Physiological assessment of coronary artery disease in the cardiac catheterization laboratory: a scientific statement from the American Heart Association Committee on Diagnostic and Interventional Cardiac Catheterization, Council on Clinical Cardiology

Should We Revisit the Clinical Value of Fractional Flow Reserve in the Era of Coronary Microvascular Dysfunction?

The understanding of coronary artery disease is evolving, with more attention given currently to the microcirculation compartment. Coronary microvascular dysfunction (CMD) is defined by any structural or functional alteration of the coronary microcirculation, and is prevalent in current clinical practice, being associated with pejorative cardiovascular prognosis. CMD can exist by itself as primary microvascular angina, or in association with a variety of cardiovascular diseases. On the other hand, fractional flow reserve (FFR) represents the gold standard for estimating the hemodynamic impact of moderate coronary artery stenosis, and as such guiding coronary revascularization in clinical practice. The fundamental clinical trials that introduced and validated the use of FFR in current clinical practice were published before acquiring more in-depth knowledge on CMD and the impact it can have on FFR measurements. However, in the setting of CMD, studies have shown that FFR can underestimate the severity of coronary stenosis. In addition, recent findings underline the limitations of FFR to guide revascularization in terms of clinical outcome in specific conditions associated with CMD, such as acute coronary syndrome or multivessel coronary artery disease. As such, new research efforts must be made to investigate the reliability of FFR or to reposition its use in guiding coronary revascularization in the context of CMD, in order to define the clinical value of FFR in this particular setting.

Computational fluid dynamics model utilizing proper orthogonal decomposition to assess coronary physiology and wall shear stress

BACKGROUND

Percutaneous coronary intervention (PCI) to alleviate symptoms and improve outcomes in patients with symptomatic coronary artery disease. However, conventional assessments like coronary angiography may not fully capture the hemodynamic significance of coronary lesions. This study explores the utility of Proper Orthogonal Decomposition (POD) in elucidating coronary flow dynamics pre- and post-stent placement.

OBJECTIVES

Through the utilization of POD modes, we aim to analyze the intricate geometries of individual patients, extracting dominant POD modes both pre- and post-PCI. By engaging these modes, our objective is to discern changes in velocity patterns and wall shear stress, offering insight into the physiological outcomes of stent interventions in coronary arteries.

METHODS

The POD method with QR-decomposition was employed to generate POD modes, decomposing the vector field of interest into spatial functions modulated by time coefficients. Patients with prior coronary artery bypass surgery, myocardial bridging, collateral arteries, or recent myocardial infarction within 48 h were excluded from the study.

RESULTS

Results demonstrated improved hemodynamic parameters post-PCI, with significant enhancements in coronary flow reserve and reduced wall shear stress. POD analysis revealed that the first five modes effectively characterized flow features, highlighting stenosis, stent deployment, and branch dynamics.

CONCLUSION

This exploratory study demonstrates POD's potential for real-time assessment of coronary lesion significance and post-intervention outcomes. Its efficiency in capturing key flow characteristics offers a promising tool for personalized decision-making in interventional cardiology, enhancing our understanding of coronary hemodynamics and optimizing treatment strategies.

Single-Center Analysis of Soluble TREM2 as a Biomarker in Coronary Microvascular Dysfunction: A Cross-Sectional Study

Background: The soluble triggering receptor expressed on myeloid cells 2 (sTREM2) is linked to the progression of cardiovascular conditions, but its role in coronary microcirculation dysfunction (CMD) is not yet clear. Methods: A cross-sectional observational study from July 2023 to May 2024 was conducted in the China-Japan Friendship Hospital, after registration in the ClinicalTrials database (Registry Name: Coronary Microvascular Dysfunction in Angina Patients With Non-obstructive Coronary Artery Disease (ANOCA-CMD); Registry Number: NCT06503640; Registry Date: 23 September 2022). This cross-sectional study involved 76 subjects, including 55 patients with CMD and 21 without CMD, admitted to the China-Japan Friendship Hospital. CMD was defined by a coronary flow reserve (CFR) < 2.5 or index of microvascular resistance (IMR) ≥ 25. sTREM2 levels were measured using an enzyme-linked immunosorbent assay. Linear correlation analysis assessed the relationship between sTREM2 levels and CFR, IMR, microvascular resistance reserve (MRR), and the resistive reserve ratio (RRR). Univariate and multivariate regression analyses further examined the association between sTREM2 and CMD. Additionally, receiver operating characteristic (ROC) analysis was used to evaluate the diagnostic accuracy of plasma sTREM2 for identifying CMD patients. Results: Elevated sTREM2 levels were found in the CMD group. Correlation analysis showed a significant positive relationship with IMR and an inverse correlation with CFR, MRR, and RRR. After adjusting for confounders, sTREM2 was found to be an independent risk factor for CMD [OR = 1.003, 95% CI 1.001-1.007, p = 0.008]. ROC analysis revealed a sensitivity of 59.46%, specificity of 90.48%, and an AUC of 0.7677 (95% CI: 0.6481-0.8872, p = 0.008) for CMD diagnosis at a threshold of 595.5 pg/mL, indicating good diagnostic performance. Conclusions: Elevated sTREM2 levels in CMD patients indicate its potential as a biomarker.

A New Semi-Quantitative Parameter to Assess Functionally Significant Coronary Disease Using Myocardial Contrast Echocardiography

Background

Quantitative flow ratio (QFR) can identify functionally significant coronary disease non-invasively. Myocardial contrast echocardiography (MCE) is a non-invasive and effective procedure for detecting abnormalities in hemodynamic coronary artery stenosis. Currently, there is no research confirming the correlation between MCE and QFR. This study aims to compare the capacity of the perfusion index (PI) from MCE to diagnose functionally significant coronary disease in patients with chest pain. The investigators use QFR as the gold standard for comparison.

Methods

112 patients referred for coronary angiography (CAG) due to suspicion of coronary artery disease (CAD) were included. 64 patients with functionally significant coronary disease were diagnosed. 48 patients were defined as CAD without functionally significant coronary disease. MCE was performed 24 h before angiography. PI was calculated for each triggering interval by adding the perfusion scores of segments and dividing by the number of segments. Logistic regression analyses were performed to evaluate the association among functionally significant coronary disease, echocardiographic and clinical parameters. Spearman correlation analysis was used to investigate the correlation between PI and QFR. A receiver operating characteristic (ROC) curve was used to assess the capability of echocardiographic and clinical parameters to diagnose functionally significant coronary disease.

Results

Patients with functionally significant coronary disease had the worse perfusion in MCE compared with those without functionally significant coronary disease. In multivariable logistic regression analysis, global perfusion index (GPI) (OR: 43.409, p < 0.001) was associated with functionally significant coronary disease in patients with CAD. Based on the Spearman correlation analysis. Left anterior descending artery (LAD)-PI showed a strong negative correlation with LAD-QFR (r = -0.652, p < 0.01). ROC curves showed LAD-PI to be superior to GPI, left circumflex artery PI (LCX-PI) and right coronary artery PI (RCA-PI) in identifying functionally significant coronary disease.

Conclusions

The PI derived from MCE has diagnostic value for functionally significant coronary disease with QFR ≤0.80 in 1 or more vessels, with LAD-PI showing the highest diagnostic efficiency. GPI is independently associated with functionally significant coronary disease, but among the branch PIs, LAD-PI has the highest diagnostic efficiency.

Is the peripheral microcirculation a window into the human coronary microvasculature?

An increasing body of evidence suggests a pivotal role for the microvasculature in the development of cardiovascular disease. A dysfunctional coronary microvascular network, specifically within endothelial cells-the inner most cell layer of vessels-is considered a strong, independent risk factor for future major adverse cardiac events. However, challenges exist with evaluating this critical vascular bed, as many of the currently available techniques are highly invasive and cost prohibitive. The more easily accessible peripheral microcirculation has surfaced as a potential surrogate in which to study mechanisms of coronary microvascular dysfunction and likewise may be used to predict poor cardiovascular outcomes. In this review, we critically evaluate a variety of prognostic, physiological, and mechanistic studies in humans to answer whether the peripheral microcirculation can add insight into coronary microvascular health. A conceptual framework is proposed that the health of the endothelium specifically may link the coronary and peripheral microvascular beds. This is supported by evidence showing a correlation between human coronary and peripheral endothelial function in vivo. Although not a replacement for investigating and understanding coronary microvascular function, the microvascular endothelium from the periphery responds similarly to (patho)physiological stress and may be leveraged to explore potential therapeutic pathways to mitigate stress-induced damage.

Evaluation of Conventional and Novel Risk Factors in Young and Aged Patients, Undergoing Coronary Artery Bypass Grafting

Aim

The aim of this study was to find out the relationship of conventional and/or novel cardiovascular risk factors with coronary artery disease severity in terms of SYNTAX scores in young (≤45 years) and aged (>45 years) patients.

Materials and Methods

The final number of patients included in the study was 132 and divided into 2 groups: Group A was young patients with age less than 45 years, and in group B, the age was more than 45 years. The SYNTAX score was determined for each case based on the preoperative coronary angiogram using the Online SYNTAX score calculator version 2.11.

Results

It was seen that 33% of patients in group A had high SYNTAX scores, as compared to only 8% in group B. This definitely shows that the younger population has more COMPLEX coronary artery lesions than the elderly.

