High-Speed On-Site Deep Learning-Based FFR-CT Algorithm: Evaluation Using Invasive Angiography as the Reference Standard.

BACKGROUND. Estimation of fractional flow reserve from coronary CTA (FFR-CT) is an established method of assessing the hemodynamic significance of coronary lesions. However, clinical implementation has progressed slowly, partly because of off-site data transfer with long turnaround times for results. OBJECTIVE. The purpose of this study was to evaluate the diagnostic performance of FFR-CT computed on-site with a high-speed deep learning-based algorithm with invasive hemodynamic indexes as the reference standard. METHODS. This retrospective study included 59 patients (46 men, 13 women; mean age, 66.5 ± 10.2 years) who underwent coronary CTA (including calcium scoring) followed within 90 days by invasive angiography with invasive fractional flow reserve (FFR) and/or instantaneous wave-free ratio measurements from December 2014 to October 2021. Coronary artery lesions were considered to have hemodynamically significant stenosis in the presence of invasive FFR of 0.80 or less and/or instantaneous wave-free ratio of 0.89 or less. A single cardiologist evaluated the CTA images using an on-site deep learning-based semiautomated algorithm entailing a 3D computational flow dynamics model to determine FFR-CT for coronary artery lesions detected with invasive angiography. Time for FFR-CT analysis was recorded. FFR-CT analysis was repeated by the same cardiologist in 26 randomly selected examinations and by a different cardiologist in 45 randomly selected examinations. Diagnostic performance and agreement were assessed. RESULTS. A total of 74 lesions were identified with invasive angiography. FFR-CT and invasive FFR had strong correlation (r = 0.81) and, in Bland-Altman analysis, bias of 0.01 and 95% limits of agreement of -0.13 to 0.15. FFR-CT had AUC for hemodynamically significant stenosis of 0.975. At a cutoff of 0.80 or less, FFR-CT had 95.9% accuracy, 93.5% sensitivity, and 97.7% specificity. In 39 lesions with severe calcifications (≥ 400 Agatston units), FFR-CT had AUC of 0.991 and at a cutoff of 0.80, 94.7% sensitivity, 95.0% specificity, and 94.9% accuracy. Mean analysis time per patient was 7 minutes 54 seconds. Intraobserver agreement (intraclass correlation coefficient, 0.85; bias, -0.01; 95% limits of agreement, -0.12 and 0.10) and interobserver agreement (intraclass correlation coefficient, 0.94; bias, -0.01; 95% limits of agreement, -0.08 and 0.07) were good to excellent. CONCLUSION. A high-speed on-site deep learning-based FFR-CT algorithm had excellent diagnostic performance for hemodynamically significant stenosis with high reproducibility. CLINICAL IMPACT. The algorithm should facilitate implementation of FFR-CT technology into routine clinical practice.

Diagnostic performance of quantitative coronary artery disease assessment using computed tomography in patients with aortic stenosis undergoing transcatheter aortic-valve implantation.

