Coronary flow velocity response to adenosine characterizes coronary microvascular function in women with chest pain and no obstructive coronary disease. Results from the pilot phase of the Women's Ischemia Syndrome Evaluation (WISE) study

Microvascular resistance reserve before and after PCI: A serial FFR and [15O] H2O PET study

BACKGROUND AND AIMS

Microvascular Resistance Reserve (MRR) has recently been introduced as a microvasculature-specific index and hypothesized to be independent of coronary stenosis. The aim of this study was to investigate the change of MRR after percutaneous coronary intervention (PCI).

METHODS

In this post-hoc analysis from the PACIFC trials, symptomatic patients underwent [15O]H2O positron emission tomography (PET) and invasive fractional flow reserve (FFR) before and after revascularization. Coronary flow reserve (CFR) from PET and invasive FFR were used to calculate MRR.

RESULTS

Among 52 patients (87 % male, age 59.4 ± 9.4 years), 61 vessels with a median FFR of 0.71 (95 % confidence interval: 0.55 to 0.74) and a mean MRR of 3.80 ± 1.23 were included. Following PCI, FFR, hyperemic myocardial blood flow (hMBF) and CFR increased significantly (all p-values ≤0.001). MRR remained unchanged after PCI (3.80 ± 1.23 before PCI versus 3.60 ± 0.97 after PCI; p=0.23). In vessels with a pre-PCI, FFR ≤0.70 pre- and post-PCI MRR were 3.90 ± 1.30 and 3.73 ± 1.14 (p=0.56), respectively. Similar findings were observed for vessels with a FFR between 0.71 and 0.80 (pre-PCI MRR 3.70 ± 1.17 vs. post PCI MRR 3.48 ± 0.76, p=0.19).

CONCLUSIONS

Our study indicates that MRR, assessed using a hybrid approach of PET and invasive FFR, is independent of the severity of epicardial stenosis. These findings suggest that MRR is a microvasculature-specific parameter.

Effects of alpha-adrenergic receptor blockade on coronary circulation in postmenopausal women

We sought to investigate the effect of the α1-adrenergic receptor blockade during handgrip exercise (Grip), isolated metaboreflex activation (Metabo), and cold pressor test (CPT) on coronary circulation in young (YW) and postmenopausal women (PMW). Ten YW and 9 PMW underwent two protocols: (1) 3 min of baseline followed by 3 min of CPT and (2) 3 min of rest, 3 min of Grip followed by 3 min of Metabo. Protocols were carried out under control conditions and α1-adrenergic receptor blockade (oral prazosin 0.03 mg·kg-1). Coronary blood velocity (CBV) and vascular conductance (CCI) were lower in PMW. Grip increased CBV only in YW (YW: Δ18.0 ± 21.1% vs. PMW: Δ4.2 ± 10.1%; p < 0.05), and the blockade did not change the CBV response to Grip in YW and PMW. During the Metabo, CBV returned to resting levels in YW and was unchanged from rest in PMW, before (YW:Δ1.7 ± 8.7% vs. PMW: Δ- 1.5 ± 8.6) and under the blockade (YW: Δ4.5 ± 14.8% vs. PMW: Δ9.1 ± 29.5%). CPT did not change CBV in both groups (YW: Δ3.9 ± 8.0 vs. PMW: Δ- 4.1 ± 6.2%), following the α1-blockade, CPT increased CBV only in YW (YW: Δ11.2 ± 12.8% vs. PMW: Δ2.2 ± 7.1%; p < 0.05 for group and condition). CCI decreased during Grip, Metabo, and CPT in YW and PMW, while the blockade prevented that decrease only in YW. The α1-adrenergic receptor plays a role in the control of coronary circulation in young women, evoking stronger vasoconstriction during CPT than Grip and Metabo in YW. PMW have impaired vasomotor control in the coronary circulation, which seems not to be caused by the α1-adrenergic receptor.

Sex differences in diagnostic modalities of coronary artery disease: Evidence from coronary microcirculation

Although atherosclerosis is usually considered a disease of the large arteries, risk factors for atherosclerosis also trigger structural and functional abnormalities at a microvascular level. In cardiac disease, microvascular dysfunction is especially relevant in women, among whom the manifestation of ischemic disease due to impaired coronary microcirculation is more common than in men. This sex-specific clinical phenotype has important clinical implications and, given the higher pre-test probability of coronary microvascular dysfunction in females, different diagnostic modalities should be used in women compared to men. In this review, we summarize invasive and non-invasive diagnostic modalities to assess coronary microvascular function, ranging from catheter-based evaluation of endothelial function to Doppler echocardiography and positron emission tomography. Moreover, we discuss different clinical settings in which microvascular disease plays an important role, underlining the importance of choosing the right diagnostic modality depending on the sex of the patients.

Invasive Coronary Assessment in Myocardial Ischemia with No Obstructive Coronary Arteries

PURPOSE OF REVIEW

The purpose of this review is threefold: (i) to give an overview of well-established invasive methods for assessing patients with ischemia with no obstructive coronary arteries (INOCA) in the cardiac catheterization laboratory; (ii) to describe the prognostic and treatment implications based on these findings, and (iii) to discuss current knowledge gaps and future perspectives.

RECENT FINDINGS

Recent studies have demonstrated that invasive coronary function testing not only allows for risk stratification of patients with INOCA but also guides medical therapy with improvement in symptoms and quality of life. Based on these findings, invasive coronary function assessment is now a class 2a recommendation in the 2021 ACC/AHA chest pain guideline to improve the diagnosis of coronary microvascular dysfunction and to enhance risk stratification. Invasive functional testing for patients with INOCA is well established and easily performed in the catheterization laboratory. Comprehensive invasive assessment is a key to differentiating INOCA endotypes and optimizing both medical therapy and preventive strategies including lifestyle modification.

Clinical and Translational Imaging and Sensing of Diabetic Microangiopathy: A Narrative Review

Microvascular changes in diabetes affect the function of several critical organs, such as the kidneys, heart, brain, eye, and skin, among others. The possibility of detecting such changes early enough in order to take appropriate actions renders the development of appropriate tools and techniques an imperative need. To this end, several sensing and imaging techniques have been developed or employed in the assessment of microangiopathy in patients with diabetes. Herein, we present such techniques; we provide insights into their principles of operation while discussing the characteristics that make them appropriate for such use. Finally, apart from already established techniques, we present novel ones with great translational potential, such as optoacoustic technologies, which are expected to enter clinical practice in the foreseeable future.

