Artificial intelligence in Medicare: utilization, spending, and access to AI-enabled clinical software.

OBJECTIVES: In 2018, CMS established reimbursement for the first Medicare-covered artificial intelligence (AI)-enabled clinical software: CT fractional flow reserve (FFRCT) to assist in the diagnosis of coronary artery disease. This study quantified Medicare utilization of and spending on FFRCT from 2018 through 2022 and characterized adopting hospitals, clinicians, and patients. STUDY DESIGN: Analysis, using 100% Medicare fee-for-service claims data, of the hospitals, clinicians, and patients who performed or received coronary CT angiography with or without FFRCT. METHODS: We measured annual trends in utilization of and spending on FFRCT among hospitals and clinicians from 2018 through 2022. Characteristics of FFRCT-adopting and nonadopting hospitals and clinicians were compared, as well as the characteristics of patients who received FFRCT vs those who did not. RESULTS: From 2018 to 2022, FFRCT billing volume in Medicare increased more than 11-fold (from 1083 to 12,363 claims). Compared with nonbilling hospitals, FFRCT-billing hospitals were more likely to be larger, part of a health system, nonprofit, and financially profitable. FFRCT-billing clinicians worked in larger group practices and were more likely to be cardiac specialists. FFRCT-receiving patients were more likely to be male and White and less likely to be dually enrolled in Medicaid or receiving disability benefits. CONCLUSIONS: In the initial 5 years of Medicare reimbursement for FFRCT, growth was concentrated among well-resourced hospitals and clinicians. As Medicare begins to reimburse clinicians for the use of AI-enabled clinical software such as FFRCT, it is crucial to monitor the diffusion of these services to ensure equal access.

Comparison of Risk Assessment Strategies for Patients with Diabetes Mellitus and Stable Chest Pain: A Coronary Computed Tomography Angiography Study.

BACKGROUND: To compare two risk assessment strategies to identify individuals likely to benefit from further imaging testing in patients with diabetes mellitus (DM) and stable chest pain (SCP) suspected of obstructive coronary artery disease (CAD). METHODS: 602 DM patients referred to coronary computed tomography angiography (CCTA) for SCP were included. They were divided into high- and low-risk groups according to the 2016 National Institute of Health and Care Excellence guideline-determined strategy (NICE strategy) which focused on symptom evaluation and 2019 European Society of Cardiology guideline-determined strategy (ESC strategy) which was based on pretest probability (PTP) sequentially determined by the ESC-PTP estimator and risk factor-weighted clinical likelihood (RF-CL) model, respectively. The associations of clinical outcomes with risk groups and net reclassification improvement (NRI) were evaluated. RESULTS: The NICE and ESC strategy classified 44% and 39% patients into the low-risk group, respectively. Compared to the NICE strategy, the ESC strategy indicated stronger associations between risk groups and events (hazard ratios: 4.24 versus 1.91), intensive clinical management, and a positive NRI (27.71%, p < 0.0001). The application of the RF-CL model ameliorated the underestimation of risk in patients with borderline ESC-PTP, which principally account for the improvement of the ESC strategy. CONCLUSION: Compared to the NICE strategy, the ESC strategy seemed to be associated with greater efficiency in identifying high risk individuals in patients with DM and SCP.

Simultaneous assessment of coronary stenosis relevance with automated computed tomography angiography and intravascular ultrasound analyses and fractional flow reserve.

OBJECTIVES: To assess the diagnostic performance of computed tomography angiography (CTA) and intravascular ultrasound (IVUS) derived minimum lumen areas (MLA) from the same lesions that correspond to an FFR ≤0.80. METHODS AND RESULTS: A total of 24 patients (33 arteries) were collected retrospectively according to the following inclusion criteria: presence of a CTA diagnostic followed by an IVUS and FFR percutaneous coronary procedures. CTA and IVUS lumen contours were automatically performed using previously validated methods.The correlation between CTA and IVUS for the MLA was r = 0.45. In terms of MLA, the mean difference between CTA and IVUS was 0.81 mm2. Of note, a much smaller CTA-derived MLA (2.10 mm2) was found to be related to significant FFR lesions compared to that of the MLA derived from IVUS (3.19 mm2). The area under the curve, accuracy, sensitivity and specificity for this CTA-derived MLA were 0.80, 0.76, 0.50 and 0.87, respectively, while these values for IVUS-derived MLA were 0.87, 0.85, 0.80 and 0.87. CONCLUSIONS: Computed tomography angiography and intravascular ultrasound-derived minimum lumen areas have moderate diagnostic efficiency, albeit slightly better for IVUS, in identifying hemodynamically severe coronary stenoses. The utility of MLA, automatically derived from either CTA or IVUS as an alternative to FFR to guide the decision to revascularize, should be tested clinically.

