Coronary microvascular reactivity to adenosine predicts adverse outcome in women evaluated for suspected ischemia results from the National Heart, Lung and Blood Institute WISE (Women's Ischemia Syndrome Evaluation) study

Nuclear cardiology in the context of multimodality imaging to detect cardiac toxicity from cancer therapeutics: Established and emerging methods

The complexity of cancer therapies has vastly expanded in the last decade, along with type and severity of cardiac toxicities associated with these treatments. Prevention of pre-clinical cardiotoxicity may improve cardiovascular outcomes and circumvent the decision to place life-sustaining chemotherapeutic agents on hold, making the early detection of cancer therapeutic related cardiac toxicity with non-invasive imaging essential to the care of these patients. There are several established methods of cardiac imaging in the areas of nuclear cardiology, echocardiography, computed tomography, and cardiac magnetic resonance imaging that are used to assess for cardiovascular toxicity of cancer treatments, with several methods under development. The following review will provide an overview of current and emerging imaging techniques in these areas.

Clinical outcomes in patients with primary stable microvascular angina: is the jury still out?

Several studies have demonstrated that angina chest pain in presence of normal or near normal coronary arteries (NCAs) is mainly related to coronary microvascular dysfunction (CMD). However, controversial findings exist about clinical outcome of these patients. In this article, we critically review characteristics and results of the main clinical studies reporting clinical outcome of stable patients with angina chest pain and non-obstructive coronary artery disease (NO-CAD). Published data indicate that clinical outcomes of these patients are heterogeneous, but those with strict criteria for primary stable microvascular angina (MVA, i.e. typical angina with NCAs mainly related to efforts) do not appear to have an increased mortality or risk of major coronary events. A major determinant of outcome in patients with MVA and NO-CAD seems instead related to non-critical atherosclerotic disease, the presence of which should suggest a more aggressive management of cardiovascular risk factors and preventive management. Future studies should assess whether CMD may have a relevant prognostic role in the latter clinical context and/or in other clinical settings of NO-CAD different from primary stable MVA.

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

OBJECTIVES

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

Impact of Targeted Therapies for Coronary Microvascular Dysfunction as Assessed by the Index of Microcirculatory Resistance

Coronary microvascular dysfunction (CMD) has emerged as an important therapeutic target in the contemporary management of ischemic heart disease. However, due to a lack of a reliable traditional "gold standard" test for CMD, optimal treatment remains undefined. The index of microcirculatory resistance (IMR) is an intra-coronary wire-based technique that provides a more reliable and quantitative assessment of CMD and has been increasingly used as a preferred endpoint for evaluating CMD treatment strategies in recent studies. IMR can help diagnose CMD in angina patients with non-obstructive epicardial coronary disease, predict peri-procedural myocardial infarction in stable patients undergoing coronary stenting, and predict long-term prognosis after acute myocardial infarction. Studies of IMR in the setting of non-ST-elevation acute coronary syndromes are still lacking. This review critically appraises the current published literature evaluating targeted therapies for CMD using IMR as the assessment tool and provides insights into evidence gaps in this important field. The index of microcirculatory resistance has rapidly evolved from a research tool to being the new "gold standard" test for evaluating coronary microvascular dysfunction.

Cardiovascular Imaging Techniques to Assess Microvascular Dysfunction

The understanding of microvascular dysfunction without evidence of epicardial coronary artery disease pales in comparison with that of obstructive epicardial coronary artery disease. A primary limitation in the past had been the lack of development of noninvasive methods of detecting and quantifying microvascular dysfunction. This limitation has particularly affected the ability to study the pathophysiology, morbidity, and treatment of this disease. More recently, almost all of the noninvasive cardiac imaging modalities have been used to quantify blood flow and advance understanding of microvascular dysfunction.

A method to measure the extent of myocardial ischemia and steal with SPECT myocardial blood flow quantitation

OBJECTIVE

We introduced a method to measure the extent of myocardial ischemia and steal with SPECT MBF quantitation.

METHODS

Eighty-seven patients who received rest/Dipyridamole-stress ^99mTc-Sestamibi (MIBI) dynamic SPECT scans and coronary angiography were included. Dynamic SPECT images were reconstructed with full physical corrections. The one-tissue kinetic model was utilized to quantify K1 and further converted to MBF with required corrections. Rest MBF, stress MBF and myocardial flow reserve (MFR) were converted to a flow status polar map by a flow diagram. Extents of 7 flow statuses were verified their cutoff points for detecting stenoses. The diagnostic performance (DP) was compared to that of MFR.

RESULTS

Cutoff point of the extent to detect ≥ 50% stenosis was 3.01% for ischemia-steal status and 20.3% for the combined status of ischemia-steal and moderate. Using these criteria, sensitivity, specificity and accuracy to detect ≥ 50% stenosis were (80%, 75%, 79%) and (86%, 68%, 80%) for ≥ 70% stenosis. The DP was superior to that of MFR < 2.0 criterion (≥ 50%: 70%, 63%, 69%; ≥ 70%: 73%, 61%, 69%) (all p < 0.015).

CONCLUSION

SPECT MBF quantitation integrated with the flow diagram can measure the extent of myocardial ischemia and steal which appeared more accurate to detect angiographic stenoses than the single MFR parameter.

Even "WISE-R?"-an Update on the NHLBI-Sponsored Women's Ischemia Syndrome Evaluation

PURPOSE OF REVIEW

For over 20 years, the Women's Ischemia Syndrome Evaluation (WISE), a program sponsored by the National Heart, Lung, and Blood Institute, has explored diverse and important aspects of ischemic heart disease in women.

RECENT FINDINGS

Women with symptoms and signs of ischemia but no significant epicardial obstructive coronary artery disease (INOCA) were documented to be at elevated risk for recurrent angina hospitalization, major adverse cardiac events, death, and health resource consumption rivaling those with obstructive coronary disease. WISE investigators have advanced our understanding of cardiovascular outcomes, systemic manifestations, psychological variables, socioeconomic factors, genetic contributions, hormonal status, advanced imaging, coronary functional findings, biomarkers, patient-reported outcomes, and treatments pertaining to women with this disease entity. This review delves into the WISE findings subsequent to a prior review1, postulates directions for future research, and asks are we "Even 'WISE-R?'".

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Optimal Use of Vasodilators for Diagnosis of Microvascular Angina in the Cardiac Catheterization Laboratory

Among patients with angina and nonobstructive coronary artery disease, those with coronary microvascular dysfunction have a poor outcome. Coronary microvascular dysfunction is usually diagnosed by assessing flow reserve with an endothelium-independent vasodilator like adenosine, but the optimal diagnostic threshold is unclear. Furthermore, the incremental value of testing endothelial function has never been assessed before. We sought to determine what pharmacological thresholds correspond to exercise pathophysiology and myocardial ischemia in patients with coronary microvascular dysfunction.

