Why names matter for women: MINOCA/INOCA (myocardial infarction/ischemia and no obstructive coronary artery disease)

Women Acute Myocardial Infarction-Identifying and Understanding the Gender Gap (WAMy-GAP): A Study Protocol

Barriers to accessing care and misinterpretations of ischemic heart disease symptoms due to lack of awareness contribute to women's delay in seeking care. Women may delay seeking treatment for up to 3 h or even up to 5 days. They often perceive themselves to be at low risk of cardiovascular disease (CVD) and prioritize family responsibilities or household chores. The causes of this delay are multifactorial and influence the decision-making process, particularly in the pre-hospital phase. The objective of this study protocol is to evaluate prodromal symptoms and identify risk behaviors in women with acute myocardial infarction (AMI). This is a protocol for a multicenter study that will be conducted using the mixed-method methodology using the McSweeney Acute and Prodromal Myocardial Infarction Symptom Survey (MAPMISS) to evaluate symptoms and semi-structured interviews to investigate behaviors. This study protocol is intended to fill an important knowledge gap on premonitory and acute symptoms of AMI in women in Italy, as well as to understand the causes and mechanisms underlying delays in accessing healthcare services during an acute event such as AMI. The investigation of this issue will facilitate the removal of gender-related inequalities in the diagnosis and treatment of acute myocardial infarction while also fostering dialogue on the barriers to behavior change.

Coronary microvascular dysfunction: prevalence and aetiology in patients with suspected myocardial ischaemia

AIM

To evaluate the prevalence, aetiology, and corresponding morbidity of coronary microvascular dysfunction (CMD) in patients with suspected myocardial ischaemia.

MATERIALS AND METHODS

The present study included 115 patients with suspected myocardial ischaemia who underwent stress perfusion cardiac magnetic resonance imaging. CMD was assessed visually based on the myocardial perfusion results. The CMR-derived myocardial perfusion reserve index (MPRI) and left ventricular (LV) strain parameters obtained using the post-processing software CVI42 were employed to evaluate LV myocardial perfusion and deformation. LV strain parameters included global longitudinal, circumferential, and radial strain (GLS, GCS, and GRS), global systolic/diastolic longitudinal, circumferential, and radial strain rates (SLSR, SCSR, SRSR, DLSR, DCSR, and DRSR).

RESULTS

Of the 115 patients, 12 patients were excluded and 103 patients were finally included in the study. CMD was observed in 79 % (81 patients, aged 53 ± 12 years) of patients. Regarding aetiology, 91 (88 %) patients had non-obstructive coronary artery disease (CAD), eight (8 %) had obstructive CAD, and four (4 %) had hypertrophic cardiomyopathy (HCM). The incidence of CMD was highest (100 %) in patients with HCM, followed by those with non-obstructive CAD (up to 79 %). There were no statistical differences between CMD and non-CMD groups in GCS, GRS, GLS, SRSR, SCSR, SLSR, DCSR, DRSR and DLSR.

CONCLUSION

The incidence of CMD was higher in patients with signs and symptoms of ischaemia. CMD occurred with non-obstructive CAD, obstructive CAD, and HCM, with the highest prevalence of CMD in HCM.

Nonobstructive epicardial coronary artery disease: an evolving concept in need of diagnostic and therapeutic guidance

For decades, we have been treating patients presenting with angina and concerning electrocardiographic changes indicative of ischemia or injury, in whom no culprit epicardial coronary stenosis was found during diagnostic coronary angiography. Unfortunately, the clinical outcomes of these patients were not better than those with recognized obstructive coronary disease. Improvements in technology have allowed us to better characterize these patients. Consequently, an increasing number of patients with ischemia and no obstructive coronary artery disease (INOCA) or myocardial infarction in the absence of coronary artery disease (MINOCA) have now gained formal recognition and are more commonly encountered in clinical practice. Although both entities might share functional similarities at their core, they pose significant diagnostic and therapeutic challenges. Unless we become more proficient in identifying these patients, particularly those at higher risk, morbidity and mortality outcomes will not improve. Though this field remains in constant flux, data continue to become available. Therefore, we thought it would be useful to highlight important milestones that have been recognized so we can all learn about these clinical entities. Despite all the progress made regarding INOCA and MINOCA, many important knowledge gaps continue to exist. For the time being, prompt identification and early diagnosis remain crucial in managing these patients. Even though we are still not clear whether intensive medical therapy alters clinical outcomes, we remain vigilant and wait for more data.

Single Nucleotide Polymorphisms in Coronary Microvascular Dysfunction

Coronary microvascular dysfunction is an underdiagnosed pathologic process that is associated with adverse clinical outcomes. There are data to suggest that coronary microvascular dysfunction, in some cases, may be genetically determined. We present an updated review of single nucleotide polymorphisms in coronary microvascular dysfunction.

Physical activity and odds of coronary heart disease among Lebanese women

BACKGROUND

It is known that physical activity (PA) is protective against cardiovascular morbidity and mortality. However, few studies have examined the association between PA, sedentary lifestyle and coronary heart disease (CHD) in women. This case-control study investigates the relationship between PA and sedentary behavior on CHD odds in Lebanese women over forty.

METHODS

One thousand five hundred selected Lebanese women (300 cases and 1200 controls) were included between 2018-2019. Cases were hospitalized women newly diagnosed with CHD, whereas the control groups were free of any heart diseases. Data on socio-demographic, lifestyle, cardiovascular factors, PA and sedentary lifestyle were collected. Multivariate logistic regressions, adjusted for covariates, were performed to investigate the association of PA domains and sedentary behavior with CHD.

RESULTS

A sedentary lifestyle combined with low activity levels increased the odds of CHD. Among cases, 46.7% participated in moderate or vigorous PA against almost 60.3% of controls. 36.3% of coronary patients had more than 10 h/day of sedentary time, with a positive correlation with CHD (adjusted OR: 1.533, 95%CI: 1.046-2.247). Conversely, moderate and high levels (respectively 600-3000 and ≥ 3000 metabolic equivalents [MET]-minutes/week) of domestic/garden PA revealed lower CHD odds (OR: 0.566, 95%CI: 0.396-0.808 and 0.193, 0.065-0.578 respectively). The detrimental influence of sedentary lifestyle appeared to be significantly reversed by weekly moderate PA, especially as weekly sedentary time was less (OR: 0.616, 95%CI: 0.427-0.888/ 6 to10h of sedentary time and OR: 0.537, 95% CI: 0.37-0.779/ ≤ 6 h), and except sedentary time exceeding 10 h daily. Two PA patterns revealed lower CHD odds: transport-related and domestic/garden PA, as early as low amount, even after adjustment for possible confounders.

CONCLUSION

The current study highlights the importance of combating sedentary behaviors and engaging in regular, easily accessible PA to reduce the odds of coronary disease among aging women. Therefore, better information regarding the benefits of physical activities such as transportation-related activities or gardening would be helpful in enhancing the prevention of CHD in aging women.

