The value of fractional flow reserve based on coronary computed tomography angiography with low-dose contrast agent in noninvasive diagnosis of coronary artery disease.

The study aimed, using invasive coronary angiography (ICA) as the gold standard, to investigate the noninvasive diagnostic value of flow reserve fraction derived from coronary computed tomography angiography (CCTA) with low-dose contrast agent in coronary artery disease (CAD). A total of 163 patients with clinical symptoms related to CAD were enrolled between 1 January 2022 and 30 January 2023. The patients received CCTA with a low dose of contrast agent to rule out CAD. If significant (CCTA ≥ 50%) stenosis is suspected, ICA is performed to further evaluate the CCTA for coronary lesions. CT-FFR is calculated from the CCTA dataset using a machine learning-based algorithm. Compared with ICA as a reference standard, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy of low-dose contrast agent CT-FFR in the diagnosis of myocardial ischemia were calculated. Coronary lesions with CT-FFR ≤0.80 were defined as hemodynamically significant. Obstructive CAD was excluded by low-contrast CCTA in 87 of 163 patients (53.7%). In the remaining 75 patients (42.35%), at least one coronary artery stenosis was greater than 50%. The accuracy, sensitivity, specificity, PPV, and NPV of low-dose contrast agent CT-FFR on a patient-based evaluation in diagnosing CAD were 93.06, 93.44, 90.01, 98.28, and 71.43%, respectively (Kappa = 0.759). The accuracy, sensitivity, specificity, PPV, and NPV of low-dose contrast agent CT-FFR on a vessel-based evaluation in diagnosing CAD were 86.72, 82.76, 91.58, 92.31, and 81.31%, respectively (Kappa = 0.735). Pearson correlation analysis showed that the ICA examination had a good correlation with CT-FFR value of low-dose contrast media ( r  = 0.731, P  < 0.01). Moreover, in 81.31% of cases, additional analysis of CT-FFR correctly excluded the hemodynamic significance of stenosis. CT-FFR based on low-dose contrast agent CCTA is a very promising noninvasive approach to exclude hemodynamically significant coronary artery stenosis in patients with suspected coronary heart disease while reducing renal burden and helping to reduce the rate of ICA in this high-risk population.

Wang Z ，Luan X ，Zhang Q ，Chu C ，Xu X ，Chai H ，Song P ... -  《-》

Usefulness of FFR-CT to exclude haemodynamically significant lesions in high-risk NSTE-ACS.

Meier D ，Andreini D ，Cosyns B ，Skalidis I ，Storozhenko T ，Mahendiran T ，Assanelli E ，Sonck J ，Roosens B ，Rotzinger DC ，Qanadli SD ，Tzimas G ，Muller O ，De Bruyne B ，Collet C ，Fournier S ... -  《-》

Prognostic value of computed tomography-derived fractional flow reserve in patients with diabetes mellitus and unstable angina.

Coronary artery calcification is commonly found in patients with type 2 diabetes mellitus (T2DM), which may compromise the diagnostic accuracy of coronary computed tomography angiography (CTA). Computed tomography-derived fractional flow reserve (CT-FFR), which integrates coronary anatomy with functional assessment, holds the potential to become a powerful diagnostic tool for evaluating calcified lesions. We aim to assess the prognostic value of CT-FFR for calcific lesions in patients with T2DM and unstable angina (UA). We conducted a retrospective study involving 3,392 patients who were diagnosed with T2DM and UA who underwent coronary CTA, with at least one visible calcification site. Of those, 1,091 patients and 1,372 vessels were recommended by cardiovascular specialists and completed invasive coronary angiography (ICA) and invasive fractional flow reserve (FFR) measurements. Simultaneously, those patients also underwent CT-FFR measurements and were divided into two groups based on CT-FFR values: one group with CT-FFR > 0.80 and the other with CT-FFR ≤ 0.80. Demographics, clinical data, the diagnostic performance of CT-FFR, analysis of calcified lesions on CTA, and major adverse events during follow-up were recorded. The diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and the area under the curve (AUC) of CT-FFR were 84.8%, 84.6%, 85.1%, 84.7%, 85.0%, and 84.8%, respectively, per patient, and 82.2%, 80.3.2%, 81.8%, 79.7%, 81.1%, and 82.9% respectively, per vessel. For lesion and calcification characteristics, the degree of stenosis, lesion length, rate of bifurcation lesions, diffusive lesions, occlusion, calcium volume, and coronary artery calcification score (CACS) were significantly higher in the CT-FFR ≤ 0.8 group compared to the CT-FFR > 0.8 group. In contrast, the minimum cross-sectional area was smaller in the CT-FFR ≤ 0.8 group than in the CT-FFR > 0.8 group. Major adverse cardiovascular and cerebrovascular events (MACCE) at the 3-year follow-up was significantly higher in the CT-FFR ≤ 0.8 group compared to the CT-FFR > 0.8 group. The CT-FFR value is an independent predictor of MACCE at the 3-year follow-up. CT-FFR demonstrated significant diagnostic performance using invasive FFR as the reference standard and proved to be an important predictive tool for assessing prognosis not only in calcified lesions but also in lesions with a CACS score of zero in patients with T2DM and UA. CT-FFR may serve as a valuable tool for guiding treatment decisions in these patients.

