瞬时无波形比值和定量血流分数评价冠状动脉临界病变准确性的对比研究

目的以血流储备分数(FFR)为标准,比较定量血流分数(QFR)和瞬时无波形比值(iFR)评估冠状动脉临界病变的准确性,并分析QFR与iFR的相关性及诊断一致率。方法回顾性纳入北京大学第三医院2015年5月至2020年6月因冠心病进行冠状动脉造影(CAG)并接受FFR和iFR检测的62例患者,收集患者的临床和CAG病变解剖学资料、靶血管iFR和FFR值,并测量同一靶血管的QFR值。以FFR≤0.80为判断心肌缺血的临界值,比较QFR和iFR与FFR评估冠状动脉临界病变的准确性,并分析QFR与iFR的相关性及诊断一致率。结果62例患者中,有53例(85.5%)靶血管为左前降支,基线直径狭窄率为48.0%(41.1%,55.7%)。iFR、QFR与FFR均具有较好的相关性[r=0.773(95%CI 0.649~0.857)、r=0.626(95%CI 0.445~0.757),均P<0.001]。QFR、iFR预测FFR≤0.80的受试者工作特征曲线下面积(AUC)比较,差异无统计学意义[0.859(95%CI 0.748~0.935)比0.875(95%CI 0.766~0.945),P=0.801];二者与FFR诊断一致率的差异无统计学意义(74.2%比79.0%,P=0.615)。QFR与iFR的相关性较弱(r=0.396,95%CI 0.162~0.587,P=0.0015)。QFR对应iFR≤0.89的AUC为0.663(95%CI 0.524~0.801,P=0.028)。QFR、iFR联合诊断策略可以与FFR达到88.7%的诊断一致率,同时减少58.1%的压力导丝使用。结论iFR与QFR评估冠状动脉临界病变具有相似的诊断准确率,但二者相关性较弱。二者联合诊断策略可进一步提高诊断准确率。     

Influence of Microcirculatory Dysfunction on Angiography-Based Functional Assessment of Coronary Stenoses

Objectives

The authors sought to evaluate the influence of coronary microcirculatory dysfunction (CMD) on the diagnostic performance of the quantitative flow ratio (QFR).

QFR Versus FFR Derived From Computed Tomography for Functional Assessment of Coronary Artery Stenosis

ObjectivesThe aim of this study was to compare diagnostic performance between quantitative flow ratio (QFR) derived from coronary angiography and fractional flow reserve derived from computed tomography (FFR_CT) using fractional flow reserve (FFR) as the reference standard.BackgroundQFR and FFR_CT are recently developed, less invasive techniques for functional assessment of coronary artery disease.MethodsQFR, FFR_CT, and FFR were measured in 152 patients (233 vessels) with stable coronary artery disease.ResultsQFR was highly correlated with FFR (r = 0.78; p < 0.001), whereas FFR_CT was moderately correlated with FFR (r = 0.63; p < 0.001). Both QFR and FFR_CT showed moderately good agreement with FFR, presenting small values of mean difference but large values of root mean squared deviation (FFR-QFR, 0.02 ± 0.09; FFR-FFR_CT, 0.03 ± 0.11). The sensitivity, specificity, positive predictive value, and negative predictive value of QFR ≤0.80 for predicting FFR ≤0.80 were 90%, 82%, 81%, and 90%, respectively. Those of FFR_CT ≤0.80 for predicting FFR ≤0.80 were 82%, 70%, 70%, and 82%, respectively. The diagnostic accuracy of QFR ≤0.80 for predicting FFR ≤0.80 was 85% (95% confidence interval [CI]: 81% to 89%), whereas that of FFR_CT ≤0.80 for predicting FFR ≤0.80 was 76% (95% CI: 70% to 80%).ConclusionsQFR and FFR_CT showed significant correlation with FFR. Mismatches between QFR and FFR and between FFR_CT and FFR were frequent.     

Diagnostic performance and limitation of quantitative flow ratio for functional assessment of intermediate coronary stenosis

BackgroundThis study aimed to simultaneously investigate diagnostic performance and limitation of quantitative flow reserve (QFR) for assessing functionally significant coronary stenosis, focusing on factors affecting diagnostic accuracy of QFR.MethodsThis study evaluated 1) QFR diagnostic accuracy compared with fractional flow reserve (FFR) in patients with stable coronary artery disease (Cohort-A, n = 95) and 2) QFR reproducibility for non-culprit lesions (NCLs) assessment between acute and staged (14±5 days later) procedures in patients with ST-segment elevation myocardial infarction (STEMI) (Cohort-B, n = 65). All coronary angiography image acquisition was performed before the introduction of QFR system into our institution.ResultsCohort-A showed good correlation (r = 0.80, p<0.0001) between QFR and FFR; diagnostic accuracy of QFR for FFR ≤0.80 was 85.2% (sensitivity 80.4%, specificity 91.0%, positive predictive value 91.1%, negative predictive value 80.0%). There were 14 lesions showing discordance between QFR and FFR, which was primarily attributable to inadequate lesion visualization due to vessel overlap/tortuosity and/or insufficient intra-coronary contrast-media injection. In Cohort-B, there was also excellent correlation between acute and staged QFR; classification agreement of acute and staged QFR was 92.3%. Five lesions showed discordance between acute and staged QFR, 4 were due to limited image acquisition and/or high coronary flow velocity at acute phase of STEMI and 1 was borderline ischemia.ConclusionsQFR-derived physiological assessment of intermediate coronary stenosis is feasible, even in the acute setting of STEMI. Adjusting some technical factors may further improve the diagnostic performance of QFR.     