Conclusion

YOUNG patients have significantly higher levels of homocysteine as compared to the elderly. Serum homocysteine correlates with SYNTAX scores in YOUNG patients, with a sensitivity of 83.33%, specificity 91.67%, and diagnostic accuracy 86.67%. Percentage of Low HDL in YOUNG is significantly higher than in the elderly.

Co-registered optical coherence tomography and X-ray angiography for the prediction of fractional flow reserve

Cardiovascular disease (CVD) stands as the leading global cause of mortality, and coronary artery disease (CAD) has the highest prevalence, contributing to 42% of these fatalities. Recognizing the constraints inherent in the anatomical assessment of CAD, Fractional Flow Reserve (FFR) has emerged as a pivotal functional diagnostic metric. Herein, we assess the potential of employing an ensemble approach with deep neural networks (DNN) to predict invasively measured Fractional Flow Reserve (FFR) using raw anatomical data extracted from both optical coherence tomography (OCT) and X-ray coronary angiography (XA). In this study, we used a challenging dataset, with 46% of the lesions falling within the FFR range of 0.75 to 0.85. Despite this complexity, our model achieved an accuracy of 84.3%, demonstrating a sensitivity of 87.5% and a specificity of 81.4%. Our results demonstrate that incorporating both OCT and XA signals, co-registered, as inputs for the DNN model leads to an important increase in overall accuracy.

Diagnostic performance of intravascular ultrasound-based fractional flow reserve in evaluating of intermediate left main stenosis

BACKGROUND

The recently introduced ultrasonic flow ratio (UFR), is a novel fast computational method to derive fractional flow reserve (FFR) from intravascular ultrasound (IVUS) images. In the present study, we evaluate the diagnostic performance of UFR in patients with intermediate left main (LM) stenosis.

METHODS

This is a prospective, single center study enrolling consecutive patients with presence of intermediated LM lesions (diameter stenosis of 30%-80% by visual estimation) underwent IVUS and FFR measurement. An independent core laboratory assessed offline UFR and IVUS-derived minimal lumen area (MLA) in a blinded fashion.

RESULTS

Both UFR and FFR were successfully achieved in 41 LM patients (mean age, 62.0 ± 9.9 years, 46.3% diabetes). An acceptable correlation between UFR and FFR was identified (r = 0.688, P < 0.0001), with an absolute numerical difference of 0.03 (standard difference: 0.01). The area under the curve (AUC) in diagnosis of physiologically significant coronary stenosis for UFR was 0.94 (95% CI: 0.87-1.01), which was significantly higher than angiographic identified stenosis > 50% (AUC = 0.66, P < 0.001) and numerically higher than IVUS-derived MLA (AUC = 0.82; P = 0.09). Patient level diagnostic accuracy, sensitivity and specificity for UFR to identify FFR ≤ 0.80 was 82.9% (95% CI: 70.2-95.7), 93.1% (95% CI: 82.2-100.0), 58.3% (95% CI: 26.3-90.4), respectively.

CONCLUSION

In patients with intermediate LM diseases, UFR was proved to be associated with acceptable correlation and high accuracy with pressure wire-based FFR as standard reference. The present study supports the use of UFR for functional evaluation of intermediate LM stenosis.

Contemporary Use of Coronary Physiology in Cardiology

Coronary angiography has a limited ability to predict the functional significance of intermediate coronary lesions. Hence, physiological assessment of coronary lesions, via fractional flow reserve (FFR) or instantaneous wave-free ratio (iFR), has been introduced to determine their functional significance. An accumulating body of evidence has consolidated the role of physiology-guided revascularization, particularly among patients with stable ischemic heart disease. The use of FFR or iFR to guide decision-making in patients with stable ischemic heart disease and intermediate coronary lesions received a class I recommendation from major societal guidelines. Nevertheless, the role of coronary physiology testing is less clear among certain patients' groups, including patients with serial coronary lesions, acute coronary syndromes, aortic stenosis, heart failure, as well as post-percutaneous coronary interventions. In this review, we aimed to discuss the utility and clinical evidence of coronary physiology (mainly FFR and iFR), with emphasis on those specific patient groups.

Assessment of the Severity of Left Anterior Descending Coronary Artery Stenoses by Enhanced Transthoracic Doppler Echocardiography: Validation of a Method Based on the Continuity Equation

BACKGROUND

To verify whether the severity of coronary stenosis could be non-invasively assessed by enhanced transthoracic coronary echo Doppler in convergent color Doppler mode (E-Doppler TTE) over a wide range of values (from mild to severe).

METHODS

Color-guided pulsed wave Doppler sampling in the left anterior descending coronary artery (LAD) was performed in 103 diseased LAD segments (corresponding to 94 patients examined) as assessed by quantitative coronary angiography (QCA) or intracoronary ultrasound (IVUS). The E-Doppler TTE examinations consisted of measuring the velocity (vel) at the stenosis site and a reference adjacent segment. Then the continuity equation (C-Eq) was applied to calculate the percent cross-sectional area reduction (%CSA) at the stenosis site. The applied formula was: %CSA = 100 × (1 - [TVIref × 0.5]/TVIs). TVI = the time velocity integral at the stenosis [s] and the reference site [ref], respectively); 0.5 = the correcting factor for a parabolic profile was used only when the % accelerated stenotic flow was >122% (AsF = diastolic peak vel at first site - diastolic peak vel at second site/diastolic peak vel at second site × 100).

RESULTS

E-Doppler TTE feasibility was 100%. Doppler and QCA/IVUS-derived %CSA stenosis showed very good agreement over a large range of values (from mild to severe), with no significant bias; the maximum difference between QCA/IVUS and transthoracic Doppler %CSA was mostly around 20% with a few patients exceeding this limit (limits of agreement = -27.53 to 23.5%). The scattering was slightly larger for the non-significant stenoses. The correlation was strong (r = 0.89, p < 0.001).

CONCLUSION

E-Doppler TTE is a feasible and reliable method for assessing the severity of LAD stenosis by applying the C-Eq.

The Association of Obstructive Sleep Apnea in Ischemia with No Obstructive Coronary Artery Disease - A Pilot Study

Obstructive sleep apnea (OSA) is increasingly recognized to be a risk factor for cardiovascular disease. This pilot study assessed the association of OSA and invasive coronary microvascular function in patients with ischemia with no obstructive coronary artery disease (INOCA). Forty-two patients with angina, were prospectively screened at a single tertiary centre covering the northern metropolitan area of South Australia, from February 2018 to December 2020 (ACTRN12618000149268). Forty patients were invited into to this observational study after coronary angiography demonstrated INOCA and functional coronary vasomotor disorder (n = 40). Twenty one participants subsequently underwent a sleep study for OSA diagnosis while 9 participants had prior formal diagnosis of OSA (ACTRN12618000227291). Of the 30 participants with OSA data, 87% (n = 26) had a diagnosis of OSA. Accordingly, 11 with mild severity, 7 with moderate severity and 8 with severe OSA. No OSA was observed in 4 participants. Participants with OSA were older [61.4±8.7 vs 49.9±9.7, P = 0.002] with similar clinical characteristics for the pattern and severity of angina and other co-morbidities. 73.3% (n = 22) had abnormal functional disorders of the epicardial coronary arteries and/or coronary microcirculation. On multivariate analysis, OSA was the only statistically significant association with functional coronary microvascular disorders [OR 53.95, 1.41 -2065.01, P = 0.032]. This study provided an observation of a significant correlation between INOCA with abnormal coronary vasomotor function and OSA in an Australian cohort. This correlation supports a possible pathophysiological interplay between these two conditions that needs to be further evaluated. The benefit of treatment of OSA in this subset remains unknown.

Abnormal physiological findings after FFR-based revascularisation deferral are associated with worse prognosis in women

The prognostic value of abnormal resting Pd/Pa and coronary flow reserve (CFR) after fractional flow reserve (FFR)-guided revascularisation deferral according to sex remains unknown. From the ILIAS Registry composed of 20 hospitals globally from 7 countries, patients with deferred lesions following FFR assessment (FFR > 0.8) were included. (NCT04485234) The primary clinical endpoint was target vessel failure (TVF) at 2-years follow-up. We included 1392 patients with 1759 vessels (n = 564 women, 31.9%). Although resting Pd/Pa was similar between the sexes (p = 0.116), women had lower CFR than men (2.5 [2.0-3.2] vs. 2.7 [2.1-3.5]; p = 0.004). During a 2-year follow-up period, TVF events occurred in 56 vessels (3.2%). The risk of 2-year TVF was significantly higher in women with low versus high resting Pd/Pa (HR: 9.79; p < 0.001), whereas this trend was not seen in men. (Sex: P-value for interaction = 0.022) Furthermore, resting Pd/Pa provided an incremental prognostic value for 2-year TVF over CFR assessment only in women. After FFR-based revascularisation deferral, low resting Pd/Pa is associated with higher risk of TVF in women, but not in men. The predictive value of Pd/Pa increases when stratified according to CFR values, with significantly high TVF rates in women in whom both indices are concordantly abnormal.Clinical Trial Registration: Inclusive Invasive Physiological Assessment in Angina Syndromes Registry (ILIAS Registry), NCT04485234.

