Practical Application of Coronary Physiologic Assessment: Asia-Pacific Expert Consensus Document: Part 1.

Coronary physiologic assessment is performed to measure coronary pressure, flow, and resistance or their surrogates to enable the selection of appropriate management strategy and its optimization for patients with coronary artery disease. The value of physiologic assessment is supported by a large body of evidence that has led to major recommendations in clinical practice guidelines. This expert consensus document aims to convey practical and balanced recommendations and future perspectives for coronary physiologic assessment for physicians and patients in the Asia-Pacific region based on updated information in the field that including both wire- and image-based physiologic assessment. This is Part 1 of the whole consensus document, which describes the general concept of coronary physiology, as well as practical information on the clinical application of physiologic indices and novel image-based physiologic assessment.

Integrated Assessment of Computational Coronary Physiology From a Single Angiographic View in Patients Undergoing TAVI.

BACKGROUND: Angiography-derived computational physiology is an appealing alternative to pressure-wire coronary physiology assessment. However, little is known about its reliability in the setting of severe aortic stenosis. This study sought to provide an integrated assessment of epicardial and microvascular coronary circulation by means of single-view angiography-derived physiology in patients with severe aortic stenosis undergoing transcatheter aortic valve implantation (TAVI). METHODS: Pre-TAVI angiographic projections of 198 stenotic coronary arteries (123 patients) were analyzed by means of Murray's law-based quantitative flow ratio and angiography microvascular resistance. Wire-based reference measurements were available for comparison: fractional flow reserve (FFR) in all cases, instantaneous wave-free ratio in 148, and index of microvascular resistance in 42 arteries. RESULTS: No difference in terms of the number of ischemia-causing stenoses was detected between FFR ≤0.80 and Murray's law-based quantitative flow ratio ≤0.80 (19.7% versus 19.2%; P=0.899), while this was significantly higher when instantaneous wave-free ratio ≤0.89 (44.6%; P=0.001) was used. The accuracy of Murray's law-based quantitative flow ratio ≤0.80 in predicting pre-TAVI FFR ≤0.80 was significantly higher than the accuracy of instantaneous wave-free ratio ≤0.89 (93.4% versus 77.0%; P=0.001), driven by a higher positive predictive value (86.9% versus 50%). Similar findings were observed when considering post-TAVI FFR ≤0.80 as reference. In 82 cases with post-TAVI angiographic projections, Murray's law-based quantitative flow ratio values remained stable, with a low rate of reclassification of stenosis significance (9.9%), similar to FFR and instantaneous wave-free ratio. Angiography microvascular resistance demonstrated a significant correlation (Rho=0.458; P=0.002) with index of microvascular resistance, showing an area under the curve of 0.887 (95% CI, 0.752-0.964) in predicting index of microvascular resistance ≥25. CONCLUSIONS: Angiography-derived physiology provides a valid, reliable, and systematic assessment of the coronary circulation in a complex scenario, such as severe aortic stenosis.

Angiography-Based Superficial Wall Strain of De Novo Stenotic Coronary Arteries: Serial Assessment of Vessels Treated with Bioresorbable Scaffold or Drug-Eluting Stent.

OBJECTIVES: This study sought to present an angiography-based computational model for serial assessment of superficial wall strain (SWS, dimensionless) of de-novo coronary stenoses treated with either bioresorbable scaffold (BRS) or drug-eluting stent (DES). BACKGROUND: A novel method for SWS allows the assessment of the mechanical status of arteries in-vivo, which may help for predicting cardiovascular outcomes. METHODS: Patients with arterial stenosis treated with BRS (n = 21) or DES (n = 21) were included from ABSORB Cohort B1 and AIDA trials. The SWS analyses were performed along with quantitative coronary angiography (QCA) at pre-PCI, post-PCI, and 5-year follow-up. Measurements of QCA and SWS parameters were quantified at the treated segment and adjacent 5-mm proximal and distal edges. RESULTS: Before PCI, the peak SWS on the 'to be treated' segment (0.79 ± 0.36) was significantly higher than at both virtual edges (0.44 ± 0.14 and 0.45 ± 0.21; both p < 0.001). The peak SWS in the treated segment significantly decreased by 0.44 ± 0.13 (p < 0.001). The surface area of high SWS decreased from 69.97mm2 to 40.08mm2 (p = 0.002). The peak SWS in BRS group decreased to a similar extent (p = 0.775) from 0.81 ± 0.36 to 0.41 ± 0.14 (p < 0.001), compared with DES group from 0.77 ± 0.39 to 0.47 ± 0.13 (p = 0.001). Relocation of high SWS to device edges was often observed in both groups after PCI (35 of 82 cases, 41.7 %). At follow-up of BRS, the peak SWS remained unchanged compared to post-PCI (0.40 ± 0.12 versus 0.36 ± 0.09, p = 0.319). CONCLUSION: Angiography-based SWS provided valuable information about the mechanical status of coronary arteries. Device implantation led to a significant decrease of SWS to a similar extent with either polymer-based scaffolds or permanent metallic stents.