El cociente de flujo cuantitativo en pacientes con estenosis aórtica grave y lesiones coronarias intermedias

Introduction and objectivesQuantitative flow ratio (QFR) is a novel noninvasive method for evaluating coronary physiology. However, data on the QFR in patients with aortic stenosis (AS) and coronary artery disease are scarce. Thus, we compared the diagnostic performance of the QFR with that of the resting distal to aortic coronary pressure (Pd/Pa) ratio, fractional flow reserve (FFR), and instantaneous wave-free ratio (iFR), as well as angiographic indices.MethodsA total of 221 AS patients with 416 vessels undergoing FFR/iFR measurements were enrolled in the study.ResultsThe mean percent diameter stenosis (%DS) was 58.6% ± 13.4% and the mean Pd/Pa ratio, FFR, iFR, and QFR were 0.95 ± 0.03, 0.85 ± 0.07, 0.90 ± 0.04, and 0.84 ± 0.07, respectively. A FFR ≤ 0.80 was noted in 26.0% of interrogated vessels, as well as an iFR ≤ 0.89 in 33.2% and QFR ≤ 0.80 in 31.7%. The QFR had better agreement with FFR (intraclass correlation coefficient [ICC], 0.96; 95% confidence interval [95%CI], 0.95-0.96) than with the iFR (ICC, 0.79; 95%CI, 0.75-0.82) and Pd/Pa ratio (ICC, 0.52; 95%CI, 0.44-0.58). In addition, the QFR showed better diagnostic accuracy (98.6% vs 94.2%; P < .001) and discriminant function (area under the curve = 0.996 vs 0.988; P < .001) when the iFR was used as the reference instead of FFR.ConclusionsIn patients with AS, the QFR has good agreement with both FFR and iFR. However, the agreement appears to be even better when the iFR is used as the reference, presumably due to the complex nature of the coronary physiology in the assessment of coronary artery disease in patients with severe AS.     

Angiography-derived functional assessment of left main coronary stenoses

Objectives

We aimed to evaluate the diagnostic accuracy of quantitative flow ratio (QFR) in left main (LM) coronary stenoses, using Fractional Flow Reserve (FFR) as reference.

Background

QFR has demonstrated a high accuracy in determining the functional relevance of coronary stenoses in non-LM. However, there is an important paucity of data regarding its diagnostic value in the specific anatomical subset of LM disease.

Methods

This is a retrospective, observational, multicenter, international, and blinded study including patients with LM stenoses. Cases with significant ostial LM disease were excluded. QFR was calculated from conventional angiograms at blinded fashion with respect to FFR.

Results

Sixty-seven patients with LM stenoses were analyzed. Overall, LM had intermediate severity, both from angiographic (diameter stenosis [%DS] 43.8 ± 11.1%) and functional perspective (FFR 0.756 ± 0.105). Mean QFR was 0.733 ± 0.159. Correlation between QFR and FFR was moderate (r = 0.590). Positive and negative predictive value, sensitivity and specificity were 85.4%, 64%, 85.4%, and 69.6% respectively. Classification agreement of QFR and FFR in terms of functional stenosis severity was 78.1%. Area under the receiver operating characteristics of QFR using FFR as reference was 0.82 [95% confidence interval [CI], 0.71−0.93], and significantly better than angiographic evaluation including %DS (area under the receiver-operating characteristic curve [AUC] 0.45 [95% CI, 0.32−0.58], p < 0.001) and minimum lumen diameter (AUC 0.60 [95% CI, 0.47−0.74], p < 0.001).

Conclusions

Compared with FFR, QFR has acceptable diagnostic performance in determining the functional relevance of LM stenosis, being better than conventional angiographic assessment. Nonetheless, caution should be taken when applying functional angiography techniques for the assessment of LM stenosis given its particular anatomical characteristics.     

定量血流分数评价左心室舒张功能不全患者心肌缺血的价值

目的 探讨定量血流分数(quantitative flow ratio,QFR)在诊断左心室舒张功能不全患者心肌缺血的价值.方法 纳入2017年1月至2018年12月间广东省人民医院心脏超声诊断为左心室舒张功能不全但收缩功能正常,同时行冠状动脉造影及血流储备分数(fractional flow reserve,FFR)...     

