Instantaneous Wave-free Ratio versus Fractional Flow Reserve to Guide PCI

Discordant Diagnostics: A Case Series of iFR and FFR Discrepancies

Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are 2 methods used to detect hemodynamically significant lesions and guide revascularization. Discrepancies between FFR and iFR values can complicate revascularization decisions. We present a series of 6 cases with discrepant FFR and iFR results. Among them, 5 were men, 5 had lesions in the right coronary artery, and one had left anterior descending disease, with an average age of 61.7 ± 11.1 years. All patients were iFR negative (mean iFR 0.94 ± 0.02) and FFR positive (mean FFR 0.75 ± 0.04). Consequently, all patients underwent revascularization.

Randomized Study Comparing Angiography Guidance With Physiology Guidance After PCI: The EASY-PREDICT Study

BACKGROUND

Physiology assessment of coronary lesion prepercutaneous coronary intervention (PCI) using hyperemic and nonhyperemic pressure ratios is useful to determine if a lesion requires treatment. Whether the physiology after PCI is superior to angiography guidance only is unknown. The study sought to investigate whether post-PCI physiology improves clinical outcomes compared with standard angiographic guidance.

METHODS

All-comers patients referred for diagnostic angiography and possible PCI were recruited in a high-volume tertiary care hospital. After uncomplicated PCI, patients were randomized to angiography guidance or target vessel physiology, including nonhyperemic pressure ratio (resting distal coronary pressure to aortic pressure ratio and diastolic pressure ratio) and fractional flow reserve. The primary outcome was the rate of target vessel failure, including cardiac death, myocardial infarction, and target vessel revascularization at 18 months post-PCI. Angina score, medications, and quality of life were also assessed.

RESULTS

Two hundred twenty-one patients were randomized in the angiography group (110 patients, 166 lesions) and the physiology group (111 patients, 159 lesions). Immediate post-PCI physiology results were deemed suboptimal in 22 (17%) cases, and operators performed further optimization steps. Final post-PCI results were resting distal coronary pressure to aortic pressure ratio of 0.95±0.04, the diastolic pressure ratio of 0.94±0.06, and the fractional flow reserve of 0.90±0.07. Ultimately, 9 lesions (7%) remained with fractional flow reserve values ≤0.80. At 18-month follow-up, target vessel failure was 17.4% in the angiography group and 18% in the physiology group (P=0.88). Rates of cardiac death (1% versus 0%; P=0.32), myocardial infarction (13% versus 11%; P=0.66), and target vessel revascularization (4% versus 7%; P=0.24) remained similar in both groups. No difference in angina score, medication, or quality of life was found.

CONCLUSIONS

In all-comers patients undergoing uncomplicated PCI, routine post-PCI physiology assessment was not associated with clinical benefit compared with standard angiographic guidance. Further study is required to determine how post-PCI physiology guidance can be helpful in selected lesions.

REGISTRATION

URL: XXX; Unique identifier: NCT04929496.

Cost-effectiveness of angiographic quantitative flow ratio-guided coronary intervention: A multicenter, randomized, sham-controlled trial

BACKGROUND

The FAVOR (Comparison of Quantitative Flow Ratio Guided and Angiography Guided Percutaneous Intervention in Patients with Coronary Artery Disease) III China trial demonstrated that percutaneous coronary intervention (PCI) lesion selection using quantitative flow ratio (QFR) measurement, a novel angiography-based approach for estimating fractional flow reserve, improved two-year clinical outcomes compared with standard angiography guidance. This study aimed to assess the cost-effectiveness of QFR-guided PCI from the perspective of the current Chinese healthcare system.

METHODS

This study is a pre-specified analysis of the FAVOR III China trial, which included 3825 patients randomized between December 25, 2018, and January 19, 2020, from 26 centers in China. Patients with stable or unstable angina pectoris or those ≥72 hours post-myocardial infarction who had at least one lesion with a diameter stenosis between 50% and 90% in a coronary artery with a ≥2.5 mm reference vessel diameter by visual assessment were randomized to a QFR-guided strategy or an angiography-guided strategy with 1:1 ratio. During the two-year follow-up, data were collected on clinical outcomes, quality-adjusted life-years (QALYs), estimated costs of index procedure hospitalization, outpatient cardiovascular medication use, and rehospitalization due to major adverse cardiac and cerebrovascular events (MACCE). The primary analysis calculated the incremental cost-effectiveness ratio (ICER) as the cost per MACCE avoided. An ICER of ¥10,000/MACCE event avoided was considered economically attractive in China.

RESULTS

At two years, the QFR-guided group demonstrated a reduced rate of MACCE compared to the angiography-guided group (10.8% vs . 14.7%, P <0.01). Total two-year costs were similar between the groups (¥50,803 ± 21,121 vs . ¥50,685 ± 23,495, P = 0.87). The ICER for the QFR-guided strategy was ¥3055 per MACCE avoided, and the probability of QFR being economically attractive was 64% at a willingness-to-pay threshold of ¥10,000/MACCE avoided. Sensitivity analysis showed that QFR-guided PCI would become cost-saving if the cost of QFR were below ¥3682 (current cost: ¥3800). Cost-utility analysis yielded an ICER of ¥56,163 per QALY gained, with a 53% probability of being cost-effective at a willingness-to-pay threshold of ¥85,000 per QALY gained.

CONCLUSION

In patients undergoing PCI, a QFR-guided strategy appears economically attractive compared to angiographic guidance from the perspective of the Chinese healthcare system.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT03656848.

Coronary artery bypass grafting with or without preoperative physiological stenosis assessment: a SWEDEHEART study

BACKGROUND AND AIMS

Physiological flow assessment of coronary stenoses, such as fractional flow reserve, are routinely used to guide percutaneous coronary intervention, but it has not been equally recognized to guide coronary artery bypass grafting (CABG). Mid-term outcomes in CABG patients with and without preoperative flow assessment were compared.

METHODS

All patients with first-time isolated CABG in Sweden 2013-2020 were identified in the SWEDEHEART registry (n = 18 211), which also provided information on flow assessment. Data were linked with three mandatory national registries. Median follow-up was 3.6 years (range 0-7.5). Incidence of all-cause mortality, stroke, new myocardial infarction, new coronary angiography, and new revascularization was compared using adjusted Cox regression models. The proportional hazard assumption was violated for new angiography and revascularization. Hence, follow-up was divided into 0-2 and >2 years.

RESULTS

Overall, 2869 patients (15.8%) had flow assessment before surgery, increasing from 7.1% in 2013% to 21.5% in 2020. Patients with flow assessment were younger, had a lower EuroSCORE II, and received fewer distal anastomoses (3.0 ± 0.9 vs 3.2 ± 1, P < .001). There were no associations between flow assessment and mortality, post-discharge myocardial infarction, or stroke. New angiography and new revascularization were not significantly different 0-2 years, but preoperative flow assessment was associated with a higher risk for new angiography [adjusted hazard ratio (aHR) 1.32, 95% confidence interval (CI) 1.08-1.62, P = .008] and new revascularization (aHR 1.55, 95% CI 1.18-2.04, P = .002) >2 years after CABG.

CONCLUSIONS

Preoperative flow assessment was not associated with improved clinical outcomes but with a higher risk for new angiography and new revascularization >2 years after CABG. The results suggest that the use of flow assessment with current cut-off levels may not be applicable in CABG, and further studies are needed.

Prognostic Value of Angiography-Derived Index of Microcirculatory Resistance in Patients with Diabetes and ST-Segment Elevation Myocardial Infarction

BACKGROUND

The occurrence of coronary microvascular dysfunction (CMD) after primary PCI in patients with diabetes mellitus (DM) and ST-elevation myocardial infarction (STEMI), and its impact on prognosis remains elusive.

METHODS

This single-centre retrospective observational study included 293 patients diagnosed with DM and STEMI. The coronary-angiography-derived index of microvascular resistance (caIMR) was calculated using the measurement software FlashAngio (Suzhou Rainmed Medical Technology Company, Ltd, Suzhou, Jiangsu, China), whereas cardiac magnetic resonance parameters were quantified using the postprocessing software Cvi42. CMD was defined as caIMR ≥ 25 U. The primary endpoint was major adverse cardiac events (MACE), defined as all-cause mortality, nonfatal myocardial infarction, ischemia-driven revascularization, and heart failure.

RESULTS

MACE occurred in 86 patients (29.4%) during a median follow-up of 31 months. A significant correlation was identified between caIMR and both microvascular obstruction (MVO) (R = 0.61, P < 0.001) and infarct size (IS) (R = 0.39, P < 0.001). Furthermore, caIMR ≥ 25 was identified as an independent risk factor for MACE (hazard ratio [HR], 2.99; 95% confidence interval [CI], 1.78-5.03; P < 0.001). In addition, the integration of caIMR into risk modelling significantly improved prediction of MACE (net reclassification improvement 0.264, P < 0.001; integrated discrimination improvement 0.060, P < 0.001). Finally, the Kaplan-Meier survival curves displayed that patients with caIMR ≥ 25 were at a higher risk of MACE (log-rank P < 0.001).

CONCLUSIONS

The caIMR demonstrated a satisfactory correlation with CMR-determined MVO and IS in patients with DM and STEMI. Elevated caIMR was independently linked to a higher risk of MACE in patients with diabetes and STEMI post-PCI, serving as an effective predictor for MACE.