BACKGROUND: Computed tomography angiography (CTA) is a cornerstone in the pre- transcatheter aortic valve replacement (TAVI) assessment. We evaluated the diagnostic performance of CTA and coronary artery calcium score (CACS) for CAD evaluation compared to invasive coronary angiography in a cohort of TAVI patients. METHODS: In consecutive TAVI patients without prior coronary revascularization and device implants, CAD was assessment by quantitative analysis in CTA. (a) Patients with non-evaluable segments were classified as obstructive CAD. (b) In patients with non-evaluable segments a CACS cut-off of 100 was applied for obstructive CAD. The reference standard was quantitative invasive coronary angiography (QCA, i.e. ≥ 50% stenosis). RESULTS: 100 consecutive patients were retrospectively included, age was 82.3 ± 6.5 years and 30% of patients had CAD. In 16% of the patients, adequate visualization of the entire coronary tree (all 16 segments) was possible with CTA, while 84% had at least one segment which was not evaluable for CAD analysis due to impaired image quality. On a per-patient analysis, where patients with low image quality were classified as CAD, CTA showed a sensitivity of 100% (95% CI 88.4-100.0), specificity of 11.4% (95% CI 5.1-21.3), PPV of 32.6% (95% CI 30.8-34.5), NPV of 100% and diagnostic accuracy of 38% (95% CI 28.5-48.3) for obstructive CAD. When applying a combined approach of CTA (in patients with good image quality) and CACS (in patients with low image quality), the sensitivity and NPV remained at 100% and obstructive CAD could be ruled out in 20% of the TAVI patients, versus 8% using CTA alone. CONCLUSION: In routinely acquired pre-TAVI CTA, the image quality was insufficient in a high proportion of patients for the assessment of the entire coronary artery tree. However, when adding CACS in patients with low image quality to quantitative CTA assessment in patients with good image quality, obstructive CAD could be ruled-out in 1/5 of the patients and may therefore constitute a strategy to streamline pre-procedural workup, and reduce risk, radiation and costs in selected TAVI patients without prior coronary revascularization or device implants.

Meta-analysis of intravascular volume expansion strategies to prevent contrast-associated acute kidney injury following invasive angiography.

OBJECTIVE: To perform a detailed analysis of published data regarding intravascular volume expansion to prevent contrast-associated acute kidney injury (CA-AKI) and to determine if an ideal dose of IV fluids can be recommended. BACKGROUND: Administration of contrast media during invasive angiography is associated with CA-AKI. Intravascular volume expansion is the most effective intervention to prevent CA-AKI, yet evidenced based protocols are lacking. METHODS: Literature review and meta-analysis of randomized controlled trials (RCT) of patients receiving IV volume expansion as prophylaxis for CA-AKI was performed. Normal saline, Lactated Ringer's and sodium bicarbonate were included. The primary outcome was incidence of CA-AKI. RESULTS: 37 RCTs studying 12,166 patients were included. Mean age was 67 ± 5 years, 70% of the patients were male. 68% had chronic kidney disease, 41% diabetes, and 30% heart failure. The incidence of CA-AKI was 9.5% (95% CI: 8-12%). IV expansion versus no volume administration was associated with a lower risk of CA-AKI (RR:0.62; 95% CI: 0.49-0.77, p < .001). Intensive IV volume expansion was associated with a reduced risk of CA-AKI(RR: 0.66; 95%CI: 0.52-0.85, p < .01). The intensive IV volume expansion arm received significantly more fluids than the standard protocols: 1,574(1,123 - 1,913) ml versus 849(558-1,067) ml (p = .03) without significant difference in the duration of infusion (median of 12 vs. 17 hr, p = .1) or pulmonary edema (1.7% vs 1.3%, p = .7). CONCLUSIONS: Despite high variability in protocols used, IV volume expansion is effective in preventing CA-AKI. Intensive IVF expansion (median 1.6 L over 17 hr) was associated with decreased risk of CA-AKI.

After ISCHEMIA: Is cardiac MRI a reliable gatekeeper for invasive angiography and myocardial revascularization?

This review surveys the findings of the International Study of Comparative Health Effectiveness with Medical and Invasive Approaches (ISCHEMIA) trial and puts them into a clinical perspective regarding its effect of the role of cardiac magnetic resonance imaging (CMR) as a well-validated gatekeeper for invasive angiography and myocardial revascularization. Noninvasive stress testing of patients with intermediate-to-high pretest likelihood for obstructive coronary artery disease (CAD) using perfusion CMR provides excellent diagnostic accuracy in detecting ischemic myocardium, and additional information from tissue characterization can guide the management of patients with stable angina toward a more individualized therapy as other non-coronary underlying causes of chest pain can be detected. Since ISCHEMIA failed to show that an invasive strategy using percutaneous coronary intervention or coronary artery bypass grafting was associated with an improved prognosis compared with initial conservative medical therapy among stable patients with moderate-to-severe ischemia, CMR as a multifaceted diagnostic imaging approach to explain patients' symptoms should be preferred over anatomical and stress testing alone. Nevertheless, the exclusion of left main coronary artery stenosis either by coronary CT or MR angiography may be required. In conclusion, the results of the ISCHEMIA trial are in good accordance with those of the MR-INFORM trial recently published in the New England Journal of Medicine, as the noninvasive management of a large proportion of patients with CAD was shown to be noninferior to current invasive strategies. Recent outcome data from trials may therefore have an impact on future guidelines to further reduce the execution of unnecessary left heart catheterizations.