The Development of a Chest-Pain Protocol for Women Presenting to the Emergency Department

Cardiovascular disease (CVD) is the leading cause of death in women worldwide, and of premature death in women in Canada. Despite improvements in cardiovascular care over the past 15-20 years, acute coronary syndrome (ACS) and CVD mortality continue to increase among women in Canada. Chest pain is a common symptom leading to emergency department visits for both men and women. However, women with ACS experience worse outcomes. compared with those of men, due to misdiagnosis or lack of diagnosis resulting in delayed care and underuse of guideline-directed medical therapies. CVD mortality rates are highest in Indigenous and racialized women and those with a disproportionately high number of adverse social determinants of health. CVD remains underrecognized, underdiagnosed, undertreated, and underresearched in women. Moreover, a lack of awareness of unique symptoms, clinical presentations, and sex-and-gender specific CVD risk factors, by healthcare professionals, leads to outcome disparities. In response to this knowledge gap, in acute recognition and management of chest-pain syndromes in women, the Canadian Women's Heart Health Alliance performed a needs assessment and review of CVD risk factors and ACS pathophysiology, through a sex and gender lens, and then developed a unique chest-pain assessment protocol utilizing modified dynamic programming algorithmic methodology. The resulting algorithmic protocol is presented. The output is intended as a quick reference algorithm that could be posted in emergency departments and other acute-care settings. Next steps include protocol implementation evaluation and impact assessment on CVD outcomes in women.

Community- and Patient-Partner Engagement in Women's Cardiovascular Disease Research: A Rapid Review of the Evidence

The primary objective of this rapid review is to describe community-partner and patient-partner engagement in women's cardiovascular disease (CVD) research. Secondary objectives are to: (i) describe the phase of the research in which community and patient partners were engaged; (ii) define the level of engagement at each research phase; and (iii) make recommendations for future engagement of community and/or patient partners in women's CVD research. Rapid review guidelines recommended by the Cochrane Rapid Reviews Methods Group and Tricco et al. were used to search 5 databases using medical subject headings (MeSH) and/or keywords. Participants included women (cis and trans) aged > 18 years who had ischemic heart disease, heart failure, or stroke. A risk of bias assessment was not undertaken. Findings are summarized and/or clustered as community-based participatory research, or patient-oriented and/or patient-partner research. Our search yielded 39,998 titles and abstracts. Of these, 35 were included in a final narrative synthesis, comprising data from 474 community and/or patient partners, including 417 (88%) women. Over 85% of community partners collaborated in the design and/or planning and implementation of women's CVD research; most originated in the US; only one originated in Canada. Most patient-oriented and patient-partner research originated in Canada. However, less than 50% of patient partners collaborated in any phase of research. Sex, gender, race, and ethnicity were rarely reported. Results suggest negligible community and inadequate patient-oriented and/or patient-partner engagement in women's CVD research in Canada. Improved CVD outcomes for women may be achieved with better community- and patient-partner collaboration across all phases of research, genders, race, and ethnicities.

Clinical aspects of ischemia with no obstructive coronary artery disease (INOCA)

Ischemia with no obstructive coronary arteries (INOCA) is defined as patients with evidence of myocardial ischemia without obstructive coronary artery disease. About 3-4 million people in the United States have INOCA, more commonly affecting women, and carries adverse morbidity, mortality, and relatively high healthcare costs. The pathophysiology of INOCA appears to be multi-factorial with a variety of contributing mechanisms. Diagnosis of INOCA is suggested by non-invasive or invasive testing consistent with myocardial ischemia. Due to the high prevalence of coronary risk factors and atherosclerosis in the INOCA population, current treatment strategies target angina, coronary atherosclerosis, and atherosclerotic risk factors, as well as burgeoning treatment of coronary microvascular dysfunction (CMD). Ongoing clinical trials are assessing different options.

Adverse Cardiovascular Events Associated With Kopi Jantan

Energy drinks (EDs) are widely accessible worldwide. In Malaysia, it is common for EDs to be premixed with sexual stimulants. ED consumption has been shown to have an association with cardiac arrest, myocardial infarction, spontaneous coronary artery dissection, and coronary vasospasm. In addition to this, EDs are associated with arrhythmias, which significantly prolong the QTc interval. Myocardial infarction with no obstructive coronary artery disease (MINOCA) is defined as a patient presenting with myocardial infarction with no obstructive coronary artery disease or ≤50% stenosis. It is a challenging and complex pathophysiology compared to obstructive coronary artery disease. MINOCA is more frequently associated with younger patients and women. Here, we report two cases related to a Malaysian local energy drink Kopi Jantan, which presented with atrial flutter and MINOCA.

Sex differences of sequential changes in coronary blood flow and microvascular function in patients with suspected angina

AIMS

This study evaluated the sex differences of sequential changes in coronary blood flows and microvascular function in patients with suspected angina but with no obstructed coronary arteries.

METHODS

A total of 202 consecutive patients who experienced chest pain but had no significant coronary artery stenosis and who underwent adenosine stress echocardiography were included in the study. Coronary blood flow (CBF) velocities were measured at 1, 2, and 3 min after adenosine infusion.

RESULTS

The mean age was 61 years, and 138 (68%) were women. Approximately 40% of patients had coronary microvascular dysfunction (CMD, coronary flow velocity reserve < 2.3), with women exhibiting higher CMD prevalence. The left ventricular (LV) mass index was similar between men and women, while women exhibited higher baseline rate pressure products (RPP). At baseline, coronary blood flow velocities were similar between the sexes. However, CBF velocities in women gradually increased during the examination; and in men, the increase was abrupt and steep during the early stages of examination (p = 0.015 for interaction between time and sex), even with similar RPP in stress. Coronary flow velocity reserve was steadily lower in women compared to men (1 min, 2.09 ± 0.86 vs 2.44 ± 0.87; 2 min, 2.39 ± 0.72 vs 2.63 ± 0.85; 3 min, 2.45 ± 0.70 vs 2.68 ± 0.73).

CONCLUSIONS

In patients with suspected angina but with no obstructed coronary arteries, CMD was especially prevalent among women. Women exhibited higher oxygen consumption, while exhibiting slower and gradual increases in CBF velocities. Conversely, men exhibited faster and steeper increases in CBF velocities even with similar RPP in stress.

MINOCA: Diagnostic work-up, risk stratification and tailored therapies

Myocardial infarction with no obstructive coronary artery disease (MINOCA) diagnostic work-up, risk stratification and tailored therapies are emerging as the recognition of this type of MI is increasingly recognized. Diagnostic workup using advanced imaging can include coronary angiography/intravascular ultrasound (IVUS)/optical coherent tomography (OCT), echo and cardiac magnetic resonance imaging (MRI). Risk stratification portends an intermediate risk compared to multivessel obstructive coronary artery disease (CAD). While event rates are high enough to warrant concern, they are relatively low enough to require trials with large sample sizes and hard outcomes. Tailored therapies include common sense therapeutic lifestyle change (TLC) and optimal medical therapy (OMT) due to the high prevalence of non-obstructive CAD, however therapeutic clinical trials are needed. Currently one large outcome trial in ischemia with no obstructive coronary artery disease (INOCA) is ongoing.