Diagnostic and Clinical Value of FFRCT in Stable Chest Pain Patients With Extensive Coronary Calcification: The FACC Study

BackgroundThe influence of extensive coronary calcifications on the diagnostic and prognostic value of coronary computed tomography angiography–derived fractional flow reserve (FFRCT) has been scantily investigated.ObjectivesThe purpose of this study was to investigate the diagnostic and short-term role of FFR_CT in chest pain patients with Agatston score (AS) >399.MethodsThis was a prospective multicenter study of 260 stable patients with suspected coronary artery disease (CAD) and AS >399. FFR_CT was measured blinded by an independent core laboratory. All patients underwent invasive coronary angiography (ICA) and FFR if indicated. The agreement of FFR_CT ≤0.80 with hemodynamically significant CAD on ICA/FFR (≥50% left main or ≥70% epicardial artery stenosis and/or FFR ≤0.80) was assessed. Patients undergoing FFR had colocation FFR_CT measured, and the lowest per-patient FFR_CT was registered in all patients. The association among per-patient FFR_CT, coronary revascularization, and major clinical events (all-cause mortality, myocardial infarction, or unstable angina hospitalization) at 90-day follow-up was evaluated.ResultsMedian age and AS were 68.5 years (IQR: 63-74 years) and 895 (IQR: 587-1,513), respectively. FFR_CT was ≤0.80 in 204 patients (78%). Colocation FFR_CT (n = 112) showed diagnostic accuracy, sensitivity, and specificity to identify hemodynamically significant CAD of 71%, 87%, and 54%. The area under the receiver-operating characteristics curve (AUC) was 0.75. When using the lowest FFR_CT (n = 260), per-patient accuracy, sensitivity, and specificity were 57%, 95%, and 32%, respectively. The AUC was 0.84. A total of 85 patients underwent revascularization, and FFR_CT was ≤0.80 in 96% of these. During follow-up, major clinical events occurred in 3 patients (1.2%), all with FFR_CT ≤0.80.ConclusionsMost patients with AS >399 had FFR_CT ≤0.80. Using ICA/FFR as the reference revealed a moderate diagnostic accuracy of colocation FFR_CT. Compared with the lowest per-patient FFR_CT, colocation FFR_CT measurement improved diagnostic accuracy and specificity. The 90-day follow-up was favorable with few coronary revascularizations and no major clinical events occurring in patients with FFR_CT >0.80. (Use of FFR-CT in Stable Intermediate Chest Pain Patients With Severe Coronary Calcium Score [FACC]; NCT03548753)     

Prognostic Implications of Plaque Characteristics and Stenosis Severity in Patients With Coronary Artery Disease

BackgroundAlthough the presence of ischemia is a key prognostic factor in patients with coronary artery disease, the presence of high-risk plaque characteristics (HRPC) is also associated with increased risk of cardiovascular events. Limited data exist regarding the prognostic implications of combined information on physiological stenosis severity assessed by fractional flow reserve (FFR) and plaque vulnerability by coronary computed tomography angiography (CTA)–defined HRPC.ObjectivesThe current study aimed to evaluate the: 1) association between physiological stenosis severity and coronary CTA-defined HRPC; and 2) prognostic implications of coronary CTA-defined HRPC according to physiological stenosis severity in patients with coronary artery disease.MethodsA total of 772 vessels (299 patients) evaluated by both coronary CTA and FFR were analyzed. The presence and number of HRPC (minimum lumen area <4 mm², plaque burden ≥70%, low attenuating plaque, positive remodeling, napkin-ring sign, or spotty calcification) were assessed using coronary CTA images. The risk of vessel-oriented composite outcome (VOCO) (a composite of vessel-related ischemia-driven revascularization, vessel-related myocardial infarction, or cardiac death) at 5 years was compared according to the number of HRPC and FFR categories.ResultsThe proportion of lesions with ≥3 HRPC was significantly decreased according to the increase in FFR values (58.6%, 46.5%, 36.8%, 15.7%, and 3.5% for FFR ≤0.60, 0.61 to ≤0.70, 0.71 to ≤0.80, 0.81 to ≤0.90, and >0.90, respectively; overall p value <0.001). Both FFR and number of HRPC showed significant association with the estimated risk of VOCO (p = 0.008 and p = 0.023, respectively). In the FFR >0.80 group, lesions with ≥3 HRPC showed significantly higher risk of VOCO than those with <3 HRPC (15.0% vs. 4.3%; hazard ratio: 3.964; 95% confidence interval: 1.451 to 10.828; p = 0.007). However, there was no significant difference in the risk of VOCO according to HRPC in the FFR ≤0.80 group. By multivariable analysis, the presence of ≥3 HRPC was independently associated with the risk of VOCO in the FFR >0.80 group.ConclusionsPhysiological stenosis severity and the number of HRPC were closely related, and both components had significant association with the risk of clinical events. However, the prognostic implication of HRPC was different according to FFR. Integration of both physiological stenosis severity and plaque vulnerability would provide better prognostic stratification of patients than either individual component alone, especially in patients with FFR >0.80. (Clinical Implication of 3-vessel Fractional Flow Reserve [3V FFR-FRIENDS study]; NCT01621438)     