The risk of acute coronary events in microvascular disease

The microvascular disease represents a widespread clinical entity in the general population, especially among women. The dysfunction of the microcirculation is often responsible for myocardial ischaemia and angina in the absence of significant stenosis of the epicardial district, while in other cases it can represent a contributing cause of angina even in the presence of coronary artery disease, cardiomyopathies or heart failure. The cardiovascular risk factors of people with microvascular disease are similar to those who develop epicardial atherosclerotic disease. However, the prognostic significance of microvascular disease remains a matter of debate. An element to be clarified, in fact, is whether subjects with dysfunction of the microcirculation and coronary tree without significant stenoses present an increased risk of myocardial infarction and sudden death. In recent years, several studies seem to confirm an association between microvascular disease and progression of coronary epicardial atherosclerosis. The prognosis of microvascular disease would therefore not be benign as was previously believed, but associated with an increased risk of cardiovascular events including revascularization, heart attack, and cardiac death.

Intracoronary nicorandil induced hyperemia for physiological assessments in the coronary artery lesions

OBJECTIVE

Maximal hyperemia is a key element of invasive physiological examination. The aim of this study was to investigate the efficacy and safety of intracoronary (IC) nicorandil in comparison with adenosine 5'-triphosphate (ATP) intravenous (i.v.) injection for fractional flow reserve (FFR) measurement in coronary artery lesions.

MATERIALS AND METHODS

In this study, 46 patients who had their FFR measured were enrolled, including 51 lesions. Hyperemia was induced by bolus 2 mg nicorandil and ATP (40 mg ATP + 36 ml saline, weight × 10 ml/h) for FFR measurement. The safety and efficacy of IC nicorandil were evaluated.

RESULTS

The mean FFR values measured by nicorandil and ATP were 0.810 ± 0.013 and 0.799 ± 0.099, p < 0.001, respectively. There was a strong correlation between FFR measured by nicorandil and ATP (r = 0.983, R 2 = 0.966, FFRnicorandil = 0.937 × FFRATP + 0.061). The rate of FFR ≤ 0.75 in the nicorandil and ATP groups was 31.37 vs. 35.29%, respectively (p = 0.841), the consistency rate was 96.08%; the FFR ≤ 0.8 rate was 41.18 and 43.14%, respectively (p = 0.674), and the consistency rate was 90.20%. In five lesions, the FFR value measured by nicorandil ranged between 0.79 and 0.82, indicating inconsistency according to FFR ≤ 0.8. The blood pressure changes caused by nicorandil and ATP were 12.96 ± 6.83 and 22.22 ± 11.44 mmHg (p < 0.001); the heart rate changes were 2.43 ± 1.31 and 6.52 ± 2.87 beats/min, respectively (p < 0.001); and the PR interval changes were 6.0 (1.0-11.0) and 9.0 (2.0-19.0) ms, respectively (p < 0.001). Visual analog scale (VAS) scores in the nicorandil group were all in the range 0-2, while in the ATP group were mostly in the range of 3-5.

CONCLUSION

Intracoronary bolus of nicorandil (2 mg) infusion induces stable hyperemia, and it could be considered as an alternative drug to ATP for FFR measurement with a lower side effect profile in most patients.

MINOCA: One Size Fits All? Probably Not—A Review of Etiology, Investigation, and Treatment

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogeneous group of conditions that include both atherosclerotic (coronary plaque disruption) and non-atherosclerotic (spontaneous coronary artery dissection, coronary artery spasm, coronary artery embolism, coronary microvascular dysfunction, and supply–demand mismatch) causes resulting in myocardial damage that is not due to obstructive coronary artery disease. Failure to identify the underlying cause may result in inadequate and inappropriate therapy in these patients. The cornerstone of managing MINOCA patients is to identify the underlying mechanism to achieve the target treatment. Intravascular imaging is able to identify different morphologic features of coronary plaques, while cardiac magnetic resonance is the gold standard for detection of myocardial infarction in the setting of MINOCA. In this review, we summarize the relevant clinical issues, contemporary diagnosis, and treatment options of MINOCA.

Relationship of Plaque Features at Coronary CT to Coronary Hemodynamics and Cardiovascular Events

Background Plaque assessments with coronary CT angiography (CCTA) and coronary flow indexes have prognostic implications. Purpose To investigate the association and additive prognostic value of plaque burden and characteristics at CCTA with coronary pressure and flow. Materials and Methods Data of patients with coronary artery disease who underwent CCTA within 90 days before physiologic assessments at tertiary cardiovascular centers between January 2011 and December 2018 were retrospectively analyzed, which included fractional flow reserve (FFR), resting distal coronary artery pressure (Pd)-to-aortic pressure (Pa) ratio (hereafter, Pd/Pa), coronary flow reserve (CFR), hyperemic flow (1/hyperemic mean transit time [Tmn]), resting flow (1/resting Tmn), and index of microcirculatory resistance (IMR). Four high-risk plaque (HRP) attributes at CCTA defined high disease burden (plaque burden, ≥70%; minimum lumen area, <4 mm²) and adverse plaque (low-attenuation plaque, positive remodeling). Their lesion-specific relationships with coronary hemodynamic parameters and major adverse cardiovascular events (MACE) were investigated using a generalized estimating equation and marginal Cox model. Results Among 406 lesions from 335 patients (mean age, 67 years ± 10 [SD]; 259 men), high disease burden is predicted by FFR (odds ratio [OR], 0.55; P < .001), resting Pd/Pa (OR, 0.47; P < .001), CFR (OR, 0.85; P = .004), and hyperemic flow (OR, 0.91; P = .03), and adverse plaque by FFR (OR, 0.67; P < .001), resting Pd/Pa (OR, 0.69; P = .001), hyperemic flow (OR, 0.76; P = .006), resting flow (OR, 0.54; P = .001), and IMR (OR, 1.27; P = .008). High disease burden (hazard ratio [HR], 4.0; P = .004) and adverse plaque (HR, 2.7; P = .02) were associated with a higher risk of MACE (n = 27) over median 2.9-year follow-up. In six lesion subsets with normal flow or pressure, at least three HRP attributes predicted a higher MACE rate (HR range, 2.6-6.3). Conclusion High-risk plaque features and plaque burden at coronary CT angiography were associated with cardiovascular events independent of coronary hemodynamic parameters. Clinical trial registration no. NCT04037163 © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Leipsic and Tzimas in this issue.

Towards a Deep-Learning Approach for Prediction of Fractional Flow Reserve from Optical Coherence Tomography

Cardiovascular disease (CVD) is the number one cause of death worldwide, and coronary artery disease (CAD) is the most prevalent CVD, accounting for 42% of these deaths. In view of the limitations of the anatomical evaluation of CAD, Fractional Flow Reserve (FFR) has been introduced as a functional diagnostic index. Herein, we evaluate the feasibility of using deep neural networks (DNN) in an ensemble approach to predict the invasively measured FFR from raw anatomical information that is extracted from optical coherence tomography (OCT). We evaluate the performance of various DNN architectures under different formulations: regression, classification—standard, and few-shot learning (FSL) on a dataset containing 102 intermediate lesions from 80 patients. The FSL approach that is based on a convolutional neural network leads to slightly better results compared to the standard classification: the per-lesion accuracy, sensitivity, and specificity were 77.5%, 72.9%, and 81.5%, respectively. However, since the 95% confidence intervals overlap, the differences are statistically not significant. The main findings of this study can be summarized as follows: (1) Deep-learning (DL)-based FFR prediction from reduced-order raw anatomical data is feasible in intermediate coronary artery lesions; (2) DL-based FFR prediction provides superior diagnostic performance compared to baseline approaches that are based on minimal lumen diameter and percentage diameter stenosis; and (3) the FFR prediction performance increases quasi-linearly with the dataset size, indicating that a larger train dataset will likely lead to superior diagnostic performance.

COlchicine to Prevent PeriprocEdural Myocardial Injury in Percutaneous Coronary Intervention (COPE-PCI): Coronary Microvascular Physiology Pilot Substudy

Aim

In this randomized pilot trial, we aimed to assess the anti-inflammatory effect of preprocedural colchicine on coronary microvascular physiology measurements before and after PCI.

Methods

Patients undergoing PCI for stable angina (SA) or non-ST-elevation myocardial infarction (NSTEMI) were randomized to oral colchicine or placebo, 6- to 24-hours before the procedure. Strict prespecified inclusion/exclusion criteria were set to ensure all patients were given the study medication, had a PCI, and had pre- and post-PCI culprit vessel invasive coronary physiology measurements. Fractional flow reserve (FFR), Index of Microvascular Resistance (IMR), Coronary Flow Reserve (CFR), and Resistive Reserve Ratio (RRR) were measured immediately before and after PCI. CMVD was defined as any one of post-PCI IMR >32 or CFR <2 or RRR <2. High-sensitive-(hs)-troponin-I, hsCRP, and leucocyte count were measured before and 24 hours after PCI.