Sex differences in the management of atherosclerotic cardiovascular disease

Disparities between women and men persist in the diagnosis, treatment, and prognosis of atherosclerotic cardiovascular disease (ASCVD). Despite growing attention to sex-based differences in cardiovascular care, there are continued disparities in short- and long-term outcomes. Such disparities highlight the need to identify pathophysiologic differences in treatment patterns for stable ischemic heart disease, non-ST elevation myocardial infarction (NSTE-ACS), ST-elevation myocardial infarction (STEMI), and myocardial infarction with non-obstructive coronary arteries (MINOCA). The role of age as an effect modifier should also be considered given that young women diagnosed with ACS continue to experience increased rates of in-hospital mortality and major adverse cardiovascular events. Both patient-directed and systems-based approaches remain integral to improve outcomes in cardiovascular care. While inadequate representation of women in clinical trials remains a barrier to the implementation of evidence-based therapies, a growing body of data has established the efficacy and safety of medications in women across acute coronary syndromes. This review seeks to feature existing data on the differential treatment guidelines, care implementation, and cardiovascular outcomes between women and men, highlighting next directions for clinical investigation.

Advanced Cardiac Imaging and Women's Chest Pain: A Question of Gender

Awareness of gender differences in cardiovascular disease (CVD) has increased: both the different impact of traditional cardiovascular risk factors on women and the existence of sex-specific risk factors have been demonstrated. Therefore, it is essential to recognize typical aspects of ischemic heart disease (IHD) in women, who usually show a lower prevalence of obstructive coronary artery disease (CAD) as a cause of acute coronary syndrome (ACS). It is also important to know how to recognize pathologies that can cause acute chest pain with a higher incidence in women, such as spontaneous coronary artery dissection (SCAD) and myocardial infarction with non-obstructive coronary arteries (MINOCA). Coronary computed tomography angiography (CCTA) and cardiac magnetic resonance imaging (CMR) gained a pivotal role in the context of cardiac emergencies. Thus, the aim of our review is to investigate the most frequent scenarios in women with acute chest pain and how advanced cardiac imaging can help in the management and diagnosis of ACS.

Myocardial Infarction with Non-Obstructive Coronary Arteries (MINOCA): Focus on Coronary Microvascular Dysfunction and Genetic Susceptibility

Among the most common causes of death worldwide, ischemic heart disease (IHD) is recognized to rank first. Even if atherosclerotic disease of the epicardial arteries is known as the leading cause of IHD, the presence of myocardial infarction with non-obstructive coronary artery disease (MINOCA) is increasingly recognized. Notwithstanding the increasing interest, MINOCA remains a puzzling clinical entity that can be classified by distinguishing different underlying mechanisms, which can be divided into atherosclerotic and non-atherosclerotic. In particular, coronary microvascular dysfunction (CMD), classifiable in non-atherosclerotic mechanisms, is a leading factor for the pathophysiology and prognosis of patients with MINOCA. Genetic susceptibility may have a role in primum movens in CMD. However, few results have been obtained for understanding the genetic mechanisms underlying CMD. Future studies are essential in order to find a deeper understanding of the role of multiple genetic variants in the genesis of microcirculation dysfunction. Progress in research would allow early identification of high-risk patients and the development of pharmacological, patient-tailored strategies. The aim of this review is to revise the pathophysiology and underlying mechanisms of MINOCA, focusing on CMD and actual knowledge about genetic predisposition to it.

Predictors of Long-Term Mortality in Patients with Stable Angina Pectoris and Coronary Slow Flow

Background and Objectives: Coronary slow flow (CSF) is an angiographic phenomenon characterized by the slow progression of an injected contrast agent during diagnostic coronary angiography in the absence of significant stenosis. Although CSF is a common angiographic finding, the long-term outcomes and mortality rates are still unknown. This study aimed to investigate the underlying causes of mortality over a 10-year period in patients diagnosed with stable angina pectoris (SAP) and CSF. Materials and Methods: This study included patients with SAP who underwent coronary angiography from 1 January 2012 to 31 December 2012. All patients displayed CSF despite having angiographically normal coronary arteries. Hypertension (HT), diabetes mellitus (DM), hyperlipidaemia, medication compliance, comorbidities, and laboratory data were recorded at the time of angiography. Thrombolysis in myocardial infarction (TIMI) frame count (TFC) was calculated for each patient. The cardiovascular (CV) and non-CV causes of long-term mortality were assessed. Results: A total of 137 patients with CSF (93 males; mean age: 52.2 ± 9.36 years) were included in this study. Twenty-one patients (15.3%) died within 10 years of follow-up. Nine (7.2%) and 12 (9.4%) patients died of non-CV and CV causes, respectively. Total mortality in patients with CSF was associated with age, HT, discontinuation of medications, and high-density lipoprotein cholesterol (HDL-C) levels. The mean TFC was associated with CV mortality. Conclusion: Patients with CSF exhibited a notable increase in cardiovascular-related and overall mortality rates after 10 years of follow-up. HT, discontinuation of medications, HDL-C levels, and mean TFC were associated with mortality in patients with CSF.

Sex-related differences in coronary vasomotor disorders: Comparisons between Western and Japanese populations

Sex-related differences in the prevalence of cardiac disorders have been elucidated beyond races. Angina/ischemia with nonobstructive coronary artery disease (AINOCA) is often observed in females. Coronary microvascular dysfunction (CMD) and coronary epicardial spasm (CES) are the principal cause of AINOCA. The clinical outcomes of Western patients with CMD were less satisfactory than expected, while the prognosis of Japanese patients with CES treated with medications including calcium channel blockers was favorable. However, the incidence and clinical features of coronary spasm endotypes were different between Western and Japanese populations. Furthermore, sex-related differences in the clinical manifestations and outcomes of patients with different spasm endotypes remain uncertain beyond race. In this article, we will review the sex differences in Japanese AINOCA patients with coronary vasomotor disorders, including CMD and CES, and compare them with those of Western patients.

[Sex and gender-specific aspects in prediabetes and diabetes mellitus-clinical recommendations (Update 2023)]

Metabolic diseases dramatically affect the life of men and women from infancy up to old age in different and manifold ways and are a major challenge for the healthcare system. The treating physicians are confronted with the different needs of women and men in the clinical routine. Gender-specific differences affect pathophysiology, screening, diagnostic and treatment strategies of diseases as well as the development of complications and mortality rates. Impairments in glucose and lipid metabolism, regulation of energy balance and body fat distribution and therefore the associated cardiovascular diseases, are greatly influenced by steroidal and sex hormones. Furthermore, education, income and psychosocial factors play an important role in the development of obesity and diabetes differently in men and women. Males appear to be at greater risk of diabetes at a younger age and at a lower body mass index (BMI) compared to women but women feature a dramatic increase in the risk of diabetes-associated cardiovascular diseases after the menopause. The estimated future years of life lost owing to diabetes is somewhat higher in women than men, with a higher increase in vascular complications in women but a higher increase of cancer deaths in men. In women prediabetes or diabetes are more distinctly associated with a higher number of vascular risk factors, such as inflammatory parameters, unfavourable changes in coagulation and higher blood pressure. Women with prediabetes and diabetes have a much higher relative risk for vascular diseases. Women are more often morbidly obese and less physically active but may have an even greater benefit in health and life expectation from increased physical activity than men. In weight loss studies men often showed a higher weight loss than women; however, diabetes prevention is similarly effective in men and women with prediabetes with a risk reduction of nearly 40%. Nevertheless, a long-term reduction in all cause and cardiovascular mortality was so far only observed in women. Men predominantly feature increased fasting blood glucose levels, women often show impaired glucose tolerance. A history of gestational diabetes or polycystic ovary syndrome (PCOS) as well as increased androgen levels and decreased estrogen levels in women and the presence of erectile dysfunction or decreased testosterone levels in men are important sex-specific risk factors for the development of diabetes. Many studies showed that women with diabetes reach their target values for HbA_1c, blood pressure and low-density lipoprotein (LDL)-cholesterol less often than their male counterparts, although the reasons are unclear. Furthermore, sex differences in the effects, pharmacokinetics and side effects of pharmacological treatment should be taken more into consideration.

