Identifying left ventricular dysfunction using prospective electrocardiogram-triggered coronary computed tomography angiography.

PURPOSE: Coronary computed tomography angiography (CCTA) is an important non-invasive tool for the assessment of coronary artery disease and the delivery of information incremental to coronary anatomy. CCTA measured left ventricular (LV) mid-diastolic volume (LVMDV) and LV mass (LVMass) have important prognostic information but the utility of prospectively ECG-triggered CCTA to predict reduced left ventricular ejection fraction (LVEF) is unknown. The objective of this study was to determine if indexed LVMDV (LVMDVi) and the LVMDV:LVMass ratio on CCTA can identify patients with reduced LVEF. MATERIALS/METHODS: 8179 patients with prospectively ECG-triggered CCTA between November 2014 and December 2019 were reviewed. A subset derivation cohort of 4352 healthy patients was used to define normal LVMDVi and LVMDV:LVMass. Sex-specific thresholds were tested in a validation cohort of 1783 patients, excluded from the derivation cohort, with cardiac disease and known LVEF. The operating characteristics for 1 SD above the mean were tested for the identification of abnormal LVEF, LVEF≤35 â€‹% and ≤30 â€‹%. RESULTS: The derivation cohort had a mean LVMDVi of 61.0 â€‹± â€‹13.7 â€‹mL/m2 and LVMDV:LVMass of 1.11 â€‹± â€‹0.24 â€‹mL/g. LVMDVi and LVMDV:LVMass were both higher in patients with reduced LVEF than those with normal LVEF (98.8 â€‹± â€‹40.8 â€‹mL/m2 vs. 63.3 â€‹± â€‹19.7 â€‹mL/m2, p â€‹< â€‹0.001, and 1.32 â€‹± â€‹0.44 â€‹mL/g vs. 1.05 â€‹± â€‹0.28 â€‹mL/g, p â€‹< â€‹0.001). Both mean LVMDVi and LVMDV:LVMass increased with the severity of LVEF reduction. Sex-specific LVMDVi thresholds were 79 â€‹% and 80 â€‹% specific for identifying abnormal LVEF in females (LVMDVi â€‹≥ â€‹69.9 â€‹mL/m2) and males (LVMDVi â€‹≥ â€‹78.8 â€‹mL/m2), respectively. LVMDV:LVMass thresholds had high specificity (87 â€‹%) in both females (LVMDVi:LVMass â€‹≥ â€‹1.39 â€‹mL/g) and males (LVMDVi:LVMass â€‹≥ â€‹1.30 â€‹mL/g). CONCLUSION: Our study provides reference thresholds for LVMDVi and LVMDV:LVMass on prospectively ECG-triggered CCTA, which may identify patients who require further LV function assessment.

Intelligent surgical workflow recognition for endoscopic submucosal dissection with real-time animal study.

Recent advancements in artificial intelligence have witnessed human-level performance; however, AI-enabled cognitive assistance for therapeutic procedures has not been fully explored nor pre-clinically validated. Here we propose AI-Endo, an intelligent surgical workflow recognition suit, for endoscopic submucosal dissection (ESD). Our AI-Endo is trained on high-quality ESD cases from an expert endoscopist, covering a decade time expansion and consisting of 201,026 labeled frames. The learned model demonstrates outstanding performance on validation data, including cases from relatively junior endoscopists with various skill levels, procedures conducted with different endoscopy systems and therapeutic skills, and cohorts from international multi-centers. Furthermore, we integrate our AI-Endo with the Olympus endoscopic system and validate the AI-enabled cognitive assistance system with animal studies in live ESD training sessions. Dedicated data analysis from surgical phase recognition results is summarized in an automatically generated report for skill assessment.

The estimation of left ventricular function using prospective ECG-triggered coronary CT angiography.