Reduced coronary flow velocity reserve in women with previous pre-eclampsia: link to increased cardiovascular disease risk

OBJECTIVES

To evaluate differences in coronary microvascular function approximately 12 years after delivery between women who had had early- (EO-PE) or late- (LO-PE) onset pre-eclampsia and those who had had a normotensive pregnancy, and to assess the relationship between microvascular function and myocardial deformation at follow-up in these women.

METHODS

This was a case-control study of 88 women who had delivered at the Department of Gynecology and Obstetrics, Randers Regional Hospital, Randers, Denmark, between 1998 and 2008. Coronary flow velocity reserve (CFVR) was assessed by Doppler echocardiography approximately 12 years after delivery. Women were grouped according to whether the pregnancy had been complicated by EO-PE (n = 29) or LO-PE (n = 20), or had been normotensive (controls) (n = 39). Study groups were matched for maternal age and time since delivery. CFVR at follow-up was compared between the study groups. Regression analysis was used to assess the association between gestational age at onset of PE and CFVR. The association between left ventricular global longitudinal strain (LV-GLS) and CFVR at follow-up was also evaluated.

RESULTS

Resting coronary flow velocity assessed 12 years after delivery was comparable between the study groups (P = 0.55), whereas peak hyperemic flow velocity was significantly lower in the EO-PE group than in the LO-PE group (P < 0.01) and controls (P < 0.0001). As such, mean CFVR at follow-up was significantly lower in the EO-PE group than in the LO-PE group (P < 0.01) and controls (P < 0.0001). CFVR was < 2.5 in 48% of women in the EO-PE group, 25% of those in the LO-PE group and 8% of controls (P < 0.01). There was a significant positive association between gestational age at diagnosis of PE and CFVR at 12-year follow-up (β1 = 1.8 (95% CI, 0.8-2.9); P < 0.01). This relationship remained significant after adjustment for cardiovascular risk factors, namely mean arterial blood pressure, glycated hemoglobin level, body mass index, low-density lipoprotein cholesterol level and smoking status (P < 0.05). There was a significant association between LV-GLS and CFVR in women who had had PE (β1 = -1.5 (95% CI, -2.2 to -0.9); R²  = 0.33, P < 0.0001).

CONCLUSIONS

Low gestational age at onset of PE, both as a continuous variable and when categorized as early onset, was associated with decreased CFVR 12 years after delivery. Nearly 50% of women who had had EO-PE had CFVR < 2.5 at follow-up. Reduced CFVR in women who had had PE was associated with subclinical myocardial dysfunction in terms of reduced LV-GLS. Copyright © 2019 ISUOG. Published by John Wiley & Sons Ltd.

Physiological Stratification of Patients With Angina Due to Coronary Microvascular Dysfunction

BACKGROUND

Coronary microvascular dysfunction (CMD) is defined by diminished flow reserve. Functional and structural CMD endotypes have recently been described, with normal and elevated minimal microvascular resistance, respectively.

OBJECTIVES

This study determined the mechanism of altered resting and maximal flow in CMD endotypes.

METHODS

A total of 86 patients with angina but no obstructive coronary disease underwent coronary pressure and flow measurement during rest, exercise, and adenosine-mediated hyperemia and were classified as the reference group or as patients with CMD by a coronary flow reserve threshold of 2.5; functional or structural endotypes were distinguished by a hyperemic microvascular resistance threshold of 2.5 mm Hg/cm/s. Endothelial function was assessed by forearm blood flow (FBF) response to acetylcholine, and nitric oxide synthase (NOS) activity was defined as the inverse of FBF reserve to NG-monomethyl-L-arginine.

RESULTS

Of the 86 patients, 46 had CMD (28 functional, 18 structural), and 40 patients formed the reference group. Resting coronary blood flow (CBF) (24.6 ± 2.0 cm/s vs. 16.6 ± 3.9 cm/s vs. 15.1 ± 4.7 cm/s; p < 0.001) and NOS activity (2.27 ± 0.96 vs. 1.77 ± 0.59 vs. 1.30 ± 0.16; p < 0.001) were higher in the functional group compared with the structural CMD and reference groups, respectively. The structural group had lower acetylcholine FBF augmentation than the functional or reference group (2.1 ± 1.8 vs. 4.1 ± 1.7 vs. 4.5 ± 2.0; p < 0.001). On exercise, oxygen demand was highest (rate-pressure product: 22,157 ± 5,497 beats/min/mm Hg vs. 19,519 ± 4,653 beats/min/mm Hg vs. 17,530 ± 4,678 beats/min/mm Hg; p = 0.004), but peak CBF was lowest in patients with structural CMD compared with the functional and reference groups.

CONCLUSIONS

Functional CMD is characterized by elevated resting flow that is linked to enhanced NOS activity. Patients with structural CMD have endothelial dysfunction, which leads to diminished peak CBF augmentation and increased demand during exercise. The value of pathophysiologically stratified therapy warrants investigation.

Coronary Functional Abnormalities in Patients With Angina and Nonobstructive Coronary Artery Disease

BACKGROUND

Approximately one-half of patients undergoing diagnostic coronary angiography for angina have no significant coronary stenosis, in whom coronary functional abnormalities could be involved.

OBJECTIVES

This study examined the significance of coronary functional abnormalities in a comprehensive manner for both epicardial and microvascular coronary arteries in patients with angina and nonobstructive coronary artery disease (CAD).

METHODS

This study prospectively enrolled 187 consecutive patients (male/female 113/74, 63.2 ± 12.3 years), who underwent acetylcholine provocation test for coronary spasm and measurement of index of microcirculatory resistance (IMR) to evaluate coronary microvascular function, and followed them for a median of 893 days.

RESULTS

Of all subjects, acetylcholine test identified 128 patients with vasospastic angina (VSA) (68%), and cardiac events occurred in 10 patients (5.3%) during the follow-up. Multivariable analysis revealed that IMR correlated with the incidence of cardiac events (hazard ratio: 1.05; 95% confidence interval: 1.02 to 1.09; p = 0.002) and receiver-operating characteristics (ROC) curve analysis identified IMR of 18.0 as the optimal cut-off value. Among the 4 groups based on the cut-off value of IMR and the presence of VSA, the Kaplan-Meier survival analysis showed a significantly worse prognosis in the group with high IMR (≥18.0) and VSA compared with other groups (log rank, p = 0.002). Importantly, intracoronary administration of fasudil, a Rho-kinase inhibitor, significantly ameliorated IMR in the VSA patients with increased IMR (p < 0.0001).

