Gatekeeper For Invasive Coronary Angiography Research Articles

Assessment of Coronary Stenosis Using Coronary CT Angiography in Patients with High Calcium Scores: Current Limitations and Future Perspectives

Coronary CT angiography (CCTA) is recognized for its role as a gatekeeper for invasive coronary angiography in patients suspected of coronary artery disease because it can detect significant coronary stenosis with high accuracy. However, heavy plaque in the coronary artery makes it difficult to visualize the lumen, which can lead to errors in the interpretation of the CCTA results. This is primarily due to the limited spatial resolution of CT scanners, resulting in blooming artifacts caused by calcium. However, coronary stenosis with high calcium scores often requires evaluation using CCTA. Technological methods to overcome these limitations include the introduction of high-resolution CT scanners, the development of reconstruction techniques, and the subtraction technique. Methods to improve reading ability, such as the setting of appropriate window width and height, and evaluation of the position of calcified plaque and residual visibility of the lumen in cross-sectional images, are also recommended.

An automated reduced order CT-FFR model for diagnosis of hemodynamically significant coronary artery disease- a prospective validation study

Abstract Background/Introduction CT derived fractional flow reserve (CT-FFR) is introduced in current guidelines as a gatekeeper for invasive coronary angiography (ICA) in symptomatic patients with intermediate stenoses on coronary CT angiography (CCTA). Traditionally, CT-FFR is validated with knowledge of the precise location of invasive FFR measurements to ensure a direct comparison. However, in a clinical setting, this information will not be available and may affect the diagnostic performance of CT-FFR. Purpose To validate the diagnostic performance of a novel physics augmented machine learning algorithm based on reduced order modelling for CT-FFR calculations, with an automated method for defining the site of CT-FFR evaluations. Methods In this prospective validation study, 108 consecutive patients with stable coronary artery disease (CAD) and at least one suspected obstructive stenosis of questionable hemodynamic significance on CCTA were included. All patients underwent a clinically indicated invasive coronary angiography. The diagnostic performance of the CT-FFR algorithm was assessed with invasive FFR at a threshold of ≤ 0,80 as reference standard. CT-FFR at the location of invasive FFR measurements (CT-FFRatloc) was compared with CCTA, CT-FFR at automatically selected locations (CT-FFRauto) and CT-FFR predictions at the distal end of the vessel (CT-FFRdistal). Results CT-FFRatloc showed good correlation with invasive FFR measurements (r=0,67) and demonstrated improved diagnostic performance compared to CCTA diameter stenosis ≥50%. alone both at lesion level (AUC= 0,85 vs 0,63, p<0,01) and at patient level (AUC=0,87 vs 0,74, p<0,01). Both specificity (84% vs 40%, p=0,01) and accuracy (81% vs 63%, p<0,01) of CT-FFRatloc was significantly increased compared to CCTA. CT-FFRauto performed equally well as CT-FFRatloc, both at lesion level (AUC= 0,82 vs AUC= 0,85, p=0,27) and patient level (AUC= 0,86 vs AUC= 0,87(p=0,67). When comparing CT-FFRdistal to CT-FFRatloc the overall diagnostic performance was poorer (AUC=0,79 vs 0,85, p<0,01). Conclusions Compared to CCTA, CT-FFRatloc showed improved diagnostic performance, including accuracy and specificity for the detection of hemodynamically significant coronary artery disease in a symptomatic population. Predictions using an automated location algorithm, CT-FFRauto, was comparable to evaluations at the location of invasive FFR measurements, CT-FFRatloc.Figure 1Figure 2

Coronary computed tomography angiographic detection of in-stent restenosis via deep learning reconstruction: a feasibility study.