Fibromuscular Dysplasia and Abdominal Aortic Aneurysms Are Dimorphic Sex-Specific Diseases With Shared Complex Genetic Architecture

BACKGROUND

The risk of arterial diseases may be elevated among family members of individuals having multifocal fibromuscular dysplasia (FMD). We sought to investigate the risk of arterial diseases in families of individuals with FMD.

METHODS

Family histories for 73 probands with FMD were obtained, which included an analysis of 463 total first-degree relatives focusing on FMD and related arterial disorders. A polygenic risk score for FMD (PRSFMD) was constructed from prior genome-wide association findings of 584 FMD cases and 7139 controls and evaluated for association with an abdominal aortic aneurysm (AAA) in a cohort of 9693 AAA cases and 294 049 controls. A previously published PRSAAA was also assessed among the FMD cases and controls.

RESULTS

Of all first degree relatives of probands, 9.3% were diagnosed with FMD, aneurysms, and dissections. Aneurysmal disease occurred in 60.5% of affected relatives and 5.6% of all relatives. Among 227 female first-degree relatives of probands, 4.8% (11) had FMD, representing a relative risk (RR)FMD of 1.5 ([95% CI, 0.75-2.8]; P=0.19) compared with the estimated population prevalence of 3.3%, though not of statistical significance. Of all fathers of FMD probands, 11% had AAAs resulting in a RRAAA of 2.3 ([95% CI, 1.12-4.6]; P=0.014) compared with population estimates. The PRSFMD was found to be associated with an AAA (odds ratio, 1.03 [95% CI, 1.01-1.05]; P=2.6×10-3), and the PRSAAA was found to be associated with FMD (odds ratio, 1.53 [95% CI, 1.2-1.9]; P=9.0×10-5) as well.

CONCLUSIONS

FMD and AAAs seem to be sex-dimorphic manifestations of a heritable arterial disease with a partially shared complex genetic architecture. Excess risk of having an AAA according to a family history of FMD may justify screening in family members of individuals having FMD.

Ischemia and no obstructive coronary arteries (INOCA): A narrative review

Myocardial ischemia with no obstructive coronary arteries (INOCA) is a chronic coronary syndrome condition that is increasingly being recognized as a substantial contributor to adverse cardiovascular mortality and outcomes, including myocardial infarction and heart failure with preserved ejection fraction (HFpEF). While INOCA occurs in both women and men, women are more likely to have the finding of INOCA and are more adversely impacted by angina, with recurrent hospitalizations and a lower quality of life with this condition. Abnormal epicardial coronary vascular function and coronary microvascular dysfunction (CMD) have been identified in a majority of INOCA patients on invasive coronary function testing. CMD can co-exist with obstructive epicardial coronary artery disease (CAD), diffuse non-obstructive epicardial CAD, and with coronary vasospasm. Epicardial vasospasm can also occur with normal coronary arteries that have no atherosclerotic plaque on intravascular imaging. While all predisposing factors are not clearly understood, cardiometabolic risk factors, and endothelium dependent and independent mechanisms that increase oxidative stress and inflammation are associated with microvascular injury, CMD and INOCA. Cardiac autonomic dysfunction has also been implicated in abnormal vasoreactivity and persistent symptoms. INOCA is under-recognized and under-diagnosed, partly due to the heterogenous patient populations and mechanisms. However, diagnostic testing methods are available to guide INOCA management. Treatment of INOCA is evolving, and focuses on cardiac risk factor control, improving ischemia, reducing atherosclerosis progression, and improving angina and quality of life. This review focuses on INOCA, relations to HFpEF, available diagnostics, current and investigational therapeutic strategies, and knowledge gaps in this condition.

Myocardial infarction with non-obstructive coronary arteries (MINOCA)

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is evident in up to 15% of all acute myocardial infarctions (AMI) and disproportionally affects females. Despite younger age, female predominance, and fewer cardiovascular risk factors, MINOCA patients have a worse prognosis than patients without cardiovascular disease and a similar prognosis compared to patients with MI and obstructive coronary artery disease (CAD). MINOCA is a syndrome with a broad differential diagnosis that includes both ischemic [coronary artery plaque disruption, coronary vasospasm, coronary microvascular dysfunction, spontaneous coronary artery dissection (SCAD), and coronary embolism/thrombosis] and non-ischemic mechanisms (Takotsubo cardiomyopathy, myocarditis, and non-ischemic cardiomyopathy)-the latter called MINOCA mimickers. Therefore, a standardized approach that includes multimodality imaging, such as coronary intravascular imaging, cardiac magnetic resonance, and in selected cases, coronary reactivity testing, including provocation testing for coronary vasospasm, is necessary to determine underlying etiology and direct treatment. Herein, we review the prevalence, characteristics, prognosis, diagnosis, and treatment of MINOCA -a syndrome often overlooked.

T2 and T2⁎ mapping and weighted imaging in cardiac MRI

Cardiac imaging is progressing from simple imaging of heart structure and function to techniques visualizing and measuring underlying tissue biological changes that can potentially define disease and therapeutic options. These techniques exploit underlying tissue magnetic relaxation times: T₁, T₂ and T₂*. Initial weighting methods showed myocardial heterogeneity, detecting regional disease. Current methods are now fully quantitative generating intuitive color maps that do not only expose regionality, but also diffuse changes - meaning that between-scan comparisons can be made to define disease (compared to normal) and to monitor interval change (compared to old scans). T₁ is now familiar and used clinically in multiple scenarios, yet some technical challenges remain. T₂ is elevated with increased tissue water - oedema. Should there also be blood troponin elevation, this oedema likely reflects inflammation, a key biological process. T₂* falls in the presence of magnetic/paramagnetic materials - practically, this means it measures tissue iron, either after myocardial hemorrhage or in myocardial iron overload. This review discusses how T₂ and T₂^⁎ imaging work (underlying physics, innovations, dependencies, performance), current and emerging use cases, quality assurance processes for global delivery and future research directions.

Coronary microvascular disease: The "Meeting Point" of Cardiology, Rheumatology and Endocrinology

BACKGROUND

Exertional chest pain/dyspnea or chest pain at rest are the main symptoms of coronary artery disease (CAD), which are traditionally attributed to insufficiency of the epicardial coronary arteries. However, 2/3 of women and 1/3 of men with angina and 10% of patients with acute myocardial infarction have no evidence of epicardial coronary artery stenosis in X-ray coronary angiography. In these cases, coronary microvascular disease (CMD) is the main causative factor.

AIMS

To present the pathophysiology of CMD in Cardiology, Rheumatology and Endocrinology.

