Coronary microvascular dysfunction, microvascular angina, and treatment strategies

Systemic microvascular dysfunction in microvascular and vasospastic angina

Aims

Coronary microvascular dysfunction and/or vasospasm are potential causes of ischaemia in patients with no obstructive coronary artery disease (INOCA). We tested the hypothesis that these patients also have functional abnormalities in peripheral small arteries.

Methods and results

Patients were prospectively enrolled and categorised as having microvascular angina (MVA), vasospastic angina (VSA) or normal control based on invasive coronary artery function tests incorporating probes of endothelial and endothelial-independent function (acetylcholine and adenosine). Gluteal biopsies of subcutaneous fat were performed in 81 subjects (62 years, 69% female, 59 MVA, 11 VSA, and 11 controls). Resistance arteries were dissected enabling study using wire myography. Maximum relaxation to ACh (endothelial function) was reduced in MVA vs. controls [median 77.6 vs. 98.7%; 95% confidence interval (CI) of difference 2.3-38%; P = 0.0047]. Endothelium-independent relaxation [sodium nitroprusside (SNP)] was similar between all groups. The maximum contractile response to endothelin-1 (ET-1) was greater in MVA (median 121%) vs. controls (100%; 95% CI of median difference 4.7-45%, P = 0.015). Response to the thromboxane agonist, U46619, was also greater in MVA (143%) vs. controls (109%; 95% CI of difference 13-57%, P = 0.003). Patients with VSA had similar abnormal patterns of peripheral vascular reactivity including reduced maximum relaxation to ACh (median 79.0% vs. 98.7%; P = 0.03) and increased response to constrictor agonists including ET-1 (median 125% vs. 100%; P = 0.02). In all groups, resistance arteries were ≈50-fold more sensitive to the constrictor effects of ET-1 compared with U46619.

Conclusions

Systemic microvascular abnormalities are common in patients with MVA and VSA. These mechanisms may involve ET-1 and were characterized by endothelial dysfunction and enhanced vasoconstriction.

Clinical trial registration

ClinicalTrials.gov registration is NCT03193294.

Non-invasive measures of coronary microcirculation: Taking the long road to the clinic

Although coronary microvascular disease is now a well-recognized entity that is associated with significant morbidity and mortality, current non-invasive strategies cannot differentiate between coronary microvascular disease (CMD) and obstructive epicardial stenosis. While the evaluation of intramyocardial blood volume as a surrogate measure for microvascular health may have limited sensitivity in early-stage disease, this strategy does enable the diagnosis of CMD in the presence of concurrent epicardial disease, bringing us one step further toward improving the management of this disease. Herein, we discuss the advantages and limitations of current non-invasive measures of CMD and the need for further investment in bringing these technologies to the bedside.

Evaluation of serum sST2 and sCD40L values in patients with microvascular angina

OBJECTIVES

Coronary microvascular dysfunction plays a major role in the pathogenesis of microvascular angina (MVA). Along with endothelial dysfunction, microvascular atherosclerosis and inflammation seem to contribute to the development of coronary microvascular dysfunction. Serum soluble ST2 (sST2) and serum soluble CD40 ligand (sCD40L) are two biomarkers associated with inflammation and atherosclerosis. The aim of this study was to investigate the role of these biomarkers in the pathogenesis of MVA and determine their possible association with coronary microvascular dysfunction.

METHODS

A total of 152 patients were included in the study. Ninety-one patients with MVA {median age 56 years (40-79), of which 55 are women} and sixty-one controls {median age 52 (38-76), of which 29 are women} were included in the study. Serum concentration of sST2 and sCD40L were measured with a commercially available ELISA kit.

RESULTS

Serum sST2 (median 13.6 ng/ml; interquartile range (IQR), 3.5-63.8 ng/ml vs median 10.6 ng/ml; IQR, 2.9-34.2 ng/ml, p < 0.0005) and sCD40L (median 5.3 ng/ml; IQR, 0.5-20.6 ng/ml vs median 2.2 ng/ml; IQR, 0.7-10.8 ng/ml, p < 0.0005) were significantly higher in patients with MVA compared to controls. Analysis of the associations between these biomarkers and potential contributors of MVA revealed that serum sST2 showed a positive correlation with LDL-cholesterol (r = 0.19, p = 0.016) and serum sCD40L concentrations correlated positively with hs-CRP (r = 0.22, p = 0.005). In logistic regression analysis, sCD40L and hs-CRP but not sST2 were found to be significantly associated with MVA.

CONCLUSION

Higher serum concentrations of sST2 and sCD40L in MVA patients may be associated with inflammatory activation and coronary microvascular dysfunction. Larger studies are required for understanding their role in the pathogenesis of inflammatory and possibly fibrotic process in MVA patients.

Coronary Microvascular Disease Pathogenic Mechanisms and Therapeutic Options: JACC State-of-the-Art Review

Coronary microvascular disease (CMD) refers to the subset of disorders affecting the structure and function of the coronary microcirculation, is prevalent in patients across a broad spectrum of cardiovascular risk factors, and is associated with an increased risk of adverse events. Contemporary evidence supports that most patients with CMD also have macrovessel atherosclerosis, which has important implications for their prognosis and management. In this state-of-the-art review, the authors summarize the pathophysiology of CMD, provide an update of diagnostic testing strategies, and classify CMD into phenotypes according to severity and coexistence with atherosclerosis. They examine emerging data highlighting the significance of CMD in specific populations, including obesity and insulin resistance, myocardial injury and heart failure with preserved ejection fraction, and nonobstructive and obstructive coronary artery disease. Finally, they discuss the role of CMD as a potential target for novel interventions beyond conventional approaches, representing a new frontier in cardiovascular disease reduction.

Identifying Myocardial Ischemia due to Coronary Microvascular Dysfunction in the Emergency Department: Introducing a New Paradigm in Acute Chest Pain Evaluation

Chest pain stands as one of the most frequent patient presentations in the emergency department (ED). Despite established diagnostic algorithms for identifying several important causes of chest pain, such as acute myocardial infarction (AMI), aortic dissection, and pulmonary embolism, guidance on managing patients with recurrent chest pain, one of the top 3 reasons for repeated hospitalization in the United States, is less defined. The assessment of symptoms, serial ECG, and necrosis biomarkers plays a major role in patient management. Notably, the recently introduced high-sensitivity troponin T (hs-TnT) assay is helping to identify ischemia in patients previously undiagnosed by conventional testing. In Europe, with the use of this assay for over a decade, the identification of patients with AMI has substantially increased, particularly of patients with type 2 AMI, which is seen in the absence of atherosclerotic obstruction of the epicardial coronaries on angiography. Use of hs-TnT is in particular relevant in women, in whom the use of a sex-specific threshold for elevated hs-TnT has almost doubled the diagnosis of AMI. With the advent of the hs-TnT assay in the United States in 2017, a similar phenomenon is expected. Thus, it is important to learn from the European experience and to develop sex-specific nuanced algorithms for the evaluation of additional causes of myocardial ischemia/necrosis, such as coronary artery vasomotor disorders and coronary microvascular dysfunction. The latter has a high prevalence among symptomatic women presenting to the ED, a group in whom recurrent chest pain is common. This commentary describes the tools available for diagnosing epicardial- and non-epicardial-related myocardial ischemia in patients with recurrent chest pain in the ED setting. A sex-specific, nuanced approach applied to select groups of patients being observed in the ED has the potential to reduce admissions and to allow for the initiation of timely, appropriate medical treatment and outpatient follow-up in an at-risk population. The costs and availability of advanced diagnostics may pose some limitation to the widespread adoption of such protocols.