Arterial stiffness but not carotid intima-media thickness progression precedes premature structural and functional cardiac damage in youth: A 7-year temporal and mediation longitudinal study

BACKGROUND AND AIMS

The longitudinal relations of cardiac indices with the aorta and carotid vessel and the time sequence for early cardiac disease development are uncharacterized in youth. We examined the temporal longitudinal associations of carotid-femoral pulse wave velocity (cfPWV) and carotid intima-media thickness (cIMT) with left ventricular hypertrophy (LVH) and diastolic dysfunction (LVDD).

METHODS

From the Avon Longitudinal Study of Parents and Children, UK birth cohort, 1856 adolescents (1011 females) at a mean (SD) age 17.7 (0.3) years were followed up for 7 years. Vicorder-measured cfPWV and ultrasound-measured cIMT were grouped in tertiles as low (reference), moderate, and high. Echocardiography measured cardiac abnormalities are left ventricular mass indexed for height2.7 (LVMI2.7) ≥51 g/m2.7 as LVH; relative wall thickness ≥44 as hiRWT; LVD function E/A <1.5 as LVD dysfunction (LVDD); and LV filling pressure E/e' ≥8 as hiLVFP. Data were analysed with generalized logit mixed-effect models, cross-lagged path, and mediation structural equation models adjusting for cardiometabolic and lifestyle factors.

RESULTS

Over follow-up, LVH prevalence increased from 3.6% to 7.2% and LVDD from 11.1 to 16.3%. High cfPWV progression was associated with worsening LVH [Odds ratio 1.23 (1.13-1.35); p < 0.001] in the total cohort, males, overweight/obese, and normotensive. High cfPWV progression was associated with worsening hiLVFP in the total cohort, females, and normal weight. Likewise, high cIMT progression was associated with worsening LVH [1.27 (1.26-1.27); p < 0.0001] in the total cohort, overweight/obese and elevated BP/hypertensive. Neither cfPWV nor cIMT progression was associated with worsening hiRWT in the total cohort. In cross-lagged models, higher baseline cfPWV was associated with future LVMI2.7 (β = 0.06, SE, 5.14, p = 0.035), RWT, LVDF, and LVFP. However, baseline LVMI2.7, RWT, LVDF, and LVFP were not associated with follow-up cfPWV. Baseline cIMT was not associated with follow-up cardiac indices and vice versa. Cumulative increased systolic blood pressure (34.3% mediation) and insulin resistance (15.1% mediation) mediated the direct associations of cumulative cfPWV with cumulative LVMI2.7.

CONCLUSIONS

Arterial stiffness progression temporally preceded worsening structural and functional cardiac damage in youth with increased systolic blood pressure and insulin resistance partly mediating the relationships. Future interventions aimed at attenuating premature cardiac damage in adolescents and young adults may consider a simultaneous treatment of both arterial stiffness, elevated blood pressure and insulin resistance.

Echocardiographic assessment of primary microvascular angina and primary coronary microvascular dysfunction

There is an increasing interest in the role of echocardiography in the evaluation of primary microvascular angina, which is attributed to primary coronary microvascular dysfunction. Valid echocardiographic techniques are expected to facilitate the diagnosis and follow-up of these patients and would be valuable for research purposes and therapy evaluation. However, adequate echocardiographic data are lacking, and the interpretation of the limited available literature is hindered by the previous addition of microvascular angina under more inclusive entities, such as cardiac syndrome X. In experienced hands, the assessment of primary coronary microvascular dysfunction in patients with suspected primary microvascular angina, using multiple echocardiographic techniques is feasible, relatively inexpensive, and safe. Exclusion of obstructive epicardial coronary artery disease is, however, a prerequisite for diagnosis. Two-dimensional transthoracic echocardiography, routine stress echocardiography, and speckle-tracking echocardiography indirectly assess primary coronary microvascular dysfunction by evaluating potential impairment in myocardial function and lack diagnostic sensitivity and specificity. Conversely, certain echocardiographic techniques, including Doppler-derived coronary flow velocity reserve and myocardial contrast echocardiography, assess some coronary microvascular dysfunction parameters and have exhibited diagnostic and prognostic potentials. Doppler-derived coronary flow velocity reserve is the best studied and only guideline-approved echocardiographic technique for documenting coronary microvascular dysfunction in patients with suspected microvascular angina. Myocardial contrast echocardiography, by comparison, can detect heterogeneous and patchy myocardial involvement by coronary microvascular dysfunction, which is an advantage over the common practice of coronary flow velocity reserve assessment in a single vessel (commonly the left anterior descending artery) which only reflects regional microvascular function. However, there is no consensus regarding the diagnostic criteria, and expertise performing this technique is limited. Echocardiography remains underexplored and inadequately utilized in the setting of microvascular angina and coronary microvascular dysfunction. Appraisal of the current echocardiographic literature regarding coronary microvascular dysfunction and microvascular angina is important to stay current with the progress in its clinical recognition and create a basis for future research and technological advancements.

Ischemia With Nonobstructive Coronary Artery Disease: Concept, Assessment, and Management

In daily clinical practice, physicians often encounter patients with angina or those with evidence of myocardial ischemia from noninvasive tests but not having obstructive coronary artery disease. This type of ischemic heart disease is referred to as ischemia with nonobstructive coronary arteries (INOCA). INOCA patients often suffer from recurrent chest pain without adequate management and are associated with poor clinical outcomes. There are several endotypes of INOCA, and each endotype should be treated based on its specific underlying mechanism. Therefore, identifying INOCA and discriminating its underlying mechanisms are important issues and of clinical interest. Invasive physiologic assessment is the first step in the diagnosis of INOCA and discriminating the underlying mechanism; additional provocation tests help physicians identify the vasospastic component in INOCA patients. Comprehensive information acquired from these invasive tests can provide a template for mechanism-specific management for patients with INOCA.

Invasive Detection of Coronary Microvascular Dysfunction: How It Began, and Where We Are Now

The landscape of interventional cardiology is ever evolving. Contemporary practice has shifted from a stenosis-centred approach to the total characterisation of both the epicardial and microcirculatory vessels. Microcirculatory dysfunction plays an important role in the pathophysiology of acute and chronic coronary syndromes, and characterisation of the microcirculation has important clinical consequences. Accordingly, the invasive diagnosis of microcirculatory dysfunction is becoming a key feature of the interventional cardiologist's toolkit. This review focuses on the methodology underpinning the invasive diagnosis of microvascular dysfunction and highlights the indices that have arisen from these methodologies.