Evaluation of in-stent restenosis (ISR), especially for small stents, remains challenging during computed tomography (CT) angiography. We used deep learning reconstruction to quantify stent strut thickness and lumen vessel diameter at the stent and compared it with values obtained using conventional reconstruction strategies. We examined 166 stents in 85 consecutive patients who underwent CT and invasive coronary angiography (ICA) within 3months of each other from 2019-2021 after percutaneous coronary intervention with coronary stent placement. The presence of ISR was defined as percent diameter stenosis ≥ 50% on ICA. We compared a super-resolution deep learning reconstruction, Precise IQ Engine (PIQE), and a model-based iterative reconstruction, Forward projected model-based Iterative Reconstruction SoluTion (FIRST). All images were reconstructed using PIQE and FIRST and assessed by two blinded cardiovascular radiographers. PIQE had a larger full width at half maximum of the lumen and smaller strut than FIRST. The image quality score in PIQE was higher than that in FIRST (4.2 ± 1.1 versus 2.7 ± 1.2, p < 0.05). In addition, the specificity and accuracy of ISR detection were better in PIQE than in FIRST (p < 0.05 for both), with particularly pronounced differences for stent diameters < 3.0mm. PIQE provides superior image quality and diagnostic accuracy for ISR, even with stents measuring < 3.0mm in diameter. With improvements in the diagnostic accuracy of in-stent stenosis, CT angiography could become a gatekeeper for ICA in post-stenting cases, obviating ICA in many patients after recent stenting with infrequent ISR and allowing non-invasive ISR detection in the late phase. • Despite CT technology advancements, evaluating in-stent stenosis severity, especially in small-diameter stents, remains challenging. • Compared with conventional methods, the Precise IQ Engine uses deep learning to improve spatial resolution. • Improved diagnostic accuracy of CT angiography helps avoid invasive coronary angiography after coronary artery stenting.

Nationwide trends of gatekeeper to invasive coronary angiography in suspected coronary artery disease

Abstract Funding Acknowledgements Type of funding sources: None. Background and Objectives Real-world trends in the utility and type of gatekeeping studies in invasive coronary angiography (ICA) requires further investigation. Methods We identified outpatients who underwent noninvasive cardiac tests or directly ICA for suspected coronary artery disease (CAD) from the nationwide Korea Health Insurance Review and Assessment Service-National Patient Sample database between 2012 and 2018. Results Among 71,401 patients, the percentage of patients who were evaluated for suspected CAD was 34.7% for treadmill test (TMT), 4.2% for single-photon emission computed tomography (SPECT), 24.2% for coronary computed tomography angiography (CCTA), 1.6% for multiple gatekeepers, and 32.3% for directly ICA without noninvasive studies (Figure 1). The proportion of CCTA as a gatekeeper showed linear increase, (18.6% in 2012 and 28.8% in 2018; p &amp;lt; 0.001), while those of TMT, SPECT, and direct ICA have decreased (p &amp;lt; 0.001, p = 0.03, and p &amp;lt; 0.001, respectively). The overall incidence of downstream ICA after gatekeeper was 13.8% (6,662/48,346), and SPECT showed higher ICA rate in pairwise comparison with TMT and CCTA (p &amp;lt; 0.001). Patients who performed gatekeepers before ICA showed higher rate of subsequent PCI (34.7% vs. 32.3%; p &amp;lt; 0.001) and CABG (3.5% vs. 1.0%; p &amp;lt; 0.001), compared to those who directly underwent ICA, and CCTA was associated with higher revascularization rate after ICA in pairwise comparison with TMT and SPECT (p &amp;lt; 0.001). Conclusion Nationwide database demonstrated that CCTA is utilized increasingly as a gatekeeper for ICA and is associated with high revascularization rate after ICA in outpatients with suspected CAD.

Nationwide Trends of Gatekeeper to Invasive Coronary Angiography in Suspected Coronary Artery Disease

Real-world trends in the utility and type of gatekeeping studies in invasive coronary angiography (ICA) requires further investigation. We identified outpatients who underwent noninvasive cardiac tests or directly ICA for suspected coronary artery disease (CAD) from the nationwide Korea Health Insurance Review and Assessment Service-National Patient Sample database between 2012 and 2018. Among 71,401 patients, the percentage of patients who were evaluated for suspected CAD was 34.7% for treadmill test (TMT), 4.2% for single-photon emission computed tomography (SPECT), 24.2% for coronary computed tomography angiography (CCTA), 1.6% for multiple gatekeepers, and 32.3% for directly ICA without noninvasive studies. The proportion of CCTA as a gatekeeper showed linear increase, (18.6% in 2012 and 28.8% in 2018; p<0.001), while those of TMT, SPECT, and direct ICA have decreased (p<0.001, p=0.03, and p<0.001, respectively). The overall incidence of downstream ICA after gatekeeper was 13.8% (6,662/48,346), and SPECT showed higher ICA rate in pairwise comparison with TMT and CCTA (p<0.001). Patients who performed gatekeepers before ICA showed higher rate of subsequent PCI (34.7% vs. 32.3%; p<0.001) and CABG (3.5% vs. 1.0%; p<0.001), compared to those who directly underwent ICA, and CCTA was associated with higher revascularization rate after ICA in pairwise comparison with TMT and SPECT (p<0.001). Nationwide database demonstrated that CCTA is utilized increasingly as a gatekeeper for ICA and is associated with high revascularization rate after ICA in outpatients with suspected CAD.