Clinical management and primary prevention of suspected coronary artery disease guided by computed tomography.

AIMS: Despite the well established role of coronary computed tomography angiography (CCTA) as a diagnostic gatekeeper, the yield of subsequent invasive coronary angiographies (ICA) remains low. We evaluated the adherence of CCTA integration in clinical management and primary prevention therapy. METHODS: We retrospectively analyzed patients referred for ICA after CCTA without known coronary artery disease (CAD) or structural cardiac pathologies. Based on computed tomography (CT) findings, patients were classified as appropriately or inappropriately referred to ICA, equaling Coronary Artery Disease - Reporting and Data System (CAD-RADS) categories 0-2 (<50% stenosis) and 3-5 (>50% stenosis), respectively. CT exams were compared regarding invasive findings and revascularizations. Integration of CT results into primary prevention measures was analyzed and compared to measures taken after ICA. RESULTS: Of 1005 patients referred for ICA, 81 (8.1%) had no obstructive CT findings and therefore no ICA indication. ICA inappropriate patients did not differ in symptom characteristics, but had a significantly lower revascularization rate (3.7% vs. 42.1%, P < 0.0001) compared with patients appropriately referred to ICA. In patients with indication for lipid-lowering therapy after the CCTA statin rate was 53.1% and significantly increased after ICA to 76.4% (P < 0.0001). In CCTA, obstructive findings in proximal-only lesions did not increase the revascularization rate (45.6% vs. 42.1%, P = 0.11) but missed nonproximal relevant stenoses (15.0% vs. 2.5%, P < 0.0001) compared with obstructive findings in all segments. CONCLUSION: The overall rate of inappropriateness was low, but there is relevant statin underutilization in eligible patients due to a lack of CT findings integration. Both ICA referrals and primary preventive therapy could be improved by the implementation of CT results based on CAD-RADS recommendations.

Assessment of Coronary Artery Disease With Computed Tomography Angiography and Inflammatory and Immune Activation Biomarkers Among Adults With HIV Eligible for Primary Cardiovascular Prevention.

Importance: Cardiovascular disease (CVD) is increased among people with HIV (PWH), but little is known regarding the prevalence and extent of coronary artery disease (CAD) and associated biological factors in PWH with low to moderate traditional CVD risk. Objectives: To determine unique factors associated with CVD in PWH and to assess CAD by coronary computed tomography angiography (CTA) and critical pathways of arterial inflammation and immune activation. Design, Setting, and Participants: This cohort study among male and female PWH, aged 40 to 75 years, without known CVD, receiving stable antiretroviral therapy, and with low to moderate atherosclerotic cardiovascular disease (ASCVD) risk according to the 2013 American College of Cardiology/American Heart Association pooled cohort equation, was part of the Randomized Trial to Prevent Vascular Events in HIV (REPRIEVE), a large, ongoing primary prevention trial of statin therapy among PWH conducted at 31 US sites. Participants were enrolled from May 2015 to February 2018. Data analysis was conducted from May to December 2020. Exposure: HIV disease. Main Outcomes and Measures: The primary outcome was the prevalence and composition of CAD assessed by coronary CTA and, secondarily, the association of CAD with traditional risk indices and circulating biomarkers, including insulin, monocyte chemoattractant protein 1 (MCP-1), interleukin (IL) 6, soluble CD14 (sCD14), sCD163, lipoprotein-associated phospholipase A2 (LpPLA2), oxidized low-density lipoprotein (oxLDL), and high-sensitivity C-reactive protein (hsCRP). Results: The sample included 755 participants, with a mean (SD) age of 51 (6) years, 124 (16%) female participants, 267 (35%) Black or African American participants, 182 (24%) Latinx participants, a low median (interquartile range) ASCVD risk (4.5% [2.6%-6.8%]), and well-controlled viremia. Overall, plaque was seen in 368 participants (49%), including among 52 of 175 participants (30%) with atherosclerotic CVD (ASCVD) risk of less than 2.5%. Luminal obstruction of at least 50% was rare (25 [3%]), but vulnerable plaque and high Leaman score (ie, >5) were more frequently observed (172 of 755 [23%] and 118 of 743 [16%], respectively). Overall, 251 of 718 participants (35%) demonstrated coronary artery calcium score scores greater than 0. IL-6, LpPLA2, oxLDL, and MCP-1 levels were higher in those with plaque compared with those without (eg, median [IQR] IL-6 level, 1.71 [1.05-3.04] pg/mL vs 1.45 [0.96-2.60] pg/mL; P = .008). LpPLA2 and IL-6 levels were associated with plaque in adjusted modeling, independent of traditional risk indices and HIV parameters (eg, IL-6: adjusted odds ratio, 1.07; 95% CI, 1.02-1.12; P = .01). Conclusions and Relevance: In this study of a large primary prevention cohort of individuals with well-controlled HIV and low to moderate ASCVD risk, CAD, including noncalcified, nonobstructive, and vulnerable plaque, was highly prevalent. Participants with plaque demonstrated higher levels of immune activation and arterial inflammation, independent of traditional ASCVD risk and HIV parameters.