Women's health: making cardiovascular disease real

PURPOSE OF REVIEW

When patients are seen for persistent chest pain in the absence of obstructive coronary artery disease, the physician must decide if the symptoms are due to myocardial ischemia in order to guide treatment.

RECENT FINDINGS

Recent findings indicate that ischemia due to coronary microvascular dysfunction (CMD) is associated with subclinical coronary atherosclerosis and an adverse prognosis. Therapeutic probe trials suggest that antiatherosclerotic and anti-ischemic therapeutic strategies may be useful. A large randomized clinical trial of high-intensity statin, maximally tolerated angiotensin-converting-enzyme inhibitor or angiotensin receptor blocker and low-dose aspirin (WARRIOR NCT#03417388) is in progress.

SUMMARY

The diagnosis of CMD should be considered in patients with persistent angina, evidence of myocardial ischemia and normal coronary angiogram. Because of the associated adverse prognosis of CMD , conservative empiric treatment or further diagnostic evaluation of the coronary microvasculature can be performed. Diagnosis involves the measurement of coronary blood blow in response to a vasodilator agent invasively or noninvasively. Treatment of CMD can include the use of traditional antianginal and antiatherosclerotic medications. Clinical trials are needed to assess therapeutic strategies on the outcomes of cardiovascular disease and quality of life, in order to develop evidence-based guidelines.

Adipose-derived cells improve left ventricular diastolic function and increase microvascular perfusion in advanced age

An early manifestation of coronary artery disease in advanced age is the development of microvascular dysfunction leading to deficits in diastolic function. Our lab has previously shown that epicardial treatment with adipose-derived stromal vascular fraction (SVF) preserves microvascular function following coronary ischemia in a young rodent model. Follow-up studies showed intravenous (i.v.) delivery of SVF allows the cells to migrate to the walls of small vessels and reset vasomotor tone. Therefore we tested the hypothesis that the i.v. cell injection of SVF would reverse the coronary microvascular dysfunction associated with aging in a rodent model. Fischer 344 rats were divided into 4 groups: young control (YC), old control (OC), old + rat aortic endothelial cells (O+EC) and old + GFP+ SVF cells (O+SVF). After four weeks, cardiac function and coronary flow reserve (CFR) were measured via echocardiography, and hearts were explanted either for histology or isolation of coronary arterioles for vessel reactivity studies. In a subgroup of animals, microspheres were injected during resting and dobutamine-stimulated conditions to measure coronary blood flow. GFP+ SVF cells engrafted and persisted in the myocardium and coronary vasculature four weeks following i.v. injection. Echocardiography showed age-related diastolic dysfunction without accompanying systolic dysfunction; diastolic function was improved in old rats after SVF treatment. Ultrasound and microsphere data both showed increased stimulated coronary blood flow in O+SVF rats compared to OC and O+EC, while isolated vessel reactivity was mostly unchanged. I.v.-injected SVF cells were capable of incorporating into the vasculature of the aging heart and are shown in this study to improve CFR and diastolic function in a model of advanced age. Importantly, SVF injection did not lead to arrhythmias or increased mortality in aged rats. SVF cells provide an autologous cell therapy option for treatment of microvascular and cardiac dysfunction in aged populations.

Local Production of Soluble Urokinase Plasminogen Activator Receptor and Plasminogen Activator Inhibitor-1 in the Coronary Circulation Is Associated With Coronary Endothelial Dysfunction in Humans

Background Soluble urokinase plasminogen activator receptor (su PAR ) is a proinflammatory biomarker associated with immune activation and fibrinolysis inhibition. Plasminogen activator inhibitor ( PAI -1) is associated with excessive fibrin accumulation, thrombus formation, and atherosclerosis. The relationship between cross-coronary su PAR and PAI -1 production and endothelial dysfunction remains unknown. Methods and Results Seventy-nine patients (age 53±10 years, 75% women) with angina and normal coronary arteries or mild coronary artery disease (<40% stenosis) on angiogram underwent acetylcholine assessment of epicardial endothelial dysfunction (mid-left anterior descending coronary artery diameter decrease >20% after acetylcholine) and mircovascular endothelial dysfunction (coronary blood flow change <50% after acetylcholine). Simultaneous left main and coronary sinus su PAR and PAI -1 levels were measured in each patient before acetylcholine administration, and cross-coronary su PAR and PAI -1 production rates were calculated. Patients' characteristics, except for age (51±10 versus 57±9, P=0.02), and resting coronary hemodynamics were not significantly different between patients with (26%) versus without (74%) epicardial endothelial dysfunction. Patients' characteristics and resting coronary hemodynamics were not significantly different between those with (62%) and those without (38%) mircovascular endothelial dysfunction. Patients with mircovascular endothelial dysfunction demonstrated local coronary su PAR production versus su PAR extraction in patients with normal microvascular function (median 25.8 [interquartile range 121.6, -23.7] versus -12.7 [52.0, -74.8] ng/min, P=0.03). Patients with epicardial endothelial dysfunction had higher median coronary PAI -1 production rates compared with those with normal epicardial endothelial function (1224.7 [12 940.7, -1915.4] versus -187.4 [4444.7, -4535.8] ng/min, P=0.03). Conclusions su PAR is released in coronary circulation of patients with mircovascular endothelial dysfunction and extracted in those with normal microvascular function. Cross-coronary PAI -1 release is higher in humans with epicardial endothelial dysfunction.

Coronary Slow-Flow Phenomenon as an Underrecognized and Treatable Source of Chest Pain: Case Series and Literature Review

Background. Coronary slow-flow phenomenon (CSFP) is characterized by delayed distal vessel opacification of contrast, in the absence of significant epicardial coronary stenosis. CSFP has been reported as a cause of chest pain and abnormal noninvasive ischemic tests and is often underrecognized. Material and Methods. Charts and angiographic records from our institution were reviewed to identify 15 consecutive patients who were diagnosed with CSFP from January 2016 to January 2017. Results. Of the 15 patients (4 females and 11 males) studied, the mean age was 59.1 years (range = 45-86 years); all had left ventricular ejection fraction >45% and without significant valvular stenosis/regurgitation. The indication for coronary angiography for all 15 patients was chest pain with abnormal noninvasive tests. Of the 11 patients who underwent previous coronary angiograms, all revealed prior evidence of CSFP. None of these patients were on calcium channel blockers (CCBs) or long-acting nitroglycerin agents before angiography. Intracoronary CCBs were effectively utilized to alleviate the angiographic finding (improvement in Thrombolysis in Myocardial Infarction frame count) in all 15 patients. Oral CCBs were started with subsequent improvement in all 15 patients (mean follow-up time = 13.6 months). Conclusion. Coronary slow-flow should be a diagnostic consideration in patients presenting with chest pain and abnormal noninvasive ischemic testing with nonobstructive epicardial vessels. CSFP remains underrecognized, and the specific standard of care for treatment has not been established. In each of the 15 cases, intracoronary nifedipine resolved the angiographic manifestation of coronary slow-flow. Furthermore, in follow-up, all patients improved symptomatically from their chest pain after oral CCBs were initiated.

