Ischemia and No Obstructive Coronary Artery Disease (INOCA): Developing Evidence-Based Therapies and Research Agenda for the Next Decade

Ischemia and no obstructive coronary arteries in patients with stable ischemic heart disease

A large proportion of patients with suspected obstructive coronary artery disease (CAD) is found to have ischemia with no obstructive coronary artery disease (INOCA). Based on current evidence, these patients are at increased risk of adverse cardiovascular events, even though they have no obstructive CAD. Importantly, INOCA is associated with recurrent clinical presentations with chest pain, impaired functional capacity, reduced health-related quality of life, and high healthcare costs. Underlying coronary microvascular dysfunction (CMD), through endothelium-dependent and independent mechanisms contribute to these adverse outcomes in INOCA. While non-invasive and invasive diagnostic testing has typically focused on identification of obstructive CAD in symptomatic patients, functional testing to detect coronary epicardial and microvascular dysfunction should be considered in those with INOCA who have persistent angina. Current diagnostic methods to clarify functional abnormalities and treatment strategies for epicardial and/or microvascular dysfunction in INOCA are reviewed.

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.

Vasodilator Strain Stress Echocardiography in Suspected Coronary Microvascular Angina

Background: In patients with Ischemia and non-obstructive coronary artery stenosis (INOCA) wall motion is rarely abnormal during stress echocardiography (SE). Our aim was to determine if patients with INOCA and reduced coronary flow velocity reserve (CVFR) have altered cardiac mechanics using two-dimensional speckle-tracking echocardiography (2DSTE) during SE. Methods: In a prospective, multicenter, international study, we recruited 135 patients with INOCA. Overall, we performed high dose (0.84 mg/kg) dipyridamole SE with combined assessment of CVFR and 2DSTE. The population was divided in patients with normal CVFR (>2, group 1, n = 95) and abnormal CVFR (≤2, group 2, n = 35). Clinical and 2DSTE parameters were compared between groups. Results: Feasibility was high for CFVR (98%) and 2DSTE (97%). A total of 130 patients (mean age 63 ± 12 years, 67 women) had complete flow and strain data. The two groups showed similar 2DSTE values at rest. At peak SE, Group 1 patients showed lower global longitudinal strain (p < 0.007), higher mechanical dispersion (p < 0.0005), lower endocardial (p < 0.001), and epicardial (p < 0.0002) layer specific strain. Conclusions: In patients with INOCA, vasodilator SE with simultaneous assessment of CFVR and strain is highly feasible. Coronary microvascular dysfunction is accompanied by an impairment of global and layer-specific deformation indices during stress.

Focus on today's evidence while keeping an eye on the future: lessons derived from hypertension in women

While evidence-based medicine has contributed enormously to the uniformity and rationale of patient care, it is necessary that we anticipate changes in order to implement their rapid translation to practice. The purpose of this review is to expose three issues regarding cardiovascular health in women, including milestones to reflect the pace at which these are incorporated into public policies. Two of these matters, as changes in the thresholds of normal blood pressure in gestation and in nonpregnant women, need further evidence and deserve to be retrospectively analyzed in high-quality databases. The third subject derives from the association of remote cardiovascular complications of hypertensive pregnancies, an example of the unnecessary delay of more than two decades to install a wide prevention strategy when the health system is not on the watch.

Relationship between hypertension and non-obstructive coronary artery disease in chronic coronary syndrome (the NORIC registry)

Background

The burden of non-obstructive coronary artery disease (CAD) in the society is high, and there is currently limited evidence-based recommendation for risk stratification and treatment. Previous studies have demonstrated an association between increasing extent of non-obstructive CAD and cardiovascular events. Whether hypertension, a modifiable cardiovascular risk factor, is associated with extensive non-obstructive CAD in patients with symptomatic chronic coronary syndrome (CCS) remains unclear.

Methods

We included 1138 patients (mean age 62±11 years, 48% women) with symptomatic CCS and non-obstructive CAD (1–49% lumen diameter reduction) by coronary computed tomography angiography (CCTA) from the Norwegian Registry for Invasive Cardiology (NORIC). The extent of non-obstructive CAD was assessed as coronary artery segment involvement score (SIS), and extensive non-obstructive CAD was adjudicated when SIS >4. Hypertension was defined as known hypertension or use of antihypertensive medication.

Results

Hypertension was found in 45% of patients. Hypertensive patients were older, with a higher SIS, calcium score, and prevalence of comorbidities and statin therapy compared to the normotensive (all p<0.05). There was no difference in the prevalence of hypertension between sexes. Univariable analysis revealed a significant association between hypertension and non-obstructive CAD. In multivariable analysis, hypertension remained associated with extensive non-obstructive CAD, independent of sex, age, smoking, diabetes, statin treatment, obesity and calcium score (OR 1.85, 95% CI [1.22–2.80], p = 0.004).

Conclusion

In symptomatic CCS, hypertension was associated with extensive non-obstructive CAD by CCTA. Whether hypertension may be a new treatment target in symptomatic non-obstructive CAD needs to be explored in future studies.

Clinical trial registration

ClinicalTrials.gov: Identifier NCT 04009421.

Diagnostic performance and prognostic impact of coronary angiography-based Index of Microcirculatory Resistance assessment: A systematic review and meta-analysis

BACKGROUND

The Index of Microcirculatory Resistance (IMR), measured with a pressure-thermistor tipped coronary guidewire has been established as a gold standard for coronary microvascular assessment. Angiography-based IMR (angio-IMR) is a novel method to derive IMR without intracoronary instrumentation or the need for adenosine.

METHODS

PubMed and Embase databases were systemically searched in November 2021 for studies that measured angio-IMR. The primary outcomes were pooled sensitivity and specificity as well as the area under the curve (AUC) of the summary receiver operating characteristic curve using IMR as a reference standard.

RESULTS

A total of 129 records were initially identified and 8 studies were included in the final analysis. Overall, 1653 lesions were included in this study, of which 733 were in patients presenting with ST-segment elevation myocardial infarction. Angio-IMR yielded high diagnostic performance predicting wire-based IMR with pooled sensitivity = 0.81 (95% confidence interval: 0.76, 0.85), specificity = 0.80 (0.72, 0.86), and AUC = 0.86 (0.82, 0.88), which was similar irrespective of patient presentation. When the clinical outcome was compared between high versus low angio-IMR in patients presenting with myocardial infarction, high angio-IMR predicted an increased risk of major adverse cardiac events (MACE).

CONCLUSION

Our study found that coronary angio-IMR has relatively high diagnostic performance as well as prognostic values predicting MACE, supporting its use in clinical practice.