CONCLUSIONS

These results indicate that in patients with angina and nonobstructive CAD, coexistence of epicardial coronary spasm and increased microvascular resistance is associated with worse prognosis, for which Rho-kinase activation may be involved.

Oxidative Stress Is Associated With Diastolic Dysfunction in Women With Ischemia With No Obstructive Coronary Artery Disease

Background Women with signs and symptoms of ischemia and no obstructive coronary artery disease often have evidence of diastolic dysfunction. Oxidative stress (OS) is associated with cardiovascular risk factors and adverse outcomes. The relationship between systemic OS and diastolic dysfunction is unknown. Methods and Results A subgroup of women (n=75) with suspected ischemia and no obstructive coronary artery disease who had both cardiac magnetic resonance imaging and OS measurements were enrolled in the WISE-CVD (Women Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction) study. Left ventricular end-diastolic pressure was measured invasively. Left ventricular end-diastolic volume and peak filling rate were assessed using cardiac magnetic resonance imaging. Aminothiol levels of plasma cystine and glutathione were measured as markers of OS. Spearman correlation and linear regression analyses were conducted. The group mean age was 54±11 years, and 61% had a resting left ventricular end-diastolic pressure >12 mm Hg. Cystine levels correlated negatively with the peak filling rate (r=-0.31, P=0.007) and positively with left ventricular end-diastolic pressure (r=0.25; P=0.038), indicating that increased OS was associated with diastolic dysfunction. After multivariate adjustment including multiple known risk factors for diastolic dysfunction and cardiovascular medications, cystine levels continued to be associated with peak filling rate (β=-0.27, P=0.049) and left ventricular end-diastolic pressure (β=0.25; P=0.035). Glutathione levels were not associated with indices of diastolic function. Conclusions OS, measured by elevated levels of cystine, is associated with diastolic dysfunction in women with evidence of ischemia and no obstructive coronary artery disease, indicating the role of OS in patients with ischemia and no obstructive coronary artery disease. Its role in the progression of heart failure with preserved ejection fraction should be explored further.

The Prognostic Significance of Quantitative Myocardial Perfusion: An Artificial Intelligence-Based Approach Using Perfusion Mapping

BACKGROUND

Myocardial perfusion reflects the macro- and microvascular coronary circulation. Recent quantitation developments using cardiovascular magnetic resonance perfusion permit automated measurement clinically. We explored the prognostic significance of stress myocardial blood flow (MBF) and myocardial perfusion reserve (MPR, the ratio of stress to rest MBF).

METHODS

A 2-center study of patients with both suspected and known coronary artery disease referred clinically for perfusion assessment. Image analysis was performed automatically using a novel artificial intelligence approach deriving global and regional stress and rest MBF and MPR. Cox proportional hazard models adjusting for comorbidities and cardiovascular magnetic resonance parameters sought associations of stress MBF and MPR with death and major adverse cardiovascular events (MACE), including myocardial infarction, stroke, heart failure hospitalization, late (>90 day) revascularization, and death.

RESULTS

A total of 1049 patients were included with a median follow-up of 605 (interquartile range, 464-814) days. There were 42 (4.0%) deaths and 188 MACE in 174 (16.6%) patients. Stress MBF and MPR were independently associated with both death and MACE. For each 1 mL·g-1·min-1 decrease in stress MBF, the adjusted hazard ratios for death and MACE were 1.93 (95% CI, 1.08-3.48, P=0.028) and 2.14 (95% CI, 1.58-2.90, P<0.0001), respectively, even after adjusting for age and comorbidity. For each 1 U decrease in MPR, the adjusted hazard ratios for death and MACE were 2.45 (95% CI, 1.42-4.24, P=0.001) and 1.74 (95% CI, 1.36-2.22, P<0.0001), respectively. In patients without regional perfusion defects on clinical read and no known macrovascular coronary artery disease (n=783), MPR remained independently associated with death and MACE, with stress MBF remaining associated with MACE only.

CONCLUSIONS

In patients with known or suspected coronary artery disease, reduced MBF and MPR measured automatically inline using artificial intelligence quantification of cardiovascular magnetic resonance perfusion mapping provides a strong, independent predictor of adverse cardiovascular outcomes.

Predicted Versus Observed Major Adverse Cardiac Event Risk in Women With Evidence of Ischemia and No Obstructive Coronary Artery Disease: A Report From WISE (Women's Ischemia Syndrome Evaluation)

Background Primary prevention risk scores are commonly used to predict cardiovascular (CVD) outcomes. The applicability of these scores in patients with evidence of myocardial ischemia but no obstructive coronary artery disease is unclear. Methods and Results Among 935 women with signs and symptoms of ischemia enrolled in WISE (Women's Ischemia Syndrome Evaluation), 567 had no obstructive coronary artery disease on angiography. Of these, 433 had had available risk data for 6 commonly used scores: Framingham Risk Score, Reynolds Risk Score, Adult Treatment Panel III, Atherosclerotic Cardiovascular Disease, Systematic Coronary Risk Evaluation, Cardiovascular Risk Score 2. Score-specific CVD rates were assessed. For each score, we evaluated predicted versus observed event rates at 10-year follow-up using c statistic. Recalibration was done for 3 of the 6 scores. The 433 women had a mean age of 56.9±9.4 years, 82.5% were white, 52.7% had hypertension, 43.6% had dyslipidemia, and 16.9% had diabetes mellitus. The observed 10-year score-specific CVD rates varied between 5.54% (Systematic Coronary Risk Evaluation) to 28.87% (Framingham Risk Score), whereas predicted event rates varied from 1.86% (Systematic Coronary Risk Evaluation) to 6.99% (Cardiovascular Risk Score 2). The majority of scores showed moderate discrimination (c statistic 0.53 for Atherosclerotic Cardiovascular Disease and Systematic Coronary Risk Evaluation; 0.78 for Framingham Risk Score) and underestimated risk (statistical discordance -58% for Adult Treatment Panel III; -84% for Atherosclerotic Cardiovascular Disease). Recalibrated Reynolds Risk Score, Atherosclerotic Cardiovascular Disease, and Framingham Risk Score had improved performance, but significant underestimation remained. Conclusions Commonly used CVD risk scores fail to accurately predict CVD rates in women with ischemia and no obstructive coronary artery disease. These results emphasize the need for new risk assessment scores to reliably assess this population.