Role of different echocardiographic modalities in the assessment of microvascular function in women with ischemia and no obstructive coronary arteries

This review summarizes current knowledge about echocardiographic modalities used to assess microvascular function and left ventricular (LV) systolic function in women with ischemia and no obstructive coronary arteries (INOCA). Although the entire pathophysiological background of this clinical entity still remains elusive, it is primarily linked to microvascular dysfunction which can be assessed by coronary flow velocity reserve. Subtle impairments of LV systolic function in women with INOCA are difficult to assess by interpretation of wall motion abnormalities. LV longitudinal function impairment is considered to be an early marker of subclinical systolic dysfunction and can be assessed by global longitudinal strain quantification.

Hidden Coronary Atherosclerosis Assessment but Not Coronary Flow Reserve Helps to Explain the Slow Coronary Flow Phenomenon in Patients with Angiographically Normal Coronary Arteries

The significance of the slow coronary flow phenomenon (SCFph), as visualized in patients (pts) with angiographically normal coronary arteries, is controversial. Absolute coronary flow reserve (CFR) in the left anterior descending coronary artery (LAD), non-invasively assessed by a transthoracic color-guided pulsed-wave Doppler (E-Doppler TTE), is a reliable parameter to assess coronary microcirculatory dysfunction (CMD). Mild and angiographically hidden epicardial atherosclerosis (Hath), as visualized by intracoronary ultrasound (IVUS), which could be the clue to atherosclerotic coronary microvascular involvement, has never been investigated together with CFR in patients. This study was aimed at assessing the value of CFR and HA in explaining the SCFph. Methods. Both non-invasive assessment of CFR in the LAD and corrected TIMI frame count assessment of the coronary contrast runoff were performed in 124 pts with angiographically normal coronary arteries. Among the whole group, 32 patients also underwent intracoronary ultrasounds in the LMCA and LAD, and the maximal plaque burden was assessed (Lesion external elastic (EEM) cross sectional area (CSA)—Lesion Lumen CSA/Lesion EEM CSA * 100). We found that 24 of the 124 pts (group 1) had the SCFph and the remaining 100 had a normal runoff (group 2). CFR, evaluated in both groups, was not significantly different, being 2.79 ± 0.79 (Mean ± SD) in group 1 and 2.90 ± 0.8 in group 2 (p = ns); in the pts also examined by IVUS (32 pts), the SCFph was always associated with hidden atherosclerosis, and a plaque burden of ≥33%. On the contrary, in the normal runoff group, any grade of PB was observed (from no athero to a PB > 70%) and remarkably, 10 pts had no signs of athero or just a minimal plaque burden. This resulted in a ROC curve analysis in which PB < 33% had a high negative predictive value (100%) in ruling out the SCFph. In addition, considering a CFR value < 2.21 as an index of coronary microcirculatory dysfunction, we found CMD in 15 pts (15%) in group 1 and in 7 pts (29%) in group 2 (p = ns). In conclusion, the SCFph is strongly connected to epicardial athero to the extent that the absence of hidden coronary athero has a very high negative predictive power in ruling out SCFph. CFR that is based on an endothelium-independent mechanism remains fairly normal in this condition. An endothelium-dependent microcirculatory constriction at rest due to atherosclerotic involvement of the coronary microvascular network is a possible explanation of the SCFph.

Association of microvascular biomarkers in fluorescein angiography with macrovascular-related mortality in clinical routine data

Purpose

Early detection of microvascular changes in the retina may be important for the risk assessment of cardiovascular health. Therefore, the purpose of this study was to investigate imaging biomarkers in fluorescein angiography (FA) as potential predictors for cardiovascular mortality.

Methods

In this retrospective, matched case-control study, we included FA images from clinical routine data between 2007 and 2018 of 100 patients who died of macrovascular events (Group 1) and 100 age- and sex-matched controls (Group 2). All patients were under treatment for different, mostly retinal, ocular diseases. FA images were used for the measurement of the foveal avascular zone (FAZ) and the arteriolar and venular caliber.

Results

Patients mean age on examination day was 69.5 ± 8.3 years with a 1:1 female:male subject ratio. Mean FAZ area of our sample was 0.340 ± 0.135 mm² for Group 1 and 0.264 ± 0.137 mm² for Group 2 (P < 0.001), showing a larger FAZ area in patients who subsequently died of macrovascular-related systemic diseases.

Conclusions

Individuals effected by a macrovascular-related disease show a larger FAZ on FA examinations before the event compared to patients which are unaffected. Our results highlight a possible role of the FAZ as additional biomarker for the cardiovascular condition.

A Practical Approach to Invasive Testing in Ischemia with No Obstructive Coronary Arteries (INOCA)

Up to 65% of women and approximately 30% of men have ischemia with no obstructive coronary artery disease (CAD; commonly known as INOCA) on invasive coronary angiography performed for stable angina. INOCA can be due to coronary microvascular dysfunction or coronary vasospasm. Despite the absence of obstructive CAD, those with INOCA have an increased risk of all-cause mortality and adverse outcomes, including recurrent angina and cardiovascular events. These patients often undergo repeat testing, including cardiac catheterization, resulting in lifetime healthcare costs that rival those for obstructive CAD. Patients with INOCA often remain undiagnosed and untreated. This review discusses the symptoms and prognosis of INOCA, offers a systematic approach to the diagnostic evaluation of these patients, and summarizes therapeutic management, including tailored therapy according to underlying pathophysiological mechanisms.

Prevalence of Coronary Microvascular Disease and Coronary Vasospasm in Patients With Nonobstructive Coronary Artery Disease: Systematic Review and Meta-Analysis

Background

A relevant proportion of patients with suspected coronary artery disease undergo invasive coronary angiography showing normal or nonobstructive coronary arteries. However, the prevalence of coronary microvascular disease (CMD) and coronary spasm in patients with nonobstructive coronary artery disease remains to be determined. The objective of this study was to determine the prevalence of coronary CMD and coronary vasospastic angina in patients with no obstructive coronary artery disease.

Methods and Results

A systematic review and meta‐analysis of studies assessing the prevalence of CMD and vasospastic angina in patients with no obstructive coronary artery disease was performed. Random‐effects models were used to determine the prevalence of these 2 disease entities. Fifty‐six studies comprising 14 427 patients were included. The pooled prevalence of CMD was 0.41 (95% CI, 0.36–0.47), epicardial vasospasm 0.40 (95% CI, 0.34–0.46) and microvascular spasm 24% (95% CI, 0.21–0.28). The prevalence of combined CMD and vasospastic angina was 0.23 (95% CI, 0.17–0.31). Female patients had a higher risk of presenting with CMD compared with male patients (risk ratio, 1.45 [95% CI, 1.11–1.90]). CMD prevalence was similar when assessed using noninvasive or invasive diagnostic methods.

Conclusions

In patients with no obstructive coronary artery disease, approximately half of the cases were reported to have CMD and/or coronary spasm. CMD was more prevalent among female patients. Greater awareness among physicians of ischemia with no obstructive coronary arteries is urgently needed for accurate diagnosis and patient‐tailored management.