Comparison of Diagnostic Performance of Fractional Flow Reserve Derived from Coronary Computed Tomographic Angiography Versus Single-Photon Emission Computed Tomographic Myocardial Perfusion Imaging

Fraction flow reserve (FFR) derived from computed tomography (FFRCT) has been proposed to be an effective gatekeeper for invasive angiographic referral. The purpose of the present study is to examine the real-world diagnostic performance of FFRCT and myocardial perfusion imaging as well as to assess the utility of FFRCT as a gatekeeper for invasive coronary angiography in patients suspected of having obstructive coronary artery disease. Total of 146 consecutive patients underwent both single-photon emission computed tomography (SPECT) and invasive FFR were evaluated. An FFRCT value 1 to 2 cm distal to a stenosis ≤0.80 was defined as positive for ischemia and a summed stress score ≥2 or transient ischemic dilatation ≥1.2 were positive for ischemia with the invasive FFR value of <0.80 serving as the gold standard. The patient-based sensitivity of FFRCT was significantly higher than SPECT (91 vs 52%, p <0.001) and exhibited similar positive predictive value (82 vs 82%, p=0.91). These trends were observed even in patients with multivessel and left main trunk disease and those with severe coronary calcification. In conclusion, our data suggest that FFRCT has higher diagnostic performance characteristics than SPECT and details the superior FFRCT analysis in detecting patients with hemodynamically significant coronary artery disease. Our results support the clinical utility of FFRCT analysis as a gatekeeper for invasive coronary angiography in clinical practice.

Prognostic value of myocardial perfusion imaging after first-line coronary computed tomography angiography: A multi-center cohort study

PurposeFurther diagnostic testing may be required after a coronary computed tomography angiography (CTA) showing suspected coronary stenosis. Whether myocardial perfusion imaging (MPI) provides further prognostic information post-CTA remains debated. We evaluated the prognosis for patients completing CTA stratified for post-CTA diagnostic work-up using real-world data. MethodsWe identified all patients in our uptake area with angina symptoms undergoing first-time CTA over a 10-year period. Follow-up time was a median of 3.7 years [1.9–5.8]. The primary endpoint was a composite of myocardial infarction or death. The secondary endpoint was late revascularization. ResultsDuring the study period 53,351 patients underwent CTA. Of these, 24% were referred for further down-stream testing, 3,547 (7%) to MPI and 9,135 (17%) to invasive coronary angiography (ICA). The primary and secondary endpoints occurred in 2,026 (3.8%) and 954 (1.8%) patients. Patient-characteristic-adjusted hazard ratios for the primary and secondary endpoint using patients with a normal CTA as reference were 1.37 (1.21–1.55) and 2.50 (1.93–3.23) for patient treated medically, 1.68 (1.39–2.03) and 6.13 (4.58–8.21) for patients referred to MPI and 1.94 (1.69–2.23) and 9.18 (7.16–11.78) for patients referred for ICA, respectively. Adjusted analysis with stratification for disease severity at CTA showed similar hazard ratios for patients treated medically after CTA and patients referred for MPI and treated medically after the MPI. ConclusionIn patients completing coronary CTA, second-line MPI testing seems to identify patients at low risk of future events. MPI seems to have the potential to act as gatekeeper for ICA after coronary CTA.