Adverse Pregnancy Outcomes Are Associated with Reduced Coronary Flow Reserve in Women With Signs and Symptoms of Ischemia Without Obstructive Coronary Artery Disease: A Report from the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction Study

Background: We assessed history of adverse pregnancy outcomes (APOs) and coronary microvascular dysfunction (CMD) in the Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD) cohort of women with signs and symptoms of ischemia without obstructive coronary artery disease (CAD). We hypothesized that women with CMD with symptoms and signs of ischemia, without obstructive CAD, are more likely to have a history of APO. Materials and Methods: WISE-CVD recruited women with suspected ischemia found to have no obstructive CAD (n = 324). A subset of these women underwent coronary reactivity testing, including coronary flow reserve (CFR) (n = 185). Relationship between history of any APO and CMD was assessed by multivariable linear regression analyses. APOs included any of the following: hypertension during pregnancy, preeclampsia, eclampsia, gestational diabetes, or intrauterine growth restriction (low-birth-weight child). Results: Overall, 79/324 (24%) women reported at least one APO. Women with APOs were younger (52 vs. 56 years, p = 0.001), were more likely obese (body mass index 32 vs. 29 kg/m2, p = 0.004), and had a history of hypertension (56% vs 36%, p = 0.002), but otherwise had no additional differences in cardiac risk variables versus women without APOs. Among the subgroup who underwent invasive CFR testing (n = 185), those with an APO had lower CFR (2.53 vs. 2.76, p = 0.016) versus those without APO. Conclusions: History of APOs in women with signs and symptoms of ischemia without obstructive CAD is associated with lower CFR indicative of CMD. Whether common pathways involving diffuse microvascular dysfunction may account for this suggested association remains unclear. Further investigation is needed to expand on these exploratory findings.

Dairy Foods and Dairy Fats: New Perspectives on Pathways Implicated in Cardiometabolic Health

Low-fat and nonfat dairy products have been promoted as part of a healthy dietary pattern by both US dietary guidelines and professional organizations for several decades. The basis for this recommendation stems in part from the putative negative cardiometabolic effects associated with saturated fat consumption. However, as nutrition research has shifted from a single nutrient to a whole-food/dietary pattern approach, the role of dairy foods and dairy fat in the diet-disease relationship is being reexamined. Most observational and experimental evidence does not support a detrimental relationship between full-fat dairy intake and cardiometabolic health, including risks of cardiovascular disease and type 2 diabetes. Indeed, an expanded understanding of the dairy food matrix and the bioactive properties of dairy fats and other constituents suggests a neutral or potentially beneficial role in cardiometabolic health. To consider how consuming dairy foods, including full-fat dairy, is associated with cardiometabolic health, this review provides an innovative perspective on mechanisms that link dairy consumption to 3 main biological systems at the core of metabolic health, the gastrointestinal, hepatic, and vascular systems.

Treatment of coronary microvascular dysfunction

Contemporary data indicate that patients with signs and symptoms of ischaemia and non-obstructive coronary artery disease (INOCA) often have coronary microvascular dysfunction (CMD) with elevated risk for adverse outcomes. Coronary endothelial (constriction with acetylcholine) and/or microvascular (limited coronary flow reserve with adenosine) dysfunction are well-documented, and extensive non-obstructive atherosclerosis is often present. Despite these data, patients with INOCA currently remain under-treated, in part, because existing management guidelines do not address this large, mostly female population due to the absence of evidence-based data. Relatively small sample-sized, short-term pilot studies of symptomatic mostly women, with INOCA, using intense medical therapies targeting endothelial, microvascular, and/or atherosclerosis mechanisms suggest symptom, ischaemia, and coronary vascular functional improvement, however, randomized, controlled outcome trials testing treatment strategies have not been completed. We review evidence regarding CMD pharmacotherapy. Potent statins in combination with angiotensin-converting enzyme inhibitor (ACE-I) or receptor blockers if intolerant, at maximally tolerated doses appear to improve angina, stress testing, myocardial perfusion, coronary endothelial function, and microvascular function. The Coronary Microvascular Angina trial supports invasive diagnostic testing with stratified therapy as an approach to improve symptoms and quality of life. The WARRIOR trial is testing intense medical therapy of high-intensity statin, maximally tolerated ACE-I plus aspirin on longer-term outcomes to provide evidence for guidelines. Novel treatments and those under development appear promising as the basis for future trial planning.

Diagnosis of coronary microvascular dysfunction in the clinic

The coronary microcirculation plays a pivotal role in the regulation of coronary blood flow and cardiac metabolism. It can adapt to acute and chronic pathologic conditions such as coronary thrombosis or long-standing hypertension. Due to the fact that the coronary microcirculation cannot be visualized in human beings in vivo, its assessment remains challenging. Thus, the clinical importance of the coronary microcirculation is still often underestimated or even neglected. Depending on the clinical condition of the respective patient, several non-invasive (e.g. transthoracic Doppler-echocardiography assessing coronary flow velocity reserve, cardiac magnetic resonance imaging, positron emission tomography) and invasive methods (e.g. assessment of coronary flow reserve (CFR) and microvascular resistance (MVR) using adenosine, microvascular coronary spasm with acetylcholine) have been established for the assessment of coronary microvascular function. Individual patient characteristics, but certainly also local availability, methodical expertise and costs will influence which methods are being used for the diagnostic work-up (non-invasive and/or invasive assessment) in a patient with recurrent symptoms and suspected coronary microvascular dysfunction. Recently, the combined invasive assessment of coronary vasoconstrictor as well as vasodilator abnormalities has been titled interventional diagnostic procedure (IDP). It involves intracoronary acetylcholine testing for the detection of coronary spasm as well as CFR and MVR assessment in response to adenosine using a dedicated wire. Currently, the IDP represents the most comprehensive coronary vasomotor assessment. Studies using the IDP to better characterize the endotypes observed will hopefully facilitate development of tailored and effective treatments.

Endothelial Vascular Function as a Surrogate of Vascular Risk and Aging in Women

Cardiovascular disease is the leading cause of morbidity and mortality in women. We suggest the need to develop a paradigm that connects sex- and age-specific nontraditional risk factors that serve as a common mechanism ultimately leading to an increased risk of cardiovascular events. Vascular injury with abnormal repair leading to functional, rather than structural, abnormalities can be regarded as accelerated vascular aging. It emerges as a common feature that can trigger the early diagnosis and risk stratification for cardiovascular disease in women. We discuss sex-specific risk factors that can contribute to vascular injury with age, and these might not always be considered by cardiovascular physicians. It is important for the primary physician to be aware of these risk factors to enable more intensified management of this at-risk population. Novel technologies that allow the assessment of vascular function noninvasively can serve as key diagnostic and therapeutic tools with which we can identify such individuals and target therapy to manage this important patient population appropriately and effectively. We hope that this article will stimulate interest in this field and encourage further research in these important areas.

