Randomized comparison of chest pain evaluation with FFRCT or standard care: Factors determining US costs.

BACKGROUND: FFRCT assesses the functional significance of lesions seen on CTCA, and may be a more efficient approach to chest pain evaluation. The FORECAST randomized trial found no significant difference in costs within the UK National Health Service, but implications for US costs are unknown. The purpose of this study was to compare costs in the FORECAST trial based on US healthcare cost weights, and to evaluate factors affecting costs. METHODS: Patients with stable chest pain were randomized either to the experimental strategy (CTCA with selective FFRCT), or to standard clinical pathways. Pre-randomization, the treating clinician declared the planned initial test. The primary outcome was nine-month cardiovascular care costs. RESULTS: Planned initial tests were CTCA in 912 patients (65%), stress testing in 393 (28%), and invasive angiography in 94 (7%). Mean US costs did not differ overall between the experimental strategy and standard care (cost difference +7% (+$324), CI -12% to +26%, p â€‹= â€‹0.49). Costs were 4% lower with the experimental strategy in the planned invasive angiography stratum (p for interaction â€‹= â€‹0.66). Baseline factors independently associated with costs were older age (+43%), male sex (+55%), diabetes (+37%), hypertension (+61%), hyperlipidemia (+94%), prior angina (+24%), and planned invasive angiography (+160%). Post-randomization cost drivers were coronary revascularization (+348%), invasive angiography (267%), and number of tests (+35%). CONCLUSIONS: Initial evaluation of chest pain using CTCA with FFRCT had similar US costs as standard care pathways. Costs were increased by baseline coronary risk factors and planned invasive angiography, and post-randomization invasive procedures and the number of tests. Registration at ClinicalTrials.gov (NCT03187639).

Early computed tomography coronary angiography in adults presenting with suspected acute coronary syndrome: the RAPID-CTCA RCT.

BACKGROUND: Acute coronary syndrome is a common medical emergency. The optimal strategy to investigate patients who are at intermediate risk of acute coronary syndrome has not been fully determined. OBJECTIVE: To investigate the role of early computed tomography coronary angiography in the investigation and treatment of adults presenting with suspected acute coronary syndrome. DESIGN: A prospective, multicentre, open, parallel-group randomised controlled trial with blinded end-point adjudication. SETTING: Thirty-seven hospitals in the UK. PARTICIPANTS: Adults (aged ≥ 18 years) presenting to the emergency department, acute medicine services or cardiology department with suspected or provisionally diagnosed acute coronary syndrome and at least one of the following: (1) a prior history of coronary artery disease, (2) a cardiac troponin level > 99th centile and (3) an abnormal 12-lead electrocardiogram. INTERVENTIONS: Early computed tomography coronary angiography in addition to standard care was compared with standard care alone. Participants were followed up for 1 year. MAIN OUTCOME MEASURE: One-year all-cause death or subsequent type 1 (spontaneous) or type 4b (stent thrombosis) myocardial infarction, measured as the time to such event adjudicated by two cardiologists blinded to the computerised tomography coronary angiography ( CTCA ) arm. Cost-effectiveness was estimated as the lifetime incremental cost per quality-adjusted life-year gained. RESULTS: Between 23 March 2015 and 27 June 2019, 1748 participants [mean age 62 years (standard deviation 13 years), 64% male, mean Global Registry Of Acute Coronary Events score 115 (standard deviation 35)] were randomised to receive early computed tomography coronary angiography (n = 877) or standard care alone (n = 871). The primary end point occurred in 51 (5.8%) participants randomised to receive computed tomography coronary angiography and 53 (6.1%) participants randomised to receive standard care (adjusted hazard ratio 0.91, 95% confidence interval 0.62 to 1.35; p = 0.65). Computed tomography coronary angiography was associated with a reduced use of invasive coronary angiography (adjusted hazard ratio 0.81, 95% confidence interval 0.72 to 0.92; p = 0.001) but no change in coronary revascularisation (adjusted hazard ratio 1.03, 95% confidence interval 0.87 to 1.21; p = 0.76), acute coronary syndrome therapies (adjusted odds ratio 1.06, 95% confidence interval 0.85 to 1.32; p = 0.63) or preventative therapies on discharge (adjusted odds ratio 1.07, 95% confidence interval 0.87 to 1.32; p = 0.52). Early computed tomography coronary angiography was associated with longer hospitalisations (median increase 0.21 days, 95% confidence interval 0.05 to 0.40 days) and higher mean total health-care costs over 1 year (£561 more per patient) than standard care. LIMITATIONS: The principal limitation of the trial was the slower than anticipated recruitment, leading to a revised sample size, and the requirement to compromise and accept a larger relative effect size estimate for the trial intervention. FUTURE WORK: The potential role of computed tomography coronary angiography in selected patients with a low probability of obstructive coronary artery disease (intermediate or mildly elevated level of troponin) or who have limited access to invasive cardiac catheterisation facilities needs further prospective evaluation. CONCLUSIONS: In patients with suspected or provisionally diagnosed acute coronary syndrome, computed tomography coronary angiography did not alter overall coronary therapeutic interventions or 1-year clinical outcomes, but it did increase the length of hospital stay and health-care costs. These findings do not support the routine use of early computed tomography coronary angiography in intermediate-risk patients with acute chest pain. TRIAL REGISTRATION: This trial is registered as ISRCTN19102565 and Clinical Trials NCT02284191. FUNDING: This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 26, No. 37. See the NIHR Journals Library website for further project information.