DEtection of ProxImal Coronary stenosis in the work-up for Transcatheter aortic valve implantation using CTA (from the DEPICT CTA collaboration)

ObjectivesComputed tomography angiography (CTA) is performed routinely in the work-up for transcatheter aortic valve implantation (TAVI), and could potentially replace invasive coronary angiography (ICA) to rule out left main (LM) and proximal coronary stenosis. The objectives were to assess the diagnostic yield and accuracy of pre-TAVI CTA to detect LM and proximal coronary stenosis of ≥ 50% and ≥ 70% diameter stenosis (DS).MethodsThe DEPICT CTA database consists of individual patient data from four studies with a retrospective design that analyzed the diagnostic accuracy of pre-TAVI CTA to detect coronary stenosis, as compared with ICA. Pooled data were used to assess diagnostic accuracy to detect coronary stenosis in the left main and the three proximal coronary segments on a per-patient and a per-segment level. We included 1060 patients (mean age: 81.5 years, 42.7% male).ResultsOn ICA, the prevalence of proximal stenosis was 29.0% (≥ 50% DS) and 15.7% (≥ 70% DS). Pre-TAVI CTA ruled out ≥ 50% DS in 51.6% of patients with a sensitivity of 96.4%, specificity of 71.2%, PPV of 57.7%, and NPV of 98.0%. For ≥ 70% DS, pre-TAVI CTA ruled out stenosis in 70.0% of patients with a sensitivity of 96.7%, specificity of 87.5%, PPV of 66.9%, and NPV of 99.0%.ConclusionCTA provides high diagnostic accuracy to rule out LM and proximal coronary stenosis in patients undergoing work-up for TAVI. Clinical application of CTA as a gatekeeper for ICA would reduce the need for ICA in 52% or 70% of patients, using a threshold of ≥ 50% or ≥ 70% DS, respectively.Key Points• Clinical application of CTA as a gatekeeper for ICA would reduce the need for ICA in 52% or 70% of TAVI patients, using a threshold of ≥ 50% or ≥ 70% diameter stenosis.• The diagnostic accuracy of CTA to exclude proximal coronary stenosis in these patients is high, with a sensitivity of 96.4% and NPV of 98.0% for a threshold of ≥ 50%, and a sensitivity of 96.7% and NPV of 99.0% for a threshold of ≥ 70% diameter stenosis.• Atrial fibrillation and heart rate did not significantly affect sensitivity and NPV. However, a heart rate of < 70 b/min during CTA was associated with a significantly improved specificity and PPV.

Computed Tomography Angiography for the Diagnosis of Coronary Artery Disease Among Patients Undergoing Transcatheter Aortic Valve Implantation

BackgroundComputed tomography angiography (CTA) is used to plan TAVI procedures. We investigated the performance of pre-TAVI CTA for excluding coronary artery disease (CAD).MethodsIn total 127 patients were included. CTA images were analyzed for the presence of ≥ 50% (significant CAD) and ≥ 70% (severe CAD) diameter stenoses in proximal coronary arteries. Results were compared with invasive coronary angiography (ICA) at vessel and patient levels. Primary endpoint was the negative predictive value (NPV) of CTA for the presence of CAD.ResultsA total of 342 vessels were analyzable. NPV of CTA was 97.5% for significant CAD and 96.3% for severe CAD. Positive predictive value and accuracy were 44.8% and 87.1% for significant CAD and 56.3% and 94.4% for severe CAD. At patient level, NPV for significant CAD was 88.6%.ConclusionPre-TAVI CTA shows good performance for ruling out CAD and could be used as a gatekeeper for ICA in selected patients.Graphical abstract

Screening for coronary artery disease in early surgical treatment of acute aortic valve infective endocarditis.

In patients with unknown coronary status undergoing surgery for acute infective endocarditis (IE), the need to screen for coronary artery disease (CAD) and the risk of embolization during invasive coronary angiography (ICA) are debated. Coronary computed tomography angiography (CCTA) is a non-invasive alternative in these patients. We aimed to evaluate the safety and feasibility of ICA and CCTA to diagnose CAD, and the necessity to treat CAD to prevent CAD-related postoperative complications. In this single-centre retrospective cohort study, all patients with acute aortic IE between 2009 and 2019 undergoing surgery were selected. Outcomes were any clinically evident embolization after preoperative ICA, in-hospital mortality, perioperative myocardial infarction or unplanned revascularization and postoperative renal function. Of the 159 included patients, CAD status was already known in 14. No preoperative diagnostics for CAD was done in 46/145, a CCTA was performed in 54/145 patients and an ICA in 52/145 patients. Significant CAD was found after CCTA in 22% and after ICA in 21% of patients. In 1 of the 52 (2%) patients undergoing preoperative ICA, a cerebral embolism occurred. The rate of perioperative myocardial infarction or unplanned revascularization in patients not screened for CAD was 2% (1 out of 46 patients). Although the risk of embolism after preoperative ICA is low, it should be carefully weighed against the estimated risk of CAD-related perioperative complications. CCTA can serve as a gatekeeper for ICA in most patients with acute aortic IE.