Coronary Microvascular Dysfunction and Estrogen Receptor Signaling

Chest pain with non-obstructive coronary artery disease (NOCAD) occurs more frequently in women than in men and is mainly related to coronary microvascular disease (CMD). The majority of CMD patients are postmenopausal women, suggesting a role for lack of estrogens in the development and progression of CMD. Patients are often discharged without a clear treatment plan due to the limited understanding of etiology and diagnostic parameters of CMD and have significantly higher rates of future cardiovascular events. Thus, there is a need for a better understanding of the underlying biology, and CMD-specific diagnostic tests and therapies. In this article, we reviewed recent studies on CMD, estrogen action in coronary microvasculature, and diagnosis and treatment options for CMD in postmenopausal women.

Introducing the Canadian Women's Heart Health Alliance ATLAS on the Epidemiology, Diagnosis, and Management of Cardiovascular Diseases in Women

Despite a global understanding that indicators and outcomes of cardiovascular disease (CVD) are known to differ between men and women, uptake of the recognition of sex and gender influences on the clinical care of women has been slow or absent. The Canadian Women’s Heart Health Alliance (CWHHA) was established as a network of experts and advocates to develop and disseminate evidence-informed strategies to transform clinical practice and augment collaborative action on women’s cardiovascular health in Canada. As an initial project, the CWHHA membership undertook an environmental scan of CVD in women in Canada from which a scientific statement could be developed to summarize critical sex- and gender-specific issues in CVD. This comprehensive review of the evidence focused on the sex- and gender-specific differences in comorbidity, risk factors, disease awareness, presentation, diagnosis, and treatment across the entire spectrum of CVD. In the process of creating the review, it was recognized that the team of CWHHA experts had also assembled an expansive collection of original research articles that were synthesized into detailed chapters reporting on the present state of the evidence unique to each cardiovascular condition in women. This work comprises an “ATLAS” on the epidemiology, diagnosis, and management of CVD in women. The overall goal of the ATLAS is to create a living document that will help clinicians and the public recognize the unique aspects of women’s heart health care and provide policy makers with information they need to ensure equitable care for women with CVD.

Coronary microvascular dysfunction

Patients with coronary microvascular dysfunction (CMVD) represent a widespread population and despite the good prognosis, many of them have a poor quality of life with strong limitations in their daily activities because of the angina symptoms. This article summarizes the most frequent clinical presentation pictures like stable and unstable microvascular angina. Main risk factors are discussed, followed by the latest updates on the subject about different pathogenic hypotheses, diagnosis and treatment. Not very well understood microvascular alterations, like slow flow phenomenon and no reflow are discussed and both prognosis and the impact of the disease in the quality of life are analyzed.

Gender differences in thrombogenicity among patients with angina and non-obstructive coronary artery disease

Women more often present with angina and non-obstructive coronary artery disease (ANOCA) and have poorer clinical outcomes than men. These findings may be related to sex associated differences in inflammation and thrombogenicity. Consecutive patients (n = 134) with ANOCA (luminal diameter stenosis < 50%) undergoing elective cardiac catheterization were included in post hoc analysis of Multi-Analyte, thrombogenic, and Genetic Markers of Atherosclerosis (MAGMA, NCT01276678) study. Patients with prior revascularization, coronary artery bypass grafting or myocardial infarction were excluded. Blood for thromboelastography, oxidized LDL β2-glycoprotein complex (AtherOx), oxidized-LDL, lipid profile, and urine for 11-dehydrothromboxane B₂ (dTxB₂) were obtained before catheterization. All women (n = 75) were post-menopausal and tended to be older than men (61.4 ± 10.6 vs. 58.6 ± 9.9 year, p = 0.12), and were significantly more thrombogenic with higher thrombin-induced platelet-fibrin strength (TIP-FCS, mm) (68.0 ± 4.5 vs. 64.5 ± 6.2 mm, p = 0.001), clotting index (0.35 ± 2.22 vs. - 0.72 ± 2.75, p = 0.02), K (measure of the speed to reach 20 mm of clot strength from an amplitude of 2 mm) (2.2 ± 1.6 vs. 1.7 ± 0.5 min, p = 0.01), and fibrinogen activity (degrees) (66.6 ± 7.1 vs. 62.9 ± 7.5, p = 0.009). Markers of inflammation were not significantly different between the two groups. Women had higher total cholesterol, total LDL, LDL subtypes 1 and 2, total HDL, HDL subtypes 2 and 3, and ApoA1 (p < 0.05 for all). On multivariate regression, TIP-FCS remained significantly higher in women (p < 0.0001). Women with ANOCA are more thrombogenic than men. This fundamental difference in thrombogenicity may affect gender-related outcomes and warrants further investigation.

Microvascular Disease and Small-Vessel Disease: The Nexus of Multiple Diseases of Women

Microvascular disease, or small-vessel disease, is a multisystem disorder with a common pathophysiological basis that differentially affects various organs in some patients. The prevalence of small-vessel disease in the heart has been found to be higher in women compared with men. Additionally, other diseases prominently affecting women, including heart failure with preserved ejection fraction, Takotsubo cardiomyopathy, cerebral small-vessel disease, preeclampsia, pulmonary arterial hypertension (PAH), endothelial dysfunction in diabetes, diabetic cardiomyopathy, rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis, may have a common etiologic linkage related to microvascular disease. To the best of our knowledge this is the first article to investigate this potential linkage. We sought to identify various diseases with a shared pathophysiology involving microvascular/endothelial dysfunction that primarily affect women, and their potential implications for disease management. Advanced imaging technologies, such as magnetic resonance imaging and positron-emission tomography, enable the detection and increased understanding of microvascular dysfunction in various diseases. Therapies that improve endothelial function, such as those used in PAH, may also be associated with benefits across the full spectrum of microvascular dysfunction. A shared pathology across multiple organ systems highlights the need for a collaborative, multidisciplinary approach among medical subspecialty practitioners who care for women with small-vessel disease. Such an approach may lead to accelerated research in diseases that affect women and their quality of life.

The systemic microcirculation in dialysis populations

In a rapidly expanding population of patients with chronic kidney disease, including 2 million people requiring renal replacement therapy, cardiovascular mortality is 15 times greater than the general population. In addition to traditional cardiovascular risk factors, more poorly defined risks related to uremia and its treatments appear to contribute to this exaggerated risk. In this context, the microcirculation may play an important early role in cardiovascular disease associated with chronic kidney disease. Experimentally, the uremic environment and dialysis have been linked to multiple pathways causing microvascular dysfunction. Coronary microvascular dysfunction is reflected in remote and more easily studied vascular beds such as the skin. There is increasing evidence for a correlation between systemic microvascular dysfunction and adverse cardiovascular outcomes. Systemic microcirculatory changes have not been extensively investigated across the spectrum of chronic kidney disease. Recent advances in non-invasive techniques studying the microcirculation in vivo in man are increasing the data available particularly in patients on hemodialysis. Here, we review current knowledge of the systemic microcirculation in dialysis populations, explore whether non-invasive techniques to study its function could be used to detect early stage cardiovascular disease, address challenges faced in studying this patient cohort and identify potential future avenues for research.