Mechanobiology of Microvascular Function and Structure in Health and Disease: Focus on the Coronary Circulation

The coronary microvasculature plays a key role in regulating the tight coupling between myocardial perfusion and myocardial oxygen demand across a wide range of cardiac activity. Short-term regulation of coronary blood flow in response to metabolic stimuli is achieved via adjustment of vascular diameter in different segments of the microvasculature in conjunction with mechanical forces eliciting myogenic and flow-mediated vasodilation. In contrast, chronic adjustments in flow regulation also involve microvascular structural modifications, termed remodeling. Vascular remodeling encompasses changes in microvascular diameter and/or density being largely modulated by mechanical forces acting on the endothelium and vascular smooth muscle cells. Whereas in recent years, substantial knowledge has been gathered regarding the molecular mechanisms controlling microvascular tone and how these are altered in various diseases, the structural adaptations in response to pathologic situations are less well understood. In this article, we review the factors involved in coronary microvascular functional and structural alterations in obstructive and non-obstructive coronary artery disease and the molecular mechanisms involved therein with a focus on mechanobiology. Cardiovascular risk factors including metabolic dysregulation, hypercholesterolemia, hypertension and aging have been shown to induce microvascular (endothelial) dysfunction and vascular remodeling. Additionally, alterations in biomechanical forces produced by a coronary artery stenosis are associated with microvascular functional and structural alterations. Future studies should be directed at further unraveling the mechanisms underlying the coronary microvascular functional and structural alterations in disease; a deeper understanding of these mechanisms is critical for the identification of potential new targets for the treatment of ischemic heart disease.

Dynamic detection and reversal of myocardial ischemia using an artificially intelligent bioelectronic medicine

Myocardial ischemia is spontaneous, frequently asymptomatic, and contributes to fatal cardiovascular consequences. Importantly, myocardial sensory networks cannot reliably detect and correct myocardial ischemia on their own. Here, we demonstrate an artificially intelligent and responsive bioelectronic medicine, where an artificial neural network (ANN) supplements myocardial sensory networks, enabling reliable detection and correction of myocardial ischemia. ANNs were first trained to decode spontaneous cardiovascular stress and myocardial ischemia with an overall accuracy of ~92%. ANN-controlled vagus nerve stimulation (VNS) significantly mitigated major physiological features of myocardial ischemia, including ST depression and arrhythmias. In contrast, open-loop VNS or ANN-controlled VNS following a caudal vagotomy essentially failed to reverse cardiovascular pathophysiology. Last, variants of ANNs were used to meet clinically relevant needs, including interpretable visualizations and unsupervised detection of emerging cardiovascular stress. Overall, these preclinical results suggest that ANNs can potentially supplement deficient myocardial sensory networks via an artificially intelligent bioelectronic medicine system.

Overview of Microvascular Angina Pectoris and Discussion of Traditional Chinese Medicine Intervention

Previous research and treatment of coronary heart disease mostly focused on the large epicardial vessels, with limited research on the small endocardial coronary arteries or arterioles that could not be detected by coronary angiography, especially microvascular angina caused by microvascular stenosis or microcirculation dysfunction. Conventional Western medicine therapies have no specific efficacy, but traditional Chinese medicine has significant advantages in this regard. In particular, traditional Chinese medicine of supplementing Qi and activating blood circulation protects the vascular endothelium, relaxes coronary microvessels, reduces myocardial no-reflow after ischemia-reperfusion, increases myocardial hypoxia tolerance, constrains the aggregation of platelet, and increases the rate of blood flow. Moreover, these treatments can significantly improve patients' symptoms through multitarget comprehensive intervention. Here, we analyzed the pathogenesis of microvascular angina pectoris, the treatment status of modern medicine, and the research on the multitarget intervention of traditional Chinese medicine to provide new research ideas for correctly identifying the role of coronary microcirculation in coronary artery disease to solve clinical problems and prevent cardiovascular events.

Mental Stress-Induced Myocardial Ischemia

PURPOSE OF REVIEW

To summarize recent evidence on mental stress-induced myocardial ischemia (MSIMI), its mechanisms, and clinical significance.

RECENT FINDINGS

MSIMI can occur in patients with normal cardiac stress testing, is only weakly related to severity of coronary artery disease (CAD), and it is often silent. Among patients with CAD, MSIMI is associated with a twofold increased risk of major adverse cardiovascular events compared to those who do not have MSIMI. Certain groups such as young women with myocardial infarction and those with psychological comorbidities are more susceptible to MSIMI. Abnormal microvascular vasoreactivity and inflammation are implicated mechanisms in MSIMI. Increased brain activity in regions that modulate autonomic reactivity to emotional stress and fear is associated with MSIMI. MSIMI has important prognostic implications in patients with CAD. Stress can no longer be ignored as a risk factor in cardiology care. Clinical trials testing effective strategies to target MSIMI are needed.

Ultra-high sensitivity cardiac troponin-I concentration and left ventricular structure and function in women with ischemia and no obstructive coronary artery disease

Aims

Women are disproportionally impacted by ischemia and no obstructive coronary artery disease (INOCA), and such women are at increased risk of developing heart failure with preserved ejection fraction (HFpEF), however the mechanisms linking these conditions remain poorly understood. The aim of this study was to determine whether ultra-high sensitivity cardiac troponin I (u-hscTnI), an indicator of cardiomyocyte injury, is associated with abnormalities in myocardial perfusion and left ventricular (LV) structure and function in women with INOCA.

Methods

327 women with INOCA enrolled in the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) study underwent vasodilator stress cardiac magnetic resonance imaging (CMRI) and u-hscTnI measurements (Simoa HD-1 Analyzer, Quanterix Corporation). Multivariable linear regression was used to evaluate associations between u-hscTnI concentrations and myocardial perfusion (MPRI), LV mass index and feature-tracking derived strain measures of LV function.

Results

u-hscTnI concentrations were quantifiable in 100% of the cohort and ranged from 0.004 to 79.6 pg/mL. In adjusted models, u-hscTnI was associated with LV mass index (+2.03; 95% CI 1.17, 2.89; p < 0.01) and early diastolic radial strain rate (SR) (+0.13; 95% CI 0.01, 0.25; p = 0.03), early diastolic circumferential SR (-0.04; 95% CI -0.08, 0.002; p = 0.06) and early diastolic longitudinal SR (-0.03; 95% CI -0.07, 0.002; p = 0.06). u-hscTnI was not associated with MPRI (p = 0.39) in adjusted models.

Conclusion

Together, these findings support cardiomyocyte injury as a putative pathway towards adverse LV remodeling and dysfunction; however, further research is needed to define the specific mechanism(s) driving myocellular injury in INOCA.