CT FFR for Ischemia-Specific CAD With a New Computational Fluid Dynamics Algorithm: A Chinese Multicenter Study

ObjectivesThe aim of this study was to validate the feasibility of a novel structural and computational fluid dynamics–based fractional flow reserve (FFR) algorithm for coronary computed tomography angiography (CTA), using alternative boundary conditions to detect lesion-specific ischemia.BackgroundA new model of computed tomographic (CT) FFR relying on boundary conditions derived from structural deformation of the coronary lumen and aorta with transluminal attenuation gradient and assumptions regarding microvascular resistance has been developed, but its accuracy has not yet been validated.MethodsA total of 338 consecutive patients with 422 vessels from 9 Chinese medical centers undergoing CTA and invasive FFR were retrospectively analyzed. CT FFR values were obtained on a novel on-site computational fluid dynamics–based CT FFR (uCT-FFR [version 1.5, United-Imaging Healthcare, Shanghai, China]). Performance characteristics of uCT-FFR and CTA in detecting lesion-specific ischemia in all lesions, intermediate lesions (luminal stenosis 30% to 70%), and “gray zone” lesions (FFR 0.75 to 0.80) were calculated with invasive FFR as the reference standard. The effect of coronary calcification on uCT-FFR measurements was also assessed.ResultsPer vessel sensitivities, specificities, and accuracies of 0.89, 0.91, and 0.91 with uCT-FFR, 0.92, 0.34, and 0.55 with CTA, and 0.94, 0.37, and 0.58 with invasive coronary angiography, respectively, were found. There was higher specificity, accuracy, and AUC for uCT-FFR compared with CTA and qualitative invasive coronary angiography in all lesions, including intermediate lesions (p < 0.001 for all). No significant difference in diagnostic accuracy was observed in the “gray zone” range versus the other 2 lesion groups (FFR ≤0.75 and >0.80; p = 0.397) and in patients with “gray zone” versus FFR ≤0.75 (p = 0.633) and versus FFR >0.80 (p = 0.364), respectively. No significant difference in the diagnostic performance of uCT-FFR was found between patients with calcium scores ≥400 and <400 (p = 0.393).ConclusionsThis novel computational fluid dynamics–based CT FFR approach demonstrates good performance in detecting lesion-specific ischemia. Additionally, it outperforms CTA and qualitative invasive coronary angiography, most notably in intermediate lesions, and may potentially have diagnostic power in gray zone and highly calcified lesions.     

Prognostic Value of QFR Measured Immediately After Successful Stent Implantation: The International Multicenter Prospective HAWKEYE Study

ObjectivesThe aim of this study was to investigate the potential role of post–percutaneous coronary intervention (PCI) quantitative flow ratio (QFR) measurements to predict clinical outcomes in patients with successful PCI.BackgroundThe prognostic value of QFR measured immediately after PCI has not been prospectively investigated.MethodsPatients undergoing complete revascularization with successful PCI and stent implantation were eligible for acquisition of projections for QFR computation. At the end of the procedure, 2 angiographic projections for each vessel treated with PCI were acquired. Computation of QFR was performed offline by an independent core laboratory. The primary outcome was the vessel-oriented composite endpoint, defined as vessel-related cardiovascular death, vessel-related myocardial infarction, and ischemia-driven target vessel revascularization.ResultsSeven hundred fifty-one vessels in 602 patients were analyzed. The median value of post-PCI QFR was 0.97 (interquartile range: 0.92 to 0.99). Lesion location in the left anterior descending coronary artery, baseline SYNTAX (Synergy Between PCI With Taxus and Cardiac Surgery) score, lesion length, and post-PCI diameter stenosis were found to be predictors of lower post-PCI QFR. Altogether, 77 events were detected in 53 treated vessels (7%). Post-PCI QFR was significantly lower in vessels with the vessel-oriented composite endpoint during follow-up, compared with those without it (0.88 [interquartile range: 0.81 to 0.99] vs. 0.97 [interquartile range: 0.93 to 0.99], respectively; p < 0.001). Receiver-operating characteristic curve analysis identified a post-PCI QFR best cutoff of ≤0.89 (area under the curve 0.77; 95% confidence interval: 0.74 to 0.80; p < 0.001). After correction for potential confounding factors, post-PCI QFR ≤0.89 was associated with a 3-fold increase in risk for the vessel-oriented composite endpoint (hazard ratio: 2.91; 95% confidence interval: 1.63 to 5.19; p < 0.001).ConclusionsLower values of QFR after complete and successful revascularization predict subsequent adverse events (Angio-Based Fractional Flow Reserve to Predict Adverse Events After Stent Implantation [HAWKEYE]; NCT02811796)     