Myocardial blood flow and myocardial flow reserve values in 13N-ammonia myocardial perfusion PET/CT using a time-efficient protocol in patients without coronary artery disease

BACKGROUND

Cardiac imaging by means of myocardial Positron Emission Tomography/Computed Tomography (PET/CT) is being used increasingly to assess coronary artery disease, to guide revascularization decisions with more accuracy, and it allows robust quantitative analysis of both regional myocardial blood flow (MBF) and myocardial flow reserve (MFR).Recently, a more time-efficient protocol has been developed in combination with a residual activity correction algorithm in which a stress acquisition is performed directly after completion of the rest acquisition to subtract remaining myocardial radioactivity.The objective of this study is to define flow values of myocardial blood flow (MBF) and Myocardial Flow Reserve (MFR) with 13N-ammonia (13NH3) myocardial perfusion PET/CT on patients without coronary artery disease using a time-efficient protocol, since reference values for this particular type of study are lacking in literature. In addition, we aim to determine the effect of the residual activity correction algorithm in this time-efficient protocol.

RESULTS

A mean MBF in rest of 1.02 ± 0.22 ml/g/min, a mean MBF in stress of 2.54 ± 0.41 ml/g/min with a mean MFR of 2.60 ± 0.61 were measured. Female patients had a significant higher MBF in rest and stress, but lower MFR; a small but significant negative correlation was measured between age and MBF in stress and MFR. Residual activity correction had a significant effect resulting in a difference in global stress MBF before and after correction of 0.39 ± 0.13 ml/g/min.

CONCLUSIONS

This study established flow values for 13NH3 myocardial PET/CT with a time-efficient protocol, and established that MBF in stress corrected for residual activity is comparable with known reference values in normal studies without temporal overlap. Further validation of the technique could be of value, e.g. by comparison to standard imaging without temporal overlap, or validation against catheterization results.

Effect of ACE-inhibition on coronary microvascular function and symptoms in normotensive women with microvascular angina: A randomized placebo-controlled trial

Objective

Studies have suggested a beneficial effect of angiotensin-converting enzyme (ACE) inhibition. To explore whether the ACE inhibitor ramipril has a direct effect on the microvasculature beyond the blood pressure (BP) lowering effect, we investigated whether ramipril improved coronary microvascular function in normotensive women with coronary microvascular dysfunction (CMD).

Methods

We included 63 normotensive women with angina, no epicardial stenosis>50% and CMD defined as a coronary flow velocity reserve (CFVR)<2.2 assessed by adenosine stress-echocardiography in a randomized double-blinded, superiority trial with 1:1 allocation to placebo or ramipril (maximum dose 10 mg depending on blood pressure) for 24±6 weeks. Primary outcome was CFVR. Secondary outcomes were left ventricular systolic and diastolic function and symptoms evaluated by Seattle Angina Questionnaire (clinicaltrials.gov, NCT02525081).

Results

Follow-up was available on 55 patients. BP remained unchanged during treatment in both groups. CFVR improved in both the ramipril (p = 0.004) and placebo group (p = 0.026) with no difference between groups (p = 0.63). Symptoms improved in both groups with no significant between-group differences. No changes were detected in parameters of systolic and diastolic function. No serious adverse reactions were reported.

Conclusions

In normotensive women with angina and CMD, treatment with ramipril had no significant effect on CFVR or symptoms compared with placebo. The effect of ACE inhibition previously reported may be mediated by blood pressure reduction.

Treatment of Angina: Where Are We?

Ischaemic heart disease is a major cause of death and disability worldwide, while angina represents its most common symptom. It is estimated that approximately 9 million patients in the USA suffer from angina and its treatment is challenging, thus the strategy to improve the management of chronic stable angina is a priority. Angina might be the result of different pathologies, ranging from the “classical” obstruction of a large coronary artery to alteration of the microcirculation or coronary artery spasm. Current clinical guidelines recommend antianginal therapy to control symptoms, before considering coronary artery revascularization. In the current guidelines, drugs are classified as being first-choice (beta-blockers, calcium channel blockers, and short-acting nitrates) or second-choice (ivabradine, nicorandil, ranolazine, trimetazidine) treatment, with the recommendation to reserve second-line modifications for patients who have contraindications to first-choice agents, do not tolerate them, or remain symptomatic. However, such a categorical approach is currently questioned. In addition, current guidelines provide few suggestions to guide the choice of drugs more suitable according to the underlying pathology or the patient comorbidities. Several other questions have recently emerged, such as: is there evidence-based data between first- and second-line treatments in terms of prognosis or symptom relief? Actually, it seems that newer antianginal drugs, which are classified as second choice, have more evidence-based clinical data that are more contemporary to support their use than what is available for the first-choice drugs. It follows that actual guidelines are based more on tradition than on evidence and there is a need for new algorithms that are more individualized to patients, their comorbidities, and pathophysiological mechanism of chronic stable angina.

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

Background

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

Methods and Results

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

Conclusions

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

Pharmacologic Treatment of Patients With Myocardial Ischemia With No Obstructive Coronary Artery Disease

Half of women and 1/3 of men with angina and ischemia on stress testing have ischemia with no obstructive coronary artery disease (INOCA). These patients have quality of life (QoL) impairment comparable with patients with obstructive coronary artery disease. Clinicians generally treat INOCA with traditional antianginal agents despite previous studies demonstrating variable response to these medications. We performed a systematic review to evaluate the efficacy and safety of available pharmacologic therapies for INOCA. We systematically searched the Cochrane Central Register of Controlled Trials, Embase, MEDLINE, and the World Health Organization International Clinical Trials Registry Platform in July 2017 for randomized controlled trials (RCTs) evaluating pharmacologic agents for INOCA. The primary outcome of interest was QoL. Secondary outcomes included subjective and objective efficacy measures and safety outcomes. We included 35 RCTs from 333 identified studies. Interventions that improved QoL with moderate-quality evidence included angiotensin-converting enzyme (ACE) inhibitor (±statin) and ranolazine. Low-to-very-low-quality evidence also suggests that ACE inhibitors, β blockers, calcium-channel blockers, nicorandil, ranolazine, and statins may decrease angina frequency and delay ischemia on stress testing. Other interventions, most notably nitrates, did not significantly improve any outcome. In conclusion, evidence for pharmacologic treatment of INOCA is generally poor, and higher-quality RCTs using a standardized definition of INOCA are needed. Moderate-quality evidence suggests that ACE inhibitors and ranolazine improve QoL. Other interventions had low-quality evidence or no evidence of efficacy.