Paradoxical coronary vasospasm and transient apical ballooning in a post-menopausal woman: An imaging case report of an unusual INOCA presentation

Ischemia with non-obstructive coronary artery disease (INOCA), a common cause of angina, can occur due to coronary vasospasm, microvascular dysfunction, endothelial dysfunction, atherosclerosis or a combination of these mechanisms. We describe a case of adenosine-associated paradoxical coronary vasospasm and Takotsubo-like apical ballooning in a postmenopausal woman with underlying mild coronary atherosclerosis and microvascular dysfunction.

Can EAT be an INOCA goalkeeper

Ischemia with non-obstructive coronary artery (INOCA) is a blind spot of coronary artery disease (CAD). Such patients are often reassured but offered no specific care, that lead to a heightened risk of adverse cerebrovascular disease (CVD) outcomes. Epicardial adipose tissue (EAT) is proven to correlate independently with CAD and its severity, but it is unknown whether EAT is a specific and sensitive indicator of INOCA. This review focuses on the INOCA epidemiology and related factors, as well as the association between EAT.

Cold Pressor Testing and Sympathetic Nervous System Contribution to Ischemia with No Obstructive Coronary Artery Disease: Results from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction Project

Study Objective

Cold Pressor Testing (CPT) is a known stimulus of the sympathetic nervous system (SNS). To better understand sympathetic contribution to coronary blood flow regulation in women with suspected ischemia and no obstructive coronary arteries (INOCA), we compared myocardial perfusion reserve during CPT stress cardiac magnetic resonance (CMR) imaging between women with suspected INOCA and reference subjects.

Design

Prospective cohort.

Setting

Academic hospital.

Participants

107 women with suspected INOCA and 21-age-matched reference women.

Interventions

CPT stress CMR was performed with measurement of myocardial perfusion reserve index (MPRI), adjusted for rate pressure product (MPRI_RPP). Invasive coronary function testing in a subset of INOCA women (n=42) evaluated for endothelial dysfunction in response to acetylcholine, including impaired coronary diameter response ≤0% and coronary blood flow response (ΔCBF) <50%.

Main Outcome Measure

MPRI_RPP.

Results

Compared to reference women, the INOCA group demonstrated higher resting RPP (p=0.005) and CPT MPRI_RPP (1.09±0.36 vs 0.83±0.18, p=0.002). Furthermore, INOCA women with impaired ΔCBF (n=23) had higher CPT MPRI_RPP (p=0.044) compared to reference women despite lower left ventricular ejection fraction (64±7 % vs 69±2 %, p=0.005) and mass-to-volume ratio (0.79±0.15 vs 0.62±0.09, p<0.0001). These differences in CPT MPRI_RPP did not persist after adjusting for age, body mass index, and history of hypertension. CPT MPRI_RPP among INOCA women did not differ based on defined acetylcholine responses.

Conclusions

Myocardial perfusion reserve to CPT stress is greater among women with INOCA compared to reference subjects. CPT induced a higher MPRI_RPP also in women with coronary endothelial dysfunction, suggesting a greater contribution of the SNS to coronary flow than endothelial dysfunction. Further investigation in a larger cohort is needed.

FT4/FT3 ratio: A novel biomarker predicts coronary microvascular dysfunction (CMD) in euthyroid INOCA patients

BACKGROUND

Ischemia and no obstructive coronary artery disease (INOCA) patients who presented coronary microvascular dysfunction (CMD) demonstrate a poor prognosis, yet the risk factors for CMD remain unclear. Subtle changes in thyroid hormone levels within the normal range, especially the free thyroxine (FT4)/free triiodothyronine (FT3) ratio, have been shown to regulate the cardiovascular system. This prospective study investigated the correlation between FT4/FT3 ratio and CMD in euthyroid patients with INOCA.

METHODS

This prospective study (www.chictr.org.cn/, ChiCTR2000037112) recruited patients with myocardial ischemia symptoms who underwent both coronary angiography (CAG) and myocardial perfusion imaging (MPI) with dynamic single-photon emission computed tomography (D-SPECT). INOCA was defined as coronary stenosis< 50% and CMD was defined as coronary flow reserve (CFR)<2.5. All patients were excluded from abnormal thyroid function and thyroid disease history.

RESULTS

Among 71 INOCA patients (15 [21.1%] CMD), FT4 and FT4/FT3 ratio in CMD group were significantly higher and both showed significantly moderate correlation with CFR (r=-0.25, p=0.03; r=-0.34, p=0.003, respectively). The ROC curve revealed that FT4/FT3 ratio had the highest efficacy for predicting CMD with an optimized cutoff value>3.39 (AUC 0.78, p<0.001, sensitivity, 80.0%; specificity, 71.4%). Multivariate logistic regression showed that FT4/FT3 ratio was an independent predictor of CMD (OR 7.62, 95% CI 1.12-51.89, p=0.038, P for trend=0.006).

CONCLUSION

In euthyroid INOCA patients, increased FT4/FT3 ratio levels are associated with the occurrence of CMD, presenting a novel biomarker for improving the risk stratification.

Coronary microvascular dysfunction as a chronic inflammatory state: Is there a role for omega-3 fatty acid treatment?

Coronary microvascular dysfunction is a ubiquitous pathologic process that is operational in ischemia with no obstructive coronary artery disease and other cardiovascular disorders including heart failure with preserved ejection fraction. It may, in fact, be a manifestation of a multi-systemic condition of small vessel dysfunction that also affects the brain and kidneys. While the pathophysiology driving coronary microvascular dysfunction is multifactorial, chronic inflammation plays an important role. Resolution of inflammation is an active process mediated, in part, by a family of locally active mediators biosynthesized from omega-3 fatty acids, collectively referred to as specialized pro-resolving mediators. Omega-3 fatty acid treatment modulates inflammation and is associated with improved cardiovascular outcomes and attenuation of plaque progression on cardiovascular imaging. Whether omega-3 fatty acid treatment attenuates coronary microvascular dysfunction is unknown.

2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This clinical practice guideline for the evaluation and diagnosis of chest pain provides recommendations and algorithms for clinicians to assess and diagnose chest pain in adult patients.

METHODS

A comprehensive literature search was conducted from November 11, 2017, to May 1, 2020, encompassing randomized and nonrandomized trials, observational studies, registries, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Additional relevant studies, published through April 2021, were also considered.

STRUCTURE

Chest pain is a frequent cause for emergency department visits in the United States. The "2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain" provides recommendations based on contemporary evidence on the assessment and evaluation of chest pain. This guideline presents an evidence-based approach to risk stratification and the diagnostic workup for the evaluation of chest pain. Cost-value considerations in diagnostic testing have been incorporated, and shared decision-making with patients is recommended.