Higher prevalence of incidental findings identified upon coronary calcium score assessment in type 2 and type 3 diabetes versus type 1 diabetes.

AIM: Noninvasive assessment of infraclinic coronary atherosclerosis by coronary artery calcium score (CAC) measurement leads to the identification of incidental findings. The aim of this study was to determine the prevalence of incidental findings following systematic CAC assessment in diabetic patients with high cardiovascular risk, to identify the determinants, and to assess the midterm consequences of these findings in patient care. METHODS: 732 consecutive asymptomatic patients (187 type 1 diabetes (TD1), 482 type 2 diabetes (TD2) and 63 type 3 diabetes (TD3)) aged 60.6±0.7 years who had a CAC assessment by Multiple Detector Computed Tomography between 2015 and 2017 were systematically included. Clinical and biological data were collected from medical electronic files. RESULTS: 117/732 diabetic patients (16.0%) had incidental findings of which 105 (14.3%) were unknown. Incidental findings were more frequent in TD3 (23.8%) and TD2 (17.0%) than in TD1 (10.7%) (p = 0.05). 76 diabetic patients (10.4%) had lung abnormalities, mainly pulmonary nodules (31 patients, 4.2%). The other incidental finding were pericardial (1.5%), vascular (1.2%), thymic (0.7%) and digestive diseases (0.5%). 42.6% of patients with incidental findings had an additional TDM and 56.8% a specialized medical advice. In 10 patients (9.3% of incidental findings), the identification of incidental finding led to a specific treatment of the underlying disease. In multivariate analysis, microalbuminuria, type of diabetes (TD2/TD3 vs TD1) and smoking were significantly associated with incidental findings (p = 0.003; p = 0.026; p = 0.050 respectively). CONCLUSIONS: Incidental findings are not rare in diabetic patients upon CAC assessment. A fraction of them are accessible to specific treatment. These findings raise the question if a systematic low dose chest TDM should be conducted in TD2 or TD3 patients and in any diabetic smokers by enlarging the window used for CAC assessment.

Combined assessment of subtended myocardial volume and myocardial blood flow for diagnosis of obstructive coronary artery disease using cardiac computed tomography: A feasibility study.