BACKGROUND: Coronary computed tomography angiography (CCTA) is vital for diagnosing coronary artery disease; however, prospective ECG-triggered acquisition, minimizing radiation exposure, limits left ventricular (LV) ejection fraction (EF) evaluation. We aimed to assess the feasibility and utility of LVEF100msec, a new index for estimating LV function using volumetric changes during 100 msec within systole. METHODS: This retrospective study analyzed patients who underwent prospective ECG-triggered CCTA with systolic acquisition between January 2015 and June 2022. The LVEF100msec was calculated using the maximum and minimum LV volumes among the three phases (300, 350, and 400 msec post-QRS) and expressed as a percentage. Patients were classified into normal, mild-moderately reduced, or severely reduced LV function categories based on the reference test. The LVEF100msec was compared among groups, and the optimal cutoff value of LVEF100msec for predicting severe LV dysfunction was investigated. RESULTS: The study included 271 patients (median age â€‹= â€‹58 years, 52% male). LVEF was normal in 188 (69.4%), mild-moderately reduced in 57 (21.0%), and severely reduced in 26 (9.6%) patients. Median LVEF100msec value was 9.0 (6.7-12.6) for normal LV function, 4.7 (3.1-8.8) for mild-moderately reduced, and 2.9 (1.5-3.8) for severely reduced LV function. LVEF100msec values significantly differed among categories (p â€‹< â€‹0.001). The optimal LVEF100msec cutoff for severe LV dysfunction was 4.3%, with an AUC of 0.924, sensitivity of 88%, and specificity of 89%. CONCLUSION: The LVEF100msec may serve as a valuable indicator of severe LV dysfunction.

Are Training Programs Ready for the Rapid Adoption of CCTA?: CBME in CCTA.

OBJECTIVES: This study sought to assess training volumes and its relationship to learning and identify potential new thresholds for determining expertise. BACKGROUND: Competency-based medical education (CBME) is being rapidly adopted and therefore training programs will need to adapt and identify new and novel methods of defining, measuring, and assessing clinical skills. METHODS: Consecutive cardiac computed tomography (CT) studies were interpreted independently by trainees and expert readers, and their interpretations (Agatston score, coronary artery disease severity, and Coronary Artery Disease Reporting and Data System) were collected. Kappa agreements were measured between trainees and experts for every 50 consecutive cases. Agreements between trainees and experts were tracked and compared with the agreement between expert readers. RESULTS: A total of 36 trainees interpreted 14,432 cardiac CT studies. Agreement between trainees and experts increased with CT case volumes, but trainees learned at different rates. Using a threshold for expertise, skill of measuring coronary calcification was achieved within 50 cases, but expertise for coronary CT angiography appeared to require a mean case volume of 750, comprising 400 abnormal cases. CONCLUSIONS: Current volume-based training guidelines may be insufficient and higher case volumes may be required. We demonstrate that tracking cardiac CT learners is feasible and that CBME could be incorporated into CT training programs.

Prognostic value of coronary computed tomography angiography in patients with prior percutaneous coronary intervention.

OBJECTIVE: We sought to determine the prognostic value of coronary computed tomography angiography (CCTA) in patients with a history of percutaneous coronary intervention (PCI). BACKGROUND: Although the prognostic value of CCTA has been well studied, its incremental value in patients with previous PCI has not been robustly investigated. METHODS: Consecutive patients with previous PCI were prospectively enrolled and CCTA images were evaluated for coronary artery disease (CAD) severity. Patients were followed for major adverse cardiovascular events (MACE) which was a composite of cardiac death and non-fatal myocardial infarction. All-cause death was assessed as a secondary endpoint. RESULTS: A total of 501 patients were analyzed with a mean follow-up time of 59.5 ± 32.0 months and 52 patients (10.4%) experienced MACE. Multivariable Cox regression analysis showed that CAD severity was a predictor of MACE with 0, 1, 2, and 3 vessel disease having annual rates of 1.3%, 2.2%, 2.2%, and 5.3%, respectively. All-cause death was similar in all categories of CAD. CONCLUSIONS: In patients with previous PCI, CAD severity as measured with CCTA has independent and incremental prognostic value.

Prognostic durability of coronary computed tomography angiography.