MATERIALS-METHODS

The pathophysiology of CMD in Cardiology, Rheumatology and Endocrinology was evaluated. It includes impaired microvascular vasodilatation, which leads to inability of the organism to deal with myocardial oxygen needs and, hence, development of ischemic pain. CMD, observed in inflammatory autoimmune rheumatic and endocrine/metabolic disorders, brings together Cardiology, Rheumatology and Endocrinology. Causative factors include persistent systemic inflammation and endocrine/metabolic abnormalities influencing directly the coronary microvasculature. In the past, the evaluation of microcirculation was feasible only with the use of invasive techniques, such as coronary flow reserve assessment. Currently, the application of advanced imaging modalities, such as cardiovascular magnetic resonance (CMR), can evaluate CMD non-invasively and without ionizing radiation.

RESULTS

CMD may present with a variety of symptoms with 1/3 to 2/3 of them expressed as typical chest pain in effort, more commonly found in women during menopause than in men. Atypical presentation includes chest pain at rest or exertional dyspnea,but post exercise symptoms are not uncommon. The treatment with nitrates is less effective in CMD, because their vasodilator action in coronary micro-circulation is less pronounced than in the epicardial coronary arteries.

DISCUSSION

Although both classic and new medications have been used in the treatment of CMD, there are still many questions regarding both the pathophysiology and the treatment of this disorder. The potential effects of anti-rheumatic and endocrine medications on the evolution of CMD need further evaluation.

CONCLUSION

CMD is a multifactorial disease leading to myocardial ischemia/fibrosis alone or in combination with epicardial coronary artery disease. Endothelial dysfunction/vasospasm, systemic inflammation, and/or neuroendocrine activation may act as causative factors and bring Cardiology, Rheumatology and Endocrinology together. Currently, the application of advanced imaging modalities, and specifically CMR, allows reliable assessment of the extent and severity of CMD. These measurements should not be limited to "pure cardiac patients", as it is known that CMD affects the majority of patients with autoimmune rheumatic and endocrine/metabolic disorders.

A Left Ventricular Mechanical Dyssynchrony-Based Nomogram for Predicting Major Adverse Cardiac Events Risk in Patients With Ischemia and No Obstructive Coronary Artery Disease

Background

The risk stratification of patients with ischemia and no obstructive coronary artery disease (INOCA) remains suboptimal. This study aims to establish a left ventricular mechanical dyssynchrony (LVMD)-based nomogram to improve the present situation.

Methods

Patients with suspected coronary artery disease (CAD) were retrospectively enrolled and divided into three groups: normal (stenosis &lt;50%, without myocardial ischemia), INOCA (stenosis &lt;50%, summed stress score &gt;4, summed difference score ≥2), and obstructive CAD (stenosis ≥50%). LVMD was defined by ROC analysis. INOCA group were followed up for the occurrence of major adverse cardiac events (MACEs: cardiovascular death, non-fatal myocardial infarction, revascularization, stroke, heart failure, and hospitalization for unstable angina). Nomogram was established using multivariate Cox regression analysis.

Results

Among 334 patients (118 [35.3%] INOCA), LVMD parameters were significantly higher in INOCA group versus normal group but they did not differ between obstructive CAD groups. In INOCA group, 27 (22.9%) MACEs occurred during a 26-month median follow-up. Proportion of LVMD was significantly higher with MACEs under both stress (63.0% vs. 22.0%, P &lt; 0.001) and rest (51.9% vs. 20.9%, P = 0.002). Kaplan–Meier analysis revealed significantly higher rate of MACEs (stress log-rank: P = 0.002; rest log-rank: P &lt; 0.001) in LVMD patients. Multivariate Cox regression analysis showed that stress LVMD (HR: 3.82; 95% CI: 1.30–11.20; P = 0.015) was an independent predictor of MACEs. The internal bootstrap resampling approach indicates that the C-index of nomogram was 0.80 (95% CI: 0.71–0.89) and the AUC values for 1 and 3 years of risk prediction were 0.68 (95% CI: 0.46–0.89) and 0.84 (95% CI: 0.72–0.95), respectively.

Conclusion

LVMD-based nomogram might provide incremental prognostic value and improve the risk stratification in INOCA patients.

Metabolic syndrome and the risk of adverse cardiovascular events in patients with myocardial infarction with non-obstructive coronary arteries

BACKGROUND AND AIMS

Metabolic syndrome (MeS) is recognized as a significant predictor of poor outcomes in coronary artery disease. However, its prognostic implications in myocardial infarction with non-obstructive coronary arteries (MINOCA) have not been examined. We aimed at investigating the role of MeS on the clinical outcomes in MINOCA patients.

METHODS AND RESULTS

Patients diagnosed with MINOCA between 2015 and 2019 were included. MeS was defined according to modified NCEP-ATPIII criteria. The primary endpoint was major adverse cardiovascular events (MACE). Cox regression analysis was used to evaluate the correlation between MeS and the hazard of MACE. The integrated discrimination improvement (IDI) and net reclassification index (NRI) were performed to assess MeS incremental predictive value. Of 281 MINOCA patients, 83 (29.5%) patients satisfied the MeS criteria. During a median follow-up duration of 28 months, MINOCA patients with MeS had a notably higher rate of MACE than those without MeS (30.1% vs. 17.6%, respectively P = 0.020). Cox regression analysis revealed that MeS was associated with an increased hazard of MACE (adjusted HR 2.126; 95% CI: 1.193-3.787, P = 0.010). When each component of MeS was analyzed as a categorized variable separately, only high fasting blood glucose and BMI ≥25 kg/m² were associated with an increased hazard of MACE. Moreover, MeS had an incremental predictive ability for MACE when added to a model with clinical risk factors.

CONCLUSION

MeS is relatively common in patients with MINOCA. The presence of MeS significantly increased the hazard of MACE among the MINOCA population.

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.

Coronary Artery Disease in Women: A Comprehensive Appraisal

Coronary artery disease (CAD) is a significant cause of illness and death amongst women. The pathophysiology, manifestations, and outcomes of CVD and CAD differ between sexes. These sex differences remain under-recognized. The aim of this review is to highlight and raise awareness of the burden and unique aspects of CAD in women. It details the unique pathophysiology of CAD in women, cardiovascular risk factors in women (both traditional and sex-specific), the clinical presentation of CAD in women, and the range of disease in obstructive and non-obstructive CAD in women.

Prognostic impact of coronary microvascular dysfunction in patients with myocardial infarction with non-obstructive coronary arteries

BACKGROUND

Myocardial infarction with non-obstructive coronary arteries (MINOCA) has been and remained a puzzling heterogeneous entity. The index of microcirculatory resistance (IMR) is a quantitative and specific index for the assessment of microvascular function. However, the role of IMR in MINOCA has not yet been studied. This study aimed to evaluate the prognostic value of coronary microvascular function, as assessed by coronary angiography‑derived index of microvascular resistance (caIMR) in MINOCA patients.

METHOD

This study included 109 MINOCA patients. Microvascular function was assessed by caIMR and was analyzed in 280 coronary arteries. The primary endpoint of the study was MACE, defined as cardiovascular death, nonfatal MI, heart failure, stroke and angina rehospitalization. The best cut-off of caIMR was derived from ROC analysis based on MACE prediction.