Autologous CD34+ Stem Cell Therapy Increases Coronary Flow Reserve and Reduces Angina in Patients With Coronary Microvascular Dysfunction

BACKGROUND

Coronary microvascular dysfunction results in angina and adverse outcomes in patients with evidence of ischemia and nonobstructive coronary artery disease; however, no specific therapy exists. CD34+ cell therapy increases microvasculature in preclinical models and improves symptoms, exercise tolerance, and mortality in refractory angina patients with obstructive coronary artery disease. The objective of this research was to evaluate the safety, tolerability, and efficacy of intracoronary CD34+ cell therapy in patients with coronary microvascular dysfunction.

METHODS

We conducted a 2-center, 20-participant trial of autologous CD34+ cell therapy (protocol CLBS16-P01; NCT03508609) in patients with ischemia and nonobstructive coronary artery disease with persistent angina and coronary flow reserve ≤2.5. Efficacy measures included coronary flow reserve, angina frequency, Canadian Cardiovascular Society angina class, Seattle Angina Questionnaire, SF-36, and modified Bruce exercise treadmill test obtained at baseline and 6 months after treatment. Autologous CD34+ cells (CLBS16) were mobilized by administration of granulocyte-colony stimulating factor 5µg/kg/day for 5 days and collected by leukapheresis. Participants received a single intracoronary left anterior descending infusion of isolated CD34+ cells in medium that enhances cell function.

RESULTS

Coronary flow reserve improved from 2.08±0.32 at baseline to 2.68±0.79 at 6 months after treatment (P<0.005). Angina frequency decreased (P<0.004), Canadian Cardiovascular Society class improved (P<0.001), and quality of life improved as assessed by the Seattle Angina Questionnaire (P≤0.03, all scales) and SF-36 (P≤0.04, all scales). There were no cell-related serious adverse events.

CONCLUSIONS

In this pilot clinical trial of microvascular angina, patients with ischemia and nonobstructive coronary artery disease receiving intracoronary infusion of CD34+ cell therapy had higher coronary flow reserve, less severe angina, and better quality of life at 6 months. The current study supports a potential therapeutic role for CD34+ cells in patients with microvascular angina. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT03508609.

Clinical presentation and management of myocardial infarction with nonobstructive coronary arteries (MINOCA): A literature review

Myocardial Infarction with Nonobstructive Coronary Arteries (MINOCA), as the name implies, is an acute myocardial infarction (MI) in the absence of significant coronary artery obstruction. Diagnosis and management of such cases have been challenging. There are many etiologies of MINOCA including coronary artery spasm, coronary microvascular dysfunction, plaque disruption, spontaneous coronary thrombosis or emboli, spontaneous coronary artery dissection, or cardiomyopathies. In this paper, the pathophysiology, diagnostic work-up, and clinical management for each subtype are described, and an overarching approach on how to evaluate and manage a patient presenting with MINOCA.

Sympathetic regulation of coronary circulation during handgrip exercise and isolated muscle metaboreflex activation in men

NEW FINDINGS

What is the central question of this study? What is the role of β- and α-adrenergic receptors in the control of the coronary circulation during handgrip exercise and isolated muscle metaboreflex activation in humans? What is the main finding and its importance? β-Adrenergic receptor, but not α-adrenergic receptor, blockade significantly blunted the increases in coronary blood velocity observed during handgrip. Coronary blood velocity was unchanged from baseline during isolated muscle metaboreflex activation. This highlights the important role of β-adrenergic receptors in the coronary circulation during handgrip in humans, and the more limited involvement of the α-adrenergic receptors.

ABSTRACT

We sought to investigate the role of β- and α-adrenergic receptors in coronary circulation during static handgrip exercise and isolated muscle metaboreflex activation in humans. Seventeen healthy young men underwent two experimental sessions, consisting of 3 min of static handgrip exercise at a target force of 40% maximum voluntary force (not achieved for the full 3 min), and 3 min of metaboreflex activation (post-exercise ischaemia) in two conditions: (1) control and β-blockade (oral propranolol), and (2) control and α-blockade (oral prazosin). In both sessions, coronary blood velocity (CBV, echocardiography) was increased during handgrip (Δ8.0 ± 7.4 cm s^-1 ) but unchanged with metaboreflex activation (Δ2.5 ± 3.2 cm s^-1 ) under control conditions. β-Blockade abolished the increase in CBV during handgrip, while CBV was unchanged from control with α-blockade. Cardiac work, estimated from rate pressure product (RPP; systolic blood pressure multiplied by heart rate), increased during handgrip and metaboreflex in control conditions in both sessions. β-Blockade reduced RPP responses to handgrip and metaboreflex, whereas α-blockade increased RPP, but the responses to handgrip and metaboreflex were unchanged. CBV and RPP were only significantly correlated during handgrip under control (r = 0.71, P < 0.01) and β-blockade (r = 0.54, P = 0.03) conditions, and the slope of this relationship was unaltered with β-blockade. Collectively, these findings indicate that β-adrenergic receptors play the primary role to the increase of coronary circulation during handgrip exercise, but CBV is unchanged with metaboreflex activation, while α-adrenergic receptor stimulation seems to exert no effect in the control of the coronary circulation during handgrip exercise and isolated muscle metaboreflex activation in humans.

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).

Risk factors for heart failure in women with ischemia and no obstructive coronary artery disease

Study objective

Women with ischemia and no obstructive coronary artery disease (INOCA) are at increased risk for heart failure (HF) hospitalizations, which is predominantly HF with preserved ejection fraction (HFpEF). We aimed to identify predictors for the development of heart failure HF in a deeply phenotyped cohort of women with INOCA and long-term prospective follow-up.

Design setting and participants

Women enrolled in the NHLBI-sponsored Women's Ischemia Syndrome Evaluation (WISE) were evaluated for baseline characteristics including clinical history, medications, physical exam, laboratory data and angiographic data. Using a multivariate Cox analysis, we assessed the association between baseline characteristics and the occurrence of HF hospitalizations in 493 women with evidence of ischemia but no obstructive coronary disease, no prior history of HF, and available follow-up data.

Results

During a median follow-up of 6-years, 18 (3.7%) women were hospitalized for HF. Diabetes mellitus and tobacco use were associated with HF hospitalization. In a multivariate analysis adjusting for known HFpEF predictors including age, diabetes, hypertension, tobacco use, and statin use, novel predictive variables included higher resting heart rate, parity and IL-6 levels and lower coronary flow reserve (CFR) and poor functional status.