AIMS: This large prospective cohort study sought to confirm the incremental prognostic value of coronary computed tomographic angiography (CCTA) measured over a prolonged follow-up duration. CCTA has diagnostic and prognostic value but data supporting its long-term prognostic value in a large prospectively recruited cohort with suspected coronary artery disease (CAD) has been limited. METHODS AND RESULTS: Consecutive patients (without history of myocardial infarction, revascularization, cardiac transplantation, and congenital heart disease) were prospectively enrolled. CCTA was evaluated for CAD severity, total plaque score (TPS), and left ventricular ejection fraction. Patients were followed for major adverse events (MAE) and major adverse cardiac events (MACE).Over a total of 99 months, 8667 consecutive CCTA patients (mean age = 57.1 ± 11.1 years, 52.9% men) were prospectively enrolled and followed for a mean duration of 7.0 ± 2.6 years. At follow-up, there were a total of 723 MAE, 278 MACE, 547 all-cause deaths, 110 cardiac deaths, and 104 non-fatal myocardial infarction. Patients without coronary atherosclerosis at the time of CCTA had a very low annual event rate for both MAE and MACE (0.45%/year and 0.19%/year, respectively). Both MAE and MACE increased with increasing TPS and severity of CAD. In patients with non-obstructive CAD and who were statin-naive, TPS ≥5 had MACE rates >0.75%/year. Patients with high-risk CAD had an annual MAE and MACE rates of 3.52%/year and 2.58%/year, respectively. Adjusted hazard ratio of the severity of CAD based on multivariable analyses indicated that the prognostic values were incremental. CONCLUSION: CCTA has independent and incremental prognostic value that is durable over time. The absence of coronary atherosclerosis portends an excellent prognosis. Patients with increasing non-obstructive plaque burden have worse prognosis and a TPS threshold ≥5 may identify a population that may benefit from statin therapy.

Left Ventricular Mass is Independently Related to Coronary Artery Atherosclerotic Burden: Feasibility of Cardiac Computed Tomography to Detect Early Geometric Left Ventricular Changes.

BACKGROUND: Left ventricular mass (LVM) is a predictor for adverse cardiovascular outcomes. Coronary atherosclerosis (coronary artery disease [CAD]) and concentric left ventricular (LV) remodeling are linked pathophysiologically by endothelial dysfunction. AIM: This study sought to determine the potential association between coronary atherosclerosis and LVM. METHODS: A total of 2384 consecutive patients, without structural heart disease or a medical history of CAD, undergoing prospective mid-diastolic electrocardiogram-gated computed tomography coronary angiography were enrolled in the study. LVM and LV mid-diastolic volume were measured using semiautomated software and indexed to body surface area. The average LV mid-diastolic wall thickness and concentricity index (LVM/LV mid-diastolic volume) were calculated. According to the Agatston Score, the patients were divided into 3 groups (Agatston=0, 0.1 to 399.9, ≥400). Similarly, patients were also divided into 4 groups on the basis of the Total Plaque Score (TPS) (0, 1 to 4, 5 to 8, and ≥9). In addition, patients were categorized according to CAD (normal coronaries, nonobstructive CAD, and obstructive stenosis [obstruction >50%]). The association between the different categories of CAD and LV measures was assessed. RESULTS: Both left ventricular mass index (LVMi) and the LV concentricity index increased with TPS categories from 55.3±12.1, 57.4±11.7, 60.9±13.6, and 63.7±15.3 g/m2 (P<0.05), and 0.935±0.424, 0.975±0.3273, 1.046±0.431, and 1.138±0.443 mL/g (P<0.01), respectively. A similar trend of increasing LVMi was observed with increasing Agatston Score (P<0.001) and CAD category (P<0.05). CONCLUSION: In patients without known structural heart disease, LVMi is independently associated with measures of CAD.

Effectiveness of point-of-care oral ivabradine for cardiac computed tomography.

BACKGROUND: Coronary CT angiography (CCTA) is increasing seen as a first line investigation in patients with suspected coronary artery disease. Heart-rate control improves the image quality and diagnostic accuracy of CCTA. Typically, beta-blockers are administered to induce sinus bradycardia. Sinus bradycardia may also be induced by ivabradine. We hypothesized that in a real-world population ivabradine would be an effective alternative to metoprolol at heart rate lowering for CCTA. METHODS: This was a retrospective analysis of consecutive patients who were exposed to an ivabradine-based (IB) versus a metoprolol-only (MO) protocol to achieve a target heart rate 65 and received heart-rate lowering medication: 1958 patients had MO, and 718 received IB protocol. Target heart rate of

A Clinical Tool to Identify Candidates for Stress-First Myocardial Perfusion Imaging.