WHY DID WE DO THE RESEARCH?: Chest pain is a common medical emergency. It is important to decide if the cause is a heart attack. The two tests that are often used are a heart recording (electrocardiogram) and a blood test (troponin levels). If both are normal, the cause of chest pain is unlikely to be a heart attack and the patient is often discharged home. If either test is positive or if the patient has had previous heart problems, then the patient may require further investigation. We wanted to test whether or not adding a heart scan called a computerised tomography coronary angiogram improved patients' care. HOW DID WE DO THE RESEARCH?: We carried out a randomised trial in which half of the patients attending hospital with chest pain had a computerised tomography coronary angiography scan as part of their assessment and half of the patients did not. In total, 1749 patients were recruited and followed up for 1 year. BRINGING IT ALL TOGETHER: The use of an additional early computerised tomography coronary angiography scan for chest pain patients of medium risk produced only small improvements in patient care.

Fractional flow reserve derived from computed tomography coronary angiography in the assessment and management of stable chest pain: the FORECAST randomized trial.

AIMS: Fractional flow reserve (FFRCT) using computed tomography coronary angiography (CTCA) determines both the presence of coronary artery disease and vessel-specific ischaemia. We tested whether an evaluation strategy based on FFRCT would improve economic and clinical outcomes compared with standard care. METHODS AND RESULTS: Overall, 1400 patients with stable chest pain in 11 centres were randomized to initial testing with CTCA with selective FFRCT (experimental group) or standard clinical care pathways (standard group). The primary endpoint was total cardiac costs at 9 months. Secondary endpoints were angina status, quality of life, major adverse cardiac and cerebrovascular events, and use of invasive coronary angiography. Randomized groups were similar at baseline. Most patients had an initial CTCA: 439 (63%) in the standard group vs. 674 (96%) in the experimental group, 254 of whom (38%) underwent FFRCT. Mean total cardiac costs were higher by £114 (+8%) in the experimental group, with a 95% confidence interval from -£112 (-8%) to +£337 (+23%), though the difference was not significant (P = 0.10). Major adverse cardiac and cerebrovascular events did not differ significantly (10.2% in the experimental group vs. 10.6% in the standard group) and angina and quality of life improved to a similar degree over follow-up in both randomized groups. Invasive angiography was reduced significantly in the experimental group (19% vs. 25%, P = 0.01). CONCLUSION: A strategy of CTCA with selective FFRCT in patients with stable angina did not differ significantly from standard clinical care pathways in cost or clinical outcomes, but did reduce the use of invasive coronary angiography.

Sex-based inequalities in contemporary UK hospital management of stable chest pain.

OBJECTIVE: We surveyed UK practice of National Institute for Health and Care Excellence (NICE) "Recent onset chest pain" guidance (CG95, 2016), stratified by sex. We looked for sex-related differences in referral to computed tomographic coronary angiography (CTCA) and subsequent functional imaging (FI), invasive coronary angiography (ICA) and revascularisation. METHODS: This was a prospective analysis of CTCA practice in 8 UK centres between 2018 and 2020. Coronary artery disease (CAD) was recorded with the CAD-reporting and data system. Local electronic records/archiving/communication systems were used to collect data regarding subsequent FI, ICA and revascularisation. RESULTS: 2301 women, 2326 men underwent CTCA; women were older (58±11 vs 55±12 years, p<0.001) but more likely to have normal coronary arteries (46% (1047) vs 29% (685); p<0.001) and less likely to have severe stenosis (7% (169) vs 13% (307); p<0.001). FI was used less for 4% (93) women, 5% (108) men; ICA was also used less for women (8% (182) vs 14% (321)), as was revascularisation (4% (83) vs 8% (177), p<0.001 for all), including those with ≥moderate CTCA stenosis undergoing ICA (53% (79) vs 61% (166); p<0.001). CONCLUSIONS: Women referred for a NICE CG95 (2016) CTCA are more likely to have normal coronary arteries and men more likely to have CAD. More men than women will then undergo ICA and revascularisation even after adjustments for CTCA disease severity. Raised awareness of these inequalities may improve contemporary chest pain care.