Diagnosis and management of coronary artery disease in early surgical treatment of acute infective endocarditis of the aortic valve

Abstract Background The need to routinely screen for coronary artery disease (CAD) in asymptomatic patients undergoing surgery for acute aortic valve infective endocarditis (IE) is debated. There is concern about the risk of embolization during invasive coronary angiography (ICA), especially in patients with vegetations. Coronary computed tomography angiography (cCTA) is a non-invasive alternative. Purpose To evaluate the prevalence of CAD in patients with acute aortic valve IE, the safety and feasibility of ICA and cCTA for diagnosis of CAD, and CAD related postoperative outcomes. Methods In this single center retrospective cohort study, all patients with acute infective aortic valve endocarditis between 2009–2019 undergoing surgery were selected. Outcomes were embolization after preoperative ICA, in-hospital mortality, perioperative myocardial infarction or unplanned revascularization. Results 159 patients (mean age 58±15, 81% male) underwent surgery. No CAD screening was done in 46/145, a cCTA was performed in 54/145 patients and an ICA in 52/145 patients. In 1 of the 52 patients undergoing preoperative ICA a cerebral embolism occurred. cCTA was not assessable on a patient level in 2 patients and 7 patients underwent both cCTA and ICA. Significant CAD was found in about 20% of patients both after cCTA and ICA. Even though just a minority of patients with CAD was treated with concomitant CABG, only 1 patient with known but untreated CAD needed unplanned revascularization postoperatively. The rate of perioperative myocardial infarction or unplanned revascularization in patients not screened for CAD was 5% (3 patients). Conclusion In patients with acute aortic valve IE the prevalence of CAD is low (14%). The risk of embolism after preoperative ICA is not negligible and should be carefully weighed against the estimated risk of CAD-related perioperative complications. cCTA might serve as a gatekeeper for ICA in many patients with acute aortic IE. Funding Acknowledgement Type of funding source: None

Is coronary computed tomography angiography a good choice for elders and high probability cases?

Abstract Introduction Coronary computed tomography angiography (cCTA) is widely considered the optimal non-invasive test to rule out coronary artery disease (CAD) and the gatekeeper for invasive coronary angiography (ICA). However, its diagnostic utility in elderly patients (pts) and in cases of high pre-test probability (PTP) is still questioned. Aim To determine whether older age and high PTP are correlated with non-diagnostic cCTA scans in pts with suspected chronic coronary syndrome (CCS). Methods Single-centre retrospective study of 302 pts with suspected CAD assigned to two groups: (A) 207 pts aged ≥70 years (y); (B) 95 aged &amp;lt;70y. Younger pts were randomly selected from our database. We excluded pts with known history of CAD and suspected acute coronary syndrome. A 192x2 dual-source CT equipment was used. Baseline demographic and clinical characteristics were collected as well as scan features and findings. We defined high PTP according to clinical Morise score. Our endpoint was the obtention of diagnostic scan (all segments evaluable). Multivariate analysis was performed to assess the determinants of non-diagnostic scans. We used SPSS Statistics 22 for statistical analysis. Results Overall, mean age was 68±9y and 53% were male. Elderly pts presented more co-morbidities (hypertension: 78.3 vs 54.7%, p&amp;lt;0.01; hyperlipidaemia: 69.1 vs 52.6%, p&amp;lt;0.01; pulmonary disease: 13.0 vs 4.2%, p=0.02) and high PTP more frequently (16.9 vs 6.3%, p&amp;lt;0.01). Total coronary calcium score (CaS) was higher in elderly pts (382.7±658.7 vs 243.5±490.8, p=0.04); per-vessel, both left anterior descending (156.7±254.2 vs 92.2±187.8, p=0.01) and left circumflex (LCX) arteries (65.5±131.3 vs 26.8±67.6, p&amp;lt;0.01) showed higher CaS in the elderly. Multiple calcified plaques (≥5) were also more common in this group (60.4 vs 45.3%, p=0.01). However, the proportion of pts with CaS considered prohibitive for angiography (13.5 vs 7.4%; p=0.12) and calcium blooming artefacts impairing interpretation (14.5 vs 12.5%; p=0.65) did not differ. A diagnostic study was more frequently obtained in younger pts but without reaching statistical significance (69.1 vs 76.8%; p=0.17). Obstructive CAD was equally identified (30.3 vs 30.4%; p=0.92) with a respective per-patient accuracy of 68.4% (13/19) and 57.1% (8/14) comparing with ICA when performed. Multivariate analysis showed that LCX CaS ≥75th percentile and multiple calcified plaques (≥5) were associated with non-diagnostic cCTA scan (Figure 1). High PTP (p=0.83) and age ≥70y (p=0.61) were not associated with the endpoint. Conclusion In this comparison study of elderly and young pts undergoing cCTA for suspected CCS, age ≥70y and high PTP were not associated with non-diagnostic tests while multiple calcified lesions and severe LCX calcification predicted inconclusive studies. Our results cast hope on the applicability of cCTA to elderly pts and cases with high PTP, although larger studies are required. Funding Acknowledgement Type of funding source: None