OBJECTIVES: This study sought to develop a clinical model that identifies a lower-risk population for coronary artery disease that could benefit from stress-first myocardial perfusion imaging (MPI) protocols and that can be used at point of care to risk stratify patients. BACKGROUND: There is an increasing interest in stress-first and stress-only imaging to reduce patient radiation exposure and improve patient workflow and experience. METHODS: A secondary analysis was conducted on a single-center cohort of patients undergoing single-photon emission computed tomography (SPECT) and positron emission tomography (PET) studies. Normal MPI was defined by the absence of perfusion abnormalities and other ischemic markers and the presence of normal left ventricular wall motion and left ventricular ejection fraction. A model was derived using a cohort of 18,389 consecutive patients who underwent SPECT and was validated in a separate cohort of patients who underwent SPECT (n = 5,819), 1 internal cohort of patients who underwent PET (n=4,631), and 1 external PET cohort (n = 7,028). RESULTS: Final models were made for men and women and consisted of 9 variables including age, smoking, hypertension, diabetes, dyslipidemia, typical angina, prior percutaneous coronary intervention, prior coronary artery bypass graft, and prior myocardial infarction. Patients with a score ≤1 were stratified as low risk. The model was robust with areas under the curve of 0.684 (95% confidence interval [CI]: 0.674 to 0.694) and 0.681 (95% CI: 0.666 to 0.696) in the derivation cohort, 0.745 (95% CI: 0.728 to 0.762) and 0.701 (95% CI: 0.673 to 0.728) in the SPECT validation cohort, 0.672 (95% CI: 0.649 to 0.696) and 0.686 (95% CI: 0.663 to 0.710) in the internal PET validation cohort, and 0.756 (95% CI: 0.740 to 0.772) and 0.737 (95% CI: 0.716 to 0.757) in the external PET validation cohort in men and women, respectively. Men and women who scored ≤1 had negative likelihood ratios of 0.48 and 0.52, respectively. CONCLUSIONS: A novel model, based on easily obtained clinical variables, is proposed to identify patients with low probability of having abnormal MPI results. This point-of-care tool may be used to identify a population that might qualify for stress-first MPI protocols.

Comparison of coronary CT angiography versus functional imaging for CABG patients: A resource utilization analysis.

AIMS: The impact of anatomical versus functional testing in patients with prior coronary artery bypass surgery (CABG) is poorly defined. We therefore sought to determine the rates of downstream investigations and the attendant healthcare costs in CABG patients undergoing CCTA versus SPECT. METHODS AND RESULTS: 2754 consecutive CABG patients were imaged by SPECT (2163) or CCTA (591). 425 patients (15.4%) underwent downstream testing which was more common in those imaged with CCTA versus SPECT (23.18% vs 13.31% respectively, p < 0.01). When a propensity score adjustment was made for differences in baseline characteristics, the findings in downstream testing persisted (p < 0.01). When patients who subsequently underwent repeat revascularization (arguably the highest risk patients) were removed from the analysis, downstream testing remained more frequent in CCTA (12.7%) versus SPECT imaged patients (8.8%) (p = 0.01). Costs of downstream tests per patient were two-fold greater in the CCTA group in comparison to the SPECT group ($366.79 ± 29.59 vs $167.35 ± 10.12 respectively, p < 0.01). Conversely, total costs which included the index costs were less in the CCTA group, $764.66 ± 29.59 versus $1396.73 ± 1012 for the SPECT cohort, p < 0.0001). CONCLUSIONS: Index imaging with SPECT versus CCTA in CABG patients was associated with fewer downstream tests, less ICA, less repeat revascularization but greater expense. Cost however is only part of the decision making process that determines an optimal index test. Until CCTA demonstrates improved risk stratification over SPECT in CABG patients it is likely SPECT will remain the preferred first imaging test.

Determining Early Remodeling Patterns in Diabetes and Hypertension Using Cardiac Computed Tomography: The Feasibility of Assessing Early LV Geometric Changes.