Test Selection for Women with Suspected Stable Ischemic Heart Disease

Ischemic heart disease (IHD) is the leading cause of death and disability among women in the United States. Identifying IHD in women presenting with stable symptoms and stratifying their risk for an IHD event can be challenging for providers, with several different tests available. This article is meant to serve as a practical guide for clinicians treating women with potentially ischemic symptoms. Evidence and American Heart Association (AHA) recommendations regarding test selection are reviewed, with a focus on the information to be gained from each test. We outline suggested courses of action to be taken in the case of a positive or negative test. Regardless of the initial test result, clinicians should view a woman's symptom presentation as an opportunity to review and modify her risk of cardiovascular events.

Prevalence and characteristics of coronary microvascular dysfunction among chest pain patients in the emergency department

Aims:

Coronary microvascular dysfunction (CMD) is common in patients with non-obstructive coronary arteries but has not been described in low-risk symptomatic patients. We therefore assessed the prevalence and characteristics of CMD in low to moderate risk patients with chest pain in an emergency department.

Methods and results:

We used three-dimensional Rb82 cardiac positron emission tomography/computed tomography to diagnose coronary artery disease (known or new regional defect, any coronary calcification) and CMD (low coronary flow reserve without coronary artery disease) in chest pain patients after being ruled out for acute myocardial infarction. Exclusions included age 30 years or less, acute myocardial infarction, hemodynamic instability, heart failure and dialysis. Among 195 participants undergoing cardiac positron emission tomography/computed tomography, 42% had CMD, 36% had coronary artery disease and 22% had normal flows; 70% were women and 84% were obese. Patients with CMD and coronary artery disease had significantly lower coronary flow reserve than normal patients (mean coronary flow reserve 1.6 and 1.9 vs. 2.6, respectively, P<0.05). However, CMD patients were younger (mean age 51 vs. 61 years), and had fewer traditional cardiac risk factors ( P<0.05) than patients with coronary artery disease. Nearly one third (31%) of patients had a prior emergency department visit for chest pain within three years of index presentation. Women were four times as likely to have CMD as men (adjusted odds ratio 4.2; 95% confidence interval 1.8, 9.6) after controlling for age, race, hypertension, diabetes, smoking, dyslipidemia, obesity and family history of coronary artery disease.

Conclusions:

Despite their low-risk profile, nearly one half of symptomatic and mostly obese emergency department patients without evidence of myocardial infarction or coronary artery disease had CMD. The results could explain the high rates of return visits associated with chest pain, although their application to the general emergency department population require validation.

Coronary microcirculatory pathophysiology: can we afford it to remain a black box?

Coronary microvascular networks play the key role in determining blood flow distribution in the heart. Matching local blood supply to tissue metabolic demand entails continuous adaptation of coronary vessels via regulation of smooth muscle tone and structural dilated vessel diameter. The importance of coronary microcirculation for relevant pathological conditions including angina in patients with normal or near-normal coronary angiograms [microvascular angina (MVA)] and heart failure with preserved ejection fraction (HFpEF) is increasingly recognized. For MVA, clinical studies have shown a prevalence of up to 40% in patients with suspected coronary artery disease and a relevant impact on adverse cardiovascular events including cardiac death, stroke, and heart failure. Despite a continuously increasing number of corresponding clinical studies, the knowledge on pathophysiological cause–effect relations involving coronary microcirculation is, however, still very limited. A number of pathophysiological hypotheses for MVA and HFpEF have been suggested but are not established to a degree, which would allow definition of nosological entities, stratification of affected patients, or development of effective therapeutic strategies. This may be related to a steep decline in experimental (animal) pathophysiological studies in this area during the last 15 years. Since technology to experimentally investigate microvascular pathophysiology in the beating heart is increasingly, in principle, available, a concerted effort to build ‘coronary microcirculatory observatories’ to close this gap and to accelerate clinical progress in this area is suggested.

Diagnosis of Microvascular Angina Using Cardiac Magnetic Resonance

BACKGROUND

In patients with angina and nonobstructive coronary artery disease (NOCAD), confirming symptoms due to coronary microvascular dysfunction (CMD) remains challenging. Cardiac magnetic resonance (CMR) assesses myocardial perfusion with high spatial resolution and is widely used for diagnosing obstructive coronary artery disease (CAD).

OBJECTIVES

The goal of this study was to validate CMR for diagnosing microvascular angina in patients with NOCAD, compared with patients with obstructive CAD and correlated to the index of microcirculatory resistance (IMR) during invasive coronary angiography.

METHODS

Fifty patients with angina (65 ± 9 years of age) and 20 age-matched healthy control subjects underwent adenosine stress CMR (1.5- and 3-T) to assess left ventricular function, inducible ischemia (myocardial perfusion reserve index [MPRI]; myocardial blood flow [MBF]), and infarction (late gadolinium enhancement). During subsequent angiography within 7 days, 28 patients had obstructive CAD (fractional flow reserve [FFR] ≤0.8) and 22 patients had NOCAD (FFR >0.8) who underwent 3-vessel IMR measurements.

RESULTS

In patients with NOCAD, myocardium with IMR <25 U had normal MPRI (1.9 ± 0.4 vs. controls 2.0 ± 0.3; p = 0.49); myocardium with IMR ≥25 U had significantly impaired MPRI, similar to ischemic myocardium downstream of obstructive CAD (1.2 ± 0.3 vs. 1.2 ± 0.4; p = 0.61). An MPRI of 1.4 accurately detected impaired perfusion related to CMD (IMR ≥25 U; FFR >0.8) (area under the curve: 0.90; specificity: 95%; sensitivity: 89%; p < 0.001). Impaired MPRI in patients with NOCAD was driven by impaired augmentation of MBF during stress, with normal resting MBF. Myocardium with FFR >0.8 and normal IMR (<25 U) still had blunted stress MBF, suggesting mild CMD, which was distinguishable from control subjects by using a stress MBF threshold of 2.3 ml/min/g with 100% positive predictive value.

CONCLUSIONS

In angina patients with NOCAD, CMR can objectively and noninvasively assess microvascular angina. A CMR-based combined diagnostic pathway for both epicardial and microvascular CAD deserves further clinical validation.