CLINICAL TRIAL REGISTRATION

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The Pullback Pressure Gradient: A Physiologic Index to Differentiate Focal From Diffuse Coronary Artery Disease

Fractional flow reserve is the most widely used physiologic index to establish the functional significance of epicardial coronary artery disease (CAD). Fractional flow reserve guides clinical decisions toward or against coronary revascularization based on a single binary decision threshold indicative of myocardial ischemia. CAD pathophysiological patterns can be evaluated by assessing the distribution of pressure losses along the coronary vessel, often displayed as a "pullback curve." Until recently, the information provided by the pullback curves was visually and subjectively interpreted, which is associated with interobserver variability. The pullback pressure gradient is a novel index that addresses this gap by assessing the longitudinal distribution of the CAD, quantifying it on a scale from 0 to 1, with higher values indicative of predominantly focal CAD and lower values of predominantly diffuse CAD. This review provides a comprehensive analysis and critical appraisal of pullback pressure gradient and future directions.

Physiological Disease Pattern as Assessed by Pull Back Pressure Gradient Index in Vessels With FFR/iFR Discordance

BACKGROUND

Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are discordant in approximately 20% of cases, and it is unclear whether this is influenced by the physiological pattern of coronary artery disease (CAD). The pull back pressure gradient index (PPGi) can objectively characterize the physiological pattern of CADs.

OBJECTIVES

The aim of this study was to evaluate whether PPGi differed in discordant groups (FFR+/iFR- vs FFR-/iFR+).

METHODS

The study enrolled 355 patients (390 vessels) with chronic coronary syndrome who had ≥1 epicardial coronary artery lesion with 40% to 90% diameter stenosis by visual assessment on invasive coronary angiography and had analyzable FFR, iFR, and PPGi derived from quantitative flow ratio. Cutoffs for hemodynamic significance were FFR ≤0.80 and iFR ≤0.89. Vessels were classified as FFR+/iFR+ (n = 103 [26.4%]), FFR-/iFR+ (n = 27 [6.9%]), FFR+/iFR- (n = 38 [9.7%]), and FFR-/iFR- (n = 222 [57%]) groups.

RESULTS

Median FFR, iFR, and quantitative flow ratio were 0.84 (Q1-Q3: 0.77-0.90), 0.92 (Q1-Q3: 0.88-0.97), and 0.83 (Q1-Q3: 0.73-0.90), respectively. FFR disagreed with iFR in 16.7% of cases (65 of 390). The median PPGi was 0.75 (Q1-Q3: 0.67-0.85). The physiological pattern of CAD was classified according to the PPGi as predominantly physiologically focal (PPGi ≥0.75) in 209 of 390 vessels (53.6%) or diffuse (PPGi < 0.75) in 181 of 390 vessels (46.4%). The median PPGi was significantly lower in FFR-/iFR+ vs FFR+/iFR- vessels (0.65 [Q1-Q3: 0.60-0.69] vs 0.82 [Q1-Q3: 0.75-0.85]; P < 0.001). Predominantly physiologically focal disease was significantly associated with FFR+/iFR- (76.3% [29 of 38]), while predominantly physiologically diffuse disease was significantly associated with FFR-/iFR+ (96.3% [26 of 27] [P < 0.001] for pattern of CAD between FFR+/iFR- and FFR-/iFR+ groups).

CONCLUSIONS

The physiological pattern of CAD is an important influencing factor in FFR/iFR discordance. (Radiographic Imaging Validation and Evaluation for Angio iFR [REVEAL iFR]; NCT03857503).

Coronary Angiography in the Evaluation of Systolic Heart Failure

The review discusses angiographic and hemodynamic features of invasive and computed tomography coronary angiography, which inform diagnosis, prognosis, and coronary revascularization in patients with systolic heart failure.

Functional Complete Revascularization as Determined by an Optimized Scoring System After Revascularization: A Post Hoc Analysis from Multi-Center PANDA III Trial

Functional complete revascularization (CR) after percutaneous coronary intervention (PCI) as determined by classic residual functional SYNTAX score (c-rFSS) has been associated with improved prognosis. In this study, the c-rFSS algorithm is optimized for a novel modified rFSS (m-rFSS) and prognostic implications of this novel scoring is determined. The m-rFSS algorithm is updated for 2 clinical scenarios, i.e., 1) lesions with suboptimal functional results, and 2) angiographic diameter stenosis <50% but functionally significant stenoses, which are not scored by c-rFSS. The major outcome is a 2-year major adverse cardiac event (MACE). A total of 1,555 patients analyzable for both c-rFSS and m-rFSS are included. After calculating m-rFSS, 12.0% (187/1,555) of patients with c-rFSS-based functional CR (c-rFSS = 0) are reclassified as having m-rFSS-based incomplete revascularization (IR, m-rFSS>0); thus, 377 (21.7%) patients have c-rFSS-based functional IR whereas 524 (33.7%) has m-rFSS-based IR. Patients with m-rFSS-based functional IR (m-rFSS>0) show a significantly higher risk for major MACE outcome (20.8% vs 5.9%; adjusted hazard ratio 3.32, 95% confidence interval: 2.34-4.71) than patients with functional CR (m-rFSS = 0). The m-rFSS is more predictive of 2-year MACE than c-rFSS (difference in C-index 0.07, p < 0.001). In this study, we optimized the classic scoring algorithm to develop a novel scoring system (m-rFSS), and revascularization completeness determined by m-rFSS is markedly associated with a 2-year prognosis.

Coronary Artery Disease and Transcatheter Aortic Valve Replacement

Concomitant coronary artery disease (CAD) and severe aortic stenosis (AS) are frequently encountered in patients evaluated for transcatheter aortic valve replacement (TAVR). Invasive coronary angiography remains the mainstay for anatomical assessment of CAD, whereas coronary computed tomography angiography may be used in patients with a low pretest probability of CAD. Adjunctive functional evaluation of coronary lesions has proven safe in the presence of AS, but uncertainty remains over the impact of AS on the results of functional testing. For patients with CAD, revascularization of significant lesions (≥90% stenosis, fractional flow reserve ≤0.80) is associated with improved clinical outcomes compared to medical therapy. However, the optimal timing of percutaneous coronary intervention (PCI) remains unclear with no clear benefit to revascularization in advance of TAVR. When planning post-TAVR PCI, careful consideration should be given to the type of valve implanted, with short-frame valves having more favorable coronary access after TAVR. Planning for future coronary access is particularly relevant for patients who have either unrevascularized obstructive coronary lesions or unknown coronary anatomy in advance of TAVR. Moreover, post-TAVR PCI will likely increase, given the younger age profile of patients being treated and the trend to defer revascularization until after valve replacement.

Angiographic Quantitative Flow Ratio-Guided Treatment of Patients With Physiologically Intermediate Coronary Lesions

BACKGROUND

The FAVOR III (Comparison of Quantitative Flow Ratio Guided and Angiography Guided Percutaneous Intervention in Patients With Coronary Artery Disease) China trial reported improved clinical outcomes with percutaneous coronary intervention guided by quantitative flow ratio (QFR) compared with angiography. Whether these benefits also apply for patients presenting with "uncertainty-zone" lesions of intermediate physiological significance is uncertain. This study aims to examine the impact of QFR guidance versus angiography guidance on the management and outcomes of percutaneous coronary intervention in uncertainty-zone lesions.

METHODS AND RESULTS

In this prespecified subgroup analysis, offline QFR assessment categorized 873 patients (22.9%) into the uncertainty-zone subgroup, defined as having an offline QFR of 0.75 to 0.85 in all coronary arteries with a lesion causing ≥50% diameter stenosis. At 2 years, the rate of major adverse cardiac events, a composite of all-cause death, myocardial infarction, or ischemia-driven revascularization, occurred in 31 patients (7.0%) in the QFR-guided group and 35 patients (8.3%) in the angiography-guided group (hazard ratio [HR], 0.85 [95% CI, 0.52-1.37]). In landmark analysis, the relative treatment effect of QFR guidance versus angiography guidance on major adverse cardiac events differed before 1 year (4.7% versus 3.8%; HR, 1.25 [95% CI, 0.65-2.40]) and after 1 year (2.3% versus 5.5%; HR, 0.41 [95% CI, 0.20-0.87]) (Pinteraction=0.03), driven by fewer nonprocedural myocardial infarctions and ischemia-driven revascularizations in the QFR-guided group after 1-year follow-up.

CONCLUSIONS

In the modest-sized subgroup of patients with physiologically intermediate lesions randomized in the FAVOR III China trial, 2-year clinical outcomes were not significantly improved with a QFR-guided revascularization strategy compared with angiography guidance.

REGISTRATION

URL: https://www.clinicaltrials.gov; Identifier: NCT03656848.

Non-invasive derivation of instantaneous free-wave ratio from invasive coronary angiography using a new deep learning artificial intelligence model and comparison with human operators' performance

Invasive coronary physiology is underused and carries risks/costs. Artificial Intelligence (AI) might enable non-invasive physiology from invasive coronary angiography (CAG), possibly outperforming humans, but has seldom been explored, especially for instantaneous wave-free Ratio (iFR). We aimed to develop binary iFR lesion classification AI models and compare them with human performance. single-center retrospective study of patients undergoing CAG and iFR. A validated encoder-decoder convolutional neural network (CNN) performed segmentation. Manual annotation of target vessel and pressure sensor location on a segmented telediastolic frame followed. Three AI models classified lesions as positive (≤ 0.89) or negative (> 0.89). Model 1 uses preprocessed vessel diameters with a transformer. Models 2/3 are EfficientNet-B5 CNNs using concatenated angiography and segmentation - Model 3 employs class-frequency-weighted Cross-Entropy Loss. Previous findings demonstrated Model 3's superiority for left anterior descending (LAD) and Model 1's for circumflex (Cx)/right coronary artery (RCA) - they were therefore unified into a vessel-based model. Ten-fold patient-level cross-validation enabled full sample training/testing. Three experienced operators performed binary iFR classification using single frames of raw/segmented images. Comparison metrics were accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV). Across 250 measurements, AI accuracy was 72%, PPV 48%, NPV 90%, sensitivity 77%, and specificity 71%. Human accuracy ranged from 54 to 74%. NPV was high for the Cx/RCA (AI: 96/98%; operators: 94/97%), but AI significantly outperformed humans in the LAD (78% vs. 60-64%). An AI model capable of binary iFR lesions classification mildly outperformed interventional cardiologists, supporting further validation studies.