Results

A total of 50 patients were randomized and met the strict prespecified inclusion/exclusion criteria: 24-colchicine and 26-placebo. Pre-PCI coronary physiology measurements, hs-troponin-I, and hsCRP were similar between groups. Although numerically lower in patients given colchicine, the proportion of patients who developed CMVD was not significantly different between groups (colchicine: 10 (42%) vs placebo: 16 (62%), p=0.16). Colchicine patients had higher post-PCI CFR and RRR vs placebo (respectively: 3.25 vs 2.00, p=0.03 & 4.25 vs 2.75, p < 0.01). Neutrophil count was lower after PCI in the colchicine arm (p=0.02), and hsCRP post-PCI remained low in both treatment arms (1.0 mg/L vs 1.7 mg/L, p=0.97). Patients randomized to colchicine had significantly less PCI-related absolute hs-troponin-I change (46 ng/L vs 152 ng/L, p=0.01).

Conclusion

In this pilot randomized substudy, colchicine given 6 to 24 hours before PCI did not statistically impact the post-PCI CMVD definition used in this study, yet it did improve post-PCI RRR and CFR measurements, with less procedure-related troponin release and less inflammation.

Coronary flow reserve and cardiovascular outcomes: a systematic review and meta-analysis

AIMS

This meta-analysis aims to quantify the association of reduced coronary flow with all-cause mortality and major adverse cardiovascular events (MACE) across a broad range of patient groups and pathologies.

METHODS AND RESULTS

We systematically identified all studies between 1 January 2000 and 1 August 2020, where coronary flow was measured and clinical outcomes were reported. The endpoints were all-cause mortality and MACE. Estimates of effect were calculated from published hazard ratios (HRs) using a random-effects model. Seventy-nine studies with a total of 59 740 subjects were included. Abnormal coronary flow reserve (CFR) was associated with a higher incidence of all-cause mortality [HR: 3.78, 95% confidence interval (CI): 2.39-5.97] and a higher incidence of MACE (HR 3.42, 95% CI: 2.92-3.99). Each 0.1 unit reduction in CFR was associated with a proportional increase in mortality (per 0.1 CFR unit HR: 1.16, 95% CI: 1.04-1.29) and MACE (per 0.1 CFR unit HR: 1.08, 95% CI: 1.04-1.11). In patients with isolated coronary microvascular dysfunction, an abnormal CFR was associated with a higher incidence of mortality (HR: 5.44, 95% CI: 3.78-7.83) and MACE (HR: 3.56, 95% CI: 2.14-5.90). Abnormal CFR was also associated with a higher incidence of MACE in patients with acute coronary syndromes (HR: 3.76, 95% CI: 2.35-6.00), heart failure (HR: 6.38, 95% CI: 1.95-20.90), heart transplant (HR: 3.32, 95% CI: 2.34-4.71), and diabetes mellitus (HR: 7.47, 95% CI: 3.37-16.55).

CONCLUSION

Reduced coronary flow is strongly associated with increased risk of all-cause mortality and MACE across a wide range of pathological processes. This finding supports recent recommendations that coronary flow should be measured more routinely in clinical practice, to target aggressive vascular risk modification for individuals at higher risk.

Association of serum cardiac troponin I and severity of coronary stenosis in patients with varied renal functions: a retrospective cohort study

BACKGROUND AND OBJECTIVE

Recent studies showed cardiac troponin I (cTnI) might be a non-invasive biomarker to estimate the severity of coronary stenosis. However, serum cTnI is also found associated with renal function. The study objective is to analyse the association of serum cTnI and severity of coronary stenosis in patients with varied renal functions.

DESIGN

A retrospective cohort study.

SETTING

The First Affiliated Hospital, College of Medicine, Zhejiang University in Hangzhou, China.

POPULATION

A total of 6487 subjects who underwent elective coronary angiography between January 2017 to June 2020 were involved in this study.

PRIMARY OUTCOMES

Severity of coronary stenosis was divided into three degrees based on Gensini score, mild coronary stenosis, moderate coronary stenosis and severe coronary stenosis.

RESULTS

By using ordinal logistic regression, serum cTnI was associated with severity of coronary stenosis (OR=1.14, p<0.05). By construction and comparison of two models for predicting severity of coronary stenosis, the addition of cTnI significantly improved the predictive ability of the model. Differences between areas under the curves were 0.03, 0.03, 0.03, 0.12 (all p<0.05). Net reclassification improvements were 0.08, 0.05, 0.05, 0.35, respectively, in varied renal functions. Compared with the participants with normal renal function and without hypertroponinaemia, groups of participants with hypertroponinaemia showed higher ORs. ORs were 3.52, 4.20, 4.45, 6.00, respectively, as renal function decreased (all p<0.05).

CONCLUSIONS

In this cohort of patients with stable coronary artery disease and varied renal functions, cTnI was intensely associated with severity of coronary stenosis which based on Gensini score. The presentation of hypertroponinaemia in patients with impaired renal function always indicates a higher risk of severe coronary stenosis.

Coronary Arterial Function and Disease in Women With No Obstructive Coronary Arteries

Ischemic heart disease (IHD) is the leading cause of mortality in women. While traditional cardiovascular risk factors play an important role in the development of IHD in women, women may experience sex-specific IHD risk factors and pathophysiology, and thus female-specific risk stratification is needed for IHD prevention, diagnosis, and treatment. Emerging data from the past 2 decades have significantly improved the understanding of IHD in women, including mechanisms of ischemia with no obstructive coronary arteries and myocardial infarction with no obstructive coronary arteries. Despite this progress, sex differences in IHD outcomes persist, particularly in young women. This review highlights the contemporary understanding of coronary arterial function and disease in women with no obstructive coronary arteries, including coronary anatomy and physiology, mechanisms of ischemia with no obstructive coronary arteries and myocardial infarction with no obstructive coronary arteries, noninvasive and invasive diagnostic strategies, and management of IHD.

Early Hyperdynamic Sepsis Alters Coronary Blood Flow Regulation in Porcine Fecal Peritonitis

Background: Sepsis is a common condition known to impair blood flow regulation and microcirculation, which can ultimately lead to organ dysfunction but such contribution of the coronary circulation remains to be clarified. We investigated coronary blood flow regulatory mechanisms, including autoregulation, metabolic regulation, and endothelial vasodilatory response, in an experimental porcine model of early hyperdynamic sepsis.

Methods: Fourteen pigs were randomized to sham (n = 7) or fecal peritonitis-induced sepsis (n = 7) procedures. At baseline, 6 and 12 h after peritonitis induction, the animals underwent general and coronary hemodynamic evaluation, including determination of autoregulatory breakpoint pressure and adenosine-induced maximal coronary vasodilation for coronary flow reserve and hyperemic microvascular resistance calculation. Endothelial-derived vasodilatory response was assessed both in vivo and ex vivo using bradykinin. Coronary arteries were sampled for pathobiological evaluation.

Results: Sepsis resulted in a right shift of the autoregulatory breakpoint pressure, decreased coronary blood flow reserve and increased hyperemic microvascular resistance from the 6th h after peritonitis induction. In vivo and ex vivo endothelial vasomotor function was preserved. Sepsis increased coronary arteries expressions of nitric oxide synthases, prostaglandin I₂ receptor, and prostaglandin F_2α receptor.

Conclusion: Autoregulation and metabolic blood flow regulation were both impaired in the coronary circulation during experimental hyperdynamic sepsis, although endothelial vasodilatory response was preserved.

Case report: Dobutamine stress intracoronary physiology and imaging to examine the functional and dynamic properties of an apparent malignant intra-arterial right coronary artery

Background

We present a case concerning a 64-year-old female with complaints of palpitations, chest pain, and an anomalous right coronary artery (RCA) from the opposite sinus (R-ACAOS) with a suspected malignant trajectory on computed tomography. She was referred to our clinic for a second opinion to re-assess the suggested treatment of coronary surgery.

Case summary

A coronary angiogram was performed demonstrating a RCA with a tapered ostium typical for an inter-arterial course. Dobutamine and adenosine stress test during simultaneous intracoronary flow, pressure, and ultrasound assessment, was performed to determine the functional significance. After 120 mcg adenosine, intracoronary baseline flow velocity increased from 14 cm/s to a peak flow velocity of 37 cm/s, demonstrating a sufficient coronary flow velocity reserve (CFVR) of 2.6. No intracoronary pressure drop during maximal hyperaemia was found. After maximum dobutamine stress, CFVR was measured 2.5. Fractional flow reserve measured 0.99. Cross-sectional area measurement through intravascular ultrasound demonstrated a diameter reduction from 14.6 mm² to 8.5 mm². Therefore, we concluded this aberrant trajectory was not of any functional relevance and should be considered non-malignant.

Discussion

There are several anatomic coronary anomalies which may contribute to coronary compression during exercise and are therefore correlated with sudden cardiac death. Right coronary artery from the opposite sinus is correlated with a low mortality rate of 0.2% in comparison to left-ACAOS at 6.3% over 20 years in participants of competitive sport. Therefore, strong evidence of ischaemia must be present before opting for surgery. Our pragmatic approach provided in our opinion enough evidence for a conservative treatment strategy.

Susceptibility to ischaemic heart disease: Focusing on genetic variants for ATP-sensitive potassium channel beyond traditional risk factors

AIMS

Ischaemic heart disease is classically associated with coronary artery disease. Recent evidences showed the correlation between coronary microvascular dysfunction and ischaemic heart disease, even independently of coronary artery disease. Ion channels represent the final effectors of blood flow regulation mechanisms and their genetic variants, in particular of Kir6.2 subunit of the ATP-sensitive potassium channel (KATP), are reported to be involved in ischaemic heart disease susceptibility. The aim of the present study is to evaluate the role of KATP channel and its genetic variants in patients with ischaemic heart disease and evaluate whether differences exist between coronary artery disease and coronary microvascular dysfunction.