Advances in Cardiovascular Health in Women over the Past Decade: Guideline Recommendations for Practice

Cardiovascular disease (CVD) remains the number one cause of death in women. It is estimated that 44 million women in the United States are either living with or at risk for heart disease. This article highlights the recent significant progress made in improving care, clinical decision-making, and policy implications for women with CVD. We provide our perspective supported by evidence-based advances in cardiovascular research and clinical care guidelines in seven areas: (1) primary CVD prevention and community heart care, (2) secondary prevention of CVD, (3) stroke, (4) heart failure and cardiomyopathies, (5) ischemia with nonobstructive coronary artery disease, (6) spontaneous coronary artery dissection, and (7) arrhythmias and device therapies. Advances in these fields have improved the lives of women living with and at risk for heart disease. With increase awareness, partnership with national organizations, sex-specific research, and changes in policy, the morbidity and mortality of CVD in women can be further reduced.

The value of real-time myocardial contrast echocardiography for detecting coronary microcirculation function in coronary artery disease patients

Objective:

The aim of this study was to evaluate the value of real-time myocardial contrast echocardiography (RT-MCE) for detecting coronary microcirculation (CM) function in coronary artery disease (CAD) patients.

Methods:

Sixty-five consecutive patients were divided into CAD (n=52) and no-CAD (n=13) groups using coronary angiography (CAG). All patients underwent RT-MCE at rest and CAG within 1 week after RT-MCE. The ventricular segments in CAD patients were divided semi-quantitatively into ischemic and non-ischemic myocardial groups based on RT-MCE images. Myocardial blood volume (A), myocardial blood flow velocity (β), and mean myocardial blood flow (A×β) were obtained. The Gensini scores were calculated for CAD patients. The receiver operating characteristic (ROC) curve areas of A, β, and A×β were calculated to assess CM function in CAD patients.

Results:

A total of 798 and 204 segments were investigated in the CAD and non-CAD groups, respectively. In CAD patients, 332 ischemic and 466 non-ischemic segments were identified. The values of A, β, and A×β were significantly different among non-CAD, CAD, ischemic, and non-ischemic groups. ROC curve areas of A, β, and A×β were 0.85, 0.79, and 0.83, respectively, and significant differences were observed in these values among three Gensini score groups of the CAD patients.

Conclusion:

Varying degrees of CM function deterioration was observed in CAD patients both in ischemic and non-ischemic areas, with the deterioration being more sever in the former.

Coronary microvascular dysfunction in diabetes mellitus

The significance, mechanisms and consequences of coronary microvascular dysfunction associated with diabetes mellitus are topics into which we have insufficient insight at this time. It is widely recognized that endothelial dysfunction that is caused by diabetes in various vascular beds contributes to a wide range of complications and exerts unfavorable effects on microcirculatory regulation. The coronary microcirculation is precisely regulated through a number of interconnected physiological processes with the purpose of matching local blood flow to myocardial metabolic demands. Dysregulation of this network might contribute to varying degrees of pathological consequences. This review discusses the most important findings regarding coronary microvascular dysfunction in diabetes from pre-clinical and clinical perspectives.

Sex as a Biological Variable in Emergency Medicine Research and Clinical Practice: A Brief Narrative Review

The National Institutes of Health recently highlighted the significant role of sex as a biological variable (SABV) in research design, outcome and reproducibility, mandating that this variable be accounted for in all its funded research studies. This move has resulted in a rapidly increasing body of literature on SABV with important implications for changing the clinical practice of emergency medicine (EM). Translation of this new knowledge to the bedside requires an understanding of how sex-based research will ultimately impact patient care. We use three case-based scenarios in acute myocardial infarction, acute ischemic stroke and important considerations in pharmacologic therapy administration to highlight available data on SABV in evidence-based research to provide the EM community with an important foundation for future integration of patient sex in the delivery of emergency care as gaps in research are filled.

Moderate-dose atorvastatin improves arterial endothelial function in patients with angina pectoris and normal coronary angiogram: a pilot study

INTRODUCTION

Endothelial dysfunction could contribute to the pathophysiology of angina pectoris (AP) in patients with normal coronary angiograms. Besides lipid-lowering effects, statins exert pleiotropic effects including improving endothelial function.

MATERIAL AND METHODS

Our double-blind study included 58 patients with AP, noninvasively confirmed myocardial ischemia and a normal coronary angiogram. The effect of once-daily 20 mg atorvastatin (A) was compared with placebo (P) for 6 months. Endothelial function was evaluated by flow-mediated dilation (FMD) of the brachial artery, and microcirculation by peripheral arterial tonometry (EndoPAT) measuring the reactive hyperemia index (RHI), indicating microcirculatory endothelial function, and the augmentation index (AI), an indicator of arterial stiffness. The impact of AP on the quality of life was monitored using the Seattle Angina Questionnaire (SAQ).

RESULTS

Brachial artery endothelial dysfunction was found in 91.4% of patients at study entry, and subnormal RHI in 41%. Group A showed an improvement of FMD compared with group P, both at 3 and 6 months (+120.8% vs. -21.2%, and +70.8% vs. -1.9%, respectively, p < 0.001). No difference was detected in the RHI. Rate-normalized AI showed an improvement (-114.49% group A vs. -30.77% group P, p = 0.077), although the differences between the groups were not significant. According to the SAQ, an improvement was found in almost all observed variables with the exception of the issue of quality of life (QoL), where patients in both groups assessed their QoL at the control study visits as poorer compared with baseline.

CONCLUSIONS

Moderate-dose atorvastatin therapy improves endothelial function of large conduit arteries in patients with AP and a normal coronary angiogram, which probably reflects positive effects on coronary artery endothelial function. No effect was found with vascular effects at the level of the peripheral microcirculation.

CYP2C19 variants and epoxyeicosatrienoic acids in patients with microvascular angina

BACKGROUND

Categorization as a cytochrome P450 (CYP) 2C19 poor metabolizer (PM) is reported to be an independent risk factor for cardiovascular disease. Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid by CYP2C19 epoxygenases and anti-inflammatory properties, especially in microvascular tissues. We examined the impact of CYP2C19 polymorphisms and EETs on the patients with microvascular angina (MVA) caused by coronary microvascular dysfunction.

METHODS AND RESULTS

We examined CYP2C19 genotypes in patients with MVA (n = 81). MVA was defined as absence of coronary artery stenosis and epicardial spasms, and the presence of inversion of lactic acid levels between intracoronary and coronary sinuses in acetylcholine-provocation test or the adenosine-triphosphate-induced coronary flow reserve ratio was below 2.5. CYP2C19 PM have two loss-of-functon alleles (*2, *3). We measured serum dihydroxyeicosatrienoic acid (DHET) as representative EET metabolite. In MVA, the patients with CYP2C19 PM were 34.6% and high sense C-reactive protein (hs-CRP) levels in CYP2C19 PM were significantly higher than that of non-PM group (0.165 ± 0.116 vs. 0.097 ± 0.113 mg/dL, P = 0.026). Moreover, DHET levels in CYP2C19 PM were significantly lower than that of non-PM (10.4 ± 4.58 vs. 15.6 ± 11.1 ng/mL, P = 0.003 (11,12-DHET); 12.1 ± 3.79 vs. 17.3 ± 6.49 ng/mL, P = 0.019 (14,15-DHET)).