Microvascular Angina: Diagnosis and Management

Recognition of suspected ischaemia with no obstructive coronary artery disease – termed INOCA – has increased over the past decades, with a key contributor being microvascular angina. Patients with microvascular angina are at higher risk for major adverse cardiac events including MI, stroke, heart failure with preserved ejection fraction and death but to date there are no clear evidence-based guidelines for diagnosis and treatment. Recently, the Coronary Vasomotion Disorders International Study Group proposed standardised criteria for diagnosis of microvascular angina using invasive and non-invasive approaches. The management strategy for remains empirical, largely due to the lack of high-levelevidence- based guidelines and clinical trials. In this review, the authors will illustrate the updated approach to diagnosis of microvascular angina and address evidence-based pharmacological and non-pharmacological treatments for patients with the condition.

Reduced Sympathetic Reserve Detectable by Heart Rate Response after Dipyridamole in Anginal Patients with Normal Coronary Arteries

Background. Patients with ischemia and normal coronary arteries (INOCA) may show abnormal cardiac sympathetic function, which could be unmasked as a reduced heart rate reserve (HRR) during dipyridamole stress echocardiography (SE). Objectives. To assess whether HRR during dipyridamole SE predicts outcome. Methods. Dipyridamole SE was performed in 292 patients with INOCA. HRR was measured as peak/rest heart rate and considered abnormal when ≤1.22 (≤1.17 in presence of permanent atrial fibrillation). All-cause death was the only endpoint. Results. HRR during SE was normal in 183 (63%) and abnormal in 109 patients (37%). During a follow-up of 10.4 ± 5.5 years, 89 patients (30%) died. The 15-year mortality rate was 27% in patients with normal and 54% in those with abnormal HRR (p < 0.0001). In a multivariable analysis, a blunted HRR during SE was an independent predictor of outcome (hazard ratio 1.86, 95% confidence intervals 1.20–2.88; p = 0.006) outperforming inducible ischemia. Conclusions. A blunted HRR during dipyridamole SE predicts a worse survival in INOCA patients, independent of inducible ischemia.

Effect of percutaneous coronary intervention on global hemodynamics and the prevalence of residual microvascular dysfunction

OBJECTIVES

We aimed to examine the changes in hyperemic coronary sinus flow (CSF) and global coronary flow reserve (g-CFR) after percutaneous coronary intervention (PCI) and investigate the predictors to improve these metrics and the prevalence of residual coronary microvascular dysfunction (CMD).

METHODS

This prospective, single-center study included 118 patients with stable coronary artery disease undergoing PCI for a single proximal lesion. Phase-contrast cine-cardiac magnetic resonance (PC-CMR) was used to assess hyperemic CSF (HCSF) and g-CFR, before and after PCI. Residual CMD was defined as concordantly impaired post-PCI HCSF (<2.3 ml/min/g) and g-CFR (<2.0).

RESULTS

HCSF significantly increased, although 38 (32.2%) patients showed a decrease. There was no significant change in g-CFR despite fractional flow reserve (FFR) improvement in all target territories. Concordantly increased HCSF and g-CFR were effectively discriminated by adding PC-CMR-derived information to pre-PCI FFR. Residual CMD was observed in 30 (25.4%) patients and was associated with pre-PCI renal dysfunction and lower pre-PCI rest and hyperemic CSF, but not with pre-PCI regional physiological indices.

CONCLUSIONS

FFR-guided PCI was associated with increased HCSF, but not with increased g-CFR. After uncomplicated PCI, one-quarter of patients showed residual CMD. Our approach may help identify patients who may benefit from increased coronary perfusion or show residual CMD.

Gender-Related Differences in Chest Pain Syndromes in the Frontiers in CV Medicine Special Issue: Sex & Gender in CV Medicine

Coronary artery disease (CAD) is the leading cause of morbidity and mortality among both women and men, yet women continue to have delays in diagnosis and treatment. The lack of recognition of sex-specific biological and socio-cultural gender-related differences in chest pain presentation of CAD may, in part, explain these disparities. Sex and gender differences in pain mechanisms including psychological susceptibility, the autonomic nervous system (ANS) reactivity, and visceral innervation likely contribute to chest pain differences. CAD risk scores and typical/atypical angina characterization no longer appear relevant and should not be used in women and men. Women more often have ischemia with no obstructive CAD (INOCA) and myocardial infarction, contributing to diagnostic and therapeutic equipoise. Existing knowledge demonstrates that chest pain often does not relate to obstructive CAD, suggesting a more thoughtful approach to percutaneous coronary intervention (PCI) and medical therapy for chest pain in stable obstructive CAD. Emerging knowledge regarding the central and ANS and visceral pain processing in patients with and without angina offers explanatory mechanisms for chest pain and should be investigated with interdisciplinary teams of cardiologists, neuroscientists, bio-behavioral experts, and pain specialists. Improved understanding of sex and gender differences in chest pain, including biological pathways as well as sociocultural contributions, is needed to improve clinical care in both women and men.

Endothelium in Coronary Macrovascular and Microvascular Diseases

ABSTRACT

The endothelium plays a pivotal role in the regulation of vascular tone by synthesizing and liberating endothelium-derived relaxing factors inclusive of vasodilator prostaglandins (eg, prostacyclin), nitric oxide (NO), and endothelium-dependent hyperpolarization factors in a distinct blood vessel size-dependent manner. Large conduit arteries are predominantly regulated by NO and small resistance arteries by endothelium-dependent hyperpolarization factors. Accumulating evidence over the past few decades has demonstrated that endothelial dysfunction and coronary vasomotion abnormalities play crucial roles in the pathogenesis of various cardiovascular diseases. Structural and functional alterations of the coronary microvasculature have been coined as coronary microvascular dysfunction (CMD), which is highly prevalent and associated with adverse clinical outcomes in many clinical settings. The major mechanisms of coronary vasomotion abnormalities include enhanced coronary vasoconstrictive reactivity at epicardial and microvascular levels, impaired endothelium-dependent and endothelium-independent coronary vasodilator capacities, and elevated coronary microvascular resistance caused by structural factors. Recent experimental and clinical research has highlighted CMD as the systemic small artery disease beyond the heart, emerging modulators of vascular functions, novel insights into the pathogenesis of cardiovascular diseases associated with CMD, and potential therapeutic interventions to CMD with major clinical implications. In this article, we will summarize the current knowledge on the endothelial modulation of vascular tone and the pathogenesis of coronary macrovascular and microvascular diseases from bench to bedside, with a special emphasis placed on the mechanisms and clinical implications of CMD.

Myocardial infarction with non-obstructive coronary artery disease

As a result of the increased use of coronary angiography in acute myocardial infarction in the last two decades, myocardial infarction with non-obstructive coronary arteries (MINOCA) has received growing attention in everyday clinical practice. At the same time, research interest in MINOCA has increased significantly. MINOCA is a heterogeneous disease entity seen in 5-10% of all patients with myocardial infarction, especially in women. Clinically, MINOCA may be difficult to distinguish from other non-ischaemic conditions that can cause similar symptoms and myocardial injury. There is still some confusion around the diagnosis, investigation and management of patients with MINOCA. The present review summarises the current knowledge of MINOCA regarding epidemiology, pathophysiology, investigation, and treatment, with a special focus on imaging modalities. In addition, remaining important knowledge gaps are highlighted.