Comparison Between the Performance of Quantitative Flow Ratio and Perfusion Imaging for Diagnosing Myocardial Ischemia

ObjectivesThis study compared the performance of the quantitative flow ratio (QFR) with single-photon emission computed tomography (SPECT) and positron emission tomography (PET) myocardial perfusion imaging (MPI) for the diagnosis of fractional flow reserve (FFR)−defined coronary artery disease (CAD).BackgroundQFR estimates FFR solely based on cine contrast images acquired during invasive coronary angiography (ICA). Head-to-head studies comparing QFR with noninvasive MPI are lacking.MethodsA total of 208 (624 vessels) patients underwent technetium-⁹⁹m tetrofosmin SPECT and [¹⁵O]H₂O PET imaging before ICA in conjunction with FFR measurements. ICA was obtained without using a dedicated QFR acquisition protocol, and QFR computation was attempted in all vessels interrogated by FFR (552 vessels).ResultsQFR computation succeeded in 286 (52%) vessels. QFR correlated well with invasive FFR overall (R = 0.79; p < 0.001) and in the subset of vessels with an intermediate (30% to 90%) diameter stenosis (R = 0.76; p < 0.001). Overall, per-vessel analysis demonstrated QFR to exhibit a superior sensitivity (70%) in comparison with SPECT (29%; p < 0.001), whereas it was similar to PET (75%; p = 1.000). Specificity of QFR (93%) was higher than PET (79%; p < 0.001) and not different from SPECT (96%; p = 1.000). As such, the accuracy of QFR (88%) was superior to both SPECT (82%; p = 0.010) and PET (78%; p = 0.004). Lastly, the area under the receiver operating characteristics curve of QFR, in the overall sample (0.94) and among vessels with an intermediate lesion (0.90) was higher than SPECT (0.63 and 0.61; p < 0.001 for both) and PET (0.82; p < 0.001 and 0.77; p = 0.002), respectively.ConclusionsIn this head-to-head comparative study, QFR exhibited a higher diagnostic value for detecting FFR-defined significant CAD compared with perfusion imaging by SPECT or PET.     

Intravascular Ultrasound-Derived Minimal Lumen Area Criteria for Functionally Significant Left Main Coronary Artery Stenosis

ObjectivesThis study sought to evaluate the intravascular ultrasound (IVUS) minimal lumen area (MLA) for functionally significant left main coronary artery (LMCA) stenosis using fractional flow reserve (FFR) as the standard.BackgroundThe evaluation of significant LMCA stenosis remains challenging.MethodsWe identified 112 patients with isolated ostial and shaft intermediate LMCA stenosis (angiographic diameter stenosis of 30% to 80%) who underwent IVUS and FFR measurement.ResultsThe FFR was ≤0.80 in 66 LMCA lesions (59%); these exhibited smaller reference vessels, smaller minimal lumen diameter, greater diameter of stenosis, longer lesion length, smaller MLA, larger plaque burden, and more frequent plaque rupture. The independent factors of an FFR of ≤0.80 were plaque rupture (odds ratio [OR]: 4.47; 95% Confidence Interval (CI): 1.35 to 14.8; p = 0.014); body mass index (OR: 1.19; 95% CI: 1.00 to 1.41; p = 0.05), age (OR: 0.95; 95% CI: 0.90 to 1.00; p = 0.031), and IVUS MLA (OR: 0.37; 95% CI: 0.25 to 0.56; p < 0.001). The optimal IVUS MLA cutoff value for an FFR of ≤0.80 was 4.5 mm² (77% sensitivity, 82% specificity, 84% positive predictive value, 75% negative predictive value, area under the curve: 0.83, 95% CI: 0.76 to 0.96; p < 0.001) overall and 4.1 to 4.5 mm² in various subgroups. Adjustment for the body surface area, body mass index, and left ventricular mass did not improve the diagnostic accuracy of the IVUS MLA.ConclusionsIn patients with isolated ostial and shaft intermediate LMCA stenosis, an IVUS-derived MLA of ≤4.5 mm² is a useful index of an FFR of ≤0.80.     

Cardiac Magnetic Resonance for Evaluating Nonculprit Lesions After Myocardial Infarction: Comparison With Fractional Flow Reserve

