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Expert recommendations on the assessment of wall shear stress in human coronary arteries: existing methodologies, technical considerations, and clinical applications

Measurement of Hyperemic Pullback Pressure Gradients to Characterize Patterns of Coronary Atherosclerosis.

Objectives We aimed to provide robust performance estimates for quantitative flow ratio (QFR) in assessment of intermediary coronary lesions. Background Angiography-based functional lesion assessment by QFR may appear as a cost saving and safe approach to expand the use of physiology-guided percutaneous coronary interventions. QFR was proven feasible and showed good diagnostic performance in mid-sized off-line and on-line studies with fractional flow reserve (FFR) as reference standard. Methods We performed a collaborative individual patient-data meta-analysis of all available prospective studies with paired assessment of QFR and FFR using the CE-marked QFR application. The main outcome was agreement of QFR and FFR using a two-step analysis strategy with a multilevel mixed model accounting for study and center level variation. Results Of 16 studies identified, four studies had prospective enrollment and provided patient level data reaching a total of 819 patients and 969 vessels with paired FFR and QFR: FAVOR Pilot (n = 73); WIFI II (n = 170); FAVOR II China (n = 304) and FAVOR II Europe-Japan (n = 272). We found an overall agreement (mean difference 0.009 ± 0.068, I2 = 39.6) of QFR with FFR. The diagnostic performance was sensitivity 84% (95%CI: 77-90, I2 = 70.1), specificity 88% (95%CI: 84-91, I2 = 60.1); positive predictive value 80% (95%CI: 76-85, I2 = 33.4), and negative predictive value 95% (95%CI: 93-96, I2 = 75.9). Conclusions Diagnostic performance of QFR was good with FFR as reference in this meta-analysis of high quality studies. QFR could provide an easy, safe, and cost-effective solution for functional evaluation of coronary artery stenosis.

Diagnostic performance of quantitative flow ratio in prospectively enrolled patients: An individual patient-data meta-analysis.

Fractional flow reserve (FFR) and instantaneous wave-free ratio are the present standard diagnostic methods for invasive assessment of the functional significance of epicardial coronary stenosis. Despite the overall trend towards more physiology-guided revascularization, there remains a gap between guideline recommendations and the clinical adoption of functional evaluation of stenosis severity. A number of image-based approaches have been proposed to compute FFR without the use of pressure wire and induced hyperaemia. In order to better understand these emerging technologies, we sought to highlight the principles, diagnostic performance, clinical applications, practical aspects, and current challenges of computational physiology in the catheterization laboratory. Computational FFR has the potential to expand and facilitate the use of physiology for diagnosis, procedural guidance, and evaluation of therapies, with anticipated impact on resource utilization and patient outcomes.

Fractional flow reserve in clinical practice: from wire-based invasive measurement to image-based computation

Aims Conventional fractional flow reserve (FFR) is measured invasively using a coronary guidewire equipped with a pressure sensor. A non-invasive derived FFR would eliminate risk of coronary injury, minimize technical limitations, and potentially increase adoption. We aimed to evaluate the diagnostic performance of a computational pressure-flow dynamics derived FFR (caFFR), applied to coronary angiography, compared to invasive FFR. Methods and results The FLASH FFR study was a prospective, multicentre, single-arm study conducted at six centres in China. Eligible patients had native coronary artery target lesions with visually estimated diameter stenosis of 30-90% and diagnosis of stable or unstable angina pectoris. Using computational pressure-fluid dynamics, in conjunction with thrombolysis in myocardial infarction (TIMI) frame count, applied to coronary angiography, caFFR was measured online in real-time and compared blind to conventional invasive FFR by an independent core laboratory. The primary endpoint was the agreement between caFFR and FFR, with a pre-specified performance goal of 84%. Between June and December 2018, matched caFFR and FFR measurements were performed in 328 coronary arteries. Total operational time for caFFR was 4.54 ± 1.48 min. caFFR was highly correlated to FFR (R = 0.89, P = 0.76) with a mean bias of -0.002 ± 0.049 (95% limits of agreement -0.098 to 0.093). The diagnostic performance of caFFR vs. FFR was diagnostic accuracy 95.7%, sensitivity 90.4%, specificity 98.6%, positive predictive value 97.2%, negative predictive value 95.0%, and area under the receiver operating characteristic curve of 0.979. Conclusions Using wire-based FFR as the reference, caFFR has high accuracy, sensitivity, and specificity. caFFR could eliminate the need of a pressure wire, technical error and potentially increase adoption of physiological assessment of coronary artery stenosis severity. Clinical trial registration URL: http://www.chictr.org.cn Unique Identifier: ChiCTR1800019522.

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Accuracy of computational pressure-fluid dynamics applied to coronary angiography to derive fractional flow reserve: FLASH FFR