Ten-Year Outcomes in Patients Undergoing Simultaneous Coronary and Renal Angiography-Does Renal Artery Stenosis Matter?

Background: We aimed to characterize the population of consecutive patients undergoing coronary angiography with simultaneous renal artery angiography and assess prognostic factors at a 10 year follow-up. Methods: The KORONEF study was a prospective, single-center, observational, and descriptive study with 492 patients included. We analyzed several baseline demographics, clinical and periprocedural characteristics, and laboratory data, and we assessed the results of coronary angiography and renal artery angiography. Results: The study population consisted of 37.2% women, and the mean age was 64.4 ± 9.9 years (min. 30 years, max. 89 years). Angiography revealed significant renal artery stenosis (RAS) in 35 (7.1%) patients. Among patients with significant RAS (≥50%), we observed more women (57.1% vs. 35.7%, p = 0.011), and patients were older (69.1 ± 10.4 years vs. 64.0 ± 9.7 years, p = 0.005). In the whole population, all-cause death was reported in 29.9% of patients, myocardial infarction (MI) rate-in 11.8%, and stroke-in 4.9%. In the multivariable analysis, independent predictors of death were age 65-75 years (HR 2.88), age > 75 years (HR 8.07), diabetes (HR 1.59), previous MI (HR 1.64), chronic kidney disease (HR 2.22), unstable angina (HR 0.37), and left ventricular ejection fraction > 60% (HR 0.43). Conclusions: Over a 10 year follow-up, the all-cause death rate was 29.9%, showing no statistically significant differences between patients with and without significant RAS.

CT angiography compared to invasive angiography for stable coronary disease as predictors of major adverse cardiovascular events- A systematic review and meta-analysis.

BACKGROUND: Computational tomography coronary angiography (CTCA) is increasingly the diagnostic test of choice for investigating patients with stable anginal symptoms. OBJECTIVES: We sought to conduct a systematic review and meta-analysis comparing CTCA with invasive coronary angiography (ICA) with regards to major adverse cardiovascular events (MACE), procedural complications and rates of revascularisation. METHODS: We conducted a systematic review and meta-analysis in line with the PRISMA statement. A literature search was conducted using PubMed, MEDLINE Ovid and Embase, with three studies included in meta-analysis. Statistical analysis was undertaken using Review Manager 5.3 for MacOS software and outcomes expressed as odds ratio, with 95% confidence intervals and sensitivity analysis was conducted. RESULTS: A total of 5662 patients were included in this study level meta-analysis. There was no difference in MACE between CT and angiography [2.97% v 3.45%, fixed-effect model, OR: 0.84 (0.62-1.14), p = 0.26, I2 0%] and no difference found in rates of myocardial infarction, death or stroke. CTCA was associated with a reduced rate of revascularisation [12.6% v 18.3%, fixed-effects model, OR: 0.64 (0.55-0.75), p<0.00001, I2 =0%]. However, CTCA was not associated with a significantly lower complication rate [0.5% v 1.72%, random effects model, OR: 0.52 (0.06-4.38), p = 0.55, I2 52%]. CONCLUSION: CTCA is a safe strategy for investigating patients with stable angina with no associated increase in MACE but a reduction in revascularisation rates.

Transradial Approach to Coronary Angiography and Percutaneous Intervention in Patients With Dextrocardia.