BACKGROUND: This study aimed to evaluate the combined diagnostic performance of coronary artery stenosis-subtended myocardial volume (Vsub) and myocardial blood flow (MBFsub) on computed tomography (CT) for detecting obstructive coronary artery disease (CAD) assessed by invasive coronary angiography (ICA) and fractional flow reserve (FFR). METHODS: Thirty-nine patients who underwent coronary CT angiography (CTA) and stress dynamic myocardial CT perfusion (CTP) prior to ICA were enrolled. Obstructive CAD was defined as severe (≥70%) or moderate (30-69%) stenosis with FFR ≤0.8 on ICA. The Vsub was semi-automatically calculated from coronary CTA data using Voronoi diagram-based myocardial segmentation. The standard CT-MBF based on the 17-segment model was calculated using dynamic stress CTP data and deconvolution analysis. The CT-MBFsub was automatically analyzed by integrating the CT-MBF and Voronoi diagram-based myocardial segmentation analyses. The diagnostic performance of combined CT-MBFsub and Vsub assessment was determined using receiver operating characteristic analysis and compared with standard CT-MBF and CT-MBFsub. RESULTS: Of 117 vessels in 39 patients, 72 vessels were suspected of significant stenosis on CTA and 33 vessels had obstructive CAD on ICA and FFR. The sensitivity and specificity for identifying obstructive CAD were 67% and 82% for standard CT-MBF, 70% and 77% for CT-MBFsub, and 85% and 82% for combined CT-MBFsub and Vsub assessment. The area under the receiver operating characteristic curve of the combined CT-MBFsub and Vsub assessment was significantly higher than those of standard CT-MBF and CT-MBFsub (0.89 vs. 0.75, 0.77; p<0.05). CONCLUSIONS: The Vsub may aid in increasing the diagnostic performance of CT-MBFsub for detecting obstructive CAD.

Clinical and Economic Implications of Inconclusive Noninvasive Test Results in Stable Patients With Suspected Coronary Artery Disease: Insights From the PROMISE Trial.

BACKGROUND: Inconclusive noninvasive tests complicate the care of patients with suspected coronary artery disease, but their prevalence and impact on management, outcomes, and costs are not well described. METHODS: PROMISE (Prospective Multicenter Imaging Study for Evaluation of Chest Pain) patients were randomized to stress testing (n=4533) or computed tomographic angiography (CTA; n=4677). We assessed relationships between inconclusive results, subsequent testing, a composite outcome (death, myocardial infarction, or hospitalization for unstable angina), and healthcare expenditures. RESULTS: Overall, 8.0% of tests were inconclusive (9.7% stress, 6.4% CTA). Compared with negative tests, inconclusive tests were more often referred to a second noninvasive test (stress: 14.6% versus 8.5%, odds ratio [OR], 1.91; CTA: 36.5% versus 8.4%, OR, 5.95; P<0.001) and catheterization (stress: 5.5% versus 2.4%, OR, 2.36; CTA: 23.4% versus 4.1%, OR, 6.49; P<0.001), and composite outcomes were higher for both inconclusive tests (stress: 3.7% versus 2.0%, hazard ratio, 1.81, P=0.034; CTA: 5.0% versus 2.2%, hazard ratio, 1.85; P=0.044) and positive tests (stress: 8.3% versus 2.0%, hazard ratio, 3.50; CTA: 9.2% versus 2.2%, hazard ratio, 3.66; P<0.001). Twenty-four-month costs were higher for inconclusive tests than negative tests by $2905 (stress) and $4030 (CTA). CONCLUSIONS: Among patients with stable chest pain undergoing a noninvasive test, inconclusive results occurred in 6% of CTA and 10% of stress tests. Compared with those with conclusive negative tests, individuals with inconclusive results more often underwent subsequent testing, had increased medical costs, and experienced worse outcomes. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01174550.

Assessment of persistent fifth aortic arch by echocardiography and computed tomography angiography.

To evaluate the utility of echocardiography (echo) in the diagnosis of persistent fifth aortic arch (PFAA), a very rare congenital aortic arch anomaly, and to compare echo and computed tomography angiography (CTA) imaging findings to improve our understanding of this anomaly.Data on the clinical diagnosis, imaging findings, and clinical management of PFAA were retrospectively analyzed in 10 suspected cases of PFAA admitted to our hospital between January 2012 and February 2017. We compared echo as a first line examination modality, and CTA and surgery results as the gold standard. Weinberg's classification was used to classify the type of PFAA.All patients (100%) received echo examination, eight patients (80%) received CTA examination, and four patients (40%) received sternotomy surgery; all recovered well after surgery. According to Weinberg's classification, 2, 6, and 2 cases (20%, 60%, and 20%) were classified as Type A, B, and C, respectively. Echo was able to diagnose 5 cases of PFAA (1 Type A case and 4 Type B cases) in the first instance. The diagnostic conformance rate of echo was 62.5% after comparisons with CTA and surgery results.The clinical manifestation of PFAA was atypical, and its diagnosis depended primarily on medical imaging. Echo has a relatively high diagnostic accuracy for PFAA, which is very valuable for its early detection.