Physiological Insight Into the Discordance Between Non-Hyperemic Pressure Ratio-Guided and Fractional Flow Reserve-Guided Revascularization

BACKGROUND

Five-year outcomes from the two major trials indicated higher mortality with instantaneous wave-free ratio (iFR)-guided revascularization compared to fractional flow reserve (FFR)-guidance, despite similar outcomes in deferred patients. This discrepancy likely comes from discordant revascularization decisions. To precisely assess the characteristic differences, including microvascular function, between resting full-cycle ratio (RFR)-guided and FFR-guided strategies, we performed virtual randomization, specially targeting discordant lesions, to simulate RFR-guided and FFR-guided groups. Microvascular resistance reserve (MRR) was utilized to assess microvascular function independently of epicardial stenosis.

METHODS AND RESULTS

We retrospectively analyzed 837 intermediate lesions in 620 patients, from our institutional physiological database, with a median follow-up of 6.9 years. Using thresholds of FFR ≤ 0.80 and RFR ≤ 0.89, lesions were categorized into concordant-high (n = 280), high-RFR/low-FFR (n = 105), low-RFR/high-FFR (n = 93), and concordant-low (n = 359) groups. Discordant and concordant lesions were virtually randomized into RFR- and FFR-guided groups. Patients were followed for 6.9 (4.6-9.1) years. Age, sex, percentage diameter stenosis, and MRR differed significantly between the RFR/FFR discordant groups. After randomization, no significant characteristic-based differences were observed between both concordant and discordant virtual RFR/FFR-guided groups. Compared with the patients with FFR-guided would-be-revascularized lesions, those with RFR-guided would-be-revascularized lesions with discordant RFR/FFR results had significantly lower MRR, higher age, and tended to be female. MRR significantly predicted all-cause death in the total and would-be-revascularized cohorts, but not in deferred patients.

CONCLUSIONS

In discordant lesions of virtually randomized RFR- and FFR-guided strategies, RFR-guided would-be-revascularized lesions were associated with impaired microvascular function (low MRR) compared with FFR-guided would-be-revascularized lesions, which may underlie the reported increased mortality in iFR-guided revascularized patients.

Hemodynamics of Proximal Coronary Lesions in Patients Undergoing Transcatheter Aortic Valve Implantation: Patient-Specific In Silico Study

Aortic stenosis (AS) frequently coexists with coronary artery disease (CAD), complicating revascularization decisions. The use of coronary physiology indices, such as the fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), and coronary flow reserve (CFR), in AS patients remains debated, particularly after transcatheter aortic valve implantation (TAVI). In this study, we employ computational fluid dynamics (CFD) to evaluate coronary hemodynamics and assess changes in the wall shear stress (WSS) before and after TAVI. Our analysis demonstrates strong agreement between CFD-derived and invasive FFR measurements, confirming CFD's reliability as a non-invasive tool for coronary physiology assessment. Furthermore, our results show no significant changes in FFR (p=0.92), iFR (p=0.67), or CFR (p=0.34) post-TAVI, suggesting that these indices remain stable following aortic valve intervention. However, a significant reduction in high WSS exposure (59% to 40.8%, p<0.001) and the oscillatory shear index (OSI: 0.32 to 0.21, p<0.001) was observed, indicating improved hemodynamic stability. These findings suggest that coronary physiology indices remain reliable for revascularization guidance post-TAVI and highlight a potential beneficial effect of aortic stenosis treatment on plaque shear stress dynamics. Our study underscores the clinical utility of CFD modeling in CAD management, paving the way for further research into its prognostic implications.

Prevalence and Clinical Outcomes of Discordant Lesions Between Fractional Flow Reserve and Nonhyperemic Pressure Ratios in Clinical Practice: The J-PRIDE Registry

BACKGROUND

Limited large-scale, real-world data exist on the prevalence and clinical impact of discordance between fractional flow reserve (FFR) and nonhyperemic pressure ratios (NHPRs).

METHODS

The J-PRIDE registry (Clinical Outcomes of Japanese Patients With Coronary Artery Disease Assessed by Resting Indices and Fractional Flow Reserve: A Prospective Multicenter Registry) prospectively enrolled 4304 lesions in 3200 patients from 20 Japanese centers. The lesions were classified into FFR+/NHPR-, FFR-/NHPR+, FFR+/NHPR+, or FFR-/NHPR groups according to cutoff values of 0.89 for NHPRs and 0.80 for FFR. The primary study end point was the cumulative 1-year incidence of target vessel failure (a composite of cardiac death, target vessel-related myocardial infarction, and clinically driven target vessel revascularization) on a lesion basis.

RESULTS

An NHPR cutoff value of 0.89, determined using online software, predicted an FFR of 0.80 across various NHPR types. Discordance between FFR and NHPRs was observed in 20% of lesions (FFR+/NHPR-, 11.2%; FFR-/NHPRs+, 8.8%). Revascularization was deferred in 42.9% and 88.4% of the FFR+/NHPR- and FFR-/NHPR+ groups, respectively. In deferred vessels, the FFR+/NHPR- and FFR-/NHPR+ groups showed a higher 1-year incidence of target vessel failure compared with the FFR-/NHPR- group (7.9% versus 5.5% versus 1.7%; for FFR+/NHPR-, adjusted hazard ratio [aHR], 4.89 [95% CI, 2.68-8.91]; P<0.001; for FFR-/NHPR+, aHR, 2.64 [95% CI, 1.49-4.69]; P<0.001). In revascularized vessels, the 1-year target vessel failure rate was numerically higher in the FFR-/NHPR+ group than in the FFR+/NHPR+ group (9.6% versus 3.4%; aHR, 2.27 [95% CI, 0.70-7.34]; P=0.17), although with similar outcomes between the FFR+/NHPR- and FFR+/NHPR+ groups (2.3% versus 3.4%; aHR, 0.96 [95% CI, 0.37-2.38]; P=0.93). The FFR+/NHPR- group benefited from revascularization compared with medical treatment (aHR, 0.26 [95% CI, 0.08-0.86]; P=0.027); the FFR-/NHPR+ group did not (aHR, 2.39 [95% CI, 0.62-9.21]; P=0.20).

CONCLUSIONS

Discordance between FFR and NHPRs was noted in 20% of lesions, and discordant deferred lesions resulted in worse outcomes than concordant negative lesions. Although the outcomes after deferring revascularization were comparable between the FFR+/NHPR- and FFR-/NHPR+ lesions, only FFR+/NHPR- lesions showed a benefit from revascularization compared with medical treatment, suggesting that an FFR-guided strategy is superior to an NHPR-guided strategy in discordant lesions.

REGISTRATION

URL: https://www.umin.ac.jp; Unique identifier: UMIN000038403.

Recent advances and clinical implications of intravascular imaging

Coronary artery disease (CAD) remains a major contributor to the global mortality rate. Accurate and detailed evaluation of atherosclerotic plaque characteristics is essential for effective risk assessment and treatment planning. Although conventional coronary angiography excels at quantifying luminal stenosis, information on plaque composition and structure remains limited. Recent advances in intravascular imaging (IVI) have bridged this gap by enabling high-resolution visualization of the vessel wall and plaque morphology, thereby enhancing treatment strategies and facilitating comprehensive risk stratification. Among the principal IVI modalities, intravascular ultrasound (IVUS), optical coherence tomography (OCT), and near-infrared spectroscopy (NIRS) provide distinct benefits. IVUS accurately measures vessel diameter and plaque burden, offering critical guidance for managing complex lesions and left main artery disease. The extremely high spatial resolution of OCT allows precise identification of high-risk plaque features, such as thin fibrous caps. NIRS complements these techniques by quantitatively assessing lipid components within plaques, making it particularly useful in predicting future cardiovascular events. In this review, we summarize the latest evidence on applying IVI modalities to the evaluation and treatment of CAD. We focus on the assessment of plaque morphology, identification of high-risk lesions, and the role of IVI-guided percutaneous coronary intervention (PCI). The continued development of hybrid imaging systems and artificial intelligence-based image analysis may produce more precise and safer PCI approaches. Consequently, IVI is poised to become indispensable in managing CAD, paving the way for more personalized treatment strategies tailored to the specific lesion characteristics of each patient.

Fractional Flow Reserve Relates Stronger to Coronary Plaque Burden Than Nonhyperemic Pressure Indexes

BACKGROUND

The relationship between fractional flow reserve (FFR), resting full-cycle ratio (RFR), instantaneous wave-free ratio (iFR), resting distal pressure/aortic pressure (Pd/Pa), and plaque burden as well as phenotype requires further elucidation.

METHODS AND RESULTS

In this single-center cohort study, patients with suspected coronary artery disease who underwent invasive coronary angiography, including routine hyperemic (FFR) and nonhyperemic invasive pressure (Pd/Pa and iFR or RFR) interrogation and computed coronary tomography angiography were prospectively enrolled. Computed coronary tomography angiography was used to assess percentage atheroma volume (PAV), positive remodeling, and low-attenuation plaque.