Conclusions

There is a considerable incidence of HF hospitalization at longer term follow-up in women with INOCA. In addition to traditional risk factors, novel risk variables that independently predict HF hospitalization include multi-parity, high IL-6, low CFR, and poor functional status. These novel risk factors may be useful to understand mechanistic pathways and future treatment targets for prevention of HFpEF.

Angiogenic CD34 Stem Cell Therapy in Coronary Microvascular Repair-A Systematic Review

Ischemia with non-obstructive coronary arteries (INOCA) is an increasingly recognized disease, with a prevalence of 3 to 4 million individuals, and is associated with a higher risk of morbidity, mortality, and a worse quality of life. Persistent angina in many patients with INOCA is due to coronary microvascular dysfunction (CMD), which can be difficult to diagnose and treat. A coronary flow reserve <2.5 is used to diagnose endothelial-independent CMD. Antianginal treatments are often ineffective in endothelial-independent CMD and thus novel treatment modalities are currently being studied for safety and efficacy. CD34+ cell therapy is a promising treatment option for these patients, as it has been shown to promote vascular repair and enhance angiogenesis in the microvasculature. The resulting restoration of the microcirculation improves myocardial tissue perfusion, resulting in the recovery of coronary microvascular function, as evidenced by an improvement in coronary flow reserve. A pilot study in INOCA patients with endothelial-independent CMD and persistent angina, treated with autologous intracoronary CD34+ stem cells, demonstrated a significant improvement in coronary flow reserve, angina frequency, Canadian Cardiovascular Society class, and quality of life (ESCaPE-CMD, NCT03508609). This work is being further evaluated in the ongoing FREEDOM (NCT04614467) placebo-controlled trial.

Sweat the small stuff: The human microvasculature and heart disease

Traditionally thought of primarily as the predominant regulator of myocardial perfusion, it is becoming more accepted that the human coronary microvasculature also exerts a more direct influence on the surrounding myocardium. Coronary microvascular dysfunction (CMD) not only precedes large artery atherosclerosis, but is associated with other cardiovascular diseases such as heart failure with preserved ejection fraction and hypertrophic cardiomyopathy. It is also highly predictive of cardiovascular events in patients with or without atherosclerotic cardiovascular disease. This review focuses on this recent paradigm shift and delves into the clinical consequences of CMD. Concepts of how resistance arterioles contribute to disease will be discussed, highlighting how the microvasculature may serve as a potential target for novel therapies and interventions. Finally, both invasive and non-invasive methods with which to assess the coronary microvasculature both for diagnostic and risk stratification purposes will be reviewed.

Sex-specific differences in coronary blood flow and flow velocity reserve in symptomatic patients with non-obstructive disease

AIMS

Reduced coronary flow velocity reserve (CFVR) is associated with adverse cardiovascular outcomes. Whether CFVR and coronary blood flow (CBF) are similar in men and women with chest pain and non-obstructive CAD remains unknown. We hypothesised sex differences in CFVR and CBF.

METHODS AND RESULTS

A total of 1,683 patients with signs/symptoms of ischaemia and angiographically unobstructed coronary arteries (<40% angiographic stenosis) underwent coronary vasomotion evaluation. CFVR was measured as hyperaemic/resting average velocity in the LAD. Mid-LAD diameter was measured with quantitative angiography and CBF calculated at rest (rCBF) and hyperaemia (hCBF). Resting microvascular resistance (rMR) was calculated as mean arterial pressure/rCBF. Of the total number of patients, 1,096 (65%) were women, median age 51 [42, 59] years. Compared to men, women had lower median CFVR (2.7 [2.4, 3.2] vs 3.1 [2.7, 3.6], p<0.001), higher rCBF (49.7 [34.0, 71.1] vs 45.9 [31.8, 68.7] ml/min, p=0.04), lower hCBF (139.5 [93.0, 195.2] vs 147.1 [95.7, 218.6] ml/min, p=0.02), but similar rMR (p=0.82). Female sex was an independent predictor of lower CFVR, higher rCBF, and lower hCBF.

CONCLUSIONS

Compared to men, women with signs/symptoms of ischaemia and non-obstructive CAD have lower CFVR, higher rCBF, and lower hCBF. Female sex is a predictor of these sex-specific differences. The clinical diagnostic and prognostic implications of sex differences in coronary physiology need further evaluation.

Effects of Oral Drugs on Coronary Microvascular Function in Patients Without Significant Stenosis of Epicardial Coronary Arteries: A Systematic Review and Meta-Analysis of Coronary Flow Reserve

Objective: This study aims to investigate the impact of cardiovascular medications on the coronary flow reserve (CFR) in patients without obstructive coronary artery disease (CAD).

Methods: We searched PubMed, EMBASE, and Cochrane databases from inception to 15 November 2019. Studies were included if they reported CFR from baseline to follow-up after oral drug therapy of patients without obstructive CAD. Data was pooled using random-effects modeling. The primary outcome was change in CFR from baseline to follow-up after oral drug therapy.

Results: A total of 46 studies including 845 subjects were included in this study. Relative to baseline, the CFR was improved by angiotensin-converting enzymes (ACEIs), aldosterone receptor antagonists (ARBs) [standard mean difference (SMD): 1.12; 95% CI: 0.77–1.47], and statins treatments (SMD: 0.61; 95%CI: 0.36–0.85). Six to 12 months of calcium channel blocker (CCB) treatments improved CFR (SMD: 1.04; 95% CI: 0.51–1.58). Beta-blocker (SMD: 0.24; 95% CI: −0.39–0.88) and ranolazine treatment (SMD: 0.31; 95% CI: −0.39–1.01) were not associated with improved CFR.

Conclusions: Therapy with ACEIs, ARBs, and statins was associated with improved CFR in patients with confirmed or suspicious CMD. CCBs also improved CFR among patients followed for 6–12 months. Beta-blocker and ranolazine had no impact on CFR.

Comprehensive treatment of microvascular angina in overweight women - a randomized controlled pilot trial

AIMS

Coronary microvascular dysfunction (CMD) carries a poor cardiovascular prognosis and may explain angina in women without obstructive coronary artery disease (CAD). Currently, no evidence-based treatment for CMD exists. We investigated whether reducing cardiovascular risk factors improves symptoms and microvascular function in women with non-endothelial dependent CMD and no obstructive CAD.

METHODS

We randomized 62 women aged 40-75, with body mass index (BMI) >25 kg/m2, angina ≥monthly, and coronary flow velocity reserve (CFVR) ≤2.5 to a 24-week intervention comprising low energy diet, exercise training, and optimized treatment of hypertension, dyslipidemia and diabetes or to control. Patients were assessed before randomization and after 24 weeks. Primary outcomes were CFVR assessed by transthoracic Doppler stress-echocardiography and angina burden by Seattle Angina Questionnaire (SAQ). Secondary outcomes were exercise capacity, body composition, glycemic control, myocardial function, and anxiety and depression symptoms.