ObjectivesThis study sought to determine the agreement between cardiac magnetic resonance (CMR) imaging and invasive measurements of fractional flow reserve (FFR) in the evaluation of nonculprit lesions after ST-segment elevation myocardial infarction (STEMI). In addition, we investigated whether fully quantitative analysis of myocardial perfusion is superior to semiquantitative and visual analysis.BackgroundThe agreement between CMR and FFR in the evaluation of nonculprit lesions in patients with STEMI with multivessel disease is unknown.MethodsSeventy-seven patients with STEMI with at least 1 intermediate (diameter stenosis 50% to 90%) nonculprit lesion underwent CMR and invasive coronary angiography in conjunction with FFR measurements at 1 month after primary intervention. The imaging protocol included stress and rest perfusion, cine imaging, and late gadolinium enhancement. Fully quantitative, semiquantitative, and visual analysis of myocardial perfusion were compared against a reference of FFR. Hemodynamically obstructive was defined as FFR ≤0.80.ResultsHemodynamically obstructive nonculprit lesions were present in 31 (40%) patients. Visual analysis displayed an area under the curve (AUC) of 0.74 (95% confidence interval [CI]: 0.62 to 0.83), with a sensitivity of 73% and a specificity of 70%. For semiquantitative analysis, the relative upslope of the stress signal intensity time curve and the relative upslope derived myocardial flow reserve had respective AUCs of 0.66 (95% CI: 0.54 to 0.77) and 0.71 (95% CI: 0.59 to 0.81). Fully quantitative analysis did not augment diagnostic performance (all p > 0.05). Stress myocardial blood flow displayed an AUC of 0.76 (95% CI: 0.64 to 0.85), with a sensitivity of 69% and a specificity of 77%. Similarly, MFR displayed an AUC of 0.82 (95% CI: 0.71 to 0.90), with a sensitivity of 82% and a specificity of 71%.ConclusionsCMR and FFR have moderate-good agreement in the evaluation of nonculprit lesions in patients with STEMI with multivessel disease. Fully quantitative, semiquantitative, and visual analysis yield similar diagnostic performance.     

Dynamic Myocardial Perfusion CT for the Detection of Hemodynamically Significant Coronary Artery Disease

ObjectivesIn this international, multicenter study, using third-generation dual-source computed tomography (CT), we investigated the diagnostic performance of dynamic stress CT myocardial perfusion imaging (CT-MPI) in addition to coronary CT angiography (CTA) compared to invasive coronary angiography (ICA) and invasive fractional flow reserve (FFR).BackgroundCT-MPI combined with coronary CTA integrates coronary artery anatomy with inducible myocardial ischemia, showing promising results for the diagnosis of hemodynamically significant coronary artery disease in single-center studies.MethodsAt 9 centers in Europe, Japan, and the United States, 132 patients scheduled for ICA were enrolled; 114 patients successfully completed coronary CTA, adenosine-stress dynamic CT-MPI, and ICA. Invasive FFR was performed in vessels with 25% to 90% stenosis. Data were analyzed by independent core laboratories. For the primary analysis, for each coronary artery the presence of hemodynamically significant obstruction was interpreted by coronary CTA with CT-MPI compared to coronary CTA alone, using an FFR of ≤0.80 and angiographic severity as reference. Territorial absolute myocardial blood flow (MBF) and relative MBF were compared using C-statistics.ResultsICA and FFR identified hemodynamically significant stenoses in 74 of 289 coronary vessels (26%). Coronary CTA with ≥50% stenosis demonstrated a per-vessel sensitivity, specificity, and accuracy for the detection of hemodynamically significant stenosis of 96% (95% CI: 91%-100%), 72% (95% CI: 66%-78%), and 78% (95% CI: 73%-83%), respectively. Coronary CTA with CT-MPI showed a lower sensitivity (84%; 95% CI: 75%-92%) but higher specificity (89%; 95% CI: 85%-93%) and accuracy (88%; 95% CI: 84%-92%). The areas under the receiver-operating characteristic curve of absolute MBF and relative MBF were 0.79 (95% CI: 0.71-0.86) and 0.82 (95% CI: 0.74-0.88), respectively. The median dose-length product of CT-MPI and coronary CTA were 313 mGy·cm and 138 mGy·cm, respectively.ConclusionsDynamic CT-MPI offers incremental diagnostic value over coronary CTA alone for the identification of hemodynamically significant coronary artery disease. Generalized results from this multicenter study encourage broader consideration of dynamic CT-MPI in clinical practice. (Dynamic Stress Perfusion CT for Detection of Inducible Myocardial Ischemia [SPECIFIC]; NCT02810795)     

Clinical Deployment of Explainable Artificial Intelligence of SPECT for Diagnosis of Coronary Artery Disease