Ticagrelor and preconditioning in patients with stable coronary artery disease (TAPER-S): a randomized pilot clinical trial

Background

Ticagrelor is a reversibly binding, direct-acting, oral, P₂Y₁₂ antagonist used for the prevention of atherothrombotic events in patients with coronary artery disease (CAD). Ticagrelor blocks adenosine reuptake through the inhibition of equilibrative nucleoside transporter 1 (ENT-1) on erythrocytes and platelets, thereby facilitating adenosine-induced physiological responses such as an increase in coronary blood flow velocity. Meanwhile, adenosine plays an important role in triggering ischemic preconditioning through the activation of the A1 receptor. Therefore, an increase in ticagrelor-enhanced adenosine bioavailability may confer beneficial effects through mechanisms related to preconditioning activation and improvement of coronary microvascular dysfunction.

Methods

To determine whether ticagrelor can trigger ischemic preconditioning and influence microvascular function, we designed this prospective, open-label, pilot study that enrolled patients with stable multivessel CAD requiring staged, fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI). Participants will be randomized in 1:1 ratios either to ticagrelor (loading dose (LD) 180 mg, maintenance dose (MD) 90 mg bid) or to clopidogrel (LD 600 mg, MD 75 mg) from 3 to 1 days before the scheduled PCI. The PCI operators will be blinded to the randomization arm. The primary endpoint is the delta (difference) between ST segment elevations (in millimeters, mm) as assessed by intracoronary electrocardiogram (ECG) during the two-step sequential coronary balloon inflation in the culprit vessel. Secondary endpoints are 1) changes in coronary flow reserve (CFR), index of microvascular resistance (IMR), and FFR measured in the culprit vessel and reference vessel at the end of PCI, and 2) angina score during inflations. This study started in 2018 with the aim of enrolling 100 patients. Based on the rate of negative FFR up to 30% and a drop-out rate up to 10%, we expect to detect an absolute difference of 4 mm among the study arms in the mean change of ST elevation following repeated balloon inflations. All study procedures were reviewed and approved by the Ethical Committee of the Catholic University of Sacred Heart.

Discussion

Ticagrelor might improve ischemia tolerance and microvascular function compared to clopidogrel, and these effects might translate to better long-term clinical outcomes.

Trial registration

EudraCT No. 2016–004746-28. No. NCT02701140. 

Trial status

Information provided in this manuscript refers to the definitive version (n. 3.0) of the study protocol, dated 31 October 2017, and includes all protocol amendments. Recruitment started on 18 September 2018 and is currently ongoing. The enrollment is expected to be completed by the end of 2019.

Trial sponsor

Fondazione Policlinico Universitario A. Gemelli – Roma, Polo di Scienze Cardiovascolari e Toraciche, Largo Agostino Gemelli 8, 00168 Rome, Italy.

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.

Stress Echocardiography in the Era of Fractional Flow Reserve

Purpose of Review

It is the aim of this review to demonstrate the relevance of stress echocardiography in the era of fractional flow reserve by establishing the current use of stress echocardiography and fractional flow reserve, underlining their physiological basis and through this demonstrating the clear differences in their application.

Recent Findings

The importance of the microcirculation is only now being understood, no more so than in the fact that abnormalities in the microcirculation, determined by abnormal coronary flow reserve, predict adverse mortality regardless of the normality of the epicardial coronary lesions. Stress echocardiography therefore gives a fuller picture of the overall cardiovascular risk to our patients in its ability to interrogate the epicardial vessels down to the microcirculation, with a number of techniques available to measure coronary flow reserve such as myocardial perfusion stress echocardiography and transthoracic Doppler stress echocardiography of epicardial coronary vessels. Fractional flow reserve can then add further information by determining whether a coronary artery lesion is responsible for myocardial ischaemia.

Summary

In an era of fractional flow reserve affording the resolution of myocardial ischaemia down to the specific lesion, it can be tempting to think that other generally non-invasive techniques no longer have a role in the investigation and management of coronary artery disease. This, however, betrays a lack of understanding of the scope and complexity of coronary artery disease from epicardial vessels down to the microvasculature, the physiological basis of the tests available and therefore what, in fact, is actually being measured. For some, fractional flow reserve is held as a gold standard by which to compare other techniques such as stress echocardiography as correct or incorrect. However, these tests do not measure the same thing, and therefore, they cannot be directly compared. Stress echocardiography gives a fuller picture through its ability to account for the coronary flow reserve, considering the epicardial vessels down to the microvasculature. Fractional flow reserve is far more specific, looking at the effect of the lesion being interrogated. Furthermore, where fractional flow reserve is normal, we now know that knowledge of the coronary flow reserve is critical as it is this that allows us to predict the overall mortality risk of our patient. We therefore require a combination of the two techniques.

Reduced Coronary Flow Reserve Is Associated with Impaired Ventricular-vascular Interaction in Patients with Obstructive Sleep Apnea

Background and Objectives

Obstructive sleep apnea (OSA) is associated with cardiac and arterial damage and adverse cardiovascular outcomes. We aimed to determine whether coronary flow reserve (CFR), which represents microvascular dysfunction, might be associated with the ventricular-vascular coupling index (VVI), which represents the afterload-adjusted contractility in patients with OSA.

Methods

We enrolled 281 patients (257 males; mean age, 43±11 years) with newly diagnosed OSA. Transthoracic echocardiography was performed, and adenosine-associated CFR was measured in the left anterior descending coronary artery. We evaluated the differences between the patients with normal CFR ≥2.5 and reduced CFR <2.5. VVI was calculated using the effective arterial elastance (Ea) and left ventricular (LV) end-systolic elastance (Ees) as follows: 10×Ea/Ees.

Results

The normal CFR group (n=214) showed increased Ees (7.28±2.31 vs. 8.14±2.33 mmHg/mL, p=0.016) and preserved VVI (3.17±1.53 vs. 2.78±1.20, p=0.044) compared with the reduced CFR group (n=67). There were no differences in LV dimension, LV ejection fraction, left atrial-volume index, E/e′, left atrial strain and LV global longitudinal strain between the 2 groups (all p>0.05). CFR was significantly correlated to Ees (r=0.139; p=0.023) and VVI (r=−0.137; p=0.025).

Conclusions

Reduced CFR is associated with decreased Ees and impaired VVI in OSA patients. It suggests the necessity of more intensive observation in OSA patients with reduced CFR to improve cardiovascular outcomes.