RESULTS

The patients were classified into high caIMR (caIMR>43U) and low caIMR (caIMR≤43U) based on a caIMR cut-off value of 43U. High caIMR was observed in 55 (50.5%) patients. A total of 27 MACE occurred during the 2 years of follow-up. MACE rate was significantly higher in patients with high caIMR than in patients with low caIMR (36.4% vs 13.0%, P=0.005). The Kaplan-Meier curves showed a significantly increased risk of MACE in patients with high caIMR (log-rank P=0.001). Cox multivariate analysis showed that caIMR>43 was a highly independent predictor of MACE (HR, 3.08; 95% CI, 1.13 - 8.35; P=0.027).

CONCLUSIONS

caIMR is a strong predictor of clinical outcome among MINOCA patients. The evaluation of IMR can provide an objective risk stratification method for patients with MINOCA.

Reduced nitric oxide bioavailability impairs myocardial oxygen balance during exercise in swine with multiple risk factors

In the present study, we tested the hypothesis that multiple risk factors, including diabetes mellitus (DM), dyslipidaemia and chronic kidney disease (CKD) result in a loss of nitric oxide (NO) signalling, thereby contributing to coronary microvascular dysfunction. Risk factors were induced in 12 female swine by intravenous streptozotocin injections (DM), a high fat diet (HFD) and renal artery embolization (CKD). Female healthy swine (n = 13) on normal diet served as controls (Normal). After 5 months, swine were chronically instrumented and studied at rest and during exercise. DM + HFD + CKD swine demonstrated significant hyperglycaemia, dyslipidaemia and impaired kidney function compared to Normal swine. These risk factors were accompanied by coronary microvascular endothelial dysfunction both in vivo and in isolated small arteries, due to a reduced NO bioavailability, associated with perturbations in myocardial oxygen balance at rest and during exercise. NO synthase inhibition caused coronary microvascular constriction in exercising Normal swine, but had no effect in DM + HFD + CKD animals, while inhibition of phosphodiesterase 5 produced similar vasodilator responses in both groups, indicating that loss of NO bioavailability was principally responsible for the observed coronary microvascular dysfunction. This was associated with an increase in myocardial 8-isoprostane levels and a decrease in antioxidant capacity, while antioxidants restored the vasodilation to bradykinin in isolated coronary small arteries, suggesting that oxidative stress was principally responsible for the reduced NO bioavailability. In conclusion, five months of combined exposure to DM + HFD + CKD produces coronary endothelial dysfunction due to impaired NO bioavailability, resulting in impaired myocardial perfusion at rest and during exercise.

Myocardial Infarction with Nonobstructive Coronary Arteries: A Diagnostic Challenge

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is a significant cause of cardiovascular morbidity, especially among non-white women younger than 55 years. It is a working diagnosis that warrants further investigation due to its varied underlying pathophysiologic mechanisms. Investigations may be hampered by unavailability of testing modalities, cost, and the expertise to carry out the tests, as they are highly specialized. Clinical history is therefore important, especially in developing countries, to predict potential causes and institute empirical treatment without the luxury of tests. Some physicians are also unaware of this phenomenon and may dismiss symptoms as functional when a coronary angiogram shows nonobstructed coronary arteries, potentially resulting in patients suffering symptoms for longer and incurring extra cost. Most importantly, it leaves them at risk of major adverse cardiovascular events. This article presents a patient with atrial fibrillation who was diagnosed with MINOCA and highlights the diagnostic challenges in evaluating MINOCA.

Coronary flow velocity reserve predicts adverse prognosis in women with angina and no obstructive coronary artery disease: results from the iPOWER study

AIMS

Many patients with angina, especially women, do not have obstructive coronary artery disease (CAD) yet have impaired prognosis. We investigated whether routine assessment of coronary microvascular dysfunction (CMD) is feasible and predicts adverse outcome in women with angina and no obstructive CAD.

METHODS AND RESULTS

After screening 7253, we included 1853 women with angina and no obstructive CAD on angiogram who were free of previous CAD, heart failure, or valvular heart disease in the prospective iPOWER (Improving Diagnosis and Treatment of Women with Angina Pectoris and Microvascular Disease) study. CMD was assessed by Doppler echocardiography in the left anterior descending artery as coronary flow velocity reserve (CFVR). Patients were followed for a composite outcome of cardiovascular death, myocardial infarction (MI), heart failure, stroke, and coronary revascularization. CFVR was obtained in 1681 patients (91%) and the median CFVR was 2.33 (quartiles 1-3: 2.00-2.74). During a median follow-up of 4.5 years, 96 events occurred. In univariate Cox regression, CFVR was associated with the composite outcome {hazard ratio (HR) 1.07 [95% confidence interval (CI) 1.03-1.11] per 0.1 unit decrease in CFVR; P < 0.001}, primarily driven by an increased risk of MI and heart failure. Results remained significant in multivariate analysis [HR 1.05 (95% CI 1.01-1.09) per 0.1 unit decrease in CFVR; P = 0.01]. In exploratory analyses, CFVR was also associated with the risk of repeated hospital admission for angina and all-cause mortality.

CONCLUSION

Assessment of CFVR by echocardiography is feasible and predictive of adverse outcome in women with angina and no obstructive CAD. Results support a more aggressive preventive management of these patients and underline the need for trials targeting CMD.

Smoking, alcohol and opioids effect on coronary microcirculation: an update overview

Smoking, heavy alcohol drinking and drug abuse are detrimental lifestyle factors leading to loss of million years of healthy life annually. One of the major health complications caused by these substances is the development of cardiovascular diseases (CVD), which accounts for a significant proportion of substance-induced death. Smoking and excessive alcohol consumption are related to the higher risk of acute myocardial infarction. Similarly, opioid addiction, as one of the most commonly used substances worldwide, is associated with cardiac events such as ischemia and myocardial infarction (MI). As supported by many studies, coronary artery disease (CAD) is considered as a major cause for substance-induced cardiac events. Nonetheless, over the last three decades, a growing body of evidence indicates that a significant proportion of substance-induced cardiac ischemia or MI cases, do not manifest any signs of CAD. In the absence of CAD, the coronary microvascular dysfunction is believed to be the main underlying reason for CVD. To date, comprehensive literature reviews have been published on the clinicopathology of CAD caused by smoking and opioids, as well as macrovascular pathological features of the alcoholic cardiomyopathy. However, to the best of our knowledge there is no review article about the impact of these substances on the coronary microvascular network. Therefore, the present review will focus on the current understanding of the pathophysiological alterations in the coronary microcirculation triggered by smoking, alcohol and opioids.

Ischemic Heart Disease Pathophysiology Paradigms Overview: From Plaque Activation to Microvascular Dysfunction

Ischemic heart disease still represents a large burden on individuals and health care resources worldwide. By conventions, it is equated with atherosclerotic plaque due to flow-limiting obstruction in large-medium sized coronary arteries. However, clinical, angiographic and autoptic findings suggest a multifaceted pathophysiology for ischemic heart disease and just some cases are caused by severe or complicated atherosclerotic plaques. Currently there is no well-defined assessment of ischemic heart disease pathophysiology that satisfies all the observations and sometimes the underlying mechanism to everyday ischemic heart disease ward cases is misleading. In order to better examine this complicated disease and to provide future perspectives, it is important to know and analyze the pathophysiological mechanisms that underline it, because ischemic heart disease is not always determined by atherosclerotic plaque complication. Therefore, in order to have a more complete comprehension of ischemic heart disease we propose an overview of the available pathophysiological paradigms, from plaque activation to microvascular dysfunction.