Comparison of coronary CT angiography-based and invasive coronary angiography-based quantitative flow ratio for functional assessment of coronary stenosis: A multicenter retrospective analysis.

BACKGROUND: The aim of this study was to evaluate the diagnostic performance of coronary CT angiography (CTA)-based quantitative flow ratio (QFR), namely CT-QFR, and compare it with invasive coronary angiography (ICA)-based Murray law QFR (µQFR), using fractional flow reserve (FFR) as the reference standard. METHODS: Patients who underwent coronary CTA, ICA and pressure wire-based FFR assessment within two months were retrospectively analyzed. CT-QFR and µQFR were computed in blinded fashion and compared with FFR, all applying the same cut-off value of ≤0.80 to identify hemodynamically significant stenosis. RESULTS: Paired comparison between CT-QFR and µQFR was performed in 191 vessels from 167 patients. Average FFR was 0.81 â€‹± â€‹0.10 and 42.4% vessels had an FFR ≤0.80. CT-QFR had a slightly lower correlation with FFR compared with µQFR, although statistically non-significant (r â€‹= â€‹0.87 versus 0.90, p â€‹= â€‹0.110). The vessel-level diagnostic performance of CT-QFR was slightly lower but without statistical significance than µQFR (AUC â€‹= â€‹0.94 versus 0.97, difference: -0.03 [95%CI: -0.00-0.06], p â€‹= â€‹0.095), and substantially higher than diameter stenosis by CTA (AUC difference: 0.17 [95%CI: -0.10-0.23], p â€‹< â€‹0.001). The patient-level diagnostic accuracy, sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio for CT-QFR to identify FFR value â€‹≤ â€‹0.80 was 88%, 90%, 86%, 86%, 91%, 6.59 and 0.12, respectively. The diagnostic accuracy of CT-QFR was 84% in extensively calcified lesions, while in vessels with no or less calcification, CT-QFR showed a comparable diagnostic accuracy with µQFR (91% versus 92%, p â€‹= â€‹0.595). Intra- and inter-observer variability in CT-QFR analysis was -0.00 â€‹± â€‹0.04 and 0.00 â€‹± â€‹0.04, respectively. CONCLUSIONS: Performance in diagnosis of hemodynamically significant coronary stenosis by CT-QFR was slightly lower but without statistical significance than µQFR, and substantially higher than CTA-derived diameter stenosis. Extensively calcified lesions reduced the diagnostic accuracy of CT-QFR.

Immediate post-procedural functional assessment of percutaneous coronary intervention: current evidence and future directions.

Percutaneous coronary intervention (PCI) guided by coronary physiology provides symptomatic benefit and improves patient outcomes. Nevertheless, over one-fourth of patients still experience recurrent angina or major adverse cardiac events following the index procedure. Coronary angiography, the current workhorse for evaluating PCI efficacy, has limited ability to identify suboptimal PCI results. Accumulating evidence supports the usefulness of immediate post-procedural functional assessment. This review discusses the incidence and possible mechanisms behind a suboptimal physiology immediately after PCI. Furthermore, we summarize the current evidence base supporting the usefulness of immediate post-PCI functional assessment for evaluating PCI effectiveness, guiding PCI optimization, and predicting clinical outcomes. Multiple observational studies and post hoc analyses of datasets from randomized trials demonstrated that higher post-PCI functional results are associated with better clinical outcomes as well as a reduced rate of residual angina and repeat revascularization. As such, post-PCI functional assessment is anticipated to impact patient management, secondary prevention, and resource utilization. Pre-PCI physiological guidance has been shown to improve clinical outcomes and reduce health care costs. Whether similar benefits can be achieved using post-PCI physiological assessment requires evaluation in randomized clinical outcome trials.