CONCLUSIONS

The decline of EET owing to CYP2C19 variants may affects coronary microvascular dysfunction via chronic inflammation.

Phosphodiesterase type 5 inhibition may reduce diastolic function in women with ischemia but no obstructive coronary artery disease

Background

Ischemia, in the absence of obstructive coronary artery disease, is prevalent in women, and associated with increased risk for major cardiovascular events. Coronary microvascular dysfunction is prevalent in these patients, and associated with impaired diastolic function. Despite our general understanding, however, optimal treatment of this cohort remains elusive.

Methods

To address this knowledge gap, we performed an open-label treatment trial to assess whether phosphodiesterase type 5 inhibition improves coronary microvascular perfusion and diastolic function in women with signs and symptoms of ischemia but no evidence of obstructive coronary artery disease. Left ventricular morphology and function, along with myocardial perfusion reserve index, were assessed by contrast-enhanced cardiac magnetic resonance imaging.

Results

A total of five women enrolled of which four completed the trial, while one was withdrawn by the investigators after developing dyspnea 1 week after treatment. Her symptoms resolved after cessation of the study medication. In contrast to our hypothesis, phosphodiesterase type 5 inhibition reduced the rate of circumferential strain in diastole in all four women who completed the trial (that is, diastolic dysfunction). This impairment could not be explained by changes in heart rate, contractility, blood pressure, or preload, and was not associated with a change in myocardial perfusion reserve index. Frequency of angina also tended to increase with treatment, with the greatest increase occurring in the patient with the greatest impairment in diastolic strain.

Conclusions

Taken together, these data question the efficacy of phosphodiesterase type 5 inhibition to treat women with ischemic heart disease, and highlight the need for further investigation.

Assessing and Modifying Coronary Artery Disease Risk in Women

OPINION STATEMENT

Despite continued advances in the field, cardiovascular disease remains the leading cause of death in women in the USA with an annual mortality rate that has remained higher for women as compared to men. The factors leading to this sex difference remain incompletely understood. Likely contributors include atypical symptoms at presentation and lack of recognition of cardiovascular risk by women and their providers alike. In addition, women have a higher burden of comorbidities at the time of disease diagnosis and can have differential pathophysiological mechanisms of their acute events. Women also can develop unique cardiovascular risk factors such as preeclampsia and hypertensive disorders of pregnancy. As a result, when women present with symptoms, even atypical, healthcare providers should increase their index level of suspicion for cardiovascular disease. Even after diagnosis, women are less likely to receive guideline-directed medical therapies and be referred for coronary angiography or cardiac rehabilitation. Thus, greater awareness of and research into the aspects of coronary disease that remain unique to women is critical, as women presenting with coronary disease continue to receive disparate care as compared to men. Improvements in awareness and care and new research avenues may reduce the incidence and complications of cardiovascular disease among women.

Targeting the dominant mechanism of coronary microvascular dysfunction with intracoronary physiology tests

The coronary microcirculation plays a key role in modulating blood supply to the myocardium. Several factors like myocardial oxygen demands, endothelial and neurogenic conditions determine its function. Although there is available evidence supporting microvascular dysfunction as an important cause of myocardial ischaemia, with both prognostic and symptomatic implications, its diagnosis and management in clinical practice is still relegated to a second plane. Both diagnostic and therapeutic approaches are hampered by the broadness of the concept of microvascular dysfunction, which fails addressing the plurality of mechanisms leading to dysfunction. Normal microcirculatory function requires both structural integrity of the microcirculatory vascular network and preserved signalling pathways ensuring adequate and brisk arteriolar resistance shifts in response to myocardial oxygen demands. Pathological mechanisms affecting these requirements include structural remodelling of microvessels, intraluminal plugging, extravascular compression or vasomotor dysregulation. Importantly, not every diagnostic technique provides evidence on which of these pathophysiological mechanisms is present or predominates in the microcirculation. In this paper we discuss the mechanisms of coronary microvascular dysfunction and the intracoronary tools currently available to detect it, as well as the potential role of each one to unmask the main underlying mechanism.

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

The Cardiovascular Disease in Women Committee of the American College of Cardiology, in conjunction with interested parties (from the National Heart, Lung, and Blood Institute, American Heart Association, and European Society of Cardiology), convened a working group to develop a consensus on the syndrome of myocardial ischemia with no obstructive coronary arteries. In general, these patients have elevated risk for a cardiovascular event (including acute coronary syndrome, heart failure hospitalization, stroke, and repeat cardiovascular procedures) compared with reference subjects and appear to be at higher risk for development of heart failure with preserved ejection fraction. A subgroup of these patients also has coronary microvascular dysfunction and evidence of inflammation. This document provides a summary of findings and recommendations for the development of an integrated approach for identifying and managing patients with ischemia with no obstructive coronary arteries and outlines knowledge gaps in the area. Working group members critically reviewed available literature and current practices for risk assessment and state-of-the-science techniques in multiple areas, with a focus on next steps needed to develop evidence-based therapies. This report presents highlights of this working group review and a summary of suggested research directions to advance this field in the next decade.

Ranolazine and Microvascular Angina by PET in the Emergency Department: Results From a Pilot Randomized Controlled Trial

PURPOSE

Coronary microvascular dysfunction (CMD) is a common but underdiagnosed cause of chest pain. Literature is scant regarding effective treatments. We explored the effect of ranolazine on coronary flow reserve (CFR) among symptomatic patients with CMD.

METHODS

This pilot double-blinded randomized controlled trial included emergency department patients with chest pain and CMD admitted to an observation unit between June 2014 and November 2015. Participants were assessed by cardiac Rb-82 positron emission tomography and computed tomography imaging at baseline and 30 days. CMD was defined as CFR <2 corrected for rate pressure product or <2.5 uncorrected, with no evidence of obstructive or nonobstructive coronary artery disease or calcification. Patients with infarction, hypertensive urgency, heart failure, or prescribed QTc-prolonging drugs were excluded. Participants were assigned to ranolazine or placebo in a 2:1 ratio. Primary outcome was change in CFR at 30 days.

FINDINGS

We enrolled 31 patients (71% female, mean [SD] age 50 [6] years) with CMD (mean [SD] corrected CFR 1.6 [0.3]). Ranolazine improved CFR at 30 days by 17% (P = 0.005) compared with 0% with placebo (P = 0.67). However, there was no significant difference in the primary outcome as measured by mean change in CFR (0.27 ranolazine compared with 0.06 placebo; 95% CI, -0.08 to 0.62).

IMPLICATIONS

The emergency department offers a unique venue to diagnose CMD with acute symptoms. In an exploratory randomized controlled trial of symptomatic patients with CMD and no coronary artery disease, promising results were seem with ranolazine and CFR improving at 30 days. Large robust clinical trials are needed to verify improvement of CMD in a sex-specific model. ClinicalTrials.gov identifier NCT02052011.