BackgroundExplainable artificial intelligence (AI) can be integrated within standard clinical software to facilitate the acceptance of the diagnostic findings during clinical interpretation.ObjectivesThis study sought to develop and evaluate a novel, general purpose, explainable deep learning model (coronary artery disease–deep learning [CAD-DL]) for the detection of obstructive CAD following single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI).MethodsA total of 3,578 patients with suspected CAD undergoing SPECT MPI and invasive coronary angiography within a 6-month interval from 9 centers were studied. CAD-DL computes the probability of obstructive CAD from stress myocardial perfusion, wall motion, and wall thickening maps, as well as left ventricular volumes, age, and sex. Myocardial regions contributing to the CAD-DL prediction are highlighted to explain the findings to the physician. A clinical prototype was integrated using a standard clinical workstation. Diagnostic performance by CAD-DL was compared to automated quantitative total perfusion deficit (TPD) and reader diagnosis.ResultsIn total, 2,247 patients (63%) had obstructive CAD. In 10-fold repeated testing, the area under the receiver-operating characteristic curve (AUC) (95% CI) was higher according to CAD-DL (AUC: 0.83 [95% CI: 0.82-0.85]) than stress TPD (AUC: 0.78 [95% CI: 0.77-0.80]) or reader diagnosis (AUC: 0.71 [95% CI: 0.69-0.72]; P < 0.0001 for both). In external testing, the AUC in 555 patients was higher according to CAD-DL (AUC: 0.80 [95% CI: 0.76-0.84]) than stress TPD (AUC: 0.73 [95% CI: 0.69-0.77]) or reader diagnosis (AUC: 0.65 [95% CI: 0.61-0.69]; P < 0.001 for all). The present model can be integrated within standard clinical software and generates results rapidly (<12 seconds on a standard clinical workstation) and therefore could readily be incorporated into a typical clinical workflow.ConclusionsThe deep-learning model significantly surpasses the diagnostic accuracy of standard quantitative analysis and clinical visual reading for MPI. Explainable artificial intelligence can be integrated within standard clinical software to facilitate acceptance of artificial intelligence diagnosis of CAD following MPI.     

Clinical Validation of a Virtual Planner for Coronary Interventions Based on Coronary CT Angiography

BackgroundLow fractional flow reserve (FFR) values after percutaneous coronary intervention (PCI) carry a worse prognosis than high post-PCI FFR values. Therefore, the ability to predict post-PCI FFR might play an important role in procedural planning. Post-PCI FFR values can now be computed from pre-PCI coronary computed tomography angiography (CTA) using the fractional flow reserve derived from coronary computed tomography angiography revascularization planner (FFR_CT Planner).ObjectivesThe aim of this study was to validate the accuracy of the FFR_CT Planner.MethodsIn this multicenter, investigator-initiated, prospective study, patients with chronic coronary syndromes and significant lesions based on invasive FFR ≤0.80 were recruited. The FFR_CT Planner was applied to the fractional flow reserve derived from coronary computed tomography angiography (FFR_CT) model, simulating PCI. The primary objective was the agreement between the predicted post-PCI FFR by the FFR_CT Planner and measured post-PCI FFR. Accuracy of the FFR_CT Planner’s luminal dimensions was assessed by using post-PCI optical coherence tomography as the reference.ResultsOverall, 259 patients were screened, with 120 patients (123 vessels) included in the final analysis. The mean patient age was 64 ± 9 years, and 24% had diabetes. Measured FFR post-PCI was 0.88 ± 0.06, and the FFR_CT Planner FFR was 0.86 ± 0.06 (mean difference: 0.02 ± 0.07 FFR unit; limits of agreement: –0.12 to 0.15). Optical coherence tomography minimal stent area was 5.60 ± 2.01 mm², and FFR_CT Planner minimal stent area was 5.0 ± 2.2 mm² (mean difference: 0.66 ± 1.21 mm²; limits of agreement: –1.7 to 3.0). The accuracy and precision of the FFR_CT Planner remained high in cases with focal and diffuse disease and with low and high calcium burden.ConclusionsThe FFR_CT-based technology was accurate and precise for predicting FFR after PCI. (Precise Percutaneous Coronary Intervention Plan Study [P3]; NCT03782688)     

Diagnostic accuracy of dual‐source computed tomography angiography for the detection of coronary in‐stent restenosis: A systematic review and meta‐analysis

We sought to perform a meta‐analysis to comprehensively evaluate the diagnostic accuracy of dual‐source computed tomography angiography (DSCTA) in detecting coronary in‐stent restenosis (CISR) when compared to invasive coronary angiography. The stent‐based research studies in which DSCTA was used as diagnostic tool for CISR, as recent as of October 2017, from several reputed scientific libraries (PubMed, Embase, Scopus, The Cochrane Library, and Web of Science) were evaluated. Study inclusion, data extraction, and risk bias assessment were conducted by two researchers independently. Pooled sensitivity (SEN), specificity (SPE), positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and area under summary receiver operator characteristics (SROC) curve (AUC) were calculated to assess the diagnostic value. In addition, heterogeneity and subgroup analysis were also carried out. A total of 13 studies with a total of 894 patients and 1384 assessable stents were included. The pooled results of DSCTA diagnosing CISR were as follows: SEN 0.92 (95% confidence interval [CI] 0.87–0.96), SPE 0.91 (95% CI 0.87–0.94), PLR 9.83 (95% CI 6.93–13.94), NLR 0.09 (95% CI 0.05–0.15), DOR 114.73 (95% CI 64.12–205.28), and AUC 0.97 (95% CI 0.95–0.98), respectively. The subgroup analysis result suggested that DSTCA performed significantly better in CISR detection when the stent diameter was ≥3 mm compared with the stent diameter <3 mm: (0.98 [0.97–0.99] vs 0.82 [0.79–0.86]) with P < .05. This study revealed that DSCTA has excellent diagnostic performance for detecting CISR and may serve as an alternative for further patient evaluation with CISR, especially for stent diameter ≥3 mm.     