Myocardial Infarction and Persistent Angina With No Obstructive Coronary Artery Disease

Women with myocardial infarction with no obstructive coronary artery disease (MINOCA) are increasingly recognized. Women with MINOCA are at high risk for major adverse cardiovascular events. In this case, we focus on the importance of early identification and management of MINOCA to improve patients’ angina and related quality of life. (Level of Difficulty: Beginner.)

Non-Obstructive Coronary Artery Disease in Women: Current Evidence and Future Directions

BACKGROUND

Over half of women who present with angina are found to have negative coronary angiographic assessments. Of these patients, up to 50% are diagnosed with coronary microvascular dysfunction (CMD), which refers to pathologic changes within the small vessels of the coronary circulation. The hallmark of the pathophysiology of CMD is that endothelial damage, which occurs due to a multitude of conditions and risk factors, is the inciting event for the development and progression of CMD. CMD leads to a mismatch in myocardial demand and perfusion, leading to signs and symptoms of cardiac ischemia in the absence of obstructive lesions in the major vessels. CMD can be diagnosed through a variety of both invasive methods that allow a more specific evaluation of the microvasculature and non-invasive imaging techniques, such as cardiac positron emission tomography (PET) and magnetic resonance imaging (MRI). Risk factors for CMD overlap significantly with those of obstructive coronary artery disease (CAD) - hypertension, hypercholesterolemia, and diabetes remain salient predictors. However, these conditions only account for 20% of CMD cases in females.

FINDINGS

Women have sex-specific risk factors such as menopause, pregnancy, polycystic ovarian syndrome (PCOS), and a higher proclivity toward chronic inflammatory disorders. Estrogen has a cardioprotective effect by increasing production of nitric oxide, a potent vasodilator released by endothelial cells. As a result, the hormonal changes of menopause may accelerate endothelial damage, and in turn, CMD. Current treatments focus on addressing the risk factors of cardiovascular disease, such as anti-hypertensive drugs, weight loss, and glucose control.

CONCLUSION

Given the multifactorial nature of CMD in women, and the extensive atypical risk factors for cardiac disease, a more nuanced approach is needed that addresses the varied pathophysiology of CMD.

The prognostic significance of coronary flow reserve in the risk stratification of patients with chronic total occlusion of the right coronary artery and the intermediary stenosis of the left coronary artery

Introduction: Coronary Flow Reserve (CFR) is a clinically useful, non-invasive diagnostic method for assessing the functional ability of coronary arteries and it is important for their long-term follow-up in patients. However, CFR has not always been sufficiently investigated in previous studies. Objective: To examine the prognostic significance of CFR in the risk stratification of patients with chronic total occlusion of the right coronary artery (RCA) and the intermediary stenosis of the left coronary artery (LAD). Material and Methods: Number of 71 patients, mean age 64 ± 7 years, (84%) patients male, having LAD stenosis, diameter 50-70%, and CTO of RCA, were referred for noninvasive estimation of functional significance of LAD stenosis. Transthoracic Doppler echocardiography was used to obtain coronary flow velocities in the distal segment of LAD. Patients were followed for the mean period of 18.3 ± 7.1 months for the occurrence of composite end point including cardiovascular death, myocardial infarction, bypass surgery and PCI. Results: During the follow-up period, there were a total of 23 adverse events (4 deaths, 2 myocardial infarction, 7 bypass surgeries and 10 PCI). Patients with CFR < 2 had significantly more adverse events (n = 9; 56.3% vs. n = 14; 25.5%; p = 0.021), they were significantly older (68 ± 9 vs. 62 ± 6; p = 0.011), with a higher incidence of a positive family history (14; 87.5% vs. 26; 47.3%; p = 0.039), as well as a significantly higher frequency of three-dose coronary disease (14; 87.5% vs. 30; 54.5%; p = 0.017). Using Kaplan-Meier estimator, we obtained that patients with CFR < 2 have a significantly shorter average period without unwanted event (15.4 ± 2.8 months vs 23.5 ± 1.1 months, Log Rank 7.407; p = 0.008). Conclusion: CFR plays an important role in stratifying the risk of patients with CTO of RCA and the intermediary stenosis of LAD.

Aortic Stiffness Is Associated with Coronary Microvascular Dysfunction in Patients with Non-obstructive Coronary Artery Disease

Objective Associations between aortic stiffness and cardiovascular disease events are mediated in part by pathways that include coronary microvascular dysfunction (CMD) and remodeling. However, the relationship between aortic stiffness and CMD remains unclear. The present study aimed to determine whether aortic stiffness causes CMD as evaluated by the hyperemic microvascular resistance index (hMVRI) in patients with non-obstructive coronary artery disease (CAD). Methods The intracoronary physiological variables in 209 coronary arteries were evaluated in 121 patients with non-obstructive CAD (fractional flow reserve >0.80) or reference vessels. The cardio-ankle vascular index (CAVI) as a measure of aortic stiffness and atherosclerotic risk factors were also measured. Results Univariate analyses showed that hMVRI correlated with age (β=0.24, p=0.007), eicosapentaenoic acid (EPA; β=-0.18, p=0.048), EPA/arachidonic acid (AA) (EPA/AA) ratio (β=-0.22, p=0.014) and CAVI (β=0.30, p=0.001). A multivariate regression analysis identified CAVI (β=0.25, p=0.007) and EPA/AA ratio (β=-0.26, SE=0.211, p=0.003) as independent determinants of hMVRI. Conclusion Aortic stiffness may cause CMD in patients with non-obstructive CAD via increased coronary microvascular resistance. Aortic stiffness is associated with CMD which is evaluated as hyperemic microvascular resistance in patients with non-obstructive CAD.

Redox Regulation of the Microcirculation

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

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.

Noninvasive Microvascular Indices Reveal Peripheral Vascular Abnormalities in Patients With Suspected Coronary Microvascular Dysfunction

BACKGROUND

Reactive hyperemia peripheral arterial tonometry and flow-mediated dilation are common noninvasive measures of peripheral vascular function. However, their relationship with the coronary circulation, particularly in coronary microvascular dysfunction (CMD), is unclear. Therefore, the purpose of this study is to compare these noninvasive measurements with coronary microvascular function after endothelial-independent, endothelial-dependent, and sympathetically mediated pharmacologic hyperemia.

METHODS

Forty-seven patients with suspected CMD completed peripheral and coronary assessments. The reactive hyperemia index was collected using the EndoPAT2000 device, whereas a subset of patients (n = 28) completed brachial artery flow-mediated dilation using duplex ultrasound. Coronary microvascular function was quantified using the resistance and flow responses to intravenous adenosine (140 μg/kg/min), dobutamine (40 μg/kg/min), and intracoronary acetylcholine (100 μg). Abnormal coronary microvascular responses to adenosine and/or acetylcholine were used to define CMD.