In-Hospital Cost Comparison of Triple-Rule-Out Computed Tomography Angiography Versus Standard of Care in Patients With Acute Chest Pain.

PURPOSE: The purpose of this study was to evaluate the utilization of invasive and noninvasive tests and compare cost in patients presenting with chest pain to the emergency department (ED) who underwent either triple-rule-out computed tomography angiography (TRO-CTA) or standard of care. MATERIALS AND METHODS: We performed a retrospective single-center analysis of 2156 ED patients who presented with acute chest pain with a negative initial troponin and electrocardiogram for myocardial injury. Patient cohorts matched by patient characteristics who had undergone TRO-CTA as a primary imaging test (n=1139) or standard of care without initial CTA imaging (n=1017) were included in the study. ED visits, utilization of tests, and costs during the initial episode of hospital care were compared. RESULTS: No significant differences in the diagnosis of coronary artery disease, pulmonary embolism, or aortic dissection were observed. Median ED waiting time (4.5 vs. 7.0 h, P<0.001), median total length of hospital stay (5.0 vs. 32.0 h, P<0.001), hospital admission rate (12.6% vs. 54.2%, P<0.001), and ED return rate to our hospital within 30 days (3.5% vs. 14.6%, P<0.001) were significantly lower in the TRO-CTA group. Moreover, reduced rates of additional testing and invasive coronary angiography (4.9% vs. 22.7%, P<0.001), and ultimately lower total cost per patient (11,783$ vs. 19,073$, P<0.001) were observed in the TRO-CTA group. CONCLUSIONS: TRO-CTA as an initial imaging test in ED patients presenting with acute chest pain was associated with shorter ED and hospital length of stay, fewer return visits within 30 days, and ultimately lower ED and hospitalization costs.

CT Angiography for Triage of Patients with Acute Minor Stroke: A Cost-effectiveness Analysis.

Background Minor stroke is common and may represent up to two-thirds of cases of acute ischemic stroke. The cost-effectiveness of CT angiography in patients with minor stroke (National Institutes of Health Stroke Scale [NIHSS] score ≤6) is not well established. Purpose To evaluate cost-effectiveness of CT angiography in the detection of large-vessel occlusion (LVO) in patients with acute minor stroke (NIHSS score ≤6). Materials and Methods A Markov decision-analytic model with a societal perspective was constructed. Three different management strategies were evaluated: (a) no vascular imaging and best medical management, (b) CT angiography for all patients and immediate thrombectomy for LVO after intravenous thrombolysis, and (c) CT angiography for all and best medical management (including intravenous thrombolysis, with rescue thrombectomy for patients with LVO and neurologic deterioration). One-way, two-way, and probabilistic sensitivity analyses were performed. Results Base-case calculation showed that CT angiography followed by immediate thrombectomy had the lowest cost ($346 007) and highest health benefits (9.26 quality-adjusted life-years [QALYs]). CT angiography followed by best medical management with possible rescue thrombectomy for patients with LVO had a slightly higher cost ($346 500) and lower health benefits (9.09 QALYs). No vascular imaging had the highest cost and lowest health benefits. The difference in health benefits compared with the CT angiography and immediate thrombectomy strategy was 0.39 QALY, which corresponds to 142 days in perfect health per patient. The conclusion was robust in a probabilistic sensitivity analysis. CT angiography was cost-effective when the probability of LVO was greater than 0.16% in patients with acute minor stroke. The net monetary benefit of performing CT angiography was higher in younger patients ($68 950 difference between CT angiography followed by immediate thrombectomy and no vascular imaging in 55-year-old patients compared with $20 931 in 85-year-old patients). Conclusion Screening for large-vessel occlusion with CT angiography in patients with acute minor stroke is cost-effective and associated with improved health outcomes. Undetected large-vessel occlusion in the absence of vascular imaging results in worse health outcomes and higher costs. © RSNA, 2020 Online supplemental material is available for this article.

Medicaid expansion and resource utilization in the emergency department.