Prognostic value of myocardial perfusion imaging with D-SPECT camera in patients with ischemia and no obstructive coronary artery disease (INOCA)

BACKGROUND

Myocardial perfusion imaging (MPI) with a novel D-SPECT camera maintains excellent prognostic value compared to conventional SPECT. However, information about the relationship between D-SPECT MPI and the prognosis in patients with ischemia and no obstructive coronary artery disease (INOCA) is limited. The objective of this study was to evaluate the prognostic value of MPI with D-SPECT in INOCA and obstructive coronary artery disease (CAD) patients.

METHODS

All consecutive patients with suspected CAD and without prior CAD who underwent D-SPECT MPI and invasive coronary angiography within 3 months were considered. INOCA and obstructive CAD were defined as < 50% and ≥ 50% coronary stenosis, respectively. Patients were followed-up for the occurrence of major adverse cardiac events (MACE: cardiovascular death, nonfatal myocardial infarction, revascularization, stroke, heart failure and angina-related rehospitalization).

RESULTS

Among 506 patients, 232 (45.8%) were INOCA patients. A total of 33.2% of the INOCA patients had abnormal D-SPECT MPI, whereas 77.7% of the obstructive CAD patients had abnormal D-SPECT MPI. In both groups, patients with abnormal D-SPECT MPI demonstrated higher MACE rates and lower survival free of MACE. In addition, patients with INOCA and abnormal D-SPECT MPI had a poor prognosis similar to that of the obstructive CAD patients. Cox regression analysis showed that the risk-adjusted hazard ratios for abnormal D-SPECT MPI were 2.55 [1.11-5.87] and 2.06 [1.03-4.10] in the INOCA and obstructive CAD patients, respectively.

CONCLUSIONS

D-SPECT MPI provides excellent prognostic information, with a more severe prognosis in patients with abnormal D-SPECT MPI. INOCA patients with abnormal D-SPECT MPI experience a poor prognosis similar to that of patients with obstructive CAD.

Development and feasibility of quantitative dynamic cardiac imaging for mice using μSPECT

BACKGROUND

Despite growing interest in coronary microvascular disease (CMVD), there is a dearth of mechanistic understanding. Mouse models offer opportunities to understand molecular processes in CMVD. We have sought to develop quantitative mouse imaging to assess coronary microvascular function.

METHODS

We used 99mTc-sestamibi to measure myocardial blood flow in mice with MILabs U-SPECT+ system. We determined recovery and crosstalk coefficients, the influx rate constant from blood to myocardium (K1), and, using microsphere perfusion, constraints on the extraction fraction curve. We used 99mTc and stannous pyrophosphate for red blood cell imaging to measure intramyocardial blood volume (IMBV) as an alternate measure of microvascular function.

RESULTS

The recovery coefficients for myocardial tissue (RT) and left ventricular arterial blood (RA) were 0.81 ± 0.16 and 1.07 ± 0.12, respectively. The assumption RT = 1 - FBV (fraction blood volume) does not hold in mice. Using a complete mixing matrix to fit a one-compartment model, we measured K1 of 0.57 ± 0.08 min-1. Constraints on the extraction fraction curve for 99mTc-sestamibi in mice for best-fit Renkin-Crone parameters were α = 0.99 and β = 0.39. Additionally, we found that wild-type mice increase their IMBV by 22.9 ± 3.3% under hyperemic conditions.

CONCLUSIONS

We have developed a framework for measuring K1 and change in IMBV in mice, demonstrating non-invasive µSPECT-based quantitative imaging of mouse microvascular function.

2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This clinical practice guideline for the evaluation and diagnosis of chest pain provides recommendations and algorithms for clinicians to assess and diagnose chest pain in adult patients.

METHODS

A comprehensive literature search was conducted from November 11, 2017, to May 1, 2020, encompassing randomized and nonrandomized trials, observational studies, registries, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Additional relevant studies, published through April 2021, were also considered.

STRUCTURE

Chest pain is a frequent cause for emergency department visits in the United States. The "2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain" provides recommendations based on contemporary evidence on the assessment and evaluation of chest pain. This guideline presents an evidence-based approach to risk stratification and the diagnostic workup for the evaluation of chest pain. Cost-value considerations in diagnostic testing have been incorporated, and shared decision-making with patients is recommended.

2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the clinical practice guideline for the evaluation and diagnosis of chest pain provides recommendations and algorithms for clinicians to assess and diagnose chest pain in adult patients.

METHODS

A comprehensive literature search was conducted from November 11, 2017, to May 1, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Additional relevant studies, published through April 2021, were also considered.

STRUCTURE

Chest pain is a frequent cause for emergency department visits in the United States. The "2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain" provides recommendations based on contemporary evidence on the assessment and evaluation of chest pain. These guidelines present an evidence-based approach to risk stratification and the diagnostic workup for the evaluation of chest pain. Cost-value considerations in diagnostic testing have been incorporated and shared decision-making with patients is recommended.

2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This clinical practice guideline for the evaluation and diagnosis of chest pain provides recommendations and algorithms for clinicians to assess and diagnose chest pain in adult patients.

METHODS

A comprehensive literature search was conducted from November 11, 2017, to May 1, 2020, encompassing randomized and nonrandomized trials, observational studies, registries, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Additional relevant studies, published through April 2021, were also considered. Structure: Chest pain is a frequent cause for emergency department visits in the United States. The "2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain" provides recommendations based on contemporary evidence on the assessment and evaluation of chest pain. This guideline presents an evidence-based approach to risk stratification and the diagnostic workup for the evaluation of chest pain. Cost-value considerations in diagnostic testing have been incorporated, and shared decision-making with patients is recommended.

2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain: Executive Summary: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

AIM

This executive summary of the clinical practice guideline for the evaluation and diagnosis of chest pain provides recommendations and algorithms for clinicians to assess and diagnose chest pain in adult patients.

METHODS

A comprehensive literature search was conducted from November 11, 2017, to May 1, 2020, encompassing studies, reviews, and other evidence conducted on human subjects that were published in English from PubMed, EMBASE, the Cochrane Collaboration, Agency for Healthcare Research and Quality reports, and other relevant databases. Additional relevant studies, published through April 2021, were also considered. Structure: Chest pain is a frequent cause for emergency department visits in the United States. The "2021 AHA/ACC/ASE/CHEST/SAEM/SCCT/SCMR Guideline for the Evaluation and Diagnosis of Chest Pain" provides recommendations based on contemporary evidence on the assessment and evaluation of chest pain. These guidelines present an evidence-based approach to risk stratification and the diagnostic workup for the evaluation of chest pain. Cost-value considerations in diagnostic testing have been incorporated and shared decision-making with patients is recommended.