Influence of Coronary Calcium on Diagnostic Performance of Machine Learning CT-FFR: Results From MACHINE Registry

ObjectivesThis study was conducted to investigate the influence of coronary artery calcium (CAC) score on the diagnostic performance of machine-learning–based coronary computed tomography (CT) angiography (cCTA)–derived fractional flow reserve (CT-FFR).BackgroundCT-FFR is used reliably to detect lesion-specific ischemia. Novel CT-FFR algorithms using machine-learning artificial intelligence techniques perform fast and require less complex computational fluid dynamics. Yet, influence of CAC score on diagnostic performance of the machine-learning approach has not been investigated.MethodsA total of 482 vessels from 314 patients (age 62.3 ± 9.3 years, 77% male) who underwent cCTA followed by invasive FFR were investigated from the MACHINE (Machine Learning based CT Angiography derived FFR: a Multi-center Registry) registry data. CAC scores were quantified using the Agatston convention. The diagnostic performance of CT-FFR to detect lesion-specific ischemia was assessed across all Agatston score categories (CAC 0, >0 to <100, 100 to <400, and ≥400) on a per-vessel level with invasive FFR as the reference standard.ResultsThe diagnostic accuracy of CT-FFR versus invasive FFR was superior to cCTA alone on a per-vessel level (78% vs. 60%) and per patient level (83% vs. 73%) across all Agatston score categories. No statistically significant differences in the diagnostic accuracy, sensitivity, or specificity of CT-FFR were observed across the categories. CT-FFR showed good discriminatory power in vessels with high Agatston scores (CAC ≥400) and high performance in low-to-intermediate Agatston scores (CAC >0 to <400) with a statistically significant difference in the area under the receiver-operating characteristic curve (AUC) (AUC: 0.71 [95% confidence interval (CI): 0.57 to 0.85] vs. 0.85 [95% CI: 0.82 to 0.89], p = 0.04). CT-FFR showed superior diagnostic value over cCTA in vessels with high Agatston scores (CAC ≥ 400: AUC 0.71 vs. 0.55, p = 0.04) and low-to-intermediate Agatston scores (CAC >0 to <400: AUC 0.86 vs. 0.63, p < 0.001).ConclusionsMachine-learning–based CT-FFR showed superior diagnostic performance over cCTA alone in CAC with a significant difference in the performance of CT-FFR as calcium burden/Agatston calcium score increased. (Machine Learning Based CT Angiography Derived FFR: a Multicenter, Registry [MACHINE] NCT02805621).     

Combined Assessment of FFR and CFR for Decision Making in Coronary Revascularization: From the Multicenter International ILIAS Registry

ObjectivesThe aim of this study was to demonstrate the clinical implications of combined assessment of fractional flow reserve (FFR) and coronary flow reserve (CFR).BackgroundCombined assessment of FFR and CFR allows detailed characterization of pathophysiology in chronic coronary syndromes. Data on the clinical implications of distinct FFR and CFR patterns are limited, leading to uncertainty regarding their relevance.MethodsPatients with chronic coronary syndromes and obstructive coronary artery disease were selected from the multicenter ILIAS (Inclusive Invasive Physiological Assessment in Angina Syndromes) registry. Patients were classified into 4 groups on the basis of FFR ≤0.80 and CFR <2.0. The endpoint was the 5-year target vessel failure (TVF) rate.ResultsA total of 2,143 patients with 2,725 lesions were included. Compared with normal FFR/normal CFR, low FFR/low CFR carried the highest risk for TVF (HR: 5.4; 95% CI: 3.2-9.3; P < 0.001), significantly higher than in revascularized vessels (P = 0.007). Discordance, with either low FFR/normal CFR or normal FFR/low CFR, was associated with increased TVF rates compared with normal FFR/normal CFR (low FFR/normal CFR: HR: 3.5 [95% CI: 2.2-5.4; P < 0.001]; normal FFR/low CFR: HR: 3.0 [95% CI: 1.9-4.7; P < 0.001]). No difference in 5-year TVF was observed between the 2 discordant groups (P = 0.57) or between the discordant groups and the revascularized group (P = 0.26 vs low FFR/normal CFR; P = 0.60 vs normal FFR/low CFR).ConclusionsImpaired coronary hemodynamics are uniformly associated with increased 5-year TVF rates. Nonrevascularized vessels with discordant FFR and CFR are associated with 5-year event rates that are equivalent to those of vessels that undergo revascularization, whereas vessels with combined low FFR and CFR exhibit event rates that are significantly higher than after revascularization. (Inclusive Invasive Physiological Assessment in Angina Syndromes Registry [ILIAS Registry]; NCT04485234)