METHODS

A total of 603 consecutive patients with indication for coronary angiography due to suspected myocardial ischaemia were enrolled. Patients were divided into three groups: coronary artery disease (G1), coronary microvascular dysfunction (G2) and normal coronary arteries (G3). Analysis of four single nucleotide polymorphisms (rs5215, rs5216, rs5218 and rs5219) of the KCNJ11 gene encoding for Kir6.2 subunit of the KATP channel was performed.

RESULTS

rs5215 A/A and G/A were significantly more represented in G1, while rs5215 G/G was significantly more represented in G3, rs5216 G/G and C/C were both more represented in G3, rs5218 C/C was more represented in G1 and rs5219 G/A was more represented in G1, while rs5219 G/G was significantly more represented in G2. At multivariate analysis, single nucleotide polymorphism rs5215_G/G seems to represent an ischaemic heart disease independent protective factor.

CONCLUSIONS

These results suggest the potential role of KATP genetic variants in ischaemic heart disease susceptibility, as an independent protective factor. They may lead to a future perspective for gene therapy against ischaemic heart disease.

Regadenoson-induced T-wave heterogeneity complements coronary stenosis detection by myocardial perfusion imaging in men and women

AIMS

We analysed whether incorporating electrocardiographic interlead T-wave heterogeneity (TWH) with myocardial perfusion imaging (MPI) during pharmacologic stress improves detection of flow-limiting lesions (FLL).

METHODS AND RESULTS

Medical records of all 103 patients at our institution who underwent stress testing with regadenoson (0.4 mg IV bolus) within 3 months of coronary angiography from September 2017 to March 2019 were studied. Cases (N = 59) had angiographically significant FLL (≥50% of left main or ≥70% of other epicardial coronary arteries ≥2 mm in diameter); controls (N = 44) were normal or had non-FLL. TWH, i.e., interlead splay of T waves, was assessed from precordial leads V4-6 by second central moment analysis. Maximum TWHV4-6 levels during regadenoson stress were 68% higher in cases than in controls (P < 0.0001). TWHV4-6 generated areas under the receiver-operating characteristic (ROC) curve of 0.79 in men (P < 0.0001) and 0.71 in women (P = 0.007). In men, the ROC-guided 54-µV TWHV4-6 cut-point for FLL produced adjusted odds of 7.3 [95% confidence interval (CI): 1.3-41.5, P = 0.03], 79% sensitivity, and 78% specificity. In women, the ROC-guided 35-µV TWHV4-6 cut-point produced adjusted odds of 4.5 (95% CI: 1.1-18.9, P = 0.04), 84% sensitivity, and 52% specificity. Adding TWHV4-6 to MPI determinations reduced false-positive results by 70%, more than doubled true-negative results, and improved adjusted odds ratio to 6.8 (95% CI: 2.2-21.4, P = 0.001) with specificity of 78% in men and 86% in women.

CONCLUSION

This observational study is the first to demonstrate the benefit of combining TWHV4-6 with MPI to enhance FLL detection during MPI with regadenoson in both men and women.

Reduced Microvascular Blood Volume as a Driver of Coronary Microvascular Disease in Patients With Non-obstructive Coronary Artery Disease: Rationale and Design of the MICORDIS Study

Background: Ischemia with non-obstructive coronary arteries (INOCA) is part of the ischemic heart disease spectrum, and is particularly observed in women. INOCA has various mechanisms, such as coronary vasospasm and coronary microvascular dysfunction (CMD). A decreased coronary flow reserve (CFR) and-or increased myocardial resistance (MR) are commonly used to diagnose CMD. However, CFR and MR do not describe all pathophysiological mechanisms underlying CMD. Increased myocardial oxygen consumption (MVO2) normally increases myocardial blood volume (MBV), independently from myocardial blood flow (MBF). In addition insulin enhances MBV in healthy skeletal muscle, and this effect is impaired in INOCA-related conditions such as diabetes and obesity. Therefore, we propose that MBV is reduced in INOCA patients.

Aim: To assess whether myocardial blood volume (MBV) is decreased in INOCA patients, at baseline, during hyperinsulinemia and during stress.

Design: The MICORDIS-study is a single-center observational cross-sectional cohort study (identifier NTR7515). The primary outcome is MBV, compared between INOCA patients and matched healthy controls. The patient group will undergo coronary function testing using a Doppler guidewire, intracoronary adenosine and acetylcholine to measure CFR and coronary vasospasm. Both the patient- and the control group will undergo myocardial contrast echocardiography (MCE) to determine MBV at baseline, during hyperinsulinemia and during stress. Subsequently, cardiac magnetic resonance (CMR) will be evaluated as a new and noninvasive diagnostic tool for CMD in INOCA patients. Microvascular endothelial function is a determinant of MBV and will be evaluated by non-invasive microvascular function testing using EndoPAT and by measuring NO production in circulating endothelial cells (ECFCs).

Prevalence of Coronary Artery Disease and Coronary Microvascular Dysfunction in Patients With Heart Failure With Preserved Ejection Fraction

Importance

Coronary artery disease (CAD) and coronary microvascular dysfunction (CMD) may contribute to the pathophysiologic characteristics of heart failure with preserved ejection fraction (HFpEF). However, the prevalence of CAD and CMD have not been systematically studied.

Objective

To examine the prevalence of CAD and CMD in hospitalized patients with HFpEF.

Design, Setting, and Participants

A total of 106 consecutive patients hospitalized with HFpEF were evaluated in this prospective, multicenter, cohort study conducted between January 2, 2017, and August 1, 2018; data analysis was performed from March 4 to September 6, 2019. Participants underwent coronary angiography with guidewire-based assessment of coronary flow reserve, index of microvascular resistance, and fractional flow reserve, followed by coronary vasoreactivity testing. Cardiac magnetic resonance imaging was performed with late gadolinium enhancement and assessment of extracellular volume. Myocardial perfusion was assessed qualitatively and semiquantitatively using the myocardial-perfusion reserve index.

Main Outcomes and Measures

The prevalence of obstructive epicardial CAD, CMD, and myocardial ischemia, infarction, and fibrosis.

Results

Of 106 participants enrolled (53 [50%] women; mean [SD] age, 72 [9] years), 75 had coronary angiography, 62 had assessment of coronary microvascular function, 41 underwent coronary vasoreactivity testing, and 52 received cardiac magnetic resonance imaging. Obstructive epicardial CAD was present in 38 of 75 participants (51%, 95% CI, 39%-62%); 19 of 38 (50%; 95% CI, 34%-66%) had no history of CAD. Endothelium-independent CMD (ie, coronary flow reserve <2.0 and/or index of microvascular resistance ≥25) was identified in 41 of 62 participants (66%; 95% CI, 53%-77%). Endothelium-dependent CMD (ie, abnormal coronary vasoreactivity) was identified in 10 of 41 participants (24%; 95% CI, 13%-40%). Overall, 45 of 53 participants (85%; 95% CI, 72%-92%) had evidence of CMD and 29 of 36 (81%; 95% CI, 64%-91%) of those without obstructive epicardial CAD had CMD. Cardiac magnetic resonance imaging findings included myocardial-perfusion reserve index less than or equal to 1.84 (ie, impaired global myocardial perfusion) in 29 of 41 patients (71%; 95% CI, 54%-83%), visual perfusion defect in 14 of 46 patients (30%; 95% CI, 19%-46%), ischemic late gadolinium enhancement (ie, myocardial infarction) in 14 of 52 patients (27%; 95% CI, 16%-41%), and extracellular volume greater than 30% (ie, diffuse myocardial fibrosis) in 20 of 48 patients (42%; 95% CI, 28%-56%). Patients with obstructive CAD had more adverse events during follow-up (28 [74%]) than those without obstructive CAD (17 [46%]).

Conclusions and Relevance

In this cohort study, 91% of patients with HFpEF had evidence of epicardial CAD, CMD, or both. Of those without obstructive CAD, 81% had CMD. Obstructive epicardial CAD and CMD appear to be common and often unrecognized in hospitalized patients with HFpEF and may be therapeutic targets.

Spectrum of clinical applications of interlead ECG heterogeneity assessment: From myocardial ischemia detection to sudden cardiac death risk stratification

Heterogeneity in depolarization and repolarization among regions of cardiac cells has long been recognized as a major factor in cardiac arrhythmogenesis. This fundamental principle has motivated development of noninvasive techniques for quantification of heterogeneity using the surface electrocardiogram (ECG). The initial approaches focused on interval analysis such as interlead QT dispersion and T_peak -T_end difference. However, because of inherent difficulties in measuring the termination point of the T wave and commonly encountered irregularities in the apex of the T wave, additional techniques have been pursued. The newer methods incorporate assessment of the entire morphology of the T wave and in some cases of the R wave as well. This goal has been accomplished using a number of promising vectorial approaches with the resting 12-lead ECG. An important limitation of vectorcardiographic analyses is that they require exquisite stability of the recordings and are not inherently suitable for use in exercise tolerance testing (ETT) and/or ambulatory ECG monitoring for provocative stress testing or evaluation of the influence of daily activities on cardiac electrical instability. The objectives of the present review are to describe a technique that has been under clinical evaluation for nearly a decade, termed "interlead ECG heterogeneity." Preclinical testing data will be briefly reviewed. We will discuss the main clinical findings with regard to sudden cardiac death risk stratification, heart failure evaluation, and myocardial ischemia detection using standard recording platforms including resting 12-lead ECG, ambulatory ECG monitoring, ETT, and pharmacologic stress testing in conjunction with single-photon emission computed tomography myocardial perfusion imaging.