RESULTS

Fifty-six participants (90%) completed the study. Median (IQR) age was 65.2 (57.1;70.7) years, BMI was 30.1 (28.4;32.7) kg/m2. The intervention resulted in relevant improvement in angina symptoms (9-21-point increase on SAQ-scales (all p<0.01)) but had no effect on CFVR (p = 0.468). Mean (CI) weight loss was 9.6 (7.80;11.48) kg, (p<0.0001). There was a significant mean (CI) decrease in depression symptoms = 1.16 (0.22;2.12), triglycerides = 0.52 (0.25;0.78) mmol/L, total cholesterol = 0.55 (0.12;0.98) mmol/L, and HbA1c in diabetics = 27.1 (1.60;52.6) mmol/mol but no effect on other secondary outcomes.

CONCLUSION

A major weight loss and intensified risk factor control resulted in significantly improved angina burden but no improvement of coronary microvascular function among women with microvascular angina.

Advances in Cardiac Computed Tomography Functional Imaging Technology

Cardiovascular disease (CVD) is the leading cause of death among patients in China, and cardiac computed tomography (CT) is one of the most commonly used examination methods for CVD. Coronary artery CT angiography can be used for the morphologic evaluation of the coronary artery. At present, cardiac CT functional imaging has become an important direction of development of CT. At present, common CT functional imaging technologies include transluminal attenuation gradient, stress dynamic CT myocardial perfusion imaging, and CT-fractional flow reserve. These three imaging modes are introduced and analyzed in this review.

Effect of Sex Difference of Coronary Microvascular Dysfunction on Long-Term Outcomes in Deferred Lesions

OBJECTIVES

This study investigated the sex difference of long-term cardiovascular outcomes on coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) in patients with deferred coronary artery lesions.

BACKGROUND

Coronary microvascular dysfunction is associated with poorer long-term outcomes. It can be assessed by CFR and the IMR.

METHODS

The study prospectively enrolled 434 patients (133 women and 301 men) and analyzed CFR, IMR, fractional flow reserve, and quantitative coronary angiography. Clinical outcomes were assessed by major adverse cardiovascular event(s) (MACE) of cardiac death, myocardial infarction, and revascularization during 5 years of follow-up. The study protocol was approved by the Institutional Review Board or Ethics Committee at each participating center, and all patients provided written informed consent. The study protocol was in accordance with the Declaration of Helsinki.

RESULTS

Women had milder epicardial disease compared with men (fractional flow reserve: 0.91 [interquartile range (IQR): 0.87 to 0.96] vs. 0.90 [IQR: 0.86 to 0.95]; p = 0.037). IMR was similar between the sexes, but CFR was lower in women (2.69 [IQR: 2.08 to 3.90] vs. 3.20 [IQR: 2.20 to 4.31]; p = 0.006) due to a shorter resting mean transit time, whereas hyperemic mean transit times were similar. At 5-year follow-up, MACE was significantly lower in women compared with men (1.1% vs. 5.5%; p = 0.017). Sex, diabetes mellitus, and CFR were independent predictors for MACE for all patients. The risk of MACE was significantly higher in men with low versus high CFR (hazard ratio: 4.58; 95% confidence interval: 1.85 to 11.30; p = 0.011) which was not seen in women.

CONCLUSIONS

There was no sex difference in microvascular function by IMR. CFR was lower in women due to a higher resting coronary flow; however, long-term clinical outcomes in deferred lesions were better in women compared with men. (Clinical, Physiological and Prognostic Implication of Microvascular Status; NCT02186093).

Pathophysiology, classification, and MRI parallels in microvascular disease of the heart and brain

Diagnostic imaging technology in vascular disease has long focused on large vessels and the pathologic processes that impact them. With improved diagnostic techniques, investigators are now able to uncover many underlying mechanisms and prognostic factors for microvascular disease. In the heart and brain, these pathologic entities include coronary microvascular disease and cerebral small vessel disease, both of which have significant impact on patients, causing angina, myocardial infarction, heart failure, stroke, and dementia. In the current paper, we will discuss parallels in pathophysiology, classification, and diagnostic modalities, with a focus on the role of magnetic resonance imaging in microvascular disease of the heart and brain. Novel approaches for streamlined imaging of the cardiac and central nervous systems including the use of intravascular contrast agents such as ferumoxytol are presented, and unmet research gaps in diagnostics are summarized.

Resting coronary velocity and myocardial performance in women with impaired coronary flow reserve: Results from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study

BACKGROUND

Women with evidence of ischemia and no obstructive coronary arteries (INOCA) often have coronary microvascular dysfunction (CMD) indicated by impaired coronary flow reserve (CFR) to adenosine. Low CFR is associated with an adverse prognosis, including incident heart failure. Because the CFR calculation relies on the baseline intrinsic coronary vasomotor flow velocity, a major determinate of CFR and the degree of variation in baseline flow alone may be an important contributor to risk of adverse outcomes in women with CMD. A better understanding of baseline blood flow in the setting of low CFR and its association with myocardial performance would be helpful.

METHODS

We evaluated 74 women who underwent invasive coronary reactivity testing in the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study and had impaired CFR (<2.32). We assessed the relationship between coronary artery baseline average peak velocity (bAPV) at rest and cardiac magnetic resonance imaging measures of left ventricular (LV) structure and function.

RESULTS

When stratified as low (<22 cm/s) versus high (≥22 cm/s) bAPV, there were no differences in cardiovascular risk factors, coronary plaque burden, or LV structure. However, low bAPV was associated with higher LV end-diastolic filling pressure (P = 0.04), lower LV ejection fraction (P = 0.001), and differences in late systolic and diastolic strain rates (P = 0.01 to 0.05).

CONCLUSIONS

In women with impaired CFR, low resting coronary flow velocity is associated with more adverse myocardial performance, which may contribute to risk for adverse outcomes and particularly heart failure in women with CMD.

