The Use and Efficacy of FFR-CT: Real-World Multicenter Audit of Clinical Data With Cost Analysis.

BACKGROUND: Fractional flow reserve-computed tomography (FFR-CT) is endorsed by UK and U.S. chest pain guidelines, but its clinical effectiveness and cost benefit in real-world practice are unknown. OBJECTIVES: The purpose of this study was to audit the use of FFR-CT in clinical practice against England's National Institute for Health and Care Excellence guidance and assess its diagnostic accuracy and cost. METHODS: A multicenter audit was undertaken covering the 3 years when FFR-CT was centrally funded in England. For coronary computed tomographic angiograms (CCTAs) submitted for FFR-CT analysis, centers provided data on symptoms, CCTA and FFR-CT findings, and subsequent management. Audit standards included using FFR-CT only in patients with stable chest pain and equivocal stenosis (50%-69%). Diagnostic accuracy was evaluated against invasive FFR, when performed. Follow-up for nonfatal myocardial infarction and all-cause mortality was undertaken. The cost of an FFR-CT strategy was compared to alternative stress imaging pathways using cost analysis modeling. RESULTS: A total of 2,298 CCTAs from 12 centers underwent FFR-CT analysis. Stable chest pain was the main symptom in 77%, and 40% had equivocal stenosis. Positive and negative predictive values of FFR-CT were 49% and 76%, respectively. A total of 46 events (2%) occurred over a mean follow-up period of 17 months; FFR-CT (cutoff: 0.80) was not predictive. The FFR-CT strategy costs £2,102 per patient compared with an average of £1,411 for stress imaging. CONCLUSIONS: In clinical practice, the National Institute for Health and Care Excellence criteria for using FFR-CT were met in three-fourths of patients for symptoms and 40% for stenosis. FFR-CT had a low positive predictive value, making its use potentially more expensive than conventional stress imaging strategies.

Quantitative assessment of myocardial blood flow in coronary artery disease by cardiovascular magnetic resonance: comparison of Fermi and distributed parameter modeling against invasive methods.

BACKGROUND: Mathematical modeling of perfusion cardiovascular magnetic resonance (CMR) data allows absolute quantification of myocardial blood flow and can potentially improve the diagnosis and prognostication of obstructive coronary artery disease (CAD), against the current clinical standard of visual assessments. This study compares the diagnostic performance of distributed parameter modeling (DP) against the standard Fermi model, for the detection of obstructive CAD, in per vessel against per patient analysis. METHODS: A pilot cohort of 28 subjects (24 included in the final analysis) with known or suspected CAD underwent adenosine stress-rest perfusion CMR at 3T. Data were analysed using Fermi and DP modeling against invasive coronary angiography and fractional flow reserve, acquired in all subjects. Obstructive CAD was defined as luminal stenosis of ≥70 % alone, or luminal stenosis ≥50 % and fractional flow reserve ≤0.80. RESULTS: On ROC analysis, DP modeling outperformed the standard Fermi model, in per vessel and per patient analysis. In per patient analysis, DP modeling-derived myocardial blood flow at stress demonstrated the highest sensitivity and specificity (0.96, 0.92) in detecting obstructive CAD, against Fermi modeling (0.78, 0.88) and visual assessments (0.79, 0.88), respectively. CONCLUSIONS: DP modeling demonstrated consistently increased diagnostic performance against Fermi modeling and showed that it may have merit for stratifying patients with at least one vessel with obstructive CAD. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov NCT01368237 Registered 6 of June 2011. URL: https://clinicaltrials.gov/ct2/show/NCT01368237.

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 (<10%), mild (10-49%), moderate (50-70%) and severe (>70%) luminal stenosis and classified as no (<10%), non-obstructive (10-70%) or obstructive (>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/m(2), 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.

Dual-energy CT angiography for assessment of regional pulmonary perfusion in patients with chronic thromboembolic pulmonary hypertension: initial experience.

OBJECTIVE: This study assessed the utility of dual-energy pulmonary CT angiography (CTA) for noninvasive assessment of regional pulmonary perfusion in patients with chronic thromboembolic pulmonary hypertension (CTEPH). Regional perfusion abnormalities were correlated with hemodynamic parameters and structural abnormalities on pulmonary CTA. SUBJECTS AND METHODS: Twenty patients with CTEPH (11 men and nine women; mean age, 61.5 years) underwent pulmonary CTA with a dual-energy technique. Right heart catheterization data were available in 15 cases. Scan parameters were as follows: tube A, 140 kV (75 mA); tube B, 80 kV (300 mA); gantry rotation, 500 milliseconds; pitch, 0.5; and collimation, 14 × 1.2 mm. An iodine map was generated via three-material-decomposition and was scored for extent of hypoperfusion. Correlation was made with mosaic attenuation pattern, extent of vascular obstruction, and right heart hemodynamics. Iodine attenuation values were analyzed within completely occluded, partially occluded, and disease-free lobes. RESULTS: A strong correlation existed between dual-energy CT-derived perfusion and mosaic attenuation pattern when both lobar (r > 0.6; n = 20; p < 0.006) and whole-lung scores were assessed (r = 0.77; n = 20; p < 0.001). There was no statistically significant correlation between dual-energy CT perfusion and vascular obstructive index, mean pulmonary artery pressure, or pulmonary vascular resistance (p > 0.08). Of 42 completely occluded lobes, 27 (64%) had demonstrable residual perfusion (mismatching), suggesting that blood supply was maintained via systemic collaterals. CONCLUSION: Dual-energy CT can offer a "one-stop" assessment of anatomy and perfusion in CTEPH. The additional information provided by dual-energy CT could have a future role in helping guide patient selection for thromboendarterectomy surgery.