Renal Dysfunction as a Predictor of Slow-Flow/No-Reflow Phenomenon and Impaired ST Segment Resolution After Percutaneous Coronary Intervention in ST-Elevation Myocardial Infarction With Initial Thrombolysis in Myocardial Infarction Grade 0

BACKGROUND

The slow-flow/no-reflow phenomenon and impaired ST segment resolution (STR) following primary percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI) predict unfavorable prognosis and are characterized by obstruction of the coronary microvascular. Several predictors of slow-flow/no-reflow have been revealed, but few studies have investigated predictors of slow-flow/no-reflow and STR exclusively in acute myocardial infarction patients with initial Thrombolysis in Myocardial Infarction (TIMI) Grade 0.

METHODS AND RESULTS

In all, 279 STEMI patients with initial TIMI Grade 0 were enrolled in the study. Slow-flow/no-reflow was defined as TIMI Grade <3 by angiography after PCI, and impaired STR was defined as STR <50% on an electrocardiogram after PCI. Slow-flow/no-reflow was observed in 31 patients. In multivariate analysis, estimated glomerular filtration rate (eGFR; odds ratio [OR] 0.97; P=0.007), a history of cerebrovascular disease (OR 4.65, P=0.007), time to recanalization ≥4 h (OR 2.76, P=0.023), and systolic blood pressure ≤90 mmHg (OR 3.45, P=0.046) were independent predictors of slow-flow/no-reflow. Impaired STR was observed in 102 of 248 patients with TIMI Grade 3. In multivariate analysis, eGFR (OR 0.94, P<0.001) and occlusion of the left anterior descending artery (OR 4.48, P<0.001) were independent predictors of impaired STR; eGFR was the only independent predictor of both slow-flow/no-reflow and impaired STR.

CONCLUSIONS

Renal dysfunction may be related to coronary microvascular dysfunction and obstruction.

Potential Role of eNOS Genetic Variants in Ischemic Heart Disease Susceptibility and Clinical Presentation

Background: IHD is determined by an inadequate coronary blood supply to the myocardium, and endothelial dysfunction may represent one of the main pathophysiological mechanisms involved. Genetic predisposition to endothelial dysfunction has been associated with IHD and its clinical manifestation. However, studies are often confounding and inconclusive for several reasons, such as interethnic differences. Validation of results in larger cohorts and new populations is needed. The aim of this study is to evaluate the associations between the allelic variants of the eNOS rs1799983 single-nucleotide polymorphism, IHD susceptibility and its clinical presentation. Methods: A total of 362 consecutive patients with suspected myocardial ischemia were enrolled. Patients were divided into three groups: G1, coronary artery disease (CAD); G2, coronary microvascular dysfunction (CMD); and G3, a control group with anatomically and functionally normal coronary arteries. Analysis of three allelic variants, GT, GG and TT, of rs1799983 for the NOS3 gene, encoding for eNOS, was performed. Results: rs1799983_GT was significantly more expressed by the ischemic groups (G1 and G2) compared to G3. The TT variant was significantly more expressed by the G1 group, compared to the G2 group. Among ischemic patients, GT was significantly more expressed in patients with acute coronary syndrome (ACS) presentation, compared to other clinical presentations. In the multivariate analysis, the allelic variant GT was found to potentially represent an independent predictor of IHD and ACS presentation. Conclusion: The presence of the SNP rs1799983_GT, encoding for eNOS, is an independent risk factor for IHD and, remarkably, for ACS presentation, independently of cardiovascular risk factors. These results may be useful for the prediction of IHD development, particularly with an acute clinical manifestation. They may allow the early identification of patients at high risk of developing IHD with an ACS, promoting a genetic-based prevention strategy against IHD.

Clinical comparison study between a newly developed optical-based fractional flow reserve device and the conventional fractional flow reserve device

BACKGROUND

Fractional flow reserve (FFR) measurement is the gold standard for identifying the functional severity of coronary artery disease. Although we can use newly developed pressure wires with optical fibers are now available, their safety and accuracy for FFR measurement are not clear. Therefore, we planned a clinical comparison study between pressure wires with optical fibers and the conventional FFR device.

METHODS

We prospectively enrolled 51 patients (51 lesions) with intermediate coronary artery stenosis. For these lesions, FFR measurements with pressure wires with optical fibers were compared with those obtained with a conventional wire.

RESULTS

All procedures were successfully completed without any complications. The procedure time with pressure wires with optical fibers and a conventional wire was 6.8 ± 3.0 and 6.9 ± 2.6 minutes (P = 0.89), respectively. There was no significant difference in FFR values between pressure wires with optical fibers and a conventional wire (0.83 ± 0.10 vs. 0.83 ± 0.12, P = 0.66). An excellent correlation was observed between FFR obtained with pressure wires with optical fibers and FFR obtained with a conventional wire (r = 0.81, P < 0.001). The pressure drift before and after FFR measurements was not significantly different between pressure wires with optical fibers and a convention wire (-0.01 ± 0.02 vs. -0.02 ± 0.06, P = 0.42). There was no significant difference in pressure drift defined as >0.03 or <-0.03 between pressure wires with optical fibers and a convention wire (13.7 vs. 17.6%, P = 0.79).

CONCLUSION

Excellent correlations were observed between FFR values measured using pressure wires with optical fibers and a conventional wire. Furthermore, measurement of FFR with pressure wires with optical fibers was as well tolerated and reliable as that with a conventional wire.

Comparison Between 5- and 1-Year Outcomes Using Cutoff Values of Pressure Drop Coefficient and Fractional Flow Reserve for Diagnosing Coronary Artery Diseases

Background

The current pressure-based coronary diagnostic index, fractional flow reserve (FFR), has a limited efficacy in the presence of microvascular disease (MVD). To overcome the limitations of FFR, the objective is to assess the recently introduced pressure drop coefficient (CDP), a fundamental fluid dynamics-based combined pressure–flow index.

Methods

We hypothesize that CDP will result in improved clinical outcomes in comparison to FFR. To test the hypothesis, chi-square test was performed to compare the percent major adverse cardiac events (%MACE) at 5 years between (a) FFR < 0.75 and CDP > 27.9 and (b) FFR < 0.80 and CDP > 25.4 groups using a prospective cohort study. Furthermore, Kaplan–Meier survival curves were compared between the FFR and CDP groups. The results were considered statistically significant for p < 0.05. The outcomes of the CDP arm were presumptive as clinical decision was solely based on the FFR.

Results

For the complete patient group, the %MACE in the CDP > 27.9 group (10 out of 35, 29%) was lower in comparison to the FFR < 0.75 group (11 out of 20, 55%), and the difference was near significant (p = 0.05). The survival analysis showed a significantly higher survival rate (p = 0.01) in the CDP > 27.9 group (n = 35) when compared to the FFR < 0.75 group (n = 20). The results remained similar for the FFR = 0.80 cutoff. The comparison of the 5-year MACE outcomes with the 1-year outcomes for the complete patient group showed similar trends, with a higher statistical significance for a longer follow-up period of 5 years.

Conclusion

Based on the MACE and survival analysis outcomes, CDP could possibly be an alternate diagnostic index for decision-making in the cardiac catheterization laboratory.

Clinical Trial Registration

www.ClinicalTrials.gov, identifier NCT01719016.

Coronary vessel detection methods for organ-mounted robots

BACKGROUND

HeartLander is a tethered robot walker that utilizes suction to adhere to the beating heart. HeartLander can be used for minimally invasive administration of cardiac medications or ablation of tissue. In order to administer injections safely, HeartLander must avoid coronary vasculature.

METHODS

Doppler ultrasound signals were recorded using a custom-made cardiac phantom and used to classify different coronary vessel properties. The classification was performed by two machine learning algorithms, the support vector machines and a deep convolutional neural network. These algorithms were then validated in animal trials.

RESULTS

Accuracy of identifying vessels above turbulent flow reached greater than 92% in phantom trials and greater than 98% in animal trials.

CONCLUSIONS

Through the use of two machine learning algorithms, HeartLander has shown the ability to identify different sized vasculature proximally above turbulent flow. These results indicate that it is feasible to use Doppler ultrasound to identify and avoid coronary vasculature during cardiac interventions using HeartLander.

A novel method for measuring absolute coronary blood flow and microvascular resistance in patients with ischaemic heart disease

AIMS

Ischaemic heart disease is the reduction of myocardial blood flow, caused by epicardial and/or microvascular disease. Both are common and prognostically important conditions, with distinct guideline-indicated management. Fractional flow reserve (FFR) is the current gold-standard assessment of epicardial coronary disease but is only a surrogate of flow and only predicts percentage flow changes. It cannot assess absolute (volumetric) flow or microvascular disease. The aim of this study was to develop and validate a novel method that predicts absolute coronary blood flow and microvascular resistance (MVR) in the catheter laboratory.