BACKGROUND: There is conflicting data on early left ventricle (LV) remodeling in diabetes mellitus (DM) and hypertension (HTN). This study examines the feasibility of cardiac computed tomography angiography (CCTA) to detect early LV geometric changes in patients with DM and HTN. METHODS: Consecutive patients (n = 5,992) who underwent prospective electrocardiography (ECG)-triggered (mid-diastolic) CCTA were screened. Patients with known structural heart disease or known LV dysfunction were excluded. Left ventricular mass (LVM), left ventricular mid-diastolic volume (LVMDV), and LV concentricity (LVM/LVMDV) were measured and indexed to body surface area. RESULTS: A total of 4,283 patients were analyzed (mean age 57 ± 10.69 years, female 46.7%). DM, HTN, and HTN + DM were present in 4.1%, 35.8% and 10.6% of patients, respectively. Compared to normal patients, HTN and HTN + DM patients had increased LVM indexed to body surface area (LVMi) (56.87 ± 17.24, 59.26 ± 13.62, and 58.56 ± 13.09, respectively; P < 0.05). There was no difference in LVMi between normal subjects and patients with DM (56.39 ± 11.50, P = 0.617).Concentricity indices were higher in patient with HTN (1.0456 ± 0.417; P < 0.001), DM (1.109 ± 0.638; P = 0.004), and HTN + DM (1.083 ± 0.311, P < 0.001) than normal individuals (0.9671 ± 0.361). There was no overlap of the 95% confidence intervals in the composite of concentricity indices and LVMi between the different groups. CONCLUSIONS: CCTA measures of LVM and concentricity index may discriminate patients with HTN and DM before overt structural heart disease.

Competency-Based Medical Education: Do the Cardiac Imaging Training Guidelines Have it Right?

OBJECTIVES: This study sought to: 1) determine if the current training volume guidelines are reasonable for attaining competence for interpreting myocardial perfusion imaging (MPI); and if not, 2) identify potential thresholds for training volumes and competence. BACKGROUND: There is a growing desire to adopt competency-based medical education (CBME). As such, the implementation of CBME will require new and novel methods of defining, measuring, and assessing clinical competence. The potential use of CBME in cardiac imaging has not been well studied. METHODS: Consecutive MPI studies were interpreted independently by trainees, and expert readers reviewed the same studies. Studies were quantified using summed scores and % left ventricular (LV) ischemia and the kappa agreement between trainee and expert were measured every 50 cases. Agreement for all MPI and abnormal MPI cases was calculated. RESULTS: A total of 24 trainees interpreted 9,668 MPI studies over 37 months. Agreement between trainees and expert readers increased with MPI case volumes but at different rates. The threshold for competence was set at 2 SDs below expert interobserver agreement. The average trainee surpassed this threshold for both summed stress score and %LV ischemia after 800 studies and after 400 abnormal MPI studies. Trainees learned at different rates and surpassed the competence threshold after different case volumes. CONCLUSIONS: The use of CBME within nuclear cardiology appears to be feasible. Our results suggest that current guidelines may be insufficient to ensure competence and would support the need to increase the MPI case volumes. The use of CBME principles would suggest that trainees may achieve competence at different rates and our results suggest a shift in focus from volume-based learning toward target agreement thresholds.

Early LV remodelling patterns in overweight and obesity: Feasibility of cardiac CT to detect early geometric left ventricular changes.

BACKGROUND: Obesity is an in independent risk factor for cardiovascular disease. GOAL: To describe the early LV remodelling pattern in patients with overweight and obesity and structurally normal hearts. METHODS: Consecutive patients (n = 2374), with structurally normal hearts and BMI ≥ 18.5 kg/m2, undergoing prospective mid-diastolic ECG gated CTCA were selected. Left ventricular mass (LVM) and Left ventricular mid-diastolic volume (LVMDV) were measured. The concentricity index (LVM/LVMDV) were calculated. According to the definitions of the World Health Organization (WHO), the patients were divided into weight categories. RESULTS: The mean LVM ±â€¯Std. deviation in the subgroups according to WHO classification was 101.68 ±â€¯28.99 g (normal weight), 115.79 ±â€¯29.14 g (overweight), 123.8 ±â€¯33.44 g (class I obesity), 125.85 ±â€¯32.89 g (class II obesity) and 132.45 ±â€¯37.85 g (class III obesity). (p < 0.001) The mean LVMDV progressed with increasing WHO weight category from 112.37 ±â€¯36.46 in patients with normal BMI to 140.26 ±â€¯43.78 in patients with class III obesity. (p < 0.001) The concentricity index was 0.935 ±â€¯0.216 g/ml in patients with normal BMI, 0.979 ±â€¯0.253 g/ml, 1.058 ±â€¯0.635 g/ml, 0.996 ±â€¯0.284 g/ml and 0.9768 ±â€¯0.244 g/ml in patients with BMI categories 25-29.99, 30-34.99, 35-39.99 and ≥40 kg/m2, respectively. CONCLUSIONS: Our study demonstrates a non-linear (inverse U-shape) relationship between increasing BMI class and concentricity index, reaching its maximum at a BMI of 30-34.99 kg/m2. Further increase in BMI results in LV dilation.