Among 241 patients with 556 vessels, FFR correlated stronger to PAV compared with Pd/Pa (r=-0.56; versus r=-0.43; P<0.01) and iFR/RFR (r=-0.47; P=0.04). Vessels with FFR and Pd/Pa discordancy showed higher PAV in case of abnormal FFR (34% versus 14%; P<0.01), whereas vessels with FFR and iFR/RFR discordancy showed similar PAV levels. FFR and iFR/RFR, but not Pd/Pa, were independently associated with the presence of low-attenuation plaque (β, -0.03, P<0.01; β, -0.03, P=0.01; and β, -0.02, P=0.10, respectively). None of the invasive pressure measurements was independently associated with positive remodeling. Pressure index discordancy was not associated with positive remodeling or low-attenuation plaque.

CONCLUSIONS

FFR correlated stronger to plaque burden, as defined by PAV, than nonhyperemic pressure indexes. For plaque phenotype, both FFR and iFR/RFR were independently associated with low-attenuation plaque, whereas none of the invasive pressure indexes was associated with positive remodeling.

Anatomic vs. Ischemia-Driven Strategies for Percutaneous Coronary Revascularization in Chronic Coronary Syndrome: A Network Meta-Analysis

INTRODUCTION

In patients with chronic coronary syndromes (CCS), the benefit of percutaneous coronary intervention (PCI) added to optimal medical therapy (OMT) remains unclear. The indication to PCI may be driven either by angiographic evaluation or ischemia assessment, thus depicting different potential strategies which have not yet been thoroughly compared.

METHODS

Randomized controlled trials (RCTs) comparing OMT versus PCI angio-guided or versus PCI non-invasive or invasive ischemia guided were identified and compared via network meta-analysis. Major adverse clinical events (MACE), as defined by each included trial, were the primary endpoint, while cardiovascular (CV) death, myocardial infarction (MI), and unplanned revascularization the secondary ones.

RESULTS

18 studies, encompassing 17,512 patients, were included, with a mean follow-up of 3.5 years. PCI guided by ischemia defined either invasively or not was associated with a reduced risk of MACE compared with OMT alone. Furthermore, PCI guided by non-invasive assessment of ischemia was associated with a reduced risk of MI compared with OMT (hazard ratio [HR]: 0.61 [95% confidence interval: 0.37-0.94). This strategy ranked best also in preventing CV death. Notably, iFR and FFR guided approaches showed the highest probability of performing best for reduction of subsequent revascularizations.

CONCLUSION

In patients with CCS, ischemia-guided PCI, either by invasive or non-invasive assessment, resulted in a reduced risk of MACE compared with OMT alone. The use of invasive or non-invasive tests influenced the benefit of ischemia-driven PCI: non-invasive tests significantly reduced risk of MI compared with OMT, while iFR or FFR showed the highest probability of reducing the need of subsequent revascularization.

Artificial Intelligence in Coronary Artery Interventions: Preprocedural Planning and Procedural Assistance

Artificial intelligence (AI) has profoundly influenced the field of cardiovascular interventions and coronary artery procedures in particular. AI has enhanced diagnostic accuracy in coronary artery disease through advanced invasive and noninvasive imaging modalities, facilitating more precise diagnosis and personalized interventional strategies. AI integration in coronary interventions has streamlined diagnostic and procedural workflows, improved procedural accuracy, increased clinician efficiency, and enhanced patient safety and outcomes. Despite its potential, AI still faces significant challenges, including concerns regarding algorithmic biases, lack of transparency in AI-driven decision making, and ethical challenges. This review explores the latest advancements of AI applications in coronary artery interventions, focusing on preprocedural planning and real-time procedural guidance. It also addresses the major limitations and obstacles that hinder the widespread clinical adoption of AI technologies in this field.

Hyperemic vs non-hyperemic indexes discordance: Role of epicardial and microvascular resistance (HyperDisco Study)

BACKGROUND

Literature reports a 20 % discordance between hyperemic (FFR) and non-hyperemic indexes (NHi) of coronary stenosis lesions. This work aims to develop and test clinically, a formula relating FFR and NHi (including iFR, RFR and Pd/Pa) to study their discordance.

METHODS

We conducted a prospective, single-center, clinical study enrolling all patients undergoing full coronary physiology assessment with Coroventis CoroFlow Cardiovascular System (Abbott Vascular, St. Paul, Minnesota) to validate the developed formula: [Formula: see text] where IMR(BMR) is the hyperemic (basal) microvascular resistance and HSR(BSR) is the hyperemic (basal) stenosis resistance.

RESULTS

A total of 51 patients were enrolled, 72 % male, average age 67.4 ± 8.9. Mean hemodynamic data were: FFR 0.87 ± 0.07, iFR 0.93 ± 0.05, RFR 0.91 ± 0.05, Pd/Pa 0.92 ± 0.05, BMR 76.6 ± 51.6 mmHg*s, IMR 28.4 ± 22.8 mmHg*s, BSR 5.5 ± 4.7 mmHg, HSR 3.8 ± 2.9 mmHg*s, coronary flow reserve (CFR) 2.9 ± 1.6, resistive reserve ratio (RRR) 3.3 ± 2.0. Lin's Concordance and Bland Altman analysis showed an optimal correlation between measured and estimated data. Sensitivity analysis showed that: (1) FFR can underestimate epicardial stenosis severity leading to FFR- vs NHi + discordance in case of elevated IMR, (2) NHi can overestimate epicardial stenosis severity leading to FFR- vs NHi + in the case of low BMR, (3) if BSR > HSR, FFR- vs NHi + discordance can occur, while if BSR < HSR, FFR+ vs NHi- discordance can occur.

CONCLUSION

(1) NHi can be more reliable in case of elevated IMR; (2) FFR-CFR combination can be more reliable for low BMR occurring to compensate an epicardial stenosis; (3) NHi-CFR combination can be more reliable when BSR > HSR, while FFR-CFR combination can be more reliable when BSR < HSR. The combination between pressure and flow indexes (FFR-CFR or NHi-CFR) is more reliable when compensatory mechanisms occur.

Comparison of different guidance strategies to percutaneous coronary intervention: A network meta-analysis of randomized clinical trials

BACKGROUND

The results of randomized clinical trials comparing the outcomes of different strategies for driving PCI are mixed, and it remains unclear which technique for driving PCI offers the greatest benefit. The aim of the study was to compare the clinical efficacy of different techniques to guide percutaneous coronary intervention (PCI).

METHODS

We search major electronic databases for randomized clinical trials evaluating clinical outcomes of PCI with stent implantation guided by coronary angiography (CA), fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), intravascular ultrasound (IVUS) and optical coherence tomography (OCT). The primary outcome was cardiac death.

RESULTS

The results from 39 randomized trials (29,614 patients) were included in the network meta-analyses. Compared with CA, the use of OCT (RR: 0.33, 95 % CI: 0.19-0.54), IVUS (RR: 0.47, 95 % CI: 0.31-0.71) and FFR (RR: 0.61, 95 % CI: 0.38-0.97) were associated with reduced risk of cardiac death; there were no differences between OCT, IVUS and OCT was ranked as the best strategy. PCI guidance using OCT, FFR and IVUS was also associated with a reduction of myocardial infarction. The use of OCT or IVUS for PCI guidance was associated with a significant reduction in target lesion failure, target vessel revascularization, target lesion revascularization and stent thrombosis, compared with CA. OCT-guided PCI was associated with a significant reduction in all-cause death compared with CA-guided PCI and with a reduction in TLF compared with FFR- and iFR-guided PCI. Pooled estimates were mostly consistent across several sensitivity analyses.

CONCLUSIONS

Compared with angiography-guided PCI, both an intravascular imaging-guided strategy and a physiology-guided strategy are associated with better clinical outcomes.

Functional assessment of coronary artery disease in patients with severe aortic stenosis: a review

A significant proportion of patients with severe aortic stenosis (AS) undergoing transcatheter aortic valve implantation (TAVI) have concomitant coronary artery disease (CAD). The best way to treat these patients is contentious. Conventional assessments of ischaemia such as fractional flow reserve (FFR) and instantaneous wave-free ratio are not validated in the context of severe AS despite having a Class I European Society of Cardiology indication in patients with isolated coronary disease. A better understanding of how we assess and interpret coronary physiology in these patients is required to optimise treatment pathways. Only one prospective, randomised trial has investigated the routine use of FFR to guide revascularisation in patients undergoing TAVI and several observational cohort studies have measured changes in hyperaemic and resting indices in patients with severe AS as well as before and after TAVI. The purpose of this review article is to provide a summary of the current data regarding the functional assessment of CAD in patients with severe AS and highlight the current best practice in this evolving area.

Diagnostic Performance of Artificial Intelligence-Based Angiography-Derived Non-Hyperemic Pressure Ratio Using Pressure Wire as Reference

BACKGROUND

The angiography-derived non-hyperemic pressure ratio (angioNHPR) is a novel index of NHPR based on artificial intelligence (AI) that does not require pressure wires. We investigated the diagnostic accuracy of angioNHPR for detecting hemodynamically relevant coronary artery disease.