Diagnostic accuracy of quantitative flow ratio for assessment of coronary stenosis significance from a single angiographic view: A novel method based on bifurcation fractal law.

OBJECTIVES: We aimed to evaluate the diagnostic accuracy of computation of fractional flow reserve (FFR) from a single angiographic view in patients with intermediate coronary stenosis. BACKGROUND: Computation of quantitative flow ratio (QFR) from a single angiographic view might increase the feasibility of routine use of computational FFR. In addition, current QFR solutions assume a linear tapering of the reference vessel size, which might decrease the diagnostic accuracy in the presence of the physiologically significant bifurcation lesions. METHODS: An artificial intelligence algorithm was proposed for automatic delineation of lumen contours of major epicardial coronary arteries including their side branches. A step-down reference diameter function was reconstructed based on the Murray bifurcation fractal law and used for QFR computation. Validation of this Murray law-based QFR (µQFR) was performed on the FAVOR II China study population. The µQFR was computed separately in two angiographic projections, starting with the one with optimal angiographic image quality. Hemodynamically significant coronary stenosis was defined by pressure wire-derived FFR ≤0.80. RESULTS: The µQFR was successfully computed in all 330 vessels of 306 patients. There was excellent correlation (r = 0.90, p < .001) and agreement (mean difference = 0.00 ± 0.05, p = .378) between µQFR and FFR. The vessel-level diagnostic accuracy for µQFR to identify hemodynamically significant stenosis was 93.0% (95% CI: 90.3 to 95.8%), with sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio, and negative likelihood ratio of 87.5% (95% CI: 80.2 to 92.8%), 96.2% (95% CI: 92.6 to 98.3%), 92.9% (95% CI: 86.5 to 96.9%), 93.1% (95% CI: 88.9 to 96.1%), 23.0 (95% CI: 11.6 to 45.5), 0.13 (95% CI: 0.08 to 0.20), respectively. Use of suboptimal angiographic image view slightly decreased the diagnostic accuracy of µQFR (AUC = 0.97 versus 0.92, difference = 0.05, p < .001). Intra- and inter-observer variability for µQFR computation was 0.00 ± 0.03, and 0.00 ± 0.03, respectively. Average analysis time for µQFR was 67 ± 22 s. CONCLUSIONS: Computation of µQFR from a single angiographic view has high feasibility and excellent diagnostic accuracy in identifying hemodynamically significant coronary stenosis. The short analysis time and good reproducibility of µQFR bear potential of wider adoption of physiological assessment in the catheterization laboratory.

Diagnostic accuracy of intracoronary optical coherence tomography-derived fractional flow reserve for assessment of coronary stenosis severity.

AIMS: A novel method for computation of fractional flow reserve (FFR) from optical coherence tomography (OCT) was developed recently. This study aimed to evaluate the diagnostic accuracy of a new OCT-based FFR (OFR) computational approach, using wire-based FFR as the reference standard. METHODS AND RESULTS: Patients who underwent both OCT and FFR prior to intervention were analysed. The lumen of the interrogated vessel and the ostia of the side branches were automatically delineated and used to compute OFR. Bifurcation fractal laws were applied to correct the change in reference lumen size due to the step-down phenomenon. OFR was compared with FFR, both using a cut-off value of 0.80 to define ischaemia. Computational analysis was performed in 125 vessels from 118 patients. Average FFR was 0.80±0.09. Accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for OFR to identify FFR ≤0.80 was 90% (95% CI: 84-95), 87% (95% CI: 77-94), 92% (95% CI: 82-97), 92% (95% CI: 82-97), and 88% (95% CI: 77-95), respectively. The AUC was higher for OFR than minimal lumen area (0.93 [95% CI: 0.87-0.97] versus 0.80 [95% CI: 0.72-0.86], p=0.002). Average OFR analysis time was 55±23 seconds for each OCT pullback. Intra- and inter-observer variability in OFR analysis was 0.00±0.02 and 0.00±0.03, respectively. CONCLUSIONS: OFR is a novel and fast method allowing assessment of flow-limiting coronary stenosis without pressure wire and induced hyperaemia. The good diagnostic accuracy and low observer variability bear the potential of improved integration of intracoronary imaging and physiological assessment.