BACKGROUND: The Affordable Care Act (ACA) has impacted the insurance mix of emergency department (ED) visits, yet the degree to which this has influenced provider behavior is not clear. METHODS: This was a difference-in-differences (DID) analysis of ED-visit data from five states in 2013 and 2014. Sample states included 3 expanding Medicaid under the ACA, 1 rejecting ACA funding and delaying an eligibility expansion, and 1 with no eligibility change. We included self-pay and Medicaid patients aged 27 to 64 years. A subsample analysis was done for chest pain visits. DID logistic models were estimated for likelihood of admission for given Medicaid-paid ED visits in expansion states as compared to non-expansion states. Among chest pain visits we assessed likelihood given visits resulted in admission or advanced cardiac imaging, where clinician discretion may be more significant. RESULTS: A total of 8,157,748 ED visits with primary payer Medicaid and self-pay were included, of which 331,422 were for chest pain. The proportion of visits paid for by Medicaid rose in expansion states by between 15.8% and 38.9%. Medicaid eligibility expansion was associated with increased odds of admission (OR 1.070 [95% CI 1.051-1.089]). Among chest pain visits, expansion was associated with increased odds of admission (OR 1.294 [95% CI 1.144-1.464]), but not advanced cardiac imaging (OR 1.099 [95% CI 0.983-1.229]). CONCLUSION: Medicaid expansion was associated with small increases in ED visit admissions across the board and among the subgroup of patients presenting with chest pain.

Assessment of CT angiographic findings in comparison with echocardiography findings of chest among patients with aortic arch anomalies.

The objective of this study was to examine the findings of computed tomographic (CT) angiography in patients with aortic arch anomalies in comparison with transthoracic echocardiography findings who referred to a private imaging center in Tehran during 2009-2012. The cases included 203 patients with clinical symptoms or echocardiogram of congenital heart disease to assess the presence of aortic arch anomalies among patients referred to imaging center. This study is a retrospective study based on the CT angiographic findings in comparison with transthoracic echocardiography findings of chest among patients with aortic arch anomalies. In this study, 203 patients with congenital anomalies were enrolled in the study, among those, 107 patients were men and 96 were female. The most common anomaly of the aortic arch was found to be coarctation (19.7%), followed by right sided arch with mirror image branching (19.2%). Furthermore, the most common cardiac anomalies associated with aortic arch anomalies were VSD, PA and PDA. The sensitivity and specificity of transthoracic echocardiography in the diagnosis of aortic arch anomalies was 59% and 100% in comparison with CT angiography. In addition, the agreement between the two methods (kappa) in the diagnosis of aortic arch anomalies was 0.72. But, transthoracic echocardiography is the first diagnostic method for patients with congenital heart disease. In some patients, the ability of this method was limited to the detection of coronary artery anomalies and thoracic vessels. Therefore, CT is used for morphological evaluation of congenital heart disease (CHD) due to its main advantages including fast acquisition time, large anatomical coverage, high speed, and great spatial resolution. Moreover, CT is essential for proper evaluation of CHD regarding its high spatial and temporal resolution.

The DAGMAR Score: D-dimer assay-guided moderation of adjusted risk. Improving specificity of the D-dimer for pulmonary embolism.

We generated a novel scoring system to improve the test characteristics of D-dimer in patients with suspected PE (pulmonary emboli). Electronic Medical Record data were retrospectively reviewed on Emergency Department (ED) patients 18 years or older for whom a D-dimer and imaging were ordered between June 4, 2012 and March 30, 2016. Symptoms (dyspnea, unilateral leg swelling, hemoptysis), age, vital signs, medical history (cancer, recent surgery, medications, history of deep vein thrombosis or PE, COPD, smoking), laboratory values (quantitative D-dimer, platelets, and mean platelet volume (MPV)), and imaging results (CT, VQ) were collected. Points were designated to factors that were significant in two multiple regression analyses, for PE or positive D-dimer. Points predictive of PE were designated positive values and points predictive of positive D-dimer, irrespective of presence of PE, were designated negative values. The DAGMAR (D-dimer Assay-Guided Moderation of Adjusted Risk) score was developed using age and platelet adjustment and points for factors associated with PE and elevated D-dimer. Of 8486 visits reviewed, 3523 were unique visits with imaging, yielding 2253 (26.5%) positive D-dimers. 3501 CT scans and 156 VQ scans were completed, detecting 198 PE. In our cohort, a DAGMAR Score < 2 equated to overall PE risk < 1.2%. Specificity improved (38% to 59%) without compromising sensitivity (94% to 96%). Use of the DAGMAR Score would have reduced CT scans from 2253 to 1556 and lead to fewer false negative results. By considering factors that affect D-dimer and also PE, we improved specificity without compromising sensitivity.