Anatomic or functional testing in stable patients with suspected CAD: contemporary role of cardiac CT in the ISCHEMIA trial era.

One of the foundations of the management of patients with suspected coronary artery disease (CAD) is to avoid unnecessary invasive coronary angiography (ICA) referrals. However, the diagnostic yield of ICA following abnormal conventional stress testing is low. The ability of ischemia testing to predict subsequent myocardial infarction and death is currently being challenged, and more than half of cardiac events among stable patients with suspected CAD occur in those with normal functional tests. The optimal management of patients with stable CAD remains controversial and ischemia-driven interventions, though improving anginal symptoms, have failed to reduce the risk of hard cardiovascular events. In this context, there is an ongoing debate whether the initial diagnostic test among patients with stable suspected CAD should be a functional test or coronary computed tomography angiography. Aside from considering the specific characteristics of individual patients and local availability and conditions, the choice of the initial test relates to whether the objective concerns its role as gatekeeper for ICA, prognosis, or treatment decision-making. Therefore, the aim of this review is to provide a contemporary overview of these issues and discuss the emerging role of CCTA as the upfront imaging tool for most patients with suspected CAD.

Abstract 04: Diagnostic Accuracy of Coronary CT in Survivors of Out-Of-Hospital Circulatory Arrest: Can CT Serve as a Gatekeeper for Invasive Coronary Angiography?

Introduction: Out-of-hospital circulatory arrest (OHCA) is commonly assumed to be from a cardiac cause although routine early invasive coronary angiography (ICA) remains controversial and has a relatively high proportion of studies without obstructive coronary artery disease (CAD). The ability of coronary CT angiography (CCTA) to detect significant CAD in OHCA survivors has not been evaluated. Methods: The prospective CT-FIRST trial enrolled 104 OHCA survivors who had an early (&lt;6 hours from hospital arrival) head-to-pelvis CT scan that included an ECG-gated CCTA (FORCE CT, Siemens). The CCTA scanned 0-90% of the cardiac cycle without routine use of beta blockers or nitroglycerin. Treating physicians were blinded to the CCTA analysis. ICA was ordered at the discretion of treating physicians. Readers blinded to corresponding studies analyzed CCTA and ICA for coronary stenoses using a 20 segment coronary model. Obstructive CAD was assumed for &gt;50% stenosis. Patient-level diagnostic accuracy calculations for CCTA to identify obstructive CAD used ICA as the standard. Results: Of the 104 enrolled patients, 28 (27%) had both CT and ICA. All CCTA studies were evaluable. Diagnostic accuracy data are shown in the Table. Overall, diagnostic accuracy measures were excellent between CCTA and ICA at the patient level. Conclusions: Early CCTA in OHCA survivors has high diagnostic accuracy for obstructive coronary artery disease and could be used as a gatekeeper to ICA.