METHODS AND RESULTS

A computational fluid dynamics (CFD) model was used to predict absolute coronary flow (QCFD) and coronary MVR using data from routine invasive angiography and pressure-wire assessment. QCFD was validated in an in vitro flow circuit which incorporated patient-specific, three-dimensional printed coronary arteries; and then in vivo, in patients with coronary disease. In vitro, QCFD agreed closely with the experimental flow over all flow rates [bias +2.08 mL/min; 95% confidence interval (error range) -4.7 to +8.8 mL/min; R2 = 0.999, P < 0.001; variability coefficient <1%]. In vivo, QCFD and MVR were successfully computed in all 40 patients under baseline and hyperaemic conditions, from which coronary flow reserve (CFR) was also calculated. QCFD-derived CFR correlated closely with pressure-derived CFR (R2 = 0.92, P < 0.001). This novel method was significantly more accurate than Doppler-wire-derived flow both in vitro (±6.7 vs. ±34 mL/min) and in vivo (±0.9 vs. ±24.4 mmHg).

CONCLUSIONS

Absolute coronary flow and MVR can be determined alongside FFR, in absolute units, during routine catheter laboratory assessment, without the need for additional catheters, wires or drug infusions. Using this novel method, epicardial and microvascular disease can be discriminated and quantified. This comprehensive coronary physiological assessment may enable a new level of patient stratification and management.

Prognostic value of quantitative flow ratio measured immediately after drug-coated balloon angioplasty for in-stent restenosis

OBJECTIVES

This study aimed to evaluate prognostic value of quantitative flow ratio (QFR) in drug-coated balloon (DCB) angioplasty for in-stent restenosis (ISR).

BACKGROUND

There is a high incidence of recurrent ISR after DCB angioplasty. QFR is a novel method for fast computation of fractional flow reserve for the target vessel based on quantitative coronary angiography (QCA) and fluid dynamics algorithms.

METHODS

Patients participating in the RESTORE ISR China randomized trial were enrolled and classified into the recurrent restenosis group and the non-recurrent restenosis group. The binary classifications followed the QCA standards of ISR. Clinical and angiographic characteristics of the groups were analyzed, and the QFRs before and after lesion preparation and after final DCB angioplasty were measured and compared.

RESULTS

A total of 208 patients who underwent follow-up angiography were enrolled in the study, with 226 lesions measured in total. QFR value after DCB angioplasty (odds ratio [OR] 0.88; 95% confidence interval [CI] 0.83-0.93; p < .0001 for 1 mm increase), lesion length (OR: 1.08; 95% CI: 1.01-1.15; p = .017), and vessel caliber lumen diameter (OR: 0.35; 95% CI 0.13-0.89; p = .027) were independently associated with recurrent restenosis after DCB angioplasty. The optimal QFR cut-off value was determined to be 0.90 with a sensitivity of 0.94, specificity of 0.56, and accuracy of 0.79 in predicting recurrent restenosis.

CONCLUSIONS

The QFR value after DCB angioplasty is a promising predictor of DES ISR.

Non-randomized comparison between revascularization and deferral for intermediate coronary stenosis with abnormal fractional flow reserve and preserved coronary flow reserve

Limited data are available regarding comparative prognosis after percutaneous coronary intervention (PCI) versus deferral of revascularization in patients with intermediate stenosis with abnormal fractional flow reserve (FFR) but preserved coronary flow reserve (CFR). From the International Collaboration of Comprehensive Physiologic Assessment Registry (NCT03690713), a total of 330 patients (338 vessels) who had coronary stenosis with FFR ≤ 0.80 but CFR > 2.0 were selected for the current analysis. Patient-level clinical outcome was assessed by major adverse cardiac events (MACE) at 5 years, a composite of all-cause death, target-vessel myocardial infarction (MI), or target-vessel revascularization. Among the study population, 231 patients (233 vessels) underwent PCI and 99 patients (105 vessels) were deferred. During 5 years of follow-up, cumulative incidence of MACE was 13.0% (31 patients) without significant difference between PCI and deferred groups (12.7% vs. 14.0%, adjusted HR 1.301, 95% CI 0.611-2.769, P = 0.495). Multiple sensitivity analyses by propensity score matching and inverse probability weighting also showed no significant difference in patient-level MACE and vessel-specific MI or revascularization. In this hypothesis-generating study, there was no significant difference in clinical outcomes between PCI and deferred groups among patients with intermediate stenosis with FFR ≤ 0.80 but CFR > 2.0. Further study is needed to confirm this finding.Clinical Trial Registration: International Collaboration of Comprehensive Physiologic Assessment Registry (NCT03690713; registration date: 10/01/2018).

Impact of coronary risk scores on disposition decision in emergency patients with chest pain

BACKGROUND

Coronary risk scores (CRS) including History, Electrocardiogram, Age, Risk Factors, Troponin (HEART) score and Emergency Department Assessment of Chest pain Score (EDACS) can help identify patients at low risk of major adverse cardiac events. In the emergency department (ED), there are wide variations in hospital admission rates among patients with chest pain.

OBJECTIVE

This study aimed to evaluate the impact of CRS on the disposition of patients with symptoms suggestive of acute coronary syndrome in the ED.

METHODS

This retrospective cohort study included 3660 adult patients who presented to the ED with chest pain between January and July in 2019. Study inclusion criteria were age > 18 years and a primary position International Statistical Classification of Diseases and Related Health Problems-10th revision coded diagnosis of angina pectoris (I20.0-I20.9) or chronic ischemic heart disease (I25.0-I25.9) by the treating ED physician. If the treating ED physician completed the electronic structured variables for CRS calculation to assist disposition planning, then the patient would be classified as the CRS group; otherwise, the patient was included in the control group.

RESULTS

Among the 2676 patients, 746 were classified into the CRS group, whereas the other 1930 were classified into the control group. There was no significant difference in sex, age, initial vital signs, and ED length of stay between the two groups. The coronary risk factors were similar between the two groups, except for a higher incidence of smokers in the CRS group (19.6% vs. 16.1%, p = 0.031). Compared with the control group, significantly more patients were discharged (70.1% vs. 64.6%) directly from the ED, while fewer patients who were hospitalized (25.9% vs. 29.7%) or against-advise discharge (AAD) (2.6% vs. 4.0%) in the CRS group. Major adverse cardiac events and mortality at 60 days between the two groups were not significantly different.

CONCLUSIONS

A higher ED discharge rate of the group using CRS may indicate that ED physicians have more confidence in discharging low-risk patients based on CRS.

The first multicentre study on coronary anomalies in the Netherlands: MuSCAT

Background

Current guidelines on coronary anomalies are primarily based on expert consensus and a limited number of trials. A gold standard for diagnosis and a consensus on the treatment strategy in this patient group are lacking, especially for patients with an anomalous origin of a coronary artery from the opposite sinus of Valsalva (ACAOS) with an interarterial course.

Aim

To provide evidence-substantiated recommendations for diagnostic work-up, treatment and follow-up of patients with anomalous coronary arteries.

Methods

A clinical care pathway for patients with ACAOS was established by six Dutch centres. Prospectively included patients undergo work-up according to protocol using computed tomography (CT) angiography, ischaemia detection, echocardiography and coronary angiography with intracoronary measurements to assess anatomical and physiological characteristics of the ACAOS. Surgical and functional follow-up results are evaluated by CT angiography, ischaemia detection and a quality-of-life questionnaire. Patient inclusion for the first multicentre study on coronary anomalies in the Netherlands started in 2020 and will continue for at least 3 years with a minimum of 2 years of follow-up. For patients with a right or left coronary artery originating from the pulmonary artery and coronary arteriovenous fistulas a registry is maintained.

Results

Primary outcomes are: (cardiac) death, myocardial ischaemia attributable to the ACAOS, re-intervention after surgery and intervention after initially conservative treatment. The influence of work-up examinations on treatment choice is also evaluated.

Conclusions

Structural evidence for the appropriate management of patients with coronary anomalies, especially (interarterial) ACAOS, is lacking. By means of a structured care pathway in a multicentre setting, we aim to provide an evidence-based strategy for the diagnostic evaluation and treatment of this patient group.

Supplementary Information

The online version of this article (10.1007/s12471-021-01556-9) contains supplementary material, which is available to authorized users.

A Hemodynamic Comparison of Myocardial Bridging and Coronary Atherosclerotic Stenosis: A Computational Model With Experimental Evaluation

Myocardial bridging (MB) and coronary atherosclerotic stenosis can impair coronary blood flow and may cause myocardial ischemia or even heart attack. It remains unclear how MB and stenosis are similar or different regarding their impacts on coronary hemodynamics. The purpose of this study was to compare the hemodynamic effects of coronary stenosis and MB using experimental and computational fluid dynamics (CFD) approaches. For CFD modeling, three MB patients with different levels of lumen obstruction, mild, moderate, and severe were selected. Patient-specific left anterior descending (LAD) coronary artery models were reconstructed from biplane angiograms. For each MB patient, the virtually healthy and stenotic models were also simulated for comparison. In addition, an in vitro flow-loop was developed, and the pressure drop was measured for comparison. The CFD simulations results demonstrated that the difference between MB and stenosis increased with increasing MB/stenosis severity and flowrate. Experimental results showed that increasing the MB length (by 140%) only had significant impact on the pressure drop in the severe MB (39% increase at the exercise), but increasing the stenosis length dramatically increased the pressure drop in both moderate and severe stenoses at all flow rates (31% and 93% increase at the exercise, respectively). Both CFD and experimental results confirmed that the MB had a higher maximum and a lower mean pressure drop in comparison with the stenosis, regardless of the degree of lumen obstruction. A better understanding of MB and atherosclerotic stenosis may improve the therapeutic strategies in coronary disease patients and prevent acute coronary syndromes.