METHODS AND RESULTS

In this retrospective single-center study, angioNHPR was assessed using the invasive NHPR as the reference standard. An angioNHPR ≤0.89 was defined as indicative of physiologically significant stenosis. Two angiographic projections ≥30° difference in angulation were selected. The lumen and centerline were automatically segmented by the prototype software, allowing for the calculation of the angioNHPR. We assessed 222 vessels from 178 patients. The accuracy of angioNHPR was 76.6% (95% confidence interval [CI] 70.4-82.0), with sensitivity 66.2% (95% CI 54.0-77.0), specificity 81.5% (95% CI 74.3-87.3), positive predictive value 62.7% (95% CI 53.6-70.9), and negative predictive value 83.7% (95% CI 78.6-87.7). The angioNHPR showed good correlation with invasive NHPR (r=0.72; 95% CI 0.64-0.77; P<0.001), and the agreement between angioNHPR and invasive NHPR was -0.01 (limits of agreement: -0.13, 0.11). The area under the curve (AUC) of angioNHPR was 0.81 (95% CI 0.75-0.86), which was significantly higher than that of 2-dimensional quantitative coronary angiography (AUC 0.69; 95% CI 0.62-0.75; P=0.007).

CONCLUSIONS

AI-based angioNHPR demonstrates good diagnostic performance using invasive NHPR as the reference standard.

Long-Term Clinical Outcomes After IFR- vs FFR-Guided Coronary Revascularization: Insights From the SWEDEHEART National Registry

BACKGROUND

Long-term data on safety and efficacy of instantaneous wave-free ratio (IFR) vs fractional flow reserve (FFR) in guiding percutaneous coronary intervention (PCI) is lacking.

OBJECTIVES

This study sought to evaluate the 5-year clinical outcomes of IFR- vs FFR-guided PCI in a real-world setting.

METHODS

We assessed the 5-year outcomes of all patients undergoing IFR or FFR assessment between January 1, 2014, and February 16, 2022, using data from the SWEDEHEART (Swedish Web-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies) registry. Two-to-1 propensity score matching was used to adjust for differences between groups. Additional analyses adjusted for propensity score, PCI center, and baseline differences remaining after matching were conducted. The primary outcome was major adverse cardiac events (MACE) defined as first occurrence of all-cause death, myocardial infarction, or repeat revascularization within 5 years.

RESULTS

Among 16,152 (65.6%) of 24,623 FFR and 8,471 (34.4%) of 24,623 IFR patients, IFR led to more frequent deferral of revascularization (5,964 of 8,471 [70.4%] vs 10,615 of 24,623 [65.7%]; P < 0.001). There was no significant difference in Kaplan-Meier event rates in MACE at 5 years between patients who underwent IFR or FFR-guided revascularization (1,993 [31.3% (95% CI: 30.0%-32.6%)] vs 3,961 [31.9% (95% CI: 31.0%-32.8%)]; adjusted HR: 0.96; 95% CI: 0.82-1.12; P = 0.60), including all-cause death, cardiovascular death, cardiac death, coronary death, new myocardial infarction, or revascularization. Subgroup analysis of deferred and treated patients revealed no difference between groups regarding MACE or its individual components.

CONCLUSIONS

In a large nationwide registry of patients undergoing physiology-based coronary revascularization, there were no significant differences in MACE or all-cause mortality between IFR and FFR-guided revascularization at 5 years.

Multimodality Imaging in the Diagnosis of Coronary Microvascular Disease: An Update

Coronary microvascular dysfunction (CMD) is characterized by structural and functional abnormalities in the coronary microvasculature which can lead to ischaemia and angina and is increasingly recognized as a major contributor to adverse cardiovascular outcomes. Despite its clinical importance, the diagnosis of CMD remains limited compared with traditional atherosclerotic coronary artery disease. Furthermore, the historical lack of non-invasive methods for detecting and quantifying CMD has hindered progress in understanding its pathophysiology and clinical implications. This review explores advancements in non-invasive cardiac imaging that have enabled the detection and quantification of CMD. It evaluates the clinical utility, strengths and limitation of these imaging modalities in diagnosing and managing CMD. Having improved our understanding of CMD pathophysiology, cardiac imaging can provide insights into its prognosis and enhance diagnostic accuracy. Continued innovation in imaging technologies is essential for advancing knowledge about CMD, leading to improved cardiovascular outcomes and patient care.

Diastolic Hyperemia-Free Ratio in Patients With Coronary Artery Disease: A Prospective Observational Study

BACKGROUND AND OBJECTIVES

Diastolic hyperemia-free ratio (DFR), an alternative to fractional flow reserve (FFR) for the assessment of intermediate coronary artery stenosis, helps reduce patients' time, and inconvenience. However, the validation data for DFR and FFR are lacking. We aimed to evaluate the diagnostic accuracy of DFR and FFR and to assess the effective decision making for revascularization using their values.

METHODS

Patients subjected to an invasive physiological study for intermediate coronary artery stenosis at a single center in South Korea between August 2022 and January 2024 were prospectively recruited. We evaluated the correlation between DFR and FFR measurements and the diagnostic accuracy of DFR ≤0.89 to predict FFR ≤ 0.80. We also compared the correlation for each coronary artery.

RESULTS

A total of 324 intermediate coronary stenotic lesions from 300 patients were evaluated using DFR and FFR values simultaneously. There was a strong linear relationship between DFR and FFR (r = 0.80; 95% confidence interval [CI], 0.76-0.84; p < 0.001). The diagnostic accuracy of the DFR was 92.0% in predicting FFR ≤0.80. When compared separately for each coronary artery, all vessels showed a strong linear relationship with no statistical differences between any of the vessels (p=0.641). There was also a strong linear relationship between DFR and distal coronary pressure/aorta pressure (r=0.93; 95% CI, 0.91-0.94; p<0.001).

CONCLUSIONS

There was a strong correlation between DFR and FFR and a high diagnostic accuracy rate of DFR compared to FFR. Good diagnostic performance of DFR was also observed in each coronary artery.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT05421169.

Coronary revascularisation deferral based on quantitative flow ratio or fractional flow reserve: a post hoc analysis of the FAVOR III Europe trial

BACKGROUND

Safe deferral of revascularisation is a key aspect of physiology-guided percutaneous coronary intervention (PCI). While recent evidence gathered in the FAVOR III Europe trial showed that quantitative flow ratio (QFR) guidance did not meet non-inferiority to fractional flow reserve (FFR) guidance, it remains unknown if QFR might have a specific value in revascularisation deferral.

AIMS

We aimed to evaluate the safety of coronary revascularisation deferral based on QFR as compared with FFR.

METHODS

Patients randomised in the FAVOR III trial in whom PCI was deferred in at least one coronary artery, based on QFR or FFR>0.80, were included in the present substudy. The primary outcome was the 1-year rate of major adverse cardiac events (MACE), with results reported for two subsets of deferred patients: (1) any study lesion deferral and (2) complete study lesion deferral.

RESULTS

A total of 523 patients (55.2%) in the QFR group and 599 patients (65.3%) in the FFR group had at least one coronary revascularisation deferral. Of these, 433 patients (82.8%) and 511 (85.3%) patients, respectively, had complete study lesion deferral. In the "complete study lesion deferral" patient group, the occurrence of MACE was significantly higher in QFR-deferred patients as compared with FFR-deferred patients (24 [5.6%] vs 14 [2.8%], adjusted hazard ratio [HR] 2.07, 95% confidence interval [CI]: 1.07-4.03; p=0.03). In the subgroup of "any study lesion deferral", the MACE rate was 5.6% vs 3.6% (QFR vs FFR), adjusted HR 1.55, 95% CI: 0.88-2.73; p=0.13.

CONCLUSIONS

QFR-based deferral of coronary artery revascularisation resulted in a higher incidence of 1-year MACE as compared with FFR-based deferral.

Caught Between Heart and Limbs: Navigating the Treatment of Patients With CAD and PAD in an Overwhelmed Healthcare System

Peripheral arterial disease (PAD) and coronary artery disease (CAD) are manifestations of atherosclerosis, affecting a substantial proportion of the population. Despite their interrelation, the prevalence of CAD in severe PAD varies, prompting the need to understand their complex relationship. This study retrospectively analyzes prospectively collected data from a high-volume vascular center to assess CAD prevalence, risk factors, and implications for patients undergoing vascular surgery. Among 667 arterial disease patients, 19.5% underwent coronary angiography, with CAD detected in 61.5% of cases. CAD varied across vascular beds. Decision-making around preoperative coronary angiography and revascularization remains complex, with benefits for high-risk patients still being debated. In accordance with current guidelines, the routine practice of coronary revascularization preceding vascular surgery is generally discouraged. This study underscores the need for risk stratification to identify patients who might benefit from coronary revascularization prior to vascular surgery while adhering to cost-effectiveness and avoiding unnecessary and time-consuming diagnostics in the majority of patients. Patient demographics, risk factors, and clinical presentation were analyzed alongside hospital stay, mortality, and complications. The study highlights the challenges in managing patients with concurrent CAD and PAD and calls for improved protocols for treating this high-risk group.

FFR, iFR, CFR, and IMR: Results from clinical trials

In this review article, we provide an overview of the definition and application of fractional flow reserve (FFR), instantaneous wave-free ratio (iFR), coronary flow reserve (CFR), and index of microvascular resistance (IMR) in the diagnosis, prognosis, and management of coronary microvascular dysfunction. We discuss their respective limitations as it relates to microvascular dysfunction. In each section, we review the most recent evidence supporting their use in microvascular and epicardial coronary artery disease. We also highlight specific clinical conditions with emerging indications for the use of these indices, including in the setting of microvascular dysfunction due to acute myocardial infarction, heart failure with preserved ejection fraction, and post-cardiac transplant.