Use of coronary computed tomography angiography in clinical practice - single centre experience in Switzerland in light of current recommendations based on pretest probability considerations.

Coronary computed tomography angiography (CCTA) is recommended as a first-line option for the exclusion of coronary artery disease in patients with low to intermediate (15&ndash;50%) pretest probability. We aimed to study the use of CCTA in clinical practice in a single centre in Switzerland in light of this recommendation. In 523 consecutive patients (age 56 &plusmn; 13 years, 48% females) undergoing CCTA during a period of 2 years, the pretest probability of coronary artery disease was assessed using the revised Diamond-Forrester model (CAD consortium score). In patients who had invasive coronary angiography following CCTA, angiographic findings and the consequences regarding management are reported. The majority of patients (n = 316; 60%) had a pretest probability &lt;15%, 188/523 (36%) had a pretest probability between 15 and 50%, and 19/523 (4%) had a pretest probability &gt;50%. The prevalences of coronary artery disease (&ge;50% lumen diameter reduction) by CCTA in patients with pretest probability &lt;15%, 15&ndash;50%, and &gt;50% were 25/316 (8%), 45/188 (24%) and 8/19 (42%), respectively. In 438/523 patients (84%), a CCTA scan showing no coronary artery disease represented the final diagnostic step. In patients undergoing invasive coronary angiography (n = 59, age 58 &plusmn; 9 years, 88% with coronary artery disease by CCTA), coronary artery disease was found in 47/59 (80%) patients and 36/59 (61%) patients underwent revascularisation. The prevalences of coronary artery disease by invasive coronary angiography in patients with pretest probability &lt;15%, 15&ndash;50%, and &gt;50% were 14/21 (67%), 28/32 (88%) and 5/6 (83%). The present data suggest that the currently used pretest probability model is still imperfect and that guideline recommendations regarding pretest probability use for the selection of CCTA candidates are not followed completely. Still, in more than 80% of patients coronary artery disease could be excluded by CCTA, while CCTA also detected a significant number of patients with coronary artery disease in the low pretest probability population. Thus, the data suggest a very judicious use of CCTA as a gatekeeper for invasive coronary angiography in current practice.

Impact of plaque characteristics on the degree of functional stenosis

Coronary CT angiography (CCTA) is mainly regarded as a gatekeeper for invasive coronary angiography, in face of its widely recognized value to noninvasively rule out significant coronary stenosis. Nevertheless, it is also increasingly recognized that this noninvasive modality can depict several atherosclerotic plaque features and quantify total coronary plaque burden. This opens a new field for cardiac CT, since these atherosclerotic features beyond stenosis severity have been correlated with the degree of functional significance, and are the focus of the present manuscript. Although recently acknowledged and documented in CCTA studies, the relation between plaque burden and functional significance has been previously described using several intracoronary imaging modalities, which are also reviewed in the manuscript, to help put in perspective the relation between anatomy and function in coronary artery disease.

Calibration Free Beam Hardening Correction for Cardiac CT Perfusion Imaging.

Myocardial perfusion imaging using CT (MPI-CT) and coronary CTA have the potential to make CT an ideal noninvasive gate-keeper for invasive coronary angiography. However, beam hardening artifacts (BHA) prevent accurate blood flow calculation in MPI-CT. BH Correction (BHC) methods require either energy-sensitive CT, not widely available, or typically a calibration-based method. We developed a calibration-free, automatic BHC (ABHC) method suitable for MPI-CT. The algorithm works with any BHC method and iteratively determines model parameters using proposed BHA-specific cost function. In this work, we use the polynomial BHC extended to three materials. The image is segmented into soft tissue, bone, and iodine images, based on mean HU and temporal enhancement. Forward projections of bone and iodine images are obtained, and in each iteration polynomial correction is applied. Corrections are then back projected and combined to obtain the current iteration's BHC image. This process is iterated until cost is minimized. We evaluate the algorithm on simulated and physical phantom images and on preclinical MPI-CT data. The scans were obtained on a prototype spectral detector CT (SDCT) scanner (Philips Healthcare). Mono-energetic reconstructed images were used as the reference. In the simulated phantom, BH streak artifacts were reduced from 12±2HU to 1±1HU and cupping was reduced by 81%. Similarly, in physical phantom, BH streak artifacts were reduced from 48±6HU to 1±5HU and cupping was reduced by 86%. In preclinical MPI-CT images, BHA was reduced from 28±6 HU to less than 4±4HU at peak enhancement. Results suggest that the algorithm can be used to reduce BHA in conventional CT and improve MPI-CT accuracy.