Computational instantaneous wave-free ratio (IFR) for patient-specific coronary artery stenoses using 1D network models.

In this work, we estimate the diagnostic threshold of the instantaneous wave-free ratio (iFR) through the use of a one-dimensional haemodynamic framework. To this end, we first compared the computed fractional flow reserve (cFFR) predicted from a 1D computational framework with invasive clinical measurements. The framework shows excellent promise and utilises minimal patient data from a cohort of 52 patients with a total of 66 stenoses. The diagnostic accuracy of the cFFR model was 75.76%, with a sensitivity of 71.43%, a specificity of 77.78%, a positive predictive value of 60%, and a negative predictive value of 85.37%. The validated model was then used to estimate the diagnostic threshold of iFR. The model determined a quadratic relationship between cFFR and the ciFR. The iFR diagnostic threshold was determined to be 0.8910 from a receiver operating characteristic curve that is in the range of 0.89 to 0.9 that is normally reported in clinical studies.

Challenges in delivering computed tomography coronary angiography as the first-line test for stable chest pain.

OBJECTIVE: The National Institute for Health and Care Excellence (NICE) clinical guidelines 'chest pain of recent onset: assessment and diagnosis' (update 2016) state CT coronary angiography (CTCA) should be offered as the first-line investigation for patients with stable chest pain. However, the current provision in the UK is unknown. We aimed to evaluate this and estimate the requirements for full implementation of the guidelines including geographical variation. Ancillary aims included surveying the number of CTCA-capable scanners and accredited practitioners in the UK. METHODS: The number of CTCA scans performed annually was surveyed across the National Health Service (NHS). The number of percutaneous coronary interventions performed for stable angina in the NHS in 2015 was applied to a model based on SCOT-HEART (CTCA in patients with suspected angina due to coronary heart disease: an open-label, parallel-group, multicentre trial) data to estimate the requirement for CTCA, for full guideline implementation. Details of CTCA-capable scanners were obtained from manufacturers and formally accredited practitioner details from professional societies. RESULTS: An estimated 42 340 CTCAs are currently performed annually in the UK. We estimate that 350 000 would be required to fully implement the guidelines. 304 CTCA-capable scanners and 198 accredited practitioners were identified. A marked geographical variation between health regions was observed. CONCLUSIONS: This study provides insight into the scale of increase in the provision of CTCA required to fully implement the updated NICE guidelines. A small specialist workforce and limited number of CTCA-capable scanners may present challenges to service expansion.

The RAPID-CTCA trial (Rapid Assessment of Potential Ischaemic Heart Disease with CTCA) - a multicentre parallel-group randomised trial to compare early computerised tomography coronary angiography versus standard care in patients presenting with suspected or confirmed acute coronary syndrome: study protocol for a randomised controlled trial.