Sensitivity of coronary hemodynamics to vascular structure variations in health and disease

Local hemodynamics play an essential role in the initiation and progression of coronary artery disease. While vascular geometry alters local hemodynamics, the relationship between vascular structure and hemodynamics is poorly understood. Previous computational fluid dynamics (CFD) studies have explored how anatomy influences plaque-promoting hemodynamics. For example, areas exposed to low wall shear stress (ALWSS) can indicate regions of plaque growth. However, small sample sizes, idealized geometries, and simplified boundary conditions have limited their scope. We generated 230 synthetic models of left coronary arteries and simulated coronary hemodynamics with physiologically realistic boundary conditions. We measured the sensitivity of hemodynamic metrics to changes in bifurcation angles, positions, diameter ratios, tortuosity, and plaque topology. Our results suggest that the diameter ratio between left coronary branches plays a substantial role in generating adverse hemodynamic phenotypes and can amplify the effect of other geometric features such as bifurcation position and angle, and vessel tortuosity. Introducing mild plaque in the models did not change correlations between structure and hemodynamics. However, certain vascular structures can induce ALWSS at the trailing edge of the plaque. Our analysis demonstrates that coronary artery vascular structure can provide key insight into the hemodynamic environments conducive to plaque formation and growth.

Deferral of left main coronary artery revascularization via IVUS or coronary physiology - Long-term outcomes from the SWEDEHEART registry

BACKGROUND

Intravascular ultrasound (IVUS) guides deferral decision-making regarding the left main coronary artery (LMCA) and improves outcomes. Further studies regarding coronary physiology to guide revascularization in the LMCA are needed. Our aim was to evaluate the outcome of LMCA deferral using IVUS or coronary physiology via instantaneous wave-free ratio (iFR) or fractional flow reserve (FFR).

METHODS

Between January 2014 and February 2022, patients undergoing evaluation with either IVUS or coronary physiology in the LMCA were included from the SWEDEHEART registry. Exclusion criteria were a minimum luminal area < 6 mm2, iFR ≤ 0.89, FFR ≤ 0.80, ad hoc percutaneous coronary intervention of lesions in the LMCA, proximal left anterior descending artery, and proximal circumflex artery, planned elective revascularization, and planned valvular surgery. The primary outcome was major adverse cardiac events (MACE), defined as a composite of all-cause death, myocardial infarction, and unplanned revascularization. Kaplan-Meier event rates and multivariable Poisson regression were used for the statistical analyses.

RESULTS

Deferral of revascularization in the LMCA was performed in 1552 patients, 33.6 % with IVUS and 66.4 % with coronary physiology (iFR 11.3 % vs. FFR 55.0 %). The median follow-up time was 2.7 years. No significant difference was seen in MACE (IVUS 40.2 % vs. coronary physiology 35.5 %; adjusted RR: 1.18; 95 %CI: 0.97-1.44; p = 0.09). The results were consistent across all investigated subgroups. The rate of all-cause death was higher in the IVUS group (adjusted RR: 1.38; 95 %CI: 1.03-1.83; p = 0.03).

CONCLUSIONS

Deferral of coronary revascularization in LMCA lesions using IVUS or coronary physiology did not differ in our combined endpoint. We observed a higher risk of all-cause death using IVUS.

Physiology-Versus Angiography-Guided Complete Coronary Revascularization in STEMI Patients with Multivessel Disease: A Network Meta-Analysis

Background: In patients with ST-segment elevation myocardial infarction (STEMI) and multivessel disease (MVD), complete revascularization (CR) is recommended over culprit-only PCI to reduce adverse cardiovascular outcomes. However, the optimal strategy for CR, whether angiography (Angio)-guided or physiology-guided, remains uncertain. Methods: This network meta-analysis included 14 randomized controlled trials (RCTs) with 11,568 patients to compare the efficacy of angio-guided CR, physiology-guided CR, and culprit-only PCI in reducing major adverse cardiovascular events (MACE), all-cause mortality, recurrent myocardial infarction (MI), cardiovascular (CV) death, and unplanned revascularization. The frequentist and Bayesian approaches were applied to assess the effectiveness of each strategy. Results: The pairwise meta-analysis showed that angio-guided CR showed superior efficacy, significantly reducing MACE (OR = 0.44; 95% CI: 0.37-0.52), recurrent myocardial infarction, and unplanned revascularization compared to culprit-only PCI. Physiology-guided CR also reduced MACE (OR = 0.64, 95% CI: 0.45-0.91) and unplanned revascularization. The network metanalysis showed that CV death was lower in the physiology-guided CR group (OR 0.56; 95% CI 0.25-1.05), suggesting a protective effect, but the difference did not reach statistical significance. Furthermore, physiology-guided CR was not significantly better than angio-guided CR in most outcomes. Conclusions: Angio-guided CR appears to provide the best overall outcomes for patients with STEMI and MVD, outperforming physiology-guided CR in most endpoints. Further large-scale trials are needed to clarify the relative efficacy of angio-guided CR and physiology-guided CR in this patient population.

Diagnostic Accuracy of Computational Fluid Dynamics-Based Fractional Flow Reserve Derived From Coronary Angiography: The ACCURATE Study

BACKGROUND

Although fractional flow reserve (FFR) is the contemporary standard to detect hemodynamically significant coronary stenosis, it remains underused for the need of pressure wire and hyperemic stimulus. Coronary angiography-derived FFR could break through these barriers. The aim of this study was to assess the feasibility and performance of a novel diagnostic modality deriving FFR from invasive coronary angiography (AccuFFRangio) for coronary physiological assessment.

METHODS AND RESULTS

The ACCURATE (Angiography-Derived Fractional Flow Reserve for Functional Evaluation of Coronary Artery Disease) study was a prospective, multicenter study conducted at 5 centers. Patients who had at least 1 lesion with a diameter stenosis of 30% to 90% were eligible. AccuFFRangio was measured on site in real time and compared with invasive FFR measurements in a blinded fashion. Primary end point was the diagnostic accuracy of AccuFFRangio in identifying functional relevant lesions. Between November 2020 and June 2021, pairwise analyses of AccuFFRangio and FFR were performed in 304 coronary arteries. AccuFFRangio showed good correlation (r=0.89; P<0.001) and agreement (mean difference: 0.01±0.06) with FFR. The diagnostic accuracy was 95.07% (95% CI, 91.99%-97.21%), which were significantly exceeded the prespecified target value (P<0.001). The sensitivity, specificity, and area under the receiver operating characteristic curve of 95.83% (95% CI, 89.67%-98.85%), 94.71% (95% CI, 90.73%-97.33%), and 0.972 (95% CI, 0.947-0.988), respectively.

CONCLUSIONS

AccuFFRangio derived from coronary angiography alone has high diagnostic accuracy, sensitivity, and specificity compared with FFR. AccuFFRangio bears the potential for increasing the adoption of functional assessment of coronary artery stenosis and improving the use of physiological guided decision-making.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT04814550.

Current Trends and Perspectives of Pressure Wire-Based Coronary Artery Bypass Grafting

Fractional flow reserve (FFR) has been well validated as a modality for evaluating myocardial ischemia, demonstrating the superiority of FFR-guided percutaneous coronary intervention (PCI) over conventional angiography-guided PCI. As a result, the strategy for coronary artery bypass grafting (CABG) is shifting toward FFR guidance. However, the advantage of FFR-guided CABG over angiography-guided CABG remains unclear. While FFR-guided CABG can help avoid unnecessary grafting in cases of moderate stenosis, it may also carry the risk of incomplete revascularization. The limited use of FFR due to the need for hyperemia has led to the development of non-hyperemic pressure ratios (NHPRs). NHPR pullback provides trans-stenotic pressure gradients, which may offer valuable insights for CABG strategies. Recently, computed tomographic coronary angiography (CTCA) has emerged as a non-invasive modality that provides accurate data on lesion length, diameter, minimum lumen area, percentage stenosis, and the volume and distribution of high-risk plaques. With the introduction of FFR-CT, CTCA is now highly anticipated to provide both functional evaluation (of myocardial ischemia) via FFR-CT and anatomical information through serial quantitative assessment. Beyond the diagnostic phase, CTCA, augmented by automatic artificial intelligence, holds great potential for guiding therapeutic interventions in the future.

Uncertainty Quantification and Sensitivity Analysis for Non-invasive Model-Based Instantaneous Wave-Free Ratio Prediction

The main objectives of this work are to validate a 1D-0D unsteady solver with a distributed stenosis model for the patient-specific estimation of resting haemodynamic indices and to assess the sensitivity of instantaneous wave-free ratio (iFR) predictions to uncertainties in input parameters. We considered 52 patients with stable coronary artery disease, for which 81 invasive iFR measurements were available. We validated the performance of our solver compared to 3D steady-state and transient results and invasive measurements. Next, we used a polynomial chaos approach to characterise the uncertainty in iFR predictions based on the inputs associated with boundary conditions (coronary flow, compliance and aortic/left ventricular pressures) and vascular geometry (radius). Agreement between iFR and the ratio between cardiac cycle averaged distal and aortic pressure waveforms (restingP d / P a $$ {P}_d/{P}_a $$ ) obtained through 1D-0D and 3D models was satisfactory, with a bias of 0.0-0.005 (±0.016-0.026). The sensitivity analysis showed that iFR estimation is mostly affected by uncertainties in vascular geometry and coronary flow (steady-state parameters). In particular, our 1D-0D method overestimates invasive iFR measurements, with a bias of -0.036 (±0.101), indicating that better flow estimates could significantly improve our modelling pipeline. Conversely, we showed that standard pressure waveforms could be used for simulations, since the impact of uncertainties related to inlet-pressure waveforms on iFR prediction is negligible. Furthermore, while compliance is the most relevant transient parameter, its effect on iFR estimates is negligible compared to that of vascular geometry and flow. Finally, we observed a strong correlation between iFR and restingP d / P a $$ {P}_d/{P}_a $$ , suggesting that steady-state simulations could replace unsteady simulations for iFR prediction.