Patients with dextrocardia present unique challenges in the catheterization laboratory. Variable coronary artery anatomy impacts percutaneous access, catheter selection and manipulation, and image acquisition. This is a review of all published reports of radial artery access for diagnostic and/or therapeutic coronary interventions in patients with dextrocardia. We conclude that the radial approach is safe and effective in these patients and should be used without hesitation. In addition, interventionalists should consider use of multipurpose catheters and possess an understanding of how mirror-image fluoroscopy impacts catheter manipulation. Furthermore, we propose a stepwise approach to arterial access, fluoroscopy, and catheter selection for operator reference while treating dextrocardia patients.

Congenital anomaly of coronary artery: absence of left circumflex artery.

The prevalence of congenital coronary artery anomalies is approximately 1% in the general population. They are a common cause of sudden death in younger persons. Congenital absence of the left circumflex artery is usually a benign condition but can cause symptoms of exertional angina. We present a case of a 59-year-old female who presented with complaints of chest pain. She was evaluated by the cardiology service. An invasive angiogram identified the absence of the circumflex artery, a large right coronary artery, and large septal and diagonal branches of the left main coronary artery possibly as a compensatory mechanism to supply blood to the LCx territories. It is important to define coronary anatomy as anomalies dictate which cardiac intervention should be attempted in cases of ischemia.

Practical Considerations of Fractional Flow Reserve Utilization to Guide Revascularization.

OPINION STATEMENT: Invasive angiography has long been the gold standard for the diagnosis of obstructive coronary artery disease (CAD). However, the relationship between angiographic measures of stenosis and coronary blood flow is complex, and there is frequent discordance between the visual assessment of a stenotic lesion and its effect on myocardial perfusion. Fractional flow reserve is a rapidly emerging invasive means of assessing the physiologic significance of an epicardial stenosis. This review provides a pragmatic understanding of the physiologic principles that guide fractional flow reserve (FFR), sheds light on its nuances, and explores the most landmark investigations. We will also discuss how the measurement of FFR can be helpful or limiting in several common clinical situations.

Cost-effectiveness of diagnostic evaluation strategies for individuals with stable chest pain syndrome and suspected coronary artery disease.

PURPOSE: To determine lifetime cost-effectiveness of diagnostic evaluation strategies for individuals with stable chest pain and suspected coronary artery disease (CAD). METHODS: Exercise treadmill testing (ETT), stress echocardiography (SE), myocardial perfusion scintigraphy (MPS), coronary computed tomographic angiography (CCTA), and invasive coronary angiography (ICA) were assessed alone, or in succession to each other. RESULTS: Initial ETT followed by imaging wherein ETT was equivocal or unable to be performed appeared more cost-effective than any strategy employing initial testing by imaging. CONCLUSION: As pre-test likelihood of CAD varies, different modalities including SE, CCTA, and MPS result in improved costs and enhanced effectiveness.

Systolic Compression of a Myocardial Bridged Coronary Artery and its Morphologic Characteristics: A Combination Study of Computed Tomography Angiography and Invasive Angiography.

BACKGROUND: Myocardial bridging (MB) is a congenital anomaly in which a segment of a major epicardial coronary artery courses through the myocardium. This anomaly can lead to myocardial ischemia, arrhythmia, and even death. The effectiveness of coronary computed tomographic angiography (CCTA) in the detection of MB and its morphological features, and the accuracy of invasive coronary angiography (ICA) in the evaluation of systolic compression have been shown in some prior studies. OBJECTIVES: The present study aimed to evaluate the correlation between the depth and the length of MB as determined using CCTA, and the degree of luminal narrowing of the involved tunneled segment as calculated using the ICA. PATIENTS AND METHODS: For this study, 109 consecutive patients diagnosed with myocardial bridging using CCTA, and who had already undergone ICA, were studied. The depth and length of the MB was determined in the CCTA, while the degree of systolic compression was calculated in the ICA. The correlation between the depth and length of the MB and the systolic compression were then evaluated. RESULTS: The degree of systolic compression was found to be correlated with the depth of the MB. However, there was no correlation between the length of the MB and the degree of systolic compression. CONCLUSION: The systolic compression of the MB was influenced by the depth of the tunneled segment, not by its length.