BACKGROUND: Emergency department attendances with chest pain requiring assessment for acute coronary syndrome (ACS) are a major global health issue. Standard assessment includes history, examination, electrocardiogram (ECG) and serial troponin testing. Computerised tomography coronary angiography (CTCA) enables additional anatomical assessment of patients for coronary artery disease (CAD) but has only been studied in very low-risk patients. This trial aims to investigate the effect of early CTCA upon interventions, event rates and health care costs in patients with suspected/confirmed ACS who are at intermediate risk. METHODS/DESIGN: Participants will be recruited in about 35 tertiary and district general hospitals in the UK. Patients ≥18 years old with symptoms with suspected/confirmed ACS with at least one of the following will be included: (1) ECG abnormalities, e.g. ST-segment depression >0.5 mm; (2) history of ischaemic heart disease; (3) troponin elevation above the 99th centile of the normal reference range or increase in high-sensitivity troponin meeting European Society of Cardiology criteria for 'rule-in' of myocardial infarction (MI). The early use of ≥64-slice CTCA as part of routine assessment will be compared to standard care. The primary endpoint will be 1-year all-cause death or recurrent type 1 or type 4b MI at 1 year, measured as the time to such event. A number of secondary clinical, process and safety endpoints will be collected and analysed. Cost effectiveness will be estimated in terms of the lifetime incremental cost per quality-adjusted life year gained. We plan to recruit 2424 (2500 with ~3% drop-out) evaluable patients (1212 per arm) to have 90% power to detect a 20% versus 15% difference in 1-year death or recurrent type 1 MI or type 4b MI, two-sided p < 0.05. Analysis will be on an intention-to-treat basis. The relationship between intervention and the primary outcome will be analysed using Cox proportional hazard regression adjusted for study site (used to stratify the randomisation), age, baseline Global Registry of Acute Coronary Events score, previous CAD and baseline troponin level. The results will be expressed as a hazard ratio with the corresponding 95% confidence intervals and p value. DISCUSSION: The Rapid Assessment of Potential Ischaemic Heart Disease with CTCA (RAPID-CTCA) trial will recruit 2500 participants across about 35 hospital sites. It will be the first study to investigate the role of CTCA in the early assessment of patients with suspected or confirmed ACS who are at intermediate risk and including patients who have raised troponin measurements during initial assessment. TRIAL REGISTRATION: ISRCTN19102565 . Registered on 3 October 2014. ClinicalTrials.gov: NCT02284191.

Assessment of the myocardium with cardiac computed tomography.

The imaging of myocardial disease is of increasing importance for cardiologists from all subspecialties, for diagnosis, risk stratification, or to facilitate therapy. While the gold standard modalities for such assessment are cardiac magnetic resonance and echocardiography, these are not universally suitable. Cardiac computed tomography (CT), well-established for the assessment of coronary artery disease (CAD), can be of value in the assessment of myocardial pathology, due to excellent patient compatibility and tolerability, high spatial resolution, and acceptable tissue characterization. This review considers the value and limitations of CT in the assessment of the myocardial sequelae of CAD, and for patients with a variety of other cardiomyopathic diseases, depicts some of the common findings, and considers current developments in this area.

Image comparative assessment using iterative reconstructions: clinical comparison of low-dose abdominal/pelvic computed tomography between adaptive statistical, model-based iterative reconstructions and traditional filtered back projection in 65 patients.

OBJECTIVES: The objective of this study was to compare image quality (objective and subjective parameters) and confidence in lesion detection between 3 image reconstruction algorithms in computed tomographic (CT) examinations of the abdomen/pelvis. MATERIALS AND METHODS: This prospective institutional review board-approved study included 65 patients (mean [SD] age, 71.3 ± 9 years; mean [SD] body mass index, 24.4 [4.8] kg) who underwent routine CT examinations of the abdomen/pelvis followed immediately by 2 low-dose scans. Raw data sets were reconstructed by using filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and a model-based iterative reconstruction (MBIR). Measurements of objective noise and CT numbers were compared using repeated-measures analysis of variance. Six subjective image quality parameters were scored. Diagnostic confidence and accuracy in detection of various elementary lesions were performed. RESULTS: Objectively, mean image noise for MBIR was significantly superior at all dose levels (P < 0.001). Subjectively, standard-dose ASIR and low-dose MBIR scans were better than standard-dose FBP scan in all parameters assessed (P < 0.05). Low-dose MBIR scans were comparable with standard-dose ASIR scans in all parameters except at noise index of 70 (approximately 85% dose reduction), where, in this case, the detection of liver lesions less than 5 mm were rated inferior (P < 0.05) with diagnostic accuracy reducing to 77.4%. CONCLUSIONS: Low-dose MBIR scan shows superior objective noise reduction compared with standard-dose FBP and ASIR. Subjectively, low-dose MBIR scans at 76% dose reduction were also superior compared with standard-dose FBP and ASIR. However, at dose reductions of 85%, small liver lesions may be missed.

Image quality assessment of standard- and low-dose chest CT using filtered back projection, adaptive statistical iterative reconstruction, and novel model-based iterative reconstruction algorithms.