Calcific versus non-calcific plaque: a CAD-RADS and FFRCT study

Coronary Artery Disease-Reporting and Data System (CAD-RADS) standardises Computed Tomography Coronary Angiography (CTCA) reporting. Coronary calcification can overestimate stenosis. We hypothesized where CADRADS category is assigned due to predominantly calcified maximal stenosis (Ca+), the CTCA-derived Fractional Flow Reserve (FFRCT) would be lower compared to predominantly non-calcified maximal stenoses (Ca-) of the same CAD-RADS category. Consecutive patients undergoing routine clinical CTCA (September 2018 to May 2020) with ≥1 stenosis ≥25% with FFRCT correlation were included. CTCA's were subdivided into Ca+ and Ca-. FFRCT was measured in the left anterior descending (LAD), left circumflex (LCx) and right coronary artery (RCA). Potentially flow-limiting classified as FFRCT≤0.8. A subset had Invasive Coronary Angiography (ICA). 561 patients screened, 320 included (60% men, 69±10 years). Ca+ in 51%, 69% and 50% of CAD-RADS 2, 3 and 4 respectively. There was no difference in the prevalence of FFRCT≤0.8 between Ca+ and Ca- stenoses for each CAD-RADS categories. No difference was demonstrated in the median maximal stenoses FFRCT or end-vessel FFRCT within CAD-RADS 2 and 4. CAD-RADS 3 Ca+ had a lower FFRCT (maximal stenosis p= .02, end-vessel p= .005) vs Ca-. No difference in the prevalence of obstructive disease at ICA between predominantly Ca+ and Ca- for any CAD-RADS category. There was no difference in median FFRCT values or rate of obstructive disease at ICA between Ca+ and Castenosis in both CAD-RADS 2 and 4. Ca+ CAD-RADS 3 was suggestive of an underestimation based on FFRCT but not corroborated at ICA.

Spatial patterns of high-risk biomechanical metrics in plaques with abnormal vs. normal physiological flow indices

BACKGROUND

Plaques associated with abnormally low physiological flow reserve indices are appropriate for percutaneous coronary intervention (PCI). However, recent trials demonstrate that PCI of ischemia-producing lesions does not reduce major adverse cardiac events (MACE). Low endothelial shear stress (ESS) or high ESS gradient (ESSG) are associated with MACE wherever they occur along the plaque. This study aims to determine the presence of high-risk ESS metrics in obstructive coronary plaques with high-risk (<0.80) vs. borderline-risk (0.80-0.89) vs. normal Instantaneous Wave-free Ratio (iFR) (>0.89).

METHODS

We included 50 coronary arteries (50 patients) with variable iFR values who underwent coronary angiography and optical coherence tomography (OCT), followed by 3D reconstruction and computational fluid dynamics calculations of ESS/ESSG. The cohort was divided into 3 groups: iFR < 0.80, iFR 0.80-0.89, and iFR > 0.89. Spatial distribution of ESS metrics was reported along the course of each plaque, and high-risk ESS metrics and their location were compared among the 3 iFR subgroups.

RESULTS

High-risk ESS features (Minimal ESS, Maximum ESSG) were similarly distributed along the course of the atherosclerotic plaque in the three iFR subgroups, both in absolute value and in location: Min ESS: 0.5 ± 0.3 vs. 0.4 ± 0.2 vs. 0.4 ± 0.2 Pa respectively (p = 0.60); Max ESSG any direction: 13.7 ± 9.4 vs. 10.4 ± 10.6 vs. 10.0 ± 7.8 Pa/mm respectively (p = 0.30). ESS metrics were spatially located up to ≥18 mm from the plaque minimal luminal area (MLA) in both directions.

CONCLUSION

High-risk ESS metrics are similarly observed in plaques with normal or abnormal iFR, both in absolute value and spatial location in reference to the MLA. Utilizing iFR to identify plaques likely to cause MACE would miss the majority of plaques mechanistically at high-risk to destabilize and cause future adverse cardiac events.

Fractional flow reserve-guided complete revascularization versus culprit-only percutaneous coronary intervention in patients with myocardial infarction: A meta-analysis of randomized controlled trials

INTRODUCTION

The optimal revascularization strategy for patients with myocardial infarction (MI) and multivessel coronary artery disease (CAD) remains an area of research and debate. Fractional flow reserve (FFR)-guided complete revascularization (CR) by percutaneous coronary intervention (PCI) has emerged as an alternative to traditional culprit-only PCI.

OBJECTIVE

To investigate the outcomes of FFR-guided CR versus culprit-only PCI in patients with MI and multivessel CAD.

METHODS

We systematically searched PubMed, Scopus and Cochrane Central databases for randomized controlled trials (RCTs) comparing FFR-guided CR versus culprit-only PCI in MI patients with multivessel CAD. Outcomes included a composite of all-cause death, MI, stroke and repeat revascularization, these individual outcomes, cardiac death, stent thrombosis (definite or probable), and contrast-induced acute kidney injury (CIAKI). Random effects models were used to generate risk ratios (RRs) with 95 % confidence intervals (CIs).

RESULT

The search identified 5 RCTs including 4618 patients with a median follow-up duration of 3 years. Compared with culprit-only PCI, FFR-guided CR was associated with less composite adverse events (RR 0.73; 95%CI 0.57-0.92; p = 0.009), cardiac death (RR 0.73; 95%CI 0.55-0.97; p = 0.03), and repeat revascularization (RR 0.61; 95%CI 0.44-0.84; p = 0.003). Both strategies were similar in terms of all-cause death, MI, stroke, stent thrombosis, and CIAKI.

CONCLUSION

FFR-guided complete revascularization appears to be superior to culprit-only PCI in reducing composite adverse events, cardiac death, and the need for repeat revascularization in patients with MI and multivessel CAD without a significant impact on recurrent myocardial infarction rates.

SOCIAL MEDIA ABSTRACT

4618-patient meta-analysis: in MI w/ multivessel #CAD, #FFR-guided complete revascularization yields less composite adverse events, cardiac death & repeat revascularization than culprit-only #PCI.

Pathophysiology, Diagnosis, and Management of Coronary Artery Disease in the Setting of Atrial Fibrillation

Atrial fibrillation (AF) and coronary artery disease are frequently associated and, when so, lead to a grim prognosis. Recent studies suggest the presence of interconnected pathophysiological pathways between the 2 conditions that can promote and aggravate each other, igniting a vicious cycle. Notwithstanding, in contrast with the attention dedicated to the management of antithrombotic treatment, research on other aspects of coronary artery disease in AF is only recently gaining traction. The clinical impact of correct assessment of coronary artery stenosis in AF is especially high, due to the antithrombotic therapy imposed by both AF and coronary stenting. Until recently, an in-depth characterization of coronary microcirculation in AF was lacking. However, contemporary studies indicate that coronary microvascular dysfunction is a frequent encounter in AF, possibly explaining the ischemic symptoms even in the absence of obstructive coronary artery disease and interfering with the use of pressure-based indices to evaluate the hemodynamic significance of coronary artery stenosis. This comprehensive review addresses our current knowledge on coronary physiology in AF and its repercussion on the invasive management of coronary artery disease in this setting.

Quantitative flow ratio versus fractional flow reserve for coronary revascularisation guidance (FAVOR III Europe): a multicentre, randomised, non-inferiority trial

BACKGROUND

Fractional flow reserve (FFR) or non-hyperaemic pressure ratios are recommended to assess functional relevance of intermediate coronary stenosis. Both diagnostic methods require the placement of a pressure wire in the coronary artery during invasive coronary angiography. Quantitative flow ratio (QFR) is an angiography-based computational method for the estimation of FFR that does not require the use of pressure wires. We aimed to investigate whether a QFR-based diagnostic strategy yields a non-inferior 12-month clinical outcome compared with an FFR-based strategy.

METHODS

FAVOR III Europe was a multicentre, randomised, open-label, non-inferiority trial comparing a QFR-based with an FFR-based diagnostic strategy for patients with intermediate coronary stenosis. Enrolment was performed in 34 centres across 11 European countries. Patients aged 18 years or older with either chronic coronary syndrome or stabilised acute coronary syndrome, and with at least one intermediate non-culprit stenosis (40-90% diameter stenosis by visual estimate; referred to here as a study lesion), were randomly assigned (1:1) to the QFR-guided or the FFR-guided group. Randomisation was done using a concealed web-based system and was stratified by diabetes and presence of a left anterior descending coronary artery study lesion. The primary endpoint was a composite of death, myocardial infarction, and unplanned revascularisation at 12 months. The predefined non-inferiority margin was 3·4% and the primary analysis was performed in the intention-to-treat population. The trial was registered with ClinicalTrials.gov (NCT03729739) and long-term follow-up is ongoing.

FINDINGS

Between Nov 6, 2018, and July 21, 2023, 2000 patients were enrolled and randomly assigned to the QFR-guided strategy (1008 patients) or the FFR-guided strategy (992 patients). The median age was 67·3 years (IQR 59·9-74·7); 1538 (76·9%) patients were male and 462 (23·1%) were female. Median follow-up time was 365 days (IQR 365-365). At 12 months, a primary endpoint event had occurred in 67 (6·7%) patients in the QFR group, and in 41 (4·2%) patients in the FFR group (hazard ratio 1·63 [95% CI 1·11-2·41]). The event proportion difference was 2·5% (90% two-sided CI 0·9-4·2). The upper limit of the 90% CI exceeded the prespecified non-inferiority margin of 3·4%. Therefore, QFR did not meet non-inferiority to FFR. A total of 18 (1·8%) patients in each group experienced an adverse procedural event, the most frequent being procedure-related myocardial infarction, which occurred in ten (1·0%) patients in the QFR group and seven (0·7%) in the FFR group. One patient in the QFR group died in relation to the index procedure.