Vasomotor Dysfunction in Patients with Ischemia and Non-Obstructive Coronary Artery Disease: Current Diagnostic and Therapeutic Strategies

Many patients who present with symptoms or objective evidence of ischemia have no or non-physiologically-significant disease on invasive coronary angiography. The diagnosis of ischemic heart disease is thus often dismissed, and patients receive false reassurance or other diagnoses are pursued. We now know that a significant proportion of these patients have coronary microvascular dysfunction and/or vasospastic disease as the underlying pathophysiology of their clinical presentation. Making the correct diagnosis of such abnormalities is important not only because they impact the quality of life, with recurring symptoms and unnecessary repeated testing, but also because they increase the risk for adverse cardiovascular events. The mainstay of diagnosis remains an invasive comprehensive physiologic assessment, which further allows stratifying these patients into appropriate “endotypes”. It has been shown that tailoring treatment to the patient’s assigned endotype improves symptoms and quality of life. In addition to the conventional drugs used in chronic stable angina, multiple newer agents are being investigated. Moreover, innovative non-pharmacologic and interventional therapies are emerging to provide a bail-out in refractory cases. Many of these novel therapies fail to show consistent benefits, but others show quite promising results.

Management of ischaemia with non-obstructive coronary arteries (INOCA)

Up to half of patients undergoing elective coronary angiography for the investigation of chest pain do not present with evidence of obstructive coronary artery disease. These patients are often discharged with a diagnosis of non-cardiac chest pain, yet many could have an ischaemic basis for their symptoms. This type of ischaemic chest pain in the absence of obstructive coronary artery disease is referred to as INOCA (ischaemia with non-obstructive coronary arteries). This comprehensive review of INOCA management looks at why these patients require treatment, who requires treatment based on diagnostic evaluation, what clinical treatment targets should be considered, how to treat patients using a personalised medicine approach, when to initiate treatment, and where future research is progressing.

Clinical characteristics and prognosis of patients with microvascular angina: an international and prospective cohort study by the Coronary Vasomotor Disorders International Study (COVADIS) Group

AIMS

To provide multi-national, multi-ethnic data on the clinical characteristics and prognosis of patients with microvascular angina (MVA).

METHODS AND RESULTS

The Coronary Vasomotor Disorders International Study Group proposed the diagnostic criteria for MVA. We prospectively evaluated the clinical characteristics of patients according to these criteria and their prognosis. The primary endpoint was the composite of major cardiovascular events (MACE), verified by institutional investigators, which included cardiovascular death, non-fatal myocardial infarction, non-fatal stroke, and hospitalization due to heart failure or unstable angina. During the period from 1 July 2015 to 31 December 2018, 686 patients with MVA were registered from 14 institutes in 7 countries from 4 continents. Among them, 64% were female and the main ethnic groups were Caucasians (61%) and Asians (29%). During follow-up of a median of 398 days (IQR 365-744), 78 MACE occurred (6.4% in men vs. 8.6% in women, P = 0.19). Multivariable Cox proportional hazard analysis disclosed that hypertension and previous history of coronary artery disease (CAD), including acute coronary syndrome and stable angina pectoris, were independent predictors of MACE. There was no sex or ethnic difference in prognosis, although women had lower Seattle Angina Questionnaire scores than men (P < 0.05).

CONCLUSIONS

This first international study provides novel evidence that MVA is an important health problem regardless of sex or ethnicity that a diagnosis of MVA portends a substantial risk for MACE associated with hypertension and previous history of CAD, and that women have a lower quality of life than men despite the comparable prognosis.

Outpatient Management of Patients With Angina With No Obstructive Coronary Arteries: How to Come to a Proper Diagnosis and Therapy

Two-thirds of women and one-third of men who undergo a clinically indicated coronary angiography for stable angina, have no obstructive coronary artery disease (CAD). Coronary vascular dysfunction is a highly prevalent underlying cause of angina in these so called “Angina with No Obstructive Coronary Arteries (ANOCA)” patients, foremost in middle aged women. Coronary vascular dysfunction encompasses various endotypes, namely epicardial and microvascular coronary spasms, impaired vasodilatation, and increased microvascular resistance. ANOCA patients, especially those with underlying coronary vascular dysfunction, have an adverse cardiovascular prognosis, poor physical functioning, and a reduced quality of life. Since standard ischemia detection tests and coronary angiograms are not designed to diagnose coronary vascular dysfunction, this ischemic heart disease is often overlooked and hence undertreated. But adequate diagnosis is vital, so that treatment can be started to reduce symptoms, reduce healthcare costs and improve quality of life and cardiovascular prognosis. The purpose of this review is to give a contemporary overview of ANOCA with focus on coronary vascular dysfunction. We will provide a possible work-up of patients suspected of coronary vascular dysfunction in the outpatient clinical setting, based on the latest scientific insights and international consensus documents. We will discuss the value of ischemia detection testing, and non-invasive and invasive methods to diagnose coronary vascular dysfunction. Furthermore, we will go into pharmacological and non-pharmacological therapeutic options including anti-anginal regimens and lifestyle interventions.

HuR/Cx40 downregulation causes coronary microvascular dysfunction in type 2 diabetes

Patients with diabetes with coronary microvascular disease (CMD) exhibit higher cardiac mortality than patients without CMD. However, the molecular mechanism by which diabetes promotes CMD is poorly understood. RNA-binding protein human antigen R (HuR) is a key regulator of mRNA stability and translation; therefore, we investigated the role of HuR in the development of CMD in mice with type 2 diabetes. Diabetic mice exhibited decreases in coronary flow velocity reserve (CFVR; a determinant of coronary microvascular function) and capillary density in the left ventricle. HuR levels in cardiac endothelial cells (CECs) were significantly lower in diabetic mice and patients with diabetes than the controls. Endothelial-specific HuR-KO mice also displayed significant reductions in CFVR and capillary density. By examining mRNA levels of 92 genes associated with endothelial function, we found that HuR, Cx40, and Nox4 levels were decreased in CECs from diabetic and HuR-KO mice compared with control mice. Cx40 expression and HuR binding to Cx40 mRNA were downregulated in CECs from diabetic mice. Cx40-KO mice exhibited decreased CFVR and capillary density, whereas endothelium-specific Cx40 overexpression increased capillary density and improved CFVR in diabetic mice. These data suggest that decreased HuR contributes to the development of CMD in diabetes through downregulation of gap junction protein Cx40 in CECs.