Nicht invasive Ischämiediagnostik – wie ist der Stand seit den ESC-Leitlinien 2013?

Coronary artery disease continues to be the leading cause of death in developed countries. As coronary atherosclerosis worsens, luminal narrowing caused by coronary plaque mass may result in haemodynamic obstruction and subsequently, angina pectoris symptoms may occur. To avoid redundant invasive procedures and minimize its complications, noninvasive imaging is often performed for an initial assessment of patients with suspected coronary artery disease, serving as a gatekeeper for invasive coronary angiography. The diagnostic accuracy and prognostic value of these strategies have been confirmed in many single-center or multi-center trials. In 2013 the updated ESC guidelines on the management on stable coronary artery disease were released, highlighting the aspect that the diagnostic algorithm is based on the pre-test-probability of coronary artery disease. The consideration of new imaging modalities such as cardiovascular magnetic resonance imaging and coronary CT angiography however, makes it harder for the referring physician to choose the right imaging modality for a patient. This article reviews the clinical utility and the limitations of the most widely used noninvasive imaging modalities and summarizes the diagnostic work-up according to the current ESC guidelines.

Computed tomography angiography for the interventional cardiologist

In recent years, coronary CT angiography (CCTA) has become a widely adopted technique, not only due to its high diagnostic accuracy, but also to the fact that CCTA provides a comprehensive evaluation of the total (obstructive and non-obstructive) coronary atherosclerotic burden. More recently, this technique has become mature, with a large body of evidence addressing its prognostic validation. In addition, CT angiography has moved from the field of 'imagers' and clinicians and entered the interventional cardiology arena, aiding in the planning of both coronary and structural heart interventions, being transcatheter aortic valve implantation one of its most successful examples. It is therefore of utmost importance that interventional cardiologists become familiar with image interpretation and up-to-date regarding several CTA features, taking advantage of this information in planning the procedure, ultimately leading to improvement in patient outcomes. On the other hand, the increasing use of CCTA as a gatekeeper for invasive coronary angiography is expected to lead to an increase in the ratio of interventional to diagnostic procedures and significant changes in the daily cath-lab routine. In a foreseeable future, cath-labs will probably offer an invasive procedure only to patients expected to undergo an intervention, perhaps becoming in this change true interventional-labs.

Computed tomography coronary imaging as a gatekeeper for invasive coronary angiography in patients with newly diagnosed heart failure of unknown aetiology

To evaluate the accuracy of cardiac computed tomography (CT) in distinguishing CAD and non-CAD heart failure (HF) and its effectiveness as a gatekeeper for invasive coronary angiography (ICA). We prospectively included 93 symptomatic patients with newly diagnosed HF of unknown aetiology (59 men; mean age 53 ± 13) and EF <45%, and/or fractional shortening <25%, and/or end-diastolic LV diameter >60 mm (men) or >55 mm (women). In all patients, the CT calcium score (CTCS) was determined. CTCS = 0 excluded CAD HF. Additional CT coronary angiography (CTCA) was performed if CTCS >0. ICA was used as the gold standard for distinguishing between CAD and non-CAD HF in patients with >20% luminal diameter narrowing on CTCA. CAD HF was defined as >50% luminal diameter narrowing in either (i) the left main coronary artery or proximal left anterior descending coronary artery or (ii) in multiple coronary arteries. Diagnostic accuracy and follow-up data (20 ± 16 months) were collected for all patients. CTCS = 0 ruled out CAD HF in 43 patients (46%). The CT algorithm had 100% sensitivity, 95% specificity, 67% positive predictive value, and 100% negative predictive value for detecting CAD HF. Patients with CTCS = 0 or non-CAD HF on CTCA had no coronary events during follow-up, and ICA could have been safely avoided in 76 out of 93 patients (82%). In patients with HF of unknown aetiology, cardiac CT combining CTCS and CTCA has high accuracy for detecting CAD HF and can be used effectively as a gatekeeper for ICA.