Differences in left ventricular measurements: Attenuation versus contour based methods.

BACKGROUND: Coronary computed tomography angiography (CCTA) left ventricle (LV) volumes have prognostic value. LV measurements however can differ depending on post-processing software. Two common methods are the contour (CON) or attenuation (ATT) based methods. This study aims to determine differences in LV volume measurements using the 2 methods. METHODS: LV mid-diastolic volumes (LVMDV) were measured using both ATT and CON from 2 vendors in 750 consecutive patients undergoing CCTA. 500 were measured in a derivation cohort to establish a linear regression equation that would correct for any detected differences between the two methods. The equation was then assessed in 250 cases in the validation cohort. Comparisons were made between intra-vendor LVMDVCON and LVMDVATT as well as inter-vendor LVMDVATT. RESULTS: In the derivation cohort, the correlation between the two methods and vendors were very good (0.98 and 0.97 respectively). LVMDVCON was 20.4 ±â€¯7.4% greater than LVMDVATT. LVMDVATT was 9.2 ±â€¯6.6% greater with one vendor compared to the other. Validation cohort corrected LVMDVATT was not statistically different to measured LVMDVATT (p = 0.45). CONCLUSION: A systematic difference was found between ATT and CON measuring methods. Using a derived linear regression equation, we were able to correct for differences in measurement techniques. The method of LVMDV measurement requires careful consideration when establishing reference values and extrapolating published study results.

Recent Advances in Surface Plasmon Resonance Imaging Sensors.

The surface plasmon resonance (SPR) sensor is an important tool widely used for studying binding kinetics between biomolecular species. The SPR approach offers unique advantages in light of its real-time and label-free sensing capabilities. Until now, nearly all established SPR instrumentation schemes are based on single- or several-channel configurations. With the emergence of drug screening and investigation of biomolecular interactions on a massive scale these days for finding more effective treatments of diseases, there is a growing demand for the development of high-throughput 2-D SPR sensor arrays based on imaging. The so-called SPR imaging (SPRi) approach has been explored intensively in recent years. This review aims to provide an up-to-date and concise summary of recent advances in SPRi. The specific focuses are on practical instrumentation designs and their respective biosensing applications in relation to molecular sensing, healthcare testing, and environmental screening.

Real-time multi-channel SPR sensing based on DMD-enabled angular interrogation.

This paper reports a digital micro-mirror device (DMD)-enabled real-time multi-channel biosensing system based on angular interrogation surface plasmon resonance (SPR). In the experiments, angular scanning is achieved by a DMD that facilitates SPR measurements using a single-point photodetector. In the four-channel measurement setup, real-time monitoring of bovine serum albumin (BSA) and anti-BSA binding interactions is performed at various concentration levels. The experimental results have verified that the system has a resolution of 3.54 × 10-6 RIU (refractive index unit); and a detection limit of 9 ng/mL. The new DMD-based SPR interrogation system presents a new design route for practical solid-state SPR biosensing with a user-selectable range of interrogation, enhanced signal-to-noise ratio, and fast data throughput.

Prognostic value of age adjusted segment involvement score as measured by coronary computed tomography: a potential marker of vascular age.

Extent of coronary atherosclerotic disease (CAD) burden on coronary computed tomography angiography (CCTA) as measured by segment involvement score (SIS) has a prognostic value. We sought to investigate the incremental prognostic value of 'age adjusted SIS' (aSIS), which may be a marker of premature atherosclerosis and vascular age. Consecutive patients were prospectively enrolled into the CONFIRM (Coronary CT Angiography EvaluatioN For Clinical Outcomes: An InteRnational Multicentre) multinational observational study. Patients were followed for the outcome of all-cause death. aSIS was calculated on CCTA for each patient, and its incremental prognostic value was evaluated. A total of 22,211 patients [mean age 58.5 ± 12.7 years, 55.8% male) with a median follow-up of 27.3 months (IQR 17.8, 35.4)] were identified. After adjustment for clinical factors and presence of obstructive CAD, higher aSIS was associated with increased death on multivariable analysis, with hazard ratio (HR) 2.40 (1.83-3.16, p < 0.001), C-statistic 0.723 (0.700-0.756), net reclassification improvement (NRI) 0.36 (0.26-0.47, p < 0.001), and relative integrated discrimination improvement (IDI) 0.33 (p = 0.009). aSIS had HR 3.48 (2.33-5.18, p < 0.001) for mortality in those without obstructive CAD, compared to HR 1.79 (1.25-2.58, p = 0.02) in those with obstructive CAD. In conclusion, aSIS has an incremental prognostic value to traditional risk factors and obstructive CAD, and may enhance CCTA risk stratification.