Comparison of Instantaneous Wave-Free Ratio (iFR) and Fractional Flow Reserve (FFR) with respect to Their Sensitivities to Cardiovascular Factors: A Computational Model-Based Study

While coronary revascularization strategies guided by instantaneous wave-free ratio (iFR) are, in general, noninferior to those guided by fractional flow reserve (FFR) with respect to the rate of major adverse cardiac events at one-year follow-up in patients with stable angina or an acute coronary syndrome, the overall accuracy of diagnosis with iFR in large patient cohorts is about 80% compared with the diagnosis with FFR. So far, it remains incompletely understood what factors contribute to the discordant diagnosis between iFR and FFR. In this study, a computational method was used to systemically investigate the respective effects of various cardiovascular factors on FFR and iFR. The results showed that deterioration in aortic valve disease (e.g., regurgitation or stenosis) led to a marked decrease in iFR and a mild increase in FFR given fixed severity of coronary artery stenosis and that increasing coronary microvascular resistance caused a considerable increase in both iFR and FFR, but the degree of increase in iFR was lower than that in FFR. These findings suggest that there is a high probability of discordant diagnosis between iFR and FFR in patients with severe aortic valve disease or coronary microcirculation dysfunction.

Impact of Sex Difference on the Discordance of Revascularization Decision Making Between Fractional Flow Reserve and Diastolic Pressure Ratio During the Wave-Free Period

Background

Sex difference in fractional flow reserve (FFR) and resting index has not been fully clarified. We sought to investigate the impact of sex on the discordance of revascularization decision making between FFR and diastolic pressure ratio during the diastolic wave‐free period (dPR_WFP).

Methods and Results

A total of 759 angiographically intermediate lesions with 30% to 80% diameter stenosis by quantitative coronary angiography in 577 patients in whom FFR and dPR_WFP were measured were investigated. dPR_WFP was measured during the wave‐free window of 5 heart cycles at an independent core laboratory. FFR ≤0.80 and dPR_WFP ≤0.89 were considered positive studies. A total of 164 vessels in 126 women (21.6%) and 595 vessels in 451 men (78.4%) were included. In lesions with negative dPR_WFP, positive FFR was less frequently observed in women (13 of 73; 17.8%) than in men (97 of 286; 33.9%) (P=0.009). In lesions with positive dPR_WFP, the frequency of negative FFR was observed in 22 of 91 vessels (24.2%) in women and 51 of 309 vessels (16.5%) in men, which did not reach statistical significance (P=0.098). In multivariable analyses, female sex was independently associated with FFR‐dPR_WFP discordance both in negative dPR_WFP cohort (odds ratio, 0.44; 95% CI, 0.21–0.98; P=0.036) and in positive dPR_WFP cohort (odds ratio, 2.41; 95% CI, 1.17–4.96; P=0.017) after adjustment for age, weight, quantitative coronary angiography data, and baseline physiological indexes.

Conclusions

The frequency of FFR‐dPR_WFP discordance was significantly associated with sex, which may indicate potential shift of optimal threshold of either FFR or dPR_WFP, or both of them, according to sex.

Design, methodology and baseline characteristics of the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD)

A significant number of women with signs and symptoms of ischemia with no obstructive coronary artery disease (INOCA) have coronary vascular dysfunction detected by invasive coronary reactivity testing (CRT). However, the noninvasive assessment of coronary vascular dysfunction has been limited.

METHODS

The Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) was a prospective study of women with suspected INOCA aimed to investigate whether (1) cardiac magnetic resonance imaging (CMRI) abnormalities in left ventricular morphology and function and myocardial perfusion predict CRT measured coronary microvascular dysfunction, (2) these persistent CMRI abnormalities at 1-year follow-up predict persistent symptoms of ischemia, and (3) these CMRI abnormalities predict cardiovascular outcomes. By design, a sample size of 375 women undergoing clinically indicated invasive coronary angiography for suspected INOCA was projected to complete baseline CMRI, a priori subgroup of 200 clinically indicated CRTs, and a priori subgroup of 200 repeat 1-year follow-up CMRIs.

RESULTS

A total of 437 women enrolled between 2008 and 2015, 374 completed baseline CMRI, 279 completed CRT, and 214 completed 1-year follow-up CMRI. Mean age was 55± 11 years, 93% had 20%-50% coronary stenosis, and 7% had <20% stenosis by angiography.

CONCLUSIONS

The WISE-CVD study investigates the utility of noninvasive CMRI to predict coronary vascular dysfunction in comparison to invasive CRT, and the prognostic value of CMRI abnormalities for persistent symptoms of ischemia and cardiovascular outcomes in women with INOCA. WISE-CVD will provide new understanding of a noninvasive imaging modality for future clinical trials.

Redox Regulation of the Microcirculation

The microcirculation maintains tissue homeostasis through local regulation of blood flow and oxygen delivery. Perturbations in microvascular function are characteristic of several diseases and may be early indicators of pathological changes in the cardiovascular system and in parenchymal tissue function. These changes are often mediated by various reactive oxygen species and linked to disruptions in pathways such as vasodilation or angiogenesis. This overview compiles recent advances relating to redox regulation of the microcirculation by adopting both cellular and functional perspectives. Findings from a variety of vascular beds and models are integrated to describe common effects of different reactive species on microvascular function. Gaps in understanding and areas for further research are outlined. © 2020 American Physiological Society. Compr Physiol 10:229-260, 2020.

Left ventricular concentric remodelling and functional impairment in women with ischaemia with no obstructive coronary artery disease and intermediate coronary flow reserve: a report from the WISE-CVD study

AIMS

Women with evidence of ischaemia but no obstructive coronary artery disease (INOCA) often have coronary microvascular dysfunction (CMD). Although invasively measured coronary flow reserve (CFR) is useful for the diagnosis of CMD, intermediate CFR values are often found of uncertain significance. We investigated myocardial flow reserve and left ventricular (LV) structural and functional remodelling in women with suspected INOCA and intermediate CFR.

METHODS AND RESULTS

Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study participants who had invasively measured intermediate CFR of 2.0≤ CFR ≤3.0 (n = 125) were included for this analysis. LV strain, peak filling rate (PFR) and myocardial perfusion reserve index (MPRI) were obtained by cardiac magnetic resonance imaging. Participants were divided: (i) Group 1 (n = 66) high MPRI ≥ 1.8, and (ii) Group 2 (n = 59) low MPRI < 1.8. The mean age was 54 ± 12 years and CFR was 2.46 ± 0.27. MPRI was significantly different but CFR did not differ between groups. LV relative wall thickness (RWT) trended higher in Group 2 and circumferential peak systolic strain and early diastolic strain rate were lower (P = 0.039 and P = 0.035, respectively), despite a similar LV ejection fraction and LV mass. PFR was higher in Group 1 and LV RWT was negatively related to PFR (r = -0.296, P = 0.001).

CONCLUSIONS

In women with suspected INOCA and intermediate CFR, those with lower MPRI had a trend towards more adverse remodelling and impaired diastolic LV function compared with those with higher MPRI. CFR was similar between the two groups. These findings provide evidence that both coronary microvessel vasomotion and structural and functional myocardial remodelling contribute to CMD.