Microvascular Coronary Artery Disease: Review Article

Recently it has become more apparent that microvascular dysfunction is responsible for morbidity and mortality in many different cardiovascular diseases. It is no longer felt to be benign, and besides accounting for angina symptoms, it likely plays a role in heart failure with preserved ejection fraction, as well as in Takotsubo syndrome and various inflammatory diseases associated with ischemia and atherosclerosis. Coronary microvascular disease can be diagnosed by means of invasive coronary reactivity testing and noninvasively by echocardiography, computerized tomography, magnetic resonance, and positron emission tomography. Unfortunately, treatment has been more empiric, and not as well evaluated by randomized trials as in other disease states. Beta blockers, nitrates, and calcium channel blockers have all been used with varying degrees of success. Given its prevalence, particularly among women, its increased recognition and importance mandates further research into prompt diagnosis and more robust studies of its treatment.

Women with Stable Angina Pectoris and No Obstructive Coronary Artery Disease: Closer to a Diagnosis

A large proportion of women with chest pain have no obstructive coronary artery disease. Recent studies have demonstrated that these women continue to have symptoms and are at increased risk of cardiovascular morbidity and mortality. Coronary microvascular dysfunction (CMD) leads to an impairment of blood flow regulation to the myocardium and possible transient ischaemia. CMD is a disease entity with several pathophysiologic aspects and diagnostic modalities continue to be developed. However, due to the complexity of the disease, it remains elusive whether CMD is the explanation for the symptoms and the poor prognosis in women with angina and no obstructive coronary artery disease.

Coronary Microvascular Dysfunction - Epidemiology, Pathogenesis, Prognosis, Diagnosis, Risk Factors and Therapy

Angina has traditionally been thought to be caused by obstructive coronary artery disease (CAD). However, a substantial number of patients with angina are found to not have obstructive CAD when undergoing coronary angiography. A significant proportion of these patients have coronary microvascular dysfunction (CMD), characterized by heightened sensitivity to vasoconstrictor stimuli and limited microvascular vasodilator capacity. With the advent of non-invasive and invasive techniques, the coronary microvasculature has been more extensively studied in the past 2 decades. CMD has been identified as a cause of cardiac ischemia, in addition to traditional atherosclerotic disease and vasospastic disease. CMD can occur alone or in the presence obstructive CAD. CMD shares many similar risk factors with macrovascular CAD. Diagnosis is achieved through detection of an attenuated response of coronary blood flow in response to vasodilatory agents. Imaging modalities such as cardiovascular magnetic resonance, positron emission tomography, and transthoracic Doppler echocardiography have become more widely used, but have not yet completely replaced the traditional intracoronary vasoreactivity testing. Treatment of CMD starts with lifestyle modification and risk factor control. The use of traditional antianginal, antiatherosclerotic medications and some novel agents may be beneficial; however, clinical trials are needed to assess the efficacy of the pharmacologic and non-pharmacologic therapeutic modalities. In addition, studies with longer-term follow-up are needed to determine the prognostic benefits of these agents. We review the epidemiology, prognosis, pathogenesis, diagnosis, risk factors and current therapies for CMD.

Management standards for stable coronary artery disease in India

Coronary artery disease (CAD) is one of the important causes of cardiovascular morbidity and mortality globally, giving rise to more than 7 million deaths annually. An increasing burden of CAD in India is a major cause of concern with angina being the leading manifestation. Stable coronary artery disease (SCAD) is characterised by episodes of transient central chest pain (angina pectoris), often triggered by exercise, emotion or other forms of stress, generally triggered by a reversible mismatch between myocardial oxygen demand and supply resulting in myocardial ischemia or hypoxia. A stabilised, frequently asymptomatic phase following an acute coronary syndrome (ACS) is also classified as SCAD. This definition of SCAD also encompasses vasospastic and microvascular angina under the common umbrella.

Association of CYP2C19 variants and epoxyeicosatrienoic acids on patients with microvascular angina

Categorization as a cytochrome P450 (CYP) 2C19 poor metabolizer (PM) is reported to be an independent risk factor for cardiovascular disease. Epoxyeicosatrienoic acids (EETs) are metabolites of arachidonic acid by CYP2C19 epoxygenases and anti-inflammatory properties, especially in microvascular tissues. We examined the association of CYP2C19 polymorphisms and EETs on microvascular angina (MVA) caused by coronary microvascular dysfunction. We examined CYP2C19 genotypes in patients with MVA ( n = 71) and healthy subjects as control ( n = 71). MVA was defined as the absence of coronary artery stenosis and epicardial spasms and the presence of inversion of lactic acid levels between intracoronary and coronary sinuses in acetylcholine-provocation test or the adenosine-triphosphate-induced coronary flow reserve ratio was below 2.5. CYP2C19 PM have two loss-of-functon alleles (*2, *3). We measured serum dihydroxyeicosatrienoic acid (DHET) as representative EET metabolite. MVA group showed significantly higher CYP2C19 PM incidence (35% vs. 16%; P = 0.007) and high sense C-reactive protein (hs-CRP) levels (0.127 ± 0.142 vs. 0.086 ± 0.097 mg/dl; P = 0.043) than those of controls. Moreover, in MVA group, hs-CRP levels in CYP2C19 PM were significantly higher than that of non-PM (0.180 ± 0.107 vs. 0.106 ± 0.149 mg/dl, P = 0.045). Multivariate analysis indicated that smoking, hypertension, high hs-CRP, and CYP2C19 PM are predictive factors for MVA. In MVA group, DHET levels for CYP2C19 PM were significantly lower than that of non-PM [10.9 ± 1.64 vs. 14.2 ± 5.39 ng/ml, P = 0.019 (11,12-DHET); 15.2 ± 4.39 vs. 17.9 ± 4.73 ng/ml, P = 0.025 (14,15-DHET)]. CYP2C19 variants are associated with MVA. The decline of EET-based defensive mechanisms owing to CYP2C19 variants may affect coronary microvascular dysfunction.

Myocardial blood flow: Putting it into clinical perspective

In recent years, positron emission tomography/computed tomography (PET/CT)-determined myocardial perfusion in conjunction with myocardial blood flow (MBF) quantification in mL·g(-1)·min(-1) has emerged from mere research application to initial clinical use in the detection and characterization of the coronary artery disease (CAD) process. The concurrent evaluation of MBF during vasomotor stress and at rest with the resulting myocardial flow reserve (MFR = MBF during stress/MBF at rest) expands the scope of conventional myocardial perfusion imaging not only to the detection of the most advanced and culprit CAD, as evidenced by the stress-related regional myocardial perfusion defect, but also to the less severe or intermediate stenosis in patients with multivessel CAD. Due to the non-specific nature of the hyperemic MBF and MFR, the interpretation of hyperemic flow increases with PET/CT necessitates an appropriate placement in the context with microvascular function, wall motion analysis, and eventually underlying coronary morphology in CAD patients. This review aims to provide a comprehensive overview of various diagnostic scenarios of PET/CT-determined myocardial perfusion and flow quantification in the detection and characterization of clinically manifest CAD.