Gender in cardiovascular medicine: chest pain and coronary artery disease

Ischaemic heart disease (IHD) remains the leading cause of morbidity and mortality among women and men yet women are more often underdiagnosed, have a delay in diagnosis, and/or receive suboptimal treatment. An implicit gender-bias with regard to lack of recognition of sex-related differences in presentation of IHD may, in part, explain these differences in women compared with men. Indeed, existing knowledge demonstrates that angina does not commonly relate to obstructive coronary artery disease (CAD). Emerging knowledge supports an inclusive approach to chest pain symptoms in women, as well as a more thoughtful consideration of percutaneous coronary intervention for angina in stable obstructive CAD, to avoid chasing our tails. Emerging knowledge regarding the cardiac autonomic nervous system and visceral pain pathways in patients with and without obstructive CAD offers explanatory mechanisms for angina. Interdisciplinary investigation approaches that involve cardiologists, biobehavioural specialists, and anaesthesia/pain specialists to improve angina treatment should be pursued.

State of the Art in Noninvasive Imaging of Ischemic Heart Disease and Coronary Microvascular Dysfunction in Women: Indications, Performance, and Limitations

PURPOSE OF REVIEW

Establishing a diagnosis of ischemic heart disease (IHD) in women, including assessment for coronary microvascular dysfunction (CMD) when indicated, can be challenging. Access to performance of invasive testing when appropriate may be limited, and noninvasive imaging assessments have evolved. This review will summarize the various noninvasive imaging modalities available for the diagnosis of IHD and CMD in women, outlining indications, performance modalities, advantages, and limitations.

RECENT FINDINGS

While stress echocardiography and single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) are widely available and can detect IHD in women, their ability to specifically identify CMD is limited. Novel developments in cardiac magnetic resonance (CMR) imaging, including spectroscopy, and positron emission tomography (PET) have changed the diagnostic landscape. Coronary computed tomographic angiography (CCTA), while unable to diagnose CMD, is developing an emerging role in the risk stratification of ischemic syndromes. Despite the discovery of increased CMD prevalence in symptomatic women and technological advances in diagnostic imaging, practitioners are limited by user expertise and center availability when choosing a diagnostic imaging modality. Knowledge of this evolving field is imperative as it highlights the need for sex-specific assessment of cardiovascular syndromes.

Myocardial Infarction With Nonobstructive Coronary Arteries

Myocardial infarction with nonobstructive coronary arteries (MINOCA) is the current term used to describe patients who have a myocardial infarction but have normal, non-obstructed coronary arteries on a coronary angiogram. There is still much debate over the definition, diagnosis, management and treatment of MINOCA. However, MINOCA is not a benign condition; prompt recognition and diagnosis can lead to better management and treatment and thus improve patient outcomes. This review article will update the most recent definition of MINOCA, discuss epidemiology and etiology, and review the diagnostic workup and management options for patients presenting with signs and symptoms of MINOCA.

Coronary Microvascular Dysfunction and the Role of Noninvasive Cardiovascular Imaging

Patients with coronary microvascular dysfunction (CMD) have significantly higher rates of cardiovascular events, including hospitalization for heart failure, sudden cardiac death, and myocardial infarction (MI). In CMD, several pathophysiological changes lead to functional and structural abnormalities in the coronary microvasculature, which disrupt the ability of the vessels to vasodilate and augment myocardial blood flow in response to increased myocardial oxygen demand, causing ischemia and angina. With the advent of more advanced non-invasive cardiac imaging techniques, the coronary microvasculature has been subjected to more intense study in the past two decades-this has led to further insights into the diagnosis, pathophysiology, treatment, prognosis and follow-up of CMD. This review will highlight and compare the salient features of the currently available non-invasive imaging modalities used in these patients, and discuss the clinical utility of these techniques in the workup and management of these patients.

Genetic dysregulation of endothelin-1 is implicated in coronary microvascular dysfunction

AIMS

Endothelin-1 (ET-1) is a potent vasoconstrictor peptide linked to vascular diseases through a common intronic gene enhancer [(rs9349379-G allele), chromosome 6 (PHACTR1/EDN1)]. We performed a multimodality investigation into the role of ET-1 and this gene variant in the pathogenesis of coronary microvascular dysfunction (CMD) in patients with symptoms and/or signs of ischaemia but no obstructive coronary artery disease (CAD).

METHODS AND RESULTS

Three hundred and ninety-one patients with angina were enrolled. Of these, 206 (53%) with obstructive CAD were excluded leaving 185 (47%) eligible. One hundred and nine (72%) of 151 subjects who underwent invasive testing had objective evidence of CMD (COVADIS criteria). rs9349379-G allele frequency was greater than in contemporary reference genome bank control subjects [allele frequency 46% (129/280 alleles) vs. 39% (5551/14380); P = 0.013]. The G allele was associated with higher plasma serum ET-1 [least squares mean 1.59 pg/mL vs. 1.28 pg/mL; 95% confidence interval (CI) 0.10-0.53; P = 0.005]. Patients with rs9349379-G allele had over double the odds of CMD [odds ratio (OR) 2.33, 95% CI 1.10-4.96; P = 0.027]. Multimodality non-invasive testing confirmed the G allele was associated with linked impairments in myocardial perfusion on stress cardiac magnetic resonance imaging at 1.5 T (N = 107; GG 56%, AG 43%, AA 31%, P = 0.042) and exercise testing (N = 87; -3.0 units in Duke Exercise Treadmill Score; -5.8 to -0.1; P = 0.045). Endothelin-1 related vascular mechanisms were assessed ex vivo using wire myography with endothelin A receptor (ETA) antagonists including zibotentan. Subjects with rs9349379-G allele had preserved peripheral small vessel reactivity to ET-1 with high affinity of ETA antagonists. Zibotentan reversed ET-1-induced vasoconstriction independently of G allele status.

CONCLUSION

We identify a novel genetic risk locus for CMD. These findings implicate ET-1 dysregulation and support the possibility of precision medicine using genetics to target oral ETA antagonist therapy in patients with microvascular angina.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03193294.

