 +/- 392 mm(3) (P = 0.26), with perfect correlation (r = 1.0; P < 0.0001; 95% limits of agreement, -35 to 32 mm(3); bias, -1.4 mm(3)). The mean absolute difference for Agatston scores between the protocols was 16.9, with excellent agreement (kappa = 0.95; P < 0.0001). Mean effective radiation dose for the 100-kVp protocol was significantly lower (1.17 mSv versus 1.70 mSv; P < 0.0001). CONCLUSION: A reduced tube current protocol using 100 kVp gives equivalent CCS results at reduced radiation exposure compared with a standard protocol at 120 kVp.

Algorithm for radiation dose reduction with helical dual source coronary computed tomography angiography in clinical practice.

BACKGROUND: Strategies to reduce the radiation dose of coronary computed tomography angiography (CCTA), while maintaining diagnostic image quality, are imperative for cardiac CT. OBJECTIVE: We aimed to reduce radiation dose during helical dual-source CCTA by combining lower tube voltage, shortest possible full tube current (FTC) window, and minimal tube current outside the FTC window, and to develop a patient-based algorithm for applying these dose-reduction components. METHODS: We compared FTC at 70% of the cardiac cycle (FTC70) to a 45% to 75% window (FTC45-75) using both 100 and 120 kVp (N=118). FTC70 was used in patients with heart rates <70 beats/min, no arrhythmia, age <65 years; 100 kVp was used in patients with body mass index (BMI) <30, a low coronary calcium score (CCS), and no stents. Objective and subjective image quality were assessed. RESULTS: Compared with FTC45-75 at 120 kVp, radiation dose was reduced by 66% for FTC70 at 100 kVp (mean radiation dose: 4.4 +/- 0.9 mSv) and by 43% for FTC70 at 120 kVp. 99% of 780 segments in the FTC70 group were of diagnostic quality. Noise, signal-to-noise ratio, and contrast-to-noise ratio were comparable between FTC70 and FTC45-75 for both 100 and 120 kVp. BMI, CCS and maximal heart rate variation were predictors of image quality. Tube voltage, FTC window width, scan length, and average heart rate were predictors of radiation dose. CONCLUSIONS: A successful patient-based algorithm for radiation dose reduction during helical CCTA using DSCT has been developed and validated in clinical practice.