Coronary Microvascular Dysfunction, Microvascular Angina, and Management

Recent analyses have found that coronary microvascular dysfunction (CMD) portends a poor prognosis in patients with and without obstructive epicardial coronary artery disease (CAD). Chest pain in the absence of epicardial CAD is a common entity. Angina caused by CMD, microvascular angina (MVA), is often indistinguishable from that caused by obstructive epicardial CAD. The recent emergence of noninvasive techniques that can identify CMD, such as stress positron-emission tomography (PET) and cardiovascular magnetic resonance (CMR) myocardial perfusion imaging, allow improved identification of MVA. Using these tools, higher risk patients with MVA can be differentiated from those at lower risk in the heterogeneous population historically labeled as cardiac syndrome X. Likewise, MVA can be diagnosed in those with obstructive epicardial CAD who have persistent angina despite successful revascularization. There is little evidence to support current treatment strategies for MVA and current literature has not clearly defined CMD or whether therapy improves prognosis.

Advanced Imaging and Diagnostic Methods in the Assessment of Suspected Ischemic Heart Disease in Women

Although differences diminish with age, outcomes are overall worse for women compared to men who present with suspected acute coronary syndrome. The reasons for this discrepancy are multifactorial, including sex-related differences in atherosclerosis biology and fluid dynamics, as well as a premature conclusion by providers that chest pain must be noncardiac in the absence of obstructive coronary artery disease. In this review of existing literature, we explore the diverse differential diagnosis in this unique set of patients. Especially in women with persistent symptoms, absence of occlusive disease should prompt consideration for subangiographic plaque disruption, epicardial or microvascular endothelial dysfunction, transient neurohormonal imbalance predisposing to Takotsubo cardiomyopathy or spontaneous coronary artery dissection, underlying systemic inflammatory conditions, thromboembolic disease, myocarditis, and sequelae of congenital heart disease. As always, a thorough history and attentive physical exam will help guide further work-up, which in many cases may warrant noninvasive imaging, such as contrast-enhanced echocardiography, cardiac magnetic resonance imaging, or positron emission tomography, with their respective means of measuring myocardial perfusion and myocardial tissue pathology. Lastly, intracoronary imaging such as intravascular ultrasound and optical coherence tomography and invasive diagnostic methods such as coronary reactivity testing continue to add to our understanding that what appear to be atypical presentations of ischemic heart disease in women may in fact be typical presentations of pathologic cousin entities that remain incompletely defined.

Human Endothelial Cell-Specific Molecule-1 (Endocan) and Coronary Artery Disease and Microvascular Angina

Endothelial cell-specific molecule-1 (endocan) is an immunoinflammatory marker linked to endothelial activation and dysfunction. We investigated the relationship between obstructive coronary artery disease (CAD), microvascular angina (MVA), and plasma levels of endocan. We included 53 healthy individuals as controls, 40 MVA patients, and 120 patients with obstructive CAD. The severity of CAD was assessed by the Gensini and SYNergy between percutaneous coronary intervention with TAXUS and Cardiac Surgery (SYNTAX) scores. Endocan levels were 382.7 (313.8-470.2) pg/mL in patients with obstructive CAD; 324.3 (277.1-460.7) pg/mL in MVA group, and 268.0 (226.4-336.5) pg/mL ( P < .001) in controls. Endocan levels in obstructive CAD and MVA groups were similar but both were significantly higher than for the control group ( P < .001 and P = .002, respectively). In subgroup analysis, similar to the hypertensive subgroup results, endocan was still an independent predictor of presence of obstructive CAD in normotensives (odds ratio = 1.005, 95% confidence interval = 1.001-1.010, P = .024). There was also an independent positive correlation between endocan levels and SYNTAX score both in the hypertensives (β = 0.414, t = 3.21, P = .002) and in the normotensives (β = .301, t = 2.23, P = .031). In conclusion, endocan could be a common predictor of the endothelium-dependent inflammatory processes, rather than related with specific risk factors.

Women and Chest Pain: Recognizing the Different Faces of Angina in the Emergency Department

Emergency departments (ED) in the United States see over eight million cases of chest pain annually. While a cardinal symptom of acute coronary syndrome (ACS), multiple emergent and non-emergent causes can attribute to chest pain. This case-based perspective describes the different sex-specific causes of angina seen in ED patients. Once coronary artery disease (CAD) is ruled out with standard protocols, microvascular dysfunction is perhaps the most prevalent but under-diagnosed cause of non-CAD related angina in ED patients. Additional causes include coronary artery spasm, coronary artery dissection, coronary artery endothelial dysfunction and myocardial bridging. Non-CAD related angina is associated with persistent chest pain causing poor function, quality of life, and recidivism. Clinicians should consider additional diagnostics to routinely screen for non-CAD related causes of angina in patients with recurrent chest pain. Future work is needed to better define the epidemiological, clinical, biological, and genetic correlates of microvascular dysfunction in these patients.

Sex differences in the impact of CYP2C19 polymorphisms and low-grade inflammation on coronary microvascular disorder

Categorization as a cytochrome P-450 (CYP) 2C19 poor metabolizer (PM) is reported to be an independent risk factor for cardiovascular disease. It is correlated with an increase in the circulating levels of high-sense C-reactive protein (hs-CRP) in women only, although its role in coronary microcirculation is unclear. We examined sex differences in the impact of the CYP2C19 genotype and low-grade inflammation on coronary microvascular disorder (CMVD). We examined CYP2C19 genotypes in patients with CMVD (n = 81) and in healthy subjects as control (n = 81). CMVD was defined as the absence of coronary artery stenosis and epicardial spasms, the presence of inverted lactic acid levels between the intracoronary and coronary sinuses, or an adenosine triphosphate-induced coronary flow reserve ratio < 2.5. CYP2C19 PMs have two loss-of-function (LOF) alleles (*2, *3). Extensive metabolizers have no LOF alleles, and intermediate metabolizers have one LOF allele. The ratio of CYP2C19 PM and hs-CRP levels in CMVD was significantly higher than that of controls, especially in women (40.9 vs. 13.8%, P = 0.013; 0.11 ± 0.06 vs. 0.07 ± 0.04 mg/dl, P = 0.001). Moreover, in each CYP2C19 genotype, hs-CRP levels in CMVD in CYP2C19 PMs were significantly higher than those of the controls, especially in women (0.15 ± 0.06 vs. 0.07 ± 0.03, P = 0.004). Multivariate analysis for CMVD indicated that the female sex, current smoking, and hypertension were predictive factors, and that high levels of hs-CRP and CYP2C19 PM were predictive factors in women only (odds ratio 3.5, 95% confidence interval 1.26-9.93, P = 0.033; odds ratio 4.1, 95% confidence interval 1.15-14.1, P = 0.038). CYP2C19 PM genotype may be a new candidate risk factor for CMVD via inflammation exclusively in the female population.