Coronary CT Angiography: Reversal of Earlier Utilization Trends.

PURPOSE: To assess recent trends in utilization of coronary CT angiography (CCTA), based upon place of service and provider specialty. MATERIALS AND METHODS: The nationwide Medicare Part B master files for 2006 through 2016 were the data source. Current Procedural Terminology, version 4 codes for CCTA were selected. The files provided procedure volume for each code. Utilization rates per 100,000 Medicare fee-for-service enrollees were then calculated. Medicare's place-of-service codes were used to identify CCTAs performed in private offices, hospital outpatient departments (HOPDs), emergency departments (EDs), and inpatient settings. Physician specialty codes were used to identify CCTAs interpreted by radiologists, cardiologists, and all other physicians as a group. Medicare practice share was defined as the percent of total Medicare utilization that was billed by each specialty. RESULTS: The total utilization rate of CCTA in the Medicare population rose sharply from 2006 to 2007, peaking at 210.3 per 100,000 enrollees in 2007. Radiologists' CCTA practice share in 2007 was 32%, compared with 60% for cardiologists. The overall utilization rate then declined to a nadir of 107.1 per 100,000 enrollees in 2013, but subsequently increased to 131.0 by 2016. By that year, radiologists' share of CCTA practice had risen to 58%, compared with 38% for cardiologists. HOPD utilization increased sharply since 2010, primarily among radiologists. In EDs and inpatient settings, greater utilization has also occurred recently, primarily among radiologists. By contrast, private office utilization has dropped sharply since 2007. CONCLUSION: After years of declining utilization, the utilization rate of CCTA is now increasing, predominantly among radiologists.

Increasing utilization of emergency department neuroimaging in Medicare beneficiaries from 1994 to 2015.

OBJECTIVE: To assess for changes in emergency department (ED) utilization of neuroimaging in Medicare fee-for-service beneficiaries from 1994 to 2015. METHODS: Using Medicare Physician Supplier Procedure Summary Master Files, annual ED volumes of head computed tomography (CT), magnetic resonance (MR), and carotid duplex ultrasound (CDUS) were assessed from 1994 through 2015. Annual volumes of head CT angiography (CTA), neck CTA, head MR angiography (MRA), and neck MRA studies were assessed from 2001 (first year of unique reporting codes) through 2015. Longitudinal population-based utilization rates were calculated using annual Medicare Part B enrollment, and utilization rates were normalized annually per 1000 ED visits. RESULTS: From 1994 through 2015, ED neuroimaging utilization rates per 1000 ED visits increased 660% overall (compound annual growth rate [CAGR] 9%); 529% for head CT (CAGR 9%); 1451% for head MRI (CAGR 14%); and by 104% for CDUS (CAGR 3%). From 2001 to 2015, rates increased 14,600% (CAGR 43%) and 17,781% (CAGR 45%) for head and neck CTA, respectively, and 525% (CAGR 14%) and 667% (CAGR 16%) for head and neck MRA, respectively. Trends were similar when volumes were normalized for annual Medicare fee-for-service enrollment. Non-contrast head CT was the most common imaging modality throughout the study period (86% of annual neuroimaging volume in 1994; 89% in 2015). CONCLUSIONS: In Medicare beneficiaries, neuroimaging utilization in the ED grew unabated from 1994 through 2015, with growth of head and neck CTA far outpacing other modalities. Non-contrast head CT remains by far the dominant ED neuroimaging examination.

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 Utility of Contrast Medium Fractional Flow Reserve in Functional Assessment Of Coronary Disease in Daily Practice.