Coronary Physiology in the Cardiac Catheterization Laboratory

Coronary angiography has been the principle modality for assessing the severity of atherosclerotic coronary artery disease for several decades. However, there is a complex relationship between angiographic coronary stenosis and the presence or absence of myocardial ischemia. Recent technological advances now allow for the assessment of coronary physiology in the catheterization laboratory at the time of diagnostic coronary angiography. Early studies focused on coronary flow reserve (CFR) but more recent work has demonstrated the physiologic accuracy and prognostic value of the fractional flow reserve (FFR) and instantaneous wave free ratio (iFR) for the assessment of coronary artery disease. These measurements have been validated in large multi-center clinical trials and have become indispensable tools for guiding revascularization in the cardiac catheterization laboratory. The physiological assessment of chest pain in the absence of epicardial coronary artery disease involves coronary thermodilution to obtain the index of microcirculatory resistance (IMR) or Doppler velocity measurement to determine the coronary flow velocity reserve (CFVR). Physiology-based coronary artery assessment brings "personalized medicine" to the catheterization laboratory and allows cardiologists and referring providers to make decisions based on objective findings and evidence-based treatment algorithms. The purpose of this review is to describe the theory, technical aspects, and relevant clinical trials related to coronary physiology assessment for an intended audience of general medical practitioners.

Sex Differences in Adenosine-Free Coronary Pressure Indexes: A CONTRAST Substudy

OBJECTIVES

The goal of this study was to investigate sex differences in adenosine-free coronary pressure indexes.

BACKGROUND

Several adenosine-free coronary pressure wire indexes have been proposed to assess the functional significance of coronary artery lesions; however, there is a theoretical concern that sex differences may affect diagnostic performance because of differences in resting flow and distal myocardial mass.

METHODS

In this CONTRAST (Can Contrast Injection Better Approximate FFR Compared to Pure Resting Physiology?) substudy, contrast fractional flow reserve (cFFR), obtained during contrast-induced submaximal hyperemia, the instantaneous wave-free ratio (iFR), and distal/proximal coronary pressure ratio (Pd/Pa) were compared with fractional flow reserve (FFR) in 547 men and 216 women. Using FFR ≤0.8 as a reference, the diagnostic performance of each index was compared.

RESULTS

Men and women had similar diameter stenosis (p = 0.78), but women were less likely to have FFR ≤0.80 than men (42.5% vs. 51.5%, p = 0.04). Sensitivity was similar among cFFR, iFR, and Pd/Pa when comparing women and men, respectively (cFFR, 77.5% vs. 75.3%; p = 0.69; iFR, 84.9% vs. 79.4%; p = 0.30; Pd/Pa, 78.8% vs. 77.3%; p = 0.78). cFFR was more specific than iFR or Pd/Pa regardless of sex (cFFR, 94.3% vs. 95.8%; p = 0.56; iFR, 75.6% vs. 80.1%; p = 0.38; Pd/Pa, 80.6% vs. 78.7%; p = 0.69). By receiver-operating characteristic curve analysis, cFFR provided better diagnostic accuracy than resting indexes irrespective of sex (p ≤ 0.0001).

CONCLUSIONS

Despite the theoretical concern, the diagnostic sensitivity and specificity of cFFR, iFR, and Pd/Pa did not differ between the sexes. Irrespective of sex, cFFR provides the best diagnostic performance.

Clinical significance of PET-CT coronary flow reserve in diagnosis of non-obstructive coronary artery disease

OBJECTIVE

To improve current knowledge of coronary flow reserve and non-obstructive coronary artery disease in terms of definition, features and clinical implications of measurement of coronary flow reserve (CFR), is an integrated measure of focal, diffuse, and small vessel coronary artery disease, can also be explained as a calculated ratio of hyperaemic to rest absolute myocardial blood flow. Non-obstructive coronary artery disease is defined as atherosclerotic plaque that does not obstruct blood flow or result in anginal symptoms. We also aimed at knowing the significance of PET in diagnosing coronary microvascular disease.

RESULTS

In our study 92% were between 41 and 60 years. 83% were males and 17% females, more patients had hypertension about 50%, few had diabetes mellitus about 16%, while those with both hypertension and diabetes mellitus were 17%. About 83% had ST segment and T wave changes on ECG. All patients and controls had normal coronaries on coronary angiography TIMI 3 flow. On further investigation by Positron emission tomography/CT we found out 58% had abnormal CFR and 42% had normal coronary flow reserve. Our findings indicate PET/CT coronary flow reserve concept provides a platform for the diagnosis of non-obstructive coronary artery disease in patients with signs and symptoms of ischemia without angiographic obstructive CAD.

Clinical Characteristics, Sex Differences, and Outcomes in Patients With Normal or Near-Normal Coronary Arteries, Non-Obstructive or Obstructive Coronary Artery Disease

Background

Normal or near‐normal coronary arteries (NNCAs) or nonobstructive coronary artery disease (CAD) are found on invasive coronary angiography in ≈55% of patients. Some attribute this to frequent referral of low‐risk patients. We sought to identify the referral indications, pretest risk, key clinical characteristics, sex, and outcomes in patients with NNCAs and nonobstructive CAD versus obstructive CAD on nonemergent invasive coronary angiography.

Methods and Results

Over 24 months, 925 consecutive patients were classified as having NNCAs (≤20% stenosis), nonobstructive CAD (21–49% stenosis), or obstructive CAD (≥50% stenosis). Outcomes included cardiac death, nonfatal myocardial infarction, and late revasclarization. NNCAs were found in 285 patients (31.0%), nonobstructive CAD in 125 (13.5%), and obstructive CAD in 513 (55.5%). NNCAs or nonobstructive CAD was found in 40.5% with stress ischemia, 27.9% after a non‐ST‐elevation myocardial infarction, and in 55.5% with stable or unstable angina. More women than men (53.5% versus 37.2%; P<0.001) had NNCAs or nonobstructive CAD across all referral indications. Pretest risk was high and ICA appropriate in 75.5% and 99.2% of patients, respectively. Annual rates of cardiac death or nonfatal myocardial infarction were 1.0%, 1.1%, and 6.7%, respectively, for patients with NNCAs, nonobstructive CAD, and obstructive CAD (P<0.001). No sex differences in outcomes were observed with either NNCAs, nonobstructive CAD, or obstructive CAD (P=0.84).

Conclusions

Many (44.5%) patients undergoing nonemergent invasive coronary angiography have NNCAs or nonobstructive CAD despite high pretest risk, including ischemia and troponin elevation. Although women had more NNCAs or nonobstructive CAD, there were no differences in event rates by sex. Patients with NNCAs and nonobstructive CAD had very low event rates.