Zhao Q ，Liu L ，Xian H ，Luo X ，Zhang D ，Hou S ，Qu C ，Zhang R ，Qu X ... -  《Cardiovascular Diabetology》

Dobutamine stress echocardiography after positive CCTA: diagnostic performance using fractional flow reserve and instantaneous wave-free ratio as reference standards.

To assess the diagnostic accuracy of dobutamine stress echocardiography (DSE) in symptomatic patients with a low to intermediate pretest probability of obstructive coronary artery disease (CAD) and a positive coronary CT angiography (CCTA). We prospectively enrolled 104 consecutive patients undergoing coronary angiography for symptoms of stable CAD and a CCTA indicative of obstructive CAD. The diagnostic performance of DSE was evaluated against two intracoronary pressure indices: (a) fractional flow reserve (FFR) with a cut-off of ≤0.80 and (b) instantaneous wave-free ratio (iFR) with a cut-off of ≤0.89, indicating haemodynamically significant stenoses. Of 102 patients, 46 (45%) had at least one significant lesion as defined by FFR, as did 37 (36%) as defined by iFR. DSE showed positive results in 33% (34/102) of cases. The discriminative power of DSE for detecting significant CAD was moderate, with areas under the curve of 0.63 (p=0.024) compared with FFR and 0.64 (p=0.025) compared with iFR. The accuracy, sensitivity and specificity of DSE were, respectively, 61%, 43%, and 75% against FFR, and 64%, 46% and 74% against iFR. The diagnostic accuracy of DSE did not differ significantly between FFR and iFR as a reference (p=0.549). In patients with positive CCTA, DSE has a moderate ability to identify haemodynamically significant CAD, with low sensitivity and moderate specificity. When assessed against FFR and iFR criteria, its additive diagnostic value is limited in patients with low to intermediate pretest probability of obstructive CAD. NCT03045601.

Tjellaug Bråten A ，Holte E ，Wiseth R ，Aakhus S ... -  《Open Heart》

Diagnostic Performance of Fractional Flow Reserve Derived From Coronary CT Angiography: The ACCURATE-CT Study.

AccuFFRct (ArteryFlow Technology) is a novel noninvasive method for calculating fractional flow reserve (FFR) from coronary computed tomography angiography (CCTA). The accuracy of AccuFFRct has not been adequately assessed. This study sought to evaluate the diagnostic performance of AccuFFRct in detecting lesion-specific ischemia. This prospective study enrolled 339 patients with 404 vessels. CCTA-derived FFR was calculated using an on-site computational fluid dynamics-based method and compared with invasive FFR. The performance of AccuFFRct was comprehensively analyzed in all lesions and subgroups, including "gray zone" lesions, various lesion classifications, clinical presentations, stenosis severities, and lesion locations. Using FFR ≤0.80 as a reference standard, the overall diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for AccuFFRct were 90.6% (95% CI: 87.3%-93.3%), 90.9% (95% CI: 85.1%-94.9%), 90.4% (95% CI: 86.1%-93.8%), 85.3% (95% CI: 79.8%-89.5%), and 94.2% (95% CI: 90.8%-96.4%), respectively. Good correlation and agreement were found between the computed AccuFFRct and measured FFR. AccuFFRct showed superior discrimination ability to CCTA (AUC: 0.93 [95% CI: 0.89-0.95] vs 0.77 [95% CI: 0.72-0.81]; P < 0.001) and quantitative coronary angiography (AUC: 0.93 [95% CI: 0.89-0.95] vs 0.89 [95% CI: 0.85-0.92]; P = 0.048) for identifying functionally significant stenosis. Notably, AccuFFRct maintained high diagnostic accuracy across the spectrum of lesion classifications, clinical presentations, stenosis severities, lesion locations, and in the "gray zone". Furthermore, in the cohort with ≥70% stenosis, AccuFFRct could significantly reduce the rate of un-necessary invasive tests (33.1% vs 6.6%; P < 0.001). The study confirms the potential of AccuFFRct as a noninvasive alternative to invasive FFR for detecting ischemia in coronary artery disease and to risk stratify patients. The results highlight AccuFFRct's robust diagnostic ability across a wide range of lesion classifications, clinical presentations, stenosis severities, lesion locations, and in the "gray zone". (Diagnostic Performance of Fractional Flow Reserve Derived From Coronary CT Angiography [ACCURATE-CT]; NCT04426396).

Li C ，Hu Y ，Jiang J ，Dong L ，Sun Y ，Tang L ，Du C ，Yin D ，Jiang W ，Leng X ，Jiang F ，Pan Y ，Jiang X ，Zhou Z ，Koo BK ，Xiang J ，Wang J ，ACCURATE-CT Investigators ... -  《-》