Coronary Microvascular Dysfunction

Many patients with chest pain undergoing coronary angiography do not show significant obstructive coronary lesions. A substantial proportion of these patients have abnormalities in the function and structure of coronary microcirculation due to endothelial and smooth muscle cell dysfunction. The coronary microcirculation has a fundamental role in the regulation of coronary blood flow in response to cardiac oxygen requirements. Impairment of this mechanism, defined as coronary microvascular dysfunction (CMD), carries an increased risk of adverse cardiovascular clinical outcomes. Coronary endothelial dysfunction accounts for approximately two-thirds of clinical conditions presenting with symptoms and signs of myocardial ischemia without obstructive coronary disease, termed "ischemia with non-obstructive coronary artery disease" (INOCA) and for a small proportion of "myocardial infarction with non-obstructive coronary artery disease" (MINOCA). More frequently, the clinical presentation of INOCA is microvascular angina due to CMD, while some patients present vasospastic angina due to epicardial spasm, and mixed epicardial and microvascular forms. CMD may be associated with focal and diffuse epicardial coronary atherosclerosis, which may reinforce each other. Both INOCA and MINOCA are more common in females. Clinical classification of CMD includes the association with conditions in which atherosclerosis has limited relevance, with non-obstructive atherosclerosis, and with obstructive atherosclerosis. Several studies already exist which support the evidence that CMD is part of systemic microvascular disease involving multiple organs, such as brain and kidney. Moreover, CMD is strongly associated with the development of heart failure with preserved ejection fraction (HFpEF), diabetes, hypertensive heart disease, and also chronic inflammatory and autoimmune diseases. Since coronary microcirculation is not visible on invasive angiography or computed tomographic coronary angiography (CTCA), the diagnosis of CMD is usually based on functional assessment of microcirculation, which can be performed by both invasive and non-invasive methods, including the assessment of delayed flow of contrast during angiography, measurement of coronary flow reserve (CFR) and index of microvascular resistance (IMR), evaluation of angina induced by intracoronary acetylcholine infusion, and assessment of myocardial perfusion by positron emission tomography (PET) and magnetic resonance (CMR).

Myocardial Infarction with Nonobstructive Coronary Arteries (MINOCA): A Review of the Current Position

Myocardial infarction with nonobstructive coronary arteries (MINOCA) remains a puzzling clinical entity that is characterized by clinical evidence of myocardial infarction (MI) with normal or near-normal coronary arteries on angiography (stenosis <50%). Major advances in understanding this condition have been made in recent years. The precise pathogenesis is poorly understood and is being studied and examined further. Guidelines indicate that MINOCA is a group of heterogeneous diseases with different mechanisms of pathology. Since there are multiple possible pathological mechanisms, it is not certain that the classical secondary prevention and treatment strategy for MI with obstructive coronary artery disease (MI-CAD) is optimal for MINOCA patients. The prognosis and predictors for MINOCA patients remain unclear. Although the prognosis is slightly better for MINOCA patients than for MI-CAD patients, MINOCA isn't always benign. The aim of this paper was to review the literature and evaluate MINOCA epidemiology, clinical features, etiology, diagnosis, treatment, and prognosis.

Experimental animal models of coronary microvascular dysfunction

Coronary microvascular dysfunction (CMD) is commonly present in patients with metabolic derangements and is increasingly recognized as an important contributor to myocardial ischaemia, both in the presence and absence of epicardial coronary atherosclerosis. The latter condition is termed 'ischaemia and no obstructive coronary artery disease' (INOCA). Notwithstanding the high prevalence of INOCA, effective treatment remains elusive. Although to date there is no animal model for INOCA, animal models of CMD, one of the hallmarks of INOCA, offer excellent test models for enhancing our understanding of the pathophysiology of CMD and for investigating novel therapies. This article presents an overview of currently available experimental models of CMD-with an emphasis on metabolic derangements as risk factors-in dogs, swine, rabbits, rats, and mice. In all available animal models, metabolic derangements are most often induced by a high-fat diet (HFD) and/or diabetes mellitus via injection of alloxan or streptozotocin, but there is also a wide variety of spontaneous as well as transgenic animal models which develop metabolic derangements. Depending on the number, severity, and duration of exposure to risk factors-all these animal models show perturbations in coronary microvascular (endothelial) function and structure, similar to what has been observed in patients with INOCA and comorbid conditions. The use of these animal models will be instrumental in identifying novel therapeutic targets and for the subsequent development and testing of novel therapeutic interventions to combat ischaemic heart disease, the number one cause of death worldwide.

Perturbations in myocardial perfusion and oxygen balance in swine with multiple risk factors: a novel model of ischemia and no obstructive coronary artery disease

Comorbidities of ischemic heart disease, including diabetes mellitus (DM), hypercholesterolemia (HC) and chronic kidney disease (CKD), are associated with coronary microvascular dysfunction (CMD). Increasing evidence suggests that CMD may contribute to myocardial ‘Ischemia and No Obstructive Coronary Artery disease’ (INOCA). In the present study, we tested the hypothesis that CMD results in perturbations in myocardial perfusion and oxygen delivery using a novel swine model with multiple comorbidities. DM (streptozotocin), HC (high-fat diet) and CKD (renal embolization) were induced in 10 female swine (DM + HC + CKD), while 12 healthy female swine on a normal diet served as controls (Normal). After 5 months, at a time when coronary atherosclerosis was still negligible, myocardial perfusion, metabolism, and function were studied at rest and during treadmill exercise. DM + HC + CKD animals showed hyperglycemia, hypercholesterolemia, and impaired kidney function. During exercise, DM + HC + CKD swine demonstrated perturbations in myocardial blood flow and oxygen delivery, necessitating a higher myocardial oxygen extraction—achieved despite reduced capillary density—resulting in lower coronary venous oxygen levels. Moreover, myocardial efficiency was lower, requiring higher oxygen consumption for a given level of myocardial work. These perturbations in myocardial oxygen balance were associated with lower myocardial lactate consumption, stroke volume, and LVdP/dt_max, suggestive of myocardial ischemia and dysfunction. Further analyses showed a reduction in adenosine-recruitable coronary flow reserve, but this was exclusively the result of an increase in basal coronary blood flow, while maximal coronary flow per gram of myocardium was maintained; the latter was consistent with the unchanged arteriolar wall/lumen ratio, arteriolar density and peri-arteriolar collagen content. However, isolated small arteries displayed selective blunting of endothelium-dependent vasodilation in response to bradykinin in DM + HC + CKD swine, suggesting that changes in coronary microvascular function rather than in structure contributed to the perturbations in myocardial oxygen delivery. In conclusion, common comorbidities in swine result in CMD, in the absence of appreciable atherosclerosis, which is severe enough to produce perturbations in myocardial oxygen balance, particularly during exercise, resembling key features of INOCA.

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.

Coronary artery disease in post-menopausal women: are there appropriate means of assessment?

The recognition of sex differences in cardiovascular disease, particularly the manifestations of coronary artery disease (CAD) in post-menopausal women, has introduced new challenges in not only understanding disease mechanisms but also identifying appropriate clinical means of assessing the efficacy of management strategies. For example, the majority of treatment algorithms for CAD are derived from the study of males, focus on epicardial stenoses, and inadequately account for the small intramyocardial vessel disease in women. However, newer investigational modalities, including stress perfusion cardiac magnetic resonance imaging and positron emission tomography are providing enhanced diagnostic accuracy and prognostication for women with microvascular disease. Moreover, these investigations may soon be complemented by simpler screening tools such as retinal vasculature imaging, as well as novel biomarkers (e.g. heat shock protein 27). Hence, it is vital that robust, sex-specific cardiovascular imaging modalities and biomarkers continue to be developed and are incorporated into practice guidelines that are used to manage women with CAD, as well as gauge the efficacy of any new treatment modalities. This review provides an overview of some of the sex differences in CAD and highlights emerging advances in the investigation of CAD in post-menopausal women.