OBJECTIVE: The purpose of this article is to compare image quality between filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and model-based iterative reconstruction (MBIR) at standard dose and two preselected low-dose scans. SUBJECTS AND METHODS: Thirty patients (16 men and 14 women; mean age, 67 years) were prospectively recruited. Patients underwent three scans (one standard-dose scan and two low-dose scans at noise indexes [NIs] of 33, 60, and 70, respectively). All three scans were reconstructed with FBP, ASIR, and MBIR. Objective and subjective image qualities were compared. Dose-length products and effective doses for each scans were recorded. Mean image noise and attenuation values were compared between different reconstruction algorithms using repeated-measures analysis of variance and paired Student t tests. The interobserver variation between the two radiologists for subjective image quality and lesion assessment was estimated by using weighted kappa statistics. RESULTS: Objective image analysis supports significant noise reduction with low-dose scans using the MBIR technique (p < 0.05). There was no significant change in mean CT numbers between different reconstructions (p > 0.05). Subjective analysis reveals no significant difference between image quality and diagnostic confidence between low-dose MBIR scans compared with standard-dose scans reconstructed using ASIR (p > 0.05). Average effective doses were 3.7, 1.2, and 0.9 mSv for standard scans at NIs of 33, 60, and 70, respectively. CONCLUSION: MBIR shows superior noise reduction and improved image quality. Substantial dose reduction can be achieved by increasing the NI parameters as tested in this study without affecting image quality and diagnostic confidence.

Assessment of image quality on effects of varying tube voltage and automatic tube current modulation with hybrid and pure iterative reconstruction techniques in abdominal/pelvic CT: a phantom study.

OBJECTIVES: The objective of this study was to compare image quality on abdominal/pelvic computed tomographic images acquired with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and novel model-based iterative reconstruction (MBIR) techniques with varying levels of automatic tube current modulation and tube voltages. METHODS: A 2-phase study was performed. In phase 1, a torso phantom was scanned at 17 different noise levels of automatic current modulation (selected using noise index [NI]) at 120 kilovolt (peak) (kVp). Images reconstructed with FBP, ASIR, and MBIR underwent objective analysis. In phase 2, additional scans were performed at 3 different kVp (80, 100, and 120 kVp at 3 different NIs (33, 50, and 70). Objective and subjective image qualities were assessed. Computed tomography dose index and dose-length products were recorded. RESULTS: The objective image analysis supports significant noise reduction with MBIR compared with ASIR and FBP (P < 0.05) at all 17 NI tested at 120 kVp. When lowering the kVp, the subjective image quality was improved, but when this is performed in conjunction with increasing NI, image quality was maintained only at moderately high NI of 50 but was degraded at higher NIs despite improving contrast-to-noise ratio. CONCLUSIONS: Our results represent the first exploration in the utility of MBIR technique with alteration of kVp in conjunction with tube current modulation in comparison with traditional methods. Objective image noise for MBIR is superior. Subjective image quality is only moderately improved. Scanning at low kVp and moderately high NI with MBIR can ensure that a balance of improved image noise and contrast can be achieved as well as reducing dose.

Image Quality Assessment in Torso Phantom Comparing Effects of Varying Automatic Current Modulation with Filtered Back Projection, Adaptive Statistical, and Model-Based Iterative Reconstruction Techniques in CT.

OBJECTIVES: To compare image quality on computed tomographic (CT) images acquired with different levels of automatic tube current modulation reconstructed with filtered back projection (FBP), adaptive statistical iterative reconstruction (ASIR), and novel model-based iterative reconstruction (MBIR) techniques. METHODS: A torso phantom was scanned at 17 different noise levels of automatic current modulation and images were reconstructed with FBP, ASIR, and MBIR. Objective and subjective image qualities were assessed. Effective dose was also calculated. RESULTS: Objective image analysis supports significant noise reduction and superior contrast to noise ratio with new a MBIR technique. Subjective image parameters were maximally rated for MBIR followed by ASIR then FBP. The reconstruction algorithms were evaluated over effective doses ranging from 0.7 to 3 mSv. CONCLUSION: MBIR shows superior reduction in noise and improved image quality (both objective and subjective analysis) compared with ASIR and FBP. It was possible to achieve meaningful image quality even at the highest noise index of 70 achieving substantial dose reduction to as low as 0.7 mSv.

Morphologic assessment of patent ductus arteriosus in adults using retrospectively ECG-gated multidetector CT.

OBJECTIVE: Noninvasive imaging of a persistently patent ductus arteriosus in adults remains a challenge. Bearing in mind the excellent spatial resolution provided by multidetector CT (MDCT), we postulated that MDCT might be used to evaluate this anatomic defect. We sought to show that MDCT can depict in detail patent ductus arteriosus in adults and allow determination of the size of the duct, degree of calcification, and morphologic classification. CONCLUSION: MDCT represents a novel method of noninvasively assessing patent ductus arteriosus in adults that provides detailed anatomic information. Comparison with invasive angiographic findings is needed to validate the technique of sizing of ducts using MDCT.