INTERPRETATION

The results of the FAVOR III Europe trial do not support the use of QFR if FFR is available to guide revascularisation decisions in patients with intermediate coronary stenosis. This finding could have implications for current clinical guidelines recommending QFR for this purpose.

FUNDING

Medis Medical Imaging Systems and Aarhus University.

Comparison of Nitroglycerin-Induced Pressure Ratio Drop and Resting Full-Cycle Ratio in a Pressure Wire Study

Background/Objectives: The acute drop in distal coronary pressure (Pd)-to-aortic pressure (Pa) ratio after intracoronary nitroglycerin (NTG-Pd/Pa) administration is an acceptable estimate of fractional flow reserve (FFR). We aimed to compare the diagnostic performance of NTG-Pd/Pa with that of the resting full-cycle ratio (RFR) in predicting the binary results of FFR. Methods: This study included two prospective studies registered under the numbers NCT04700397 and NCT03693157. Altogether, 202 vessels were included. The optimal cutoff of NTG-Pd/Pa for predicting FFR ≤ 0.8 was identified and validated in another prospective registry. We used the McNemar's test and the DeLong method to compare the diagnostic efficiency of NTG-Pd/Pa vs. RFR in predicting FFR ≤ 0.8 in a pooled cohort. Results: NTG-Pd/Pa was strongly correlated with FFR (r = 0.945, p < 0.001). The NTG-Pd/Pa cutoff for predicting FFR ≤ 0.8 was 0.85 in both the derivation and validation cohorts. The area under the receiver-operating characteristic curve (AUC) and accuracy in predicting FFR ≤ 0.8 were higher for NTG-Pd/Pa than for RFR in the pooled cohort (AUC 0.97 vs. 0.91, p < 0.001; accuracy 91% vs. 84%, p < 0.001). The sensitivity and negative predictive values were also higher for NTG-Pd/Pa than for RFR (all p < 0.05). The specificity and positive predictive value were numerically higher for NTG-Pd/Pa than for RFR (all p > 0.05). Conclusions: The diagnostic performance of NTG-Pd/Pa may surpass that of the RFR in predicting the binary results of the FFR.

Contemporary Functional Coronary Angiography: An Update

Functional coronary angiography (FCA) is a novel modality for assessing the physiology of coronary lesions, going beyond anatomical visualization by traditional coronary angiography. FCA incorporates indices like fractional flow reserve (FFR) and instantaneous wave-free ratio (IFR), which utilize pressure measurements across coronary stenoses to evaluate hemodynamic impacts and to guide revascularization strategies. In this review, we present traditional and evolving modalities and uses of FCA. We will also evaluate the existing evidence and discuss the applicability of FCA in various clinical scenarios. Finally, we provide insight into emerging evidence, current challenges, and future directions in FCA.

Fractional Flow Reserve Implications for Clinical Decision Making in Coronary Artery Disease

Fractional flow reserve (FFR) is regarded as the gold standard for assessing the functional significance of coronary artery lesions. However, its utilization in clinical practice remains limited. This study aims to determine whether FFR results can influence treatment decisions for coronary artery disease compared to visual assessments of angiographic images. We conducted a retrospective study involving 63 patients diagnosed with either chronic coronary syndrome (n = 39, 61.9%) or acute coronary syndrome (n = 24, 38.1%) who underwent an FFR assessment. Three experienced interventional cardiologists (>300 PCI procedures/year) reevaluated 105 ambiguous coronary lesions in these patients, blinded to the FFR results. The objective was to assess lesion significance and determine the treatment strategy based on a visual angiographic evaluation. The three operators reached concordant agreement (≥two operators) to perform PCI in 60 (57.1%) of the evaluated lesions based on the angiographic assessment. Of these, nine lesions (15%) were deemed functionally non-significant by FFR (FFR > 0.80). Conversely, they agreed to defer PCI in 45 (42.9%) lesions, but 4 lesions (8.9%) were found to be functionally significant (FFR ≤ 0.80) and required a re-evaluation for PCI. Visual-guided decision making by interventional cardiologists shows variability and does not always align with the functional significance of coronary lesions as determined by FFR. Incorporating FFR into routine decision making could enhance treatment accuracy and patient outcomes.

Noninvasive and fast method of calculation for instantaneous wave-free ratio based on haemodynamics and deep learning

BACKGROUND AND OBJECTIVES

Instantaneous wave-free ratio (iFR) is a new invasive indicator of myocardial ischaemia, and its diagnostic performance is as good as the "gold standard" of myocardial ischaemia diagnosis: fractional flow reserve (FFR). iFR can be approximated by iFRCT, which is calculated based on noninvasive coronary CT angiography (CTA) images and computational fluid dynamics (CFD). However, the existing methods for calculating iFRCT fail to accurately simulate the resting state of the coronary artery, resulting in low computational accuracy. Furthermore, the use of CFD technology limits its computational efficiency, making it difficult to meet clinical application needs. The role of coronary microcirculatory resistance compensation suggests that microcirculatory resistance can be adaptively reduced to compensate for increases in coronary stenotic resistance, thereby maintaining stable myocardial perfusion in the resting state. It is therefore necessary to consider this compensation mechanism to establish a high-fidelity microcirculation resistance model in the resting state in line with human physiology, and so to achieve accurate calculation of iFRCT.

METHODS

In this study we successfully collected clinical data, such as FFR, in 205 stenotic vessels from 186 patients with coronary heart disease. A neural network model was established to predict coronary artery stenosis resistance. Based on the compensation mechanism of coronary microcirculation resistance, an iterative solution algorithm for microcirculation resistance in the resting state was developed. Combining the two methods, a simplified single-branch model combining coronary stenosis and microcirculation resistance was established, and the noninvasive and rapid numerical calculation of iFRCT was performed.

RESULTS

The results showed that the mean squared error (MSE) between the pressure drop predicted by the neural network value for the coronary artery stenosis model and the ground truth in the test set was 0.053 %, and correlation analysis proved that there was a good correlation between them (r = 0.99, p < 0.001). With reference to clinical diagnosis of myocardial ischaemia (using FFR as the gold standard), the diagnostic accuracy of the iFRCT calculation model for the 205 cases was 88.29 % (r = 0.71, p < 0.001), and the total calculation time was < 8 s.

CONCLUSIONS

The results of this study demonstrate the utility of a simplified single-branch model in an iFRCT calculation method based on haemodynamics and deep learning, which is important for noninvasive and rapid diagnosis of myocardial ischaemia.

Influence of the pressure wire on the fractional flow reserve calculation: CFD analysis of an ideal vessel and clinical patients with stenosis

BACKGROUND AND OBJECTIVE

Fractional Flow Reserve (FFR) is generally considered the gold standard in hemodynamics to assess the impact of a stenosis on the blood flow. The standard procedure to measure involves the displacement of a pressure guide along the circulatory system until it is placed next to the lesion to be analyzed. The main objective of the present study is to analyze the influence of the pressure guide on the invasive FFR measurements and its implications in clinical practice.

METHODS

We studied the influence of pressure wires on the measurement of Fractional Flow Reserve (FFR) through a combination of Computational Fluid Dynamics (CFD) simulations using 45 clinical patient data with 58 lesions and ideal geometries. The analysis is conducted considering patients that were subjected to a computer tomography and also have direct measurements using a pressure guide. Influence of the stenosis severity, degree of occlusion and blood viscosity has also been studied.

RESULTS

The influence of pressure wires specifically affects severe stenosis with a lumen diameter reduction of 50 % or greater. This type of stenosis leads to reduced hyperemic flow and increased coronary pressure drop. Thus, we identified that the placement of wires during FFR measurements results in partial obstruction of the coronary artery lumen, leading to increased pressure drop and subsequent reduction in blood flow. The severity of low FFR values associated with severe stenosis may be prone to overestimation when compared to stenosis without severe narrowing. These results have practical implications, particularly in the interpretation of lesions falling within the "gray zone" (0,75-0,80).

CONCLUSIONS

The pressure wire's presence significantly alters the flow on severe lesions, which has an impact on the FFR calculation. In contrast, the impact of the pressure wire appears to be reduced when the FFR is larger than 0.8. The findings provide critical information for physicians, emphasizing the need for cautious interpretation of FFR values, particularly in severe stenosis. It also offers insights into improving the correlation between FFRct models and invasive measurements by incorporating the influence of pressure wires.

State-of-the-art percutaneous coronary intervention for left main coronary artery disease in Japan

Percutaneous coronary intervention for left main coronary artery disease (LM-PCI) represents a high-risk yet life-saving procedure that has evolved significantly over the years. This review outlines the current state-of-the-art practices for LM-PCI in Japan in detail, emphasizing the integration of coronary physiology and intracoronary imaging alongside with evidence-based standardized technique using latest drug-eluting stents. These advancements enable precise lesion assessment, stent sizing, and optimal deployment, thereby enhancing procedural safety and efficacy. Despite discrepancies between current guidelines favoring coronary artery bypass grafting and real-world practice trends towards increased LM-PCI adoption, particularly in elderly populations with multiple comorbidities, careful patient selection and procedural planning are critical. Future perspectives include further refining LM-PCI through conducting randomized controlled trials integrating advanced techniques and addressing the issue of ostial left circumflex lesions and nationwide standardization of medical care for LM disease.

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

AIMS

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).

METHODS

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.

RESULTS

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).

CONCLUSION

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.

TRIAL REGISTRATION NUMBER

NCT03045601.