Prognostic value of vasodilator response using rubidium-82 positron emission tomography myocardial perfusion imaging in patients with coronary artery disease.

BACKGROUND: Prognostic value of positron emission tomography (PET) myocardial perfusion imaging (MPI) is well established. There is paucity of data on how the prognostic value of PET relates to the hemodynamic response to vasodilator stress. We hypothesize that inadequate hemodynamic response will affect the prognostic value of PET MPI. METHODS AND RESULTS: Using a multicenter rubidium (Rb)-82 PET registry, 3406 patients who underwent a clinically indicated rest/stress PET MPI with a vasodilator agent were analyzed. Patients were categorized as, "responders" [increase in heart rate ≥ 10 beats per minute (bpm) and decrease in systolic blood pressure (SBP) ≥10 mmHg], "partial responders" (either a change in HR or SBP), and "non-responders" (no change in HR or SBP). Primary outcome was all-cause death (ACD), and secondary outcome was cardiac death (CD). Ischemic burden was measured using summed stress score (SSS) and % left ventricular (LV) ischemia. After a median follow-up of 1.68 years (interquartile range = 1.17- 2.55), there were 7.9% (n = 270) ACD and 2.6% (n = 54) CD. Responders with a normal PET MPI had an annualized event rate (AER) of 1.22% (SSS of 0-3) and 1.58% (% LV ischemia = 0). Partial and non-responders had higher AER with worsening levels of ischemic burden. In the presence of severe SSS ≥12 and LV ischemia of ≥10%, partial responders had an AER of 10.79% and 10.36%, compared to non-responders with an AER of 19.4% and 12.43%, respectively. Patient classification was improved when SSS was added to a model containing clinical variables (NRI: 42%, p < 0.001) and responder category was added (NRI: 61%, p < 0.001). The model including clinical variables, SSS and hemodynamic response has good discrimination ability (Harrell C statistics: 0.77 [0.74-0.80]). CONCLUSION: Hemodynamic response during a vasodilator Rb-82 PET MPI is predictive of ACD. Partial and non-responders may require additional risk stratification leading to altered patient management.

Appropriate Use Criteria for Cardiac Computed Tomography: Does Computed Tomography Have Incremental Value in All Appropriate Use Criteria Categories?

PURPOSE: Cardiac imaging expenditures have come under scrutiny, and a focus on appropriate use criteria (AUC) has arisen to ensure cost-effective resource utilization. Although AUC has been developed by clinical experts, it has not undergone rigorous quality assurance testing to ensure that inappropriate indications for testing yield little clinical benefit. The objective of the study was to evaluate the potential incremental prognostic value of coronary computed tomographic angiography (CCTA) in the different AUC categories. MATERIALS AND METHODS: Consecutive patients enrolled into a cardiac CT Registry were collated. Patient indications were reviewed and based on the 2010 AUC (appropriate, uncertain, and inappropriate). Patients were followed-up for death, myocardial infarction (MI), and late revascularization, with the primary composite endpoint being cardiac death, nonfatal MI, and late revascularization. The prognostic value of CCTA over clinical variables in each of the AUC categories was assessed. RESULTS: Indications for CCTA were appropriate, uncertain, and inappropriate in 1284 (66.5%), 312 (16.2%), and 334 (17.3%) patients, respectively. Rates of all-cause of death, cardiac death, nonfatal MI, and late revascularization were similar across patients with appropriate, uncertain, and inappropriate indications for CCTA. Moreover, in each AUC category, CCTA had incremental prognostic value over a routine clinical risk score (National Cholesterol Education Program) with hazard ratios of 9.98, 7.39, and 5.61. CONCLUSIONS: CCTA has incremental prognostic value in all AUC categories, even when the reason for the study was deemed "inappropriate." This suggests that CCTA may still have clinical value in "inappropriate" indications and that further quality assurance AUC studies are needed.