The Role of Mental Stress in Ischaemia with No Obstructive Coronary Artery Disease and Coronary Vasomotor Disorders

Ischaemic heart disease has been estimated to affect 126.5 million people globally. Approximately 70% of patients with angina and suspected myocardial ischaemia show no signs of obstructed coronary arteries after coronary angiography, but may still demonstrate ischaemia. Ischaemia with no obstructive coronary artery disease (INOCA) is increasingly acknowledged as a serious condition because of its association with poor quality of life and elevated risk for cardiovascular events. The negative effects of psychological stress on INOCA are gaining more attention. Psychological stress is associated with adverse cardiovascular outcomes such as mental stress-induced myocardial ischaemia. Psychological stress includes anxiety, depression, anger and personality disturbances. Coronary microvascular dysfunction and coronary arterial spasm are phenotypes of coronary vasomotor disorders that are triggered by psychological distress and depression, thereby increasing cardiovascular disease risk. Coronary vasomotor disorders are often co-existent in INOCA patients and might be considered as a contributing factor to mental stress-associated adverse cardiovascular outcomes. Additionally, psychological stress induces endothelial dysfunction more often in (young) women with INOCA than in men. Overall, many studies demonstrate an association between mental stress, coronary microvascular dysfunction and coronary vasospasm in patients with INOCA - especially women. Future research on stress-reducing therapies that target coronary vasomotor disorders in patients with INOCA is needed. This is particularly the case in young adolescents, in whom this type of ischaemic heart disease is increasing.

Insights to advance our management of myocardial ischemia: From obstructive epicardial disease to functional coronary alterations

Study objective

The Coronary Vasomotor Disorders International Study Group (COVADIS) invited leading experts to address strategies to enhance our clinical understanding of INOCA with an emphasis on the management of coronary vasomotor disorders.

Design

Under-recognition of coronary vasomotor disorders, distinguishing different presentations of angina due to vasospasm and/or abnormal microvascular vasodilatation, developing invasive/non-invasive testing and treatment protocols, integrating diagnostic protocols into cardiologists' workflow and trials to inform guideline development were identified as key knowledge gaps and will be briefly addressed in this Viewpoint article.

Setting

Virtual international meeting.

Participants

Leading international experts in ischemic heart disease with no obstructive coronary artery disease.

Interventions

None.

Main outcome measures

None.

Results

Topics discussed include: 1. Obstructive epicardial disease, functional vasospasm and microvascular disorders; 2. Under-recognition of coronary vasomotor disorders in clinical practice; 3. Complexity of coronary vasomotor disorders; 4. Understanding different presentations - vasospastic disease and microvascular angina; 5. Invasive/noninvasive testing and treatment protocols for vasospasm and microvascular angina assessment; 6. Treatment challenges; 7. Integrating diagnostic protocols into cardiologists' workflow; 8. The path forward to advance our approach to managing myocardial ischemia.

Conclusions

Obstructive epicardial disease, functional vasospasm and microvascular disorders often co-exist and contribute to myocardial ischemia. Under-recognition, the complexity of coronary vasomotor disorders, understanding different presentations, testing and treatment protocols, treatment challenges, and integrating diagnostic protocols into cardiologists' workflow all contribute to the path forward to advance our management of myocardial ischemia for improved patient outcomes.

Syndrome of Nonobstructive Coronary Artery Diseases: A Comprehensive Overview of Open Artery Ischemia

Syndromes of cardiac ischemia with nonobstructive coronary arteries have been increasingly recognized as a clinical entity with heterogeneous clinical presentations, commonly encountered in women. Knowledge of pathophysiology and clinical risk factors is key to ensuring appropriate diagnostic evaluation and management for these often-neglected patients. In this review, we discuss the epidemiology, risk factors, and clinical presentations of these syndromes. We provide algorithms for diagnosis and management of these entities based on current scientific knowledge and highlight some of the key knowledge gaps and ongoing trials in this emerging field.

Transient recovery of epicardial and torso ST-segment ischemic signals during cardiac stress tests: A possible physiological mechanism

BACKGROUND

Acute myocardial ischemia has several characteristic ECG findings, including clinically detectable ST-segment deviations. However, the sensitivity and specificity of diagnosis based on ST-segment changes are low. Furthermore, ST-segment deviations have been shown to be transient and spontaneously recover without any indication the ischemic event has subsided.

OBJECTIVE

Assess the transient recovery of ST-segment deviations on remote recording electrodes during a partial occlusion cardiac stress test and compare them to intramyocardial ST-segment deviations.

METHODS

We used a previously validated porcine experimental model of acute myocardial ischemia with controllable ischemic load and simultaneous electrical measurements within the heart wall, on the epicardial surface, and on the torso surface. Simulated cardiac stress tests were induced by occluding a coronary artery while simultaneously pacing rapidly or infusing dobutamine to stimulate cardiac function. Postexperimental imaging created anatomical models for data visualization and quantification. Markers of ischemia were identified as deviations in the potentials measured at 40% of the ST-segment. Intramural cardiac conduction speed was also determined using the inverse gradient method. We assessed changes in intramyocardial ischemic volume proportion, conduction speed, clinical presence of ischemia on remote recording arrays, and regional changes to intramyocardial ischemia. We defined the peak deviation response time as the time interval after onset of ischemia at which maximum ST-segment deviation was achieved, and ST-recovery time was the interval when ST deviation returned to below thresholded of ST elevation.

RESULTS

In both epicardial and torso recordings, the peak ST-segment deviation response time was 4.9±1.1 min and the ST-recovery time was approximately 7.9±2.5 min, both well before the termination of the ischemic stress. At peak response time, conduction speed was reduced by 50% and returned to near baseline at ST-recovery. The overall ischemic volume proportion initially increased, on average, to 37% at peak response time; however, it recovered to only 30% at the ST-recovery time. By contrast, the subepicardial region of the myocardial wall showed 40% ischemic volume at peak response time and recovered much more strongly to 25% as epicardial ST-segment deviations returned to baseline.

CONCLUSION

Our data show that remote ischemic signal recovery correlates with a recovery of the subepicardial myocardium, whereas subendocardial ischemic development persists.

Hitzeman T, Cook‐Wiens G, Pepine CJ, Handberg E, Anderson RD, Petersen J, Hong T, M. Shaw R, Bairey Merz CN. Association of coronary microvascular dysfunction and cardiac bridge integrator 1, a cardiomyocyte dysfunction biomarker

BACKGROUND

Coronary microvascular dysfunction (CMD) is associated with heart failure with preserved ejection fraction (HFpEF); however, pathophysiology is not well described.

HYPOTHESIS

We hypothesized that CMD in women with suspected ischemia with no obstructive coronary artery disease (INOCA) is associated with cardiomyocyte dysfunction reflected by plasma levels of a cardiomyocyte calcium handling protein, cardiac bridge integrator 1 (cBIN1).