Aims Pressure-wire assessment of coronary stenosis is considered the invasive reference standard for detection of ischaemia-generating lesions. Recently, methods to estimate the fractional flow reserve (FFR) from conventional angiography without the use of a pressure wire have been developed, and were shown to have an excellent diagnostic accuracy. The present systematic review and meta-analysis aimed at determining the diagnostic performance of angiography-derived FFR for the diagnosis of haemodynamically significant coronary artery disease. Methods and results A systematic review and meta-analysis of studies assessing the diagnostic performance of angiography-derived FFR systems were performed. The primary outcome of interest was pooled sensitivity and specificity. Thirteen studies comprising 1842 vessels were included in the final analysis. A Bayesian bivariate meta-analysis yielded a pooled sensitivity of 89% (95% credible interval 83-94%), specificity of 90% (95% credible interval 88-92%), positive likelihood ratio (+LR) of 9.3 (95% credible interval 7.3-11.7) and negative likelihood ratio (-LR) of 0.13 (95% credible interval 0.07-0.2). The summary area under the receiver-operating curve was 0.84 (95% credible interval 0.66-0.94). Meta-regression analysis did not find differences between the methods for pressure-drop calculation (computational fluid dynamics vs. mathematical formula), type of analysis (on-line vs. off-line) or software packages. Conclusion The accuracy of angiography-derived FFR was good to detect haemodynamically significant lesions with pressure-wire measured FFR as a reference. Computational approaches and software packages did not influence the diagnostic accuracy of angiography-derived FFR. A diagnostic strategy trial with angiography-derived FFR evaluating clinical endpoints is warranted.

Diagnostic performance of angiography-derived fractional flow reserve: a systematic review and Bayesian meta-analysis.


 
 
 Type of funding sources: None.
 
 
 
 The totality of atherosclerotic plaque derived from coronary computed tomography angiography (CCTA) – atherosclerotic plaque burden - emerges as a comprehensive measure to assess the intensity of medical treatment that patients need. This study examines the differences in age onset and prognostic significance of atherosclerotic plaque burden between women and men.
 
 
 
 From a large multi-center CCTA registry the Leiden CCTA score was calculated in 24,950 men and women. This score incorporates plaque extent, severity, location and composition into a single value, and was divided into 3 risk groups as described previously. Median Leiden CCTA score values were modeled per increasing age to assess the delay in onset of plaque in women. Further, sex-differences in the prognostic value for major adverse cardiac events (MACE, myocardial infarction or all-cause death) were investigated using multivariable cox regression analysis, adjusted for age and cardiovascular risk factors. Sex specific differences in prognostic importance are evaluated with interactions, including a pre-defined age threshold of ≥55 years indicating menopause.
 
 
 
 A total of 11,678 women (age 58.5 ± 12.4 years) and 13,272 men (age 55.6 ± 12.5 years) were followed for 3.7 years. The age where the median Leiden CCTA risk score was above zero was 12 years higher in women versus men (64–68 yr in women vs 52–56 yr in men, p<0.001). The Leiden CCTA risk score was independently associated with MACE: score 6–20: HR 2.29 (1.69–3.10); score >20: HR 6.71 (4.36–10.32) in women, and score 6–20: HR 1.64 (1.29–2.08); score >20: HR 2.38 (1.73–3.29) in men. The risk was significantly higher for women within the highest risk group (adjusted p-interaction = 0.003). In pre-menopausal women, the Leiden CCTA risk score was equally predictive comparable with men. In postmenopausal women, the prognostic value was higher for women, especially in the highest Leiden CCTA risk score (score 6–20: HR 2.21 [1.57–3.11]; score >20: HR 6.11 [3.84–9.70] in women; score 6–20: HR 1.57 [1.19–2.09]; score >20: HR 2.25 [1.58–3.22] in men), with a significant interaction for the highest risk group (adjusted p-interaction=0.004).
 
 
 
 Women developed coronary atherosclerosis approximately 12 years later than men. Post-menopausal women within the highest atherosclerotic burden group were at significantly higher risk for MACE than their male counterparts, which may have implications of the medical treatment intensity.


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Sex and age-specific interactions of coronary atherosclerotic plaque onset and prognosis from coronary CT


 
 
 Type of funding sources: Public hospital(s). Main funding source(s): Scripps Health Krueger Wyeth Grant
 
 
 
 ACS results from unstable atherosclerotic plaques. Current measures to assess risk do not consider the patient’s coronary atherosclerotic composition. This was a case control study using a prospective single-center registry of patients undergoing CCTA (N=2,700) from 2017–2020 to assess the association between plaque characterization and the occurrence of ACS.
 
 
 
 ACS cases were adjudicated independently by two cardiologists using data from the EMR. Patients with prior ACS prior to CCTA, were excluded. Controls were selected 1:1 by nearest neighbor propensity matching (R. v. 4.0.3.) based on age, sex, smoking, HTN, HLD, and DM. Plaque burden and stenosis features were calculated by a commercially available artificial intelligence (AI) coronary analysis (Figure 1).
 
 
 
 There were 21 cases and 21 controls. Mean age of 68, 43% women, 5% Hispanic, 29% smoking hx, 76% HTN, 81% HLD, 24% DM, CAD-RADS score 2.3, and CAC of 487. Median time from CT to ACS for cases was 329 days. Presence of total non-calcified plaque, calcified plaque, fibro-fatty plaque, maximum stenosis diameter percentage and total plaque were each associated with greater risk of ACS (Table 1).
 
 
 
 AI assessment of CCTA plaque characteristics were associated with ACS. This study shows the association between AI derived coronary atherosclerotic features and development of ACS in patients undergoing CCTA and highlights the potential utility of using AI-driven plaque characterization to predict ACS.


/pdf/are-artificial-intelligence-derived-coronary-atherosclerotic-23ltg1r1.pdf

Alexandre van Rosendael

Papers

Diagnostic performance of angiography-derived fractional flow reserve: a systematic review and Bayesian meta-analysis.

Sex and age-specific interactions of coronary atherosclerotic plaque onset and prognosis from coronary CT

Are artificial intelligence derived coronary atherosclerotic characteristics associated with subsequent development of acute coronary syndrome (ACS)