Search

Background: Myocardial ischaemia with non-obstructive coronary arteries (INOCA) represents a challenging and frequent, but largely underdiagnosed, condition., Aims: We aimed to investigate the feasibility and diagnostic value of angiography-derived coronary microcirculatory resistance in patients with INOCA syndrome., Methods: This is an investigator-driven, prospective and blinded study. The diagnostic yield of angiography-derived index of coronary microcirculatory resistance (angio-IMR) was investigated against thermodilution-derived IMR (thermo-IMR) in patients with clinically indicated coronary angiography due to suspected myocardial ischaemia and angiographically normal or non-obstructive coronary arteries. The angio-IMR was derived from resting angiograms (contrast-flow angio-IMR [cAngio-IMR]) by an expert analyst blinded to the thermo-IMR. An independent, blinded, physiology core laboratory analysed the raw intracoronary physiology data and provided the final thermo-IMR values., Results: A total of 104 patients (108 coronary vessels) were analysed after fulfilling predefined inclusion criteria. Most patients were female (67%). Obstructive epicardial disease was angiographically (percent diameter stenosis <50%) and physiologically (fractional flow reserve>0.80) ruled out in all cases. Median thermo-IMR and cAngio-IMR were 16.6 (12.7, 23.0) and 16.8 (12.8, 23.1) units, respectively (median difference -0.31, 95% confidence interval: -1.53 to 1.00; p=0.654). cAngio-IMR showed good correlation (Pearson coefficient 0.76; p<0.001), agreement (mean bias 0.4), discriminatory power (area under the curve from the receiver operator characteristics 0.865; p<0.001) and accuracy (85%), compared to thermo-IMR (≥25 U)., Conclusions: Evaluating coronary microcirculatory resistance in patients with INOCA syndrome using cAngio-IMR is feasible and accurate. By circumventing the need of coronary instrumentation and hyperaemic drugs, this method may facilitate the assessment of coronary microcirculatory resistance in patients with suspected INOCA., Clinicaltrials: gov: NCT04827498.

Aims: Functional assessment of non-culprit lesions (NCL) in patients presenting with ST-elevation myocardial infarction (STEMI) and multivessel disease constitutes an unmet need. This study aimed to evaluate the diagnostic accuracy of quantitative flow ratio (QFR) in the functional assessment of NCL during the acute phase of STEMI., Methods and Results: This was a retrospective, observational, multicentre study including patients with STEMI and staged fractional flow reserve (FFR) assessment of NCL. QFR in NCL was calculated from the coronary angiogram acquired during primary PCI in a blinded fashion with respect to FFR. The diagnostic value of QFR in the STEMI population was compared with a propensity score-matched population of stable angina patients. Eighty-two patients (91 NCL) were included. Target lesions were of both angiographic and functional (mean FFR 0.82±0.09) intermediate severity. The diagnostic performance of QFR was high (AUC 0.91 [95% CI: 0.85-0.97]) and similar to that observed in the matched control population (AUC 0.91 vs 0.94, p=0.5). The diagnostic accuracy of QFR was very high (>95%) in those vessels (61.5%) with QFR values out of a ROC-defined "grey zone" (0.75-0.85). A hybrid FFR/QFR approach (FFR only when QFR is in the grey zone) would adequately classify 96.7% of NCL, avoiding 58.5% of repeat diagnostic procedures., Conclusions: QFR has a good diagnostic accuracy in assessing the functional relevance of NCL during primary PCI, similar to the accuracy observed in stable patients.

Background: Simplification of functional stenosis assessment with pressure guidewires may facilitate adoption of physiology-guided revascularization. An important step in this regard is the avoidance of hyperemic agents, required for fractional flow reserve (FFR) calculation. We evaluate the merits of a hybrid algorithms that combines the translesional pressure ratio (Pd/Pa) obtained at rest, after contrast medium injection (cFFR) and after adenosine administration (FFR)., Methods and Results: Eighty-six patients with 108 de novo intermediate coronary stenoses were included in this prospective, multicenter study. Using prespecified cut-off values that correctly identified stenosis with a 95% of agreement (<0.89 and >0.96 for Pd/Pa; <0.84 and > 0.87 for cFFR) we tested the efficiency of three different multi-step strategies combining the three indices to classify stenosis severity, using FFR-only measurement as reference. All three different hybrid algorithms (Pd/Pa-FFR; cFFR-FFR; Pd/Pa-cFFR-FFR) have more than 95% of agreement with FFR. Yet, the novel Pd/Pa-cFFR-FFR hybrid strategy demonstrated the best performance, avoiding the need of adenosine and medium contrast in 90% and 48% of cases, respectively., Conclusions: A hybrid Pd/Pa-cFFR-FFR decision-making algorithm could be an alternative and valuable strategy to increase the adoption of a physiology-guided PCI using conventional pressure guidewires and consoles., (© 2018 Wiley Periodicals, Inc.)

Objectives: The authors sought to evaluate the influence of coronary microcirculatory dysfunction (CMD) on the diagnostic performance of the quantitative flow ratio (QFR)., Background: Functional angiographic assessment of coronary stenoses based on fluid dynamics, such as QFR, constitutes an attractive alternative to fractional flow reserve (FFR). However, it is unknown whether CMD affects the reliability of angiography-based functional indices., Methods: FFR and the index of microcirculatory resistance (IMR) were measured in 300 vessels (248 patients) as part of a multicenter international registry. QFR was calculated at a blinded core laboratory. Vessels were classified into 2 groups according to microcirculatory status: low IMR (<23 U), and high IMR (≥23 U, CMD). The impact of CMD on the diagnostic performance of QFR, as well as on incremental value of QFR over quantitative angiography, was assessed using FFR as reference., Results: Percent diameter stenosis (%DS) and FFR were similar in low- and high-IMR groups (%DS 51 ± 12% vs. 53 ± 11%; p = 0.16; FFR 0.80 ± 0.11 vs. 0.81 ± 0.11; p = 0.23, respectively). In the overall cohort, classification agreement (CA) between QFR and FFR and diagnostic efficiency of QFR (area under the receiver-operating characteristics curve [AUC]) were high (CA: 88%; AUC: 0.93 [95% confidence interval (CI): 0.90 to 0.96]). However, when assessed according to microcirculatory status, a significantly lower CA and AUC of QFR were found in the high-IMR group as compared with the low-IMR group (CA: 76% vs. 92%; p < 0.001; AUC: 0.88 [95% CI: 0.79 to 0.94] vs. 0.96 [95% CI: 0.92 to 0.98]; p < 0.05). Compared with angiographic assessment, QFR increased by 0.20 (p < 0.001) and by 0.16 (p < 0.001) the AUC of %DS in low- and high-IMR groups, respectively. Independent predictors of misclassification between QFR and FFR were high IMR and acute coronary syndrome., Conclusions: CMD decreases the diagnostic performance of QFR. However, even in the presence of CMD, QFR remains superior to angiography alone in ascertaining functional stenosis severity., (Copyright © 2018 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)