Coronary Flow and Reserve by Enhanced Transthoracic Doppler Trumps Coronary Anatomy by Computed Tomography in Assessing Coronary Artery Stenosis

We report the case of a 71-year-old patient with many risk factors for coronary atherosclerosis, who underwent computed coronary angiography (CTA), in accordance with the guidelines, for recent onset atypical chest pain. CTA revealed critical (>50% lumen diameter narrowing) stenosis of the proximal anterior descending coronary, and the patient was scheduled for invasive coronary angiography (ICA). Before ICA he underwent enhanced transthoracic echo-Doppler (E-Doppler TTE) for coronary flow detection by color-guided pulsed-wave Doppler recording of the left main (LMCA) and whole left anterior descending coronary artery (LAD,) along with coronary flow reserve (CFR) in the distal LAD calculated as the ratio, of peak flow velocity during i.v. adenosine (140 mcg/Kg/m) to resting flow velocity. E-Doppler TTE mapping revealed only mild stenosis (28% area narrowing) of the mid LAD and a CFR of 3.20, in perfect agreement with the color mapping showing no flow limiting stenosis in the LMCA and LAD. ICA revealed only a very mild stenosis in the mid LAD and mild atherosclerosis in the other coronaries (intimal irregularities). Thus, coronary stenosis was better predicted by E-Doppler TTE than by CTA. Coronary flow and reserve as assessed by E-Doppler TTE trumps coronary anatomy as assessed by CTA, without exposing the patient to harmful radiation and iodinated contrast medium.

The reasons why fractional flow reserve and instantaneous wave-free ratio are similar using wave separation analysis

Background and objectives

Fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are the two most commonly used coronary indices of physiological stenosis severity based on pressure. To minimize the effect of wedge pressure (P_wedge), FFR is measured during hyperemia conditions, and iFR is calculated as the ratio of distal and aortic pressures (P_d/P_a) in the wave-free period. The goal of this study was to predict P_wedge using the backward wave (P_back) through wave separation analysis (WSA) and to reflect the effect of P_wedge on FFR and iFR to identify the relationship between the two indices.

Methods

An in vitro circulation system was constructed to calculate P_wedge. The measurements were performed in cases with stenosis percentages of 48, 71, and 88% and with hydrostatic pressures of 10 and 30 mmHg. Then, the correlation between P_back by WSA and P_wedge was calculated. In vivo coronary flow and pressure were simultaneously measured for 11 vessels in all patients. The FFR and iFR values were reconstructed as the ratios of forward wave at distal and proximal sites during hyperemia and at rest, respectively.

Results

Based on the in vitro results, the correlation between P_back and P_wedge was high (r = 0.990, p < 0.0001). In vivo results showed high correlations between FFR and reconstructed FFR (r = 0.992, p < 0.001) and between iFR and reconstructed iFR (r = 0.930, p < 0.001).

Conclusions

Reconstructed FFR and iFR were in good agreement with conventional FFR and iFR. FFR and iFR can be expressed as the variation of trans-stenotic forward pressure, indicating that the two values are inferred from the same formula under different conditions.

The interventionist mindset: The ten eyes rule in cath lab

This article addresses the skillfulness role of the interventionist in the Cath lab. It argues that the interventionist plays a crucial role and should possess certain mental-manual dexterity and hand-eye coordination skills. The article suggests a series of measures that collectively determine the successful role of the interventionist in the Cath lab. This is of utmost importance given the sensitive nature of the cardiovascular procedures, the potential costs of its failure for the patient, and the key action played by the interventionist in determining the failure or success of the procedure.

New transluminal attenuation gradient derived from dynamic coronary CT angiography: diagnostic ability of ischemia detected by 13N-ammonia PET

Coronary computed tomography angiography (CCTA) has low specificity for detecting significant functional coronary stenosis. We developed a new transluminal attenuation gradient (TAG)-derived dynamic CCTA with dose modulation, and we investigated its diagnostic performance for myocardial ischemia depicted by ¹³N-ammonia positron emission tomography (PET). Data from 48 consecutive patients who had undergone both dynamic CCTA and ¹³N-ammonia PET were retrospectively analyzed. Dynamic CCTA was continuously performed in mid-diastole for five cardiac cycles with prospective electrocardiography gating after a 10-s contrast medium injection. One scan of the dynamic CCTA was performed as a boost scan for conventional CCTA at the peak phase of the ascending aorta. Absolute TAG values at five phases around the boost scan were calculated. The dynamic TAG index (DTI) was defined as the ratio of the maximum absolute TAG to the standard deviation of five TAG values. We categorized the coronary territories as non-ischemia or ischemia based on the ¹³N-ammonia PET results. A receiver operating characteristic (ROC) analysis was performed to determine the optimal cutoff of the DTI for identifying ischemia. The DTI was significantly higher for ischemia compared to non-ischemia (8.8 ± 3.9 vs. 4.6 ± 2.0, p < 0.01). The ROC analysis revealed 5.60 as the optimal DTI cutoff to detect ischemia, with an area under the curve of 0.87, 85.7% sensitivity, and 76.2% specificity. TAG provided no additional diagnostic value for the detection of ischemia. We propose the DTI derived from dynamic CCTA as a novel coronary flow index. The DTI is a valid technique for detecting functional coronary stenosis.

End-stage renal failure is associated with impaired coronary microvascular function

BACKGROUND

Cardiovascular disease is the leading cause of death in patients with chronic kidney disease. Studies investigating the disproportionate burden of cardiovascular disease have occurred predominantly in the peripheral vasculature, often used noninvasive imaging modalities, and infrequently recruited patients receiving dialysis. This study sought to evaluate invasive coronary dynamic vascular function in patients with end-stage renal failure (ESRF).

PATIENTS AND METHODS

Patients referred for invasive coronary angiography prior to renal transplantation were invited to participate. Control patients were recruited in parallel. Baseline characteristics were obtained. Coronary diameter (via quantitative coronary angiography) and coronary blood flow (via Doppler Flowire) were measured; macrovascular endothelial-dependent and independent effects were evaluated in response to intracoronary acetylcholine infusion (10 and 10 mol/l) and intracoronary glyceryl trinitrate, respectively. Microvascular function was evaluated by response to adenosine and expressed as coronary flow velocity reserve. Mean values were compared.

RESULTS

Thirty patients were evaluated: 15 patients with ESRF (mean age 52.1 ± 9, male 73%) and 15 control patients (mean age 53.3 ± 13, male 60%). Comorbidity profile, aside from ESRF, was well matched. Baseline coronary blood flow was similar between groups (101.6 ± 10.3 vs. 103.4 ± 9.1 ml/min, P = 0.71), as was endothelial-dependent response to acetylcholine (159.1 ± 16.9 vs. 171.1 ± 16.8 ml/min, P = 0.41). Endothelial-independent response to glyceryl trinitrate was no different between groups (14.3 ± 3.1 vs. 13.1 ± 2.3%, P = 0.73. A significantly reduced coronary flow velocity reserve was observed in the ESRF cohort compared to controls (2.34 ± 0.4 vs. 3.05 ± 0.3, P = 0.003).

CONCLUSION

Patients with ESRF had preserved endothelial-dependent function however compared to controls, demonstrated significantly attenuated microvascular reserve. An impaired response to adenosine may not only represent a component of the pathophysiological milieu in patients with ESRF but may also provide a basis for the suboptimal diagnostic performance of vasodilatory stress in this population.

Assessment of Vascular Dysfunction in Patients Without Obstructive Coronary Artery Disease: Why, How, and When

Ischemic heart disease secondary to coronary vascular dysfunction causes angina and impairs quality of life and prognosis. About one-half of patients with symptoms and signs of ischemia turn out not to have obstructive coronary artery disease, and coronary vascular dysfunction may be relevant. Adjunctive tests of coronary vasomotion include guidewire-based techniques with adenosine and reactivity testing, typically by intracoronary infusion of acetylcholine. The CorMicA (Coronary Microvascular Angina) trial provided evidence that routine management guided by an interventional diagnostic procedure and stratified therapy improves angina and quality of life in patients with angina but no obstructive coronary artery disease. In this paper, the COVADIS study group provide a comprehensive review of why, how, and when coronary vascular dysfunction should be assessed invasively. They discuss the rationale through a shared understanding of vascular pathophysiology and clinical evidence. They propose a consensus approach to how an interventional diagnostic procedure is performed with focus on practical aspects. Finally, the authors discuss the clinical scenarios in patients with stable and acute coronary syndromes in which measurement of coronary vascular function may be helpful for patient care.