Rest and stress transluminal attenuation gradient and contrast opacification difference for detection of hemodynamically significant stenoses in patients with suspected coronary artery disease.

This study evaluated the feasibility of stress 320 detector CT coronary angiography (CTA) derived transluminal attenuation gradient (TAG320) and contrast opacification (CO) difference to detect hemodynamically significant stenoses as determined by invasive fractional flow reserve (FFR ≤ 0.80). Twenty-seven patients, including 51 vessels on rest CTA were studied. 16 (31 %) vessels were not interpretable on stress CTA largely secondary to motion artefacts. Receiver operating characteristic curve analysis showed a comparable area under the curve (AUC) for rest and stress TAG320 (0.78 and 0.75) which was higher than CTA alone (0.68), and rest and stress CO difference (0.76 and 0.67). Compared with rest CTA, stress CTA demonstrated inferior image quality (Median Likert score 4 vs. 3, P < 0.0001) and required a higher mean radiation exposure (3.2 vs. 5.1 mSv, P < 0.0001). Stress TAG320 and CO difference is less feasible and was not superior in diagnostic performance when compared with rest TAG320 and CO difference.

Diagnostic performance of 64-row coronary CT angiography in detecting significant stenosis as compared with conventional invasive coronary angiography.

BACKGROUND: The aim of the present study is to evaluate the accuracy of 64-multidetector-row computed tomography angiography (CTA) in comparison to conventional invasive angiography (CIA) in the diagnosis of significant stenosis (≥ 50%) of coronary artery tree. METHODS: Assessment of CTA in the detection of coronary artery disease (CAD) was performed in patients referred because of symptoms or stress studies suggestive of ischemia. For this purpose, among more than 1000 cases of coronary CTA in a 20 months period a study population of 54 patients suspected to have significant stenosis of the coronary artery tree was investigated. The CIA procedure was performed in these patients one month after CTA. The accuracy of CTA in detecting significant stenosis was compared to CIA. RESULTS: For vessel based analysis of 179 coronary vessels, CTA had a sensitivity of 96%, specificity of 87.5%, positive predictive value of 90.5%, and negative predictive value of 94.6%. For patient-base analysis, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of CTA were 97.9%, 28.6%, 66.6%, and 90.2%, respectively. CONCLUSION: The findings of this study reveal that CT angiography with 64-slice scanner could be considered as a suitable technique for rapid triage of patients presenting to hospitals with chest pain. High values of sensitivity and PPV reveal the good performance of CTA in detecting CAD.

Prevalence of patent foramen ovale in a consecutive cohort of 261 patients undergoing routine "coronary" 64-multi-detector cardiac computed tomography.

BACKGROUND: A patent foramen ovale (PFO) is strongly associated with cryptogenic stroke (CS), neurological and other phenomena. The reported prevalence of PFO varies according to the imaging technique used and population studied. PURPOSE: To measure prospectively, the prevalence of PFO in a cohort of consecutive patients attending for routine "coronary" CT angiography using standard, everyday coronary protocols including low-dose prospective ECG gated studies. METHODS: Standard coronary imaging protocols were used. PFOs were graded according to the classification of Williamson et al. RESULTS: 261 patients were studied. A PFO was identified in 22.6% (11.5% grade 1 (closed flap), 6.5% grade 2 (open flap) and 4.6% grade 3 (open flap with jet)). A further 6.1% had an atrial septal aneurysm. CONCLUSIONS: The prevalence of all grades of PFO (22.6%) and open flap PFO (11.1% = grade 2 and 3) with this technique compares with 24.3% by trans-oesophageal echocardiography (TOE) and 14.9% by saline contrast echocardiography (SCE). Further comparative studies are required but we believe an open flap PFO or ASA should be identified and recorded during cardiac CT. This approach may identify those at risk of cryptogenic stroke as well as avoid unnecessary tests in stroke patients.