METHODS

Women with suspected INOCA undergoing coronary function testing were included. Coronary flow reserve, vasodilation to nitroglycerin, change in coronary blood flow (ΔCBF), and vasodilation to acetylcholine (ΔAch) were evaluated. cBIN1 score (CS) levels in these women (n = 39) were compared to women with HFpEF (n = 20), heart failure with reduced ejection fraction (HFrEF) (n = 36), and reference controls (RC) (n = 50). Higher CS indicates cardiomyocyte tubule dysfunction.

RESULTS

INOCA, HFpEF, and HFrEF women were older than RC (p < .05). Higher CS was associated with vasoconstriction to acetylcholine (r = -0.43, p = .011) with a trend towards lower ΔCBF (r = 0.30, p = .086). Higher CS was specific for ΔAch and ΔCBF but had limited sensitivity. INOCA women had higher CS than RC, but lower CS than HFpEF/HFrEF groups (p < .001).

CONCLUSIONS

CS, a plasma biomarker indicating poor cardiomyocyte health, was higher in women with suspected INOCA as compared to RC, but lower than in women with HFpEF. Elevated CS in suspected INOCA patients represents an intermediate group between health and disease, supporting the hypothesis that CMD may progress to HFpEF. Larger prospective cohort studies are needed to confirm the pathophysiological relationship between cBIN1, CMD, and HFpEF.

Doppler Echocardiography Assessment of Coronary Microvascular Function in Patients With Angina and No Obstructive Coronary Artery Disease

Echocardiographic evaluation is an essential part of the diagnostic work-up in patients with known or suspected cardiovascular disease. Transthoracic Doppler echocardiography (TTDE) enables straightforward and reliable visualization of flow in the left anterior descending artery. In the absence of obstructive coronary artery disease, low TTDE-derived coronary flow velocity reserve (CFVR) is considered a marker of coronary microvascular dysfunction (CMD). TTDE CFVR is free from ionizing radiation and widely available, utilizing high-frequency transducers, pharmacologic vasodilator stress, and pulsed-wave Doppler quantification of diastolic peak flow velocities. European Society of Cardiology guidelines recommend TTDE CFVR evaluation only following preceding anatomic invasive or non-invasive coronary imaging excluding obstructive CAD. Accordingly, clinical use of TTDE CFVR is limited and CMD frequently goes undiagnosed. An evolving body of evidence underlines that low CFVR is an important and robust predictor of adverse prognosis and continuing symptoms in angina patients both with and without obstructive CAD. The majority of angina patients have no obstructive CAD, particularly among women. This has led to the suggestion that there may be a gender-specific female atherosclerotic phenotype with less epicardial obstruction, and a low CFVR signifying CMD instead. Nevertheless, available evidence indicates low CFVR is an equally important prognostic marker in both men and women. In this review, TTDE CFVR was evaluated regarding indication, practical and technical aspects, and interpretation of results. Association with symptoms and prognosis, comparison with alternative invasive and non-invasive imaging modalities, and possible interventions in angina patients with low CFVR were discussed, and key research questions were proposed.

Assessing Microvascular Dysfunction in Angina With Unobstructed Coronary Arteries: JACC Review Topic of the Week

Coronary microvascular dysfunction is a highly prevalent condition of both structural and functional coronary disorders in patients with angina and nonobstructive coronary artery disease (ANOCA). Current diagnostic modalities to assess microvascular function are related to prognosis, but these modalities have several technical shortcomings and lack the opportunity to determine true coronary blood flow and microvascular resistance. Intracoronary continuous thermodilution assessment of absolute coronary flow (Q) and microvascular resistance (R) was recently shown to be safe and feasible in ANOCA. Further exploration and implementation could lead to a better understanding and treatment of patients with ANOCA. This review discuss the coronary pathophysiology of microvascular dysfunction, provides an overview of noninvasive and invasive diagnostics, and focuses on the novel continuous thermodilution method. Finally, how these measurements of absolute Q and R could be integrated and how this would affect future clinical care are discussed.

Pathophysiology and Diagnosis of Coronary Functional Abnormalities

Approximately one-half of patients undergoing diagnostic coronary angiography for angina have no significant coronary atherosclerotic stenosis. This clinical condition has recently been described as ischaemia with non-obstructive coronary arteries (INOCA). Coronary functional abnormalities are central to the pathogenesis of INOCA, including epicardial coronary spasm and coronary microvascular dysfunction composed of a variable combination of increased vasoconstrictive reactivity and/or reduced vasodilator function. During the last decade - in INOCA patients in particular - evidence for the prognostic impact of coronary functional abnormalities has accumulated and various non-invasive and invasive diagnostic techniques have enabled the evaluation of coronary vasomotor function in a comprehensive manner. In this review, the authors briefly summarise the recent advances in the understanding of pathophysiology and diagnosis of epicardial coronary artery spasm and coronary microvascular dysfunction.

Cardiac medication use in patients with suspected ischaemia without obstructive coronary arteries: sex differences and psychological distress

BACKGROUND

Ischaemia without obstructive coronary arteries (INOCA) is more prevalent in women and associated with psychological distress. Pharmacological treatment goals are angina relief and cardiovascular risk management. The present study aims to examine sex differences in cardiac and non-cardiac medication use, as well as medication and sex differences related to consistent psychological distress in patients with suspected INOCA.

DESIGN

A TweeSteden mild stenosis observational cohort study in patients with suspected INOCA as detected by ischaemic reason for referral and non-obstructive arteries based on coronary angiography or computed tomography.

METHODS

Medication documented in the hospital records of 488 patients (53% women) was coded as angina relief medication, blood-pressure-lowering medication, antithrombotics, statins, and non-cardiac medication, using the Anatomical Therapeutic Chemical code. Depressive symptoms and anxiety were recoded as 'consistent distress' (above the cut-off score for depression and anxiety on validated questionnaires), 'inconsistent distress' (above the cut-off for depression or anxiety) or 'no distress' (below the cut-off).

RESULTS

No sex differences were observed in cardiac medication use. Women used anxiolytic benzodiazepines more often (12% vs 4%, p = 0.002) compared to men. Consistent distress was more prevalent in women (22% vs 15%, p = 0.004) and was related to the use of more angiotensin-converting enzyme inhibitors/angiotensin receptor blockers and diuretics in women and to calcium antagonist use as well as lower adherence levels in men. Women who reported chest pain more often received angina relief medication and blood-pressure-lowering medication than men.

CONCLUSION

No sex differences were observed in cardiac medication use in patients with suspected INOCA. Psychological distress may reflect hypertension and subsequent medication use in women, and experiencing chest pain and subsequent medication use in men.