BACKGROUND: Adenosine induced hyperaemic fractional flow reserve (aFFR) is a validated predictor of clinical outcome and part of routine interventional practice. Protocol issues associated with the adenosine infusion limit the use of aFFR in clinical practice. Contrast medium induced hyperaemic FFR (cFFR) is a simpler procedure from a practical standpoint. We compared the two in a real world setting. METHODS: We analysed 76 patients that had both cFFR and aFFR assessment of 100 angiographically indeterminate coronary stenosis. cFFR was performed with intracoronary contrast medium injections (10ml for left coronary lesions and 8ml for right coronary lesions). The diagnostic performance of cFFR was analysed and compared to the gold standard aFFR. RESULTS: Mean cFFR was 0.87 (±0.07) and mean aFFR was 0.84 (±0.08). Bland-Altman analysis revealed a close agreement between cFFR and aFFR (0.035±0.032; 95% CI: -0.028 to 0.098) and good linear correlation (r=0.92, r2=0.86; p<0.0001). Using cFFR cut-off values of ≤0.83 in predicting an aFFR value of ≤0.80 or a cFFR value ≥0.88, predicting an aFFR value of >0.80 yielded a sensitivity of 100%, specificity of 96.1%, positive predictive value of 92.3%, negative predictive value of 100% and diagnostic accuracy of 96%. Only 24% of cFFR values were in the 0.84 to 0.87 range. CONCLUSION: Contrast medium induced hyperaemic FFR as an initial assessment may limit the need for adenosine to when cFFR falls in the 0.84 to 0.87 range. The use of adenosine infusion potentially could have been avoided in the majority of patients in this study.

Age- and sex-based resource utilisation and costs in patients with acute chest pain undergoing cardiac CT angiography: pooled evidence from ROMICAT II and ACRIN-PA trials.

OBJECTIVES: To determine resource utilisation according to age and gender-specific subgroups in two large randomized diagnostic trials. METHODS: We pooled patient-specific data from ACRIN-PA 4005 and ROMICAT II that enrolled subjects with acute chest pain at 14 US sites. Subjects were randomized between a standard work-up and a pathway utilizing cardiac computed tomography angiography (CCTA) and followed for the occurrence of acute coronary syndrome (ACS) and resource utilisation during index hospitalisation and 1-month follow-up. Study endpoints included diagnostic accuracy of CCTA for the detection of ACS as well as resource utilisation. RESULTS: Among 1240 patients who underwent CCTA, negative predictive value of CCTA to rule out ACS remained very high (≥99.4%). The proportion of patients undergoing additional diagnostic testing and cost increased with age for both sexes (p < 0.001), and was higher in men as compared to women older than 60 years (43.1% vs. 23.4% and $4559 ± 3382 vs. $3179 ± 2562, p < 0.01; respectively). Cost to rule out ACS was higher in men (p < 0.001) and significantly higher for patients older than 60 years ($2860-5935 in men, p < 0.001). CONCLUSIONS: CCTA strategy in patients with acute chest pain results in varying resource utilisation according to age and gender-specific subgroups, mandating improved selection for advanced imaging. KEY POINTS: • In this analysis, CAD and ACS increased with age and male gender. • CCTA in patients with acute chest pain results in varying resource utilisation. • Significant increase of diagnostic testing and cost with age for both sexes. • Cost to rule out ACS is higher in men and patients >60 years. • Improved selection of subjects for cardiac CTA result in more resource-driven implementation.

Coronary CT Angiography Derived Fractional Flow Reserve: The Game Changer in Noninvasive Testing.

PURPOSE OF REVIEW: To summarize the scientific basis of CT derived fractional flow reserve (FFRCT) and present an updated review on the evidence from clinical trials and real-world observational data RECENT FINDINGS: In prospective multicenter studies of patients with stable coronary artery disease (CAD), FFRCT showed high diagnostic performance. More recently, FFRCT has advanced to the realm of clinical utility and real-world clinical practice with emerging data showing that FFRCT when compared to standard care is efficient in safely reducing downstream utilization of invasive coronary angiography (ICA), and costs, as well as improving the diagnostic yield of ICA. Moreover, FFRCT may broaden applicability of frontline coronary CTA testing to patients with high pre-test risk of CAD. Introducing FFRCT into clinical practice has the potential to significantly improve the management of patients with stable CAD. The optimal FFRCT testing interpretation strategy, as well as the relative cost-efficiency of FFRCT against standard noninvasive functional testing, need further investigation.