RESULTS

The reactive hyperemia index (No CMD: 0.85 ± 0.23 vs CMD: 0.61 ± 0.26, P < 0.05) and flow-mediated dilation (No CMD: 7.2 ± 2.3 vs CMD: 4.8 ± 3.1; P < 0.05) were attenuated in patients with CMD. Whereas the reactive hyperemia index was correlated with the resistance and flow responses to dobutamine (ρ = -0.44 and ρ = 0.39, respectively; P < 0.05), flow-mediated dilation was correlated with the resistance responses to both adenosine (ρ = -0.48; P < 0.05) and acetylcholine (ρ = -0.66; P < 0.05). Lastly, the reactive hyperemia index and flow-mediated dilation had sensitivities of 80% and 69% and specificities of 71% and 93%, respectively, for identifying patients with CMD.

CONCLUSIONS

Peripheral vascular function is attenuated in CMD, and noninvasive measurements are associated with coronary responses to pharmaceutical stimulation.

Ischemia and No Obstructive Coronary Artery Disease: Prevalence and Correlates of Coronary Vasomotion Disorders

BACKGROUND

Determine the prevalence and correlates of microvascular and vasospastic angina in patients with symptoms and signs of ischemia but no obstructive coronary artery disease (INOCA).

METHODS

Three hundred ninety-one patients with angina were enrolled at 2 regional centers over 12 months from November 2016 (NCT03193294). INOCA subjects (n=185; 47%) had more limiting dyspnea (New York Heart Association classification III/IV 54% versus 37%; odds ratio [OR], 2.0 [1.3-3.0]; P=0.001) and were more likely to be female (68% INOCA versus 38% in coronary artery disease; OR, 1.9 [1.5 to 2.5]; P<0.001) but with lower cardiovascular risk scores (ASSIGN score median 20% versus 24%; P=0.003). INOCA subjects had similar burden of angina (Seattle Angina Questionnaire) but reduced quality of life compared with coronary artery disease; subjects (EQ5D-5 L index 0.60 versus 0.65 units; P=0.041).

RESULTS

An interventional diagnostic procedure with reference invasive tests including coronary flow reserve, microvascular resistance, and vasomotor responses to intracoronary acetylcholine (vasospasm provocation) was performed in 151 INOCA subjects. Overall, 78 (52%) had isolated microvascular angina, 25 (17%) had isolated vasospastic angina, 31 (20%) had both, and 17 (11%) had noncardiac chest pain. Regression analysis showed inducible ischemia on treadmill testing (OR, 7.5 [95% CI, 1.7-33.0]; P=0.008) and typical angina (OR, 2.7 [1.1-6.6]; P=0.032) were independently associated with microvascular angina. Female sex tended to associate with a diagnosis of microvascular angina although this was not significant (OR, 2.7 [0.9-7.9]; P=0.063). Vasospastic angina was associated with smoking (OR, 9.5 [2.8-32.7]; P<0.001) and age (OR, 1.1 per year, [1.0-1.2]; P=0.032].

CONCLUSIONS

Over three quarters of patients with INOCA have identifiable disorders of coronary vasomotion including microvascular and vasospastic angina. These patients have comparable angina burden but reduced quality of life compared to patients with obstructive coronary artery disease. Microvascular angina and vasospastic angina are distinct disorders that may coexist but differ in associated clinical characteristics, symptoms, and angina severity.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT03193294.

Coronary Microvascular Dysfunction Is Associated With Myocardial Ischemia and Abnormal Coronary Perfusion During Exercise

BACKGROUND

Coronary microvascular dysfunction (MVD) is defined by impaired flow augmentation in response to a pharmacological vasodilator in the presence of nonobstructive coronary artery disease. It is unknown whether diminished coronary vasodilator response correlates with abnormal exercise physiology or inducible myocardial ischemia.

METHODS

Patients with angina and nonobstructive coronary artery disease had simultaneous coronary pressure and flow velocity measured using a dual sensor-tipped guidewire during rest, supine bicycle exercise, and adenosine-mediated hyperemia. Microvascular resistance (MR) was calculated as coronary pressure divided by flow velocity. Wave intensity analysis quantified the proportion of accelerating wave energy (perfusion efficiency). Global myocardial blood flow and subendocardial:subepicardial perfusion ratio were quantified using 3-Tesla cardiac magnetic resonance imaging during hyperemia and rest; inducible ischemia was defined as hyperemic subendocardial:subepicardial perfusion ratio <1.0. Patients were classified as having MVD if coronary flow reserve <2.5 and controls if coronary flow reserve ≥2.5, with researchers blinded to the classification.

RESULTS

Eighty-five patients were enrolled (78% female, 57±10 years), 45 (53%) were classified as having MVD. Of the MVD group, 82% had inducible ischemia compared with 22% of controls (P<0.001); global myocardial perfusion reserve was 2.01±0.41 and 2.68±0.49 (P<0.001). In controls, coronary perfusion efficiency improved from rest to exercise and was unchanged during hyperemia (59±11% vs 65±14% vs 57±18%; P=0.02 and P=0.14). In contrast, perfusion efficiency decreased during both forms of stress in MVD (61±12 vs 44±10 vs 42±11%; both P<0.001). Among patients with a coronary flow reserve <2.5, 62% had functional MVD, with normal minimal MR (hyperemic MR<2.5 mmHg/cm/s), and 38% had structural MVD with elevated hyperemic MR. Resting MR was lower in those with functional MVD (4.2±1.0 mmHg/cm/s) than in those with structural MVD (6.9±1.7 mmHg/cm/s) or controls (7.3±2.2 mmHg/cm/s; both P<0.001). During exercise, the structural group had a higher systolic blood pressure (188±25 mmHg) than did those with functional MVD (161±27 mmHg; P=0.004) and controls (156±30 mmHg; P<0.001). Functional and structural MVD had similar stress myocardial perfusion and exercise perfusion efficiency values.

CONCLUSION

In patients with angina and nonobstructive coronary artery disease, diminished coronary flow reserve characterizes a cohort with inducible ischemia and a maladaptive physiological response to exercise. We have identified 2 endotypes of MVD with distinctive systemic vascular responses to exercise; whether endotypes have a different prognosis or require different treatments merits further investigation.

Inflammation and Coronary Microvascular Dysfunction in Autoimmune Rheumatic Diseases

Autoimmune rheumatic diseases (ARDs) form a heterogeneous group of disorders that include systemic lupus erythematosus (SLE), systemic sclerosis (SSc), rheumatoid arthritis (RA), idiopathic inflammatory myopathies (IIMs), and systemic vasculitis. Coronary microvascular dysfunction (CMD) is quite common in patients with ARDs and is linked to increased cardiovascular morbidity and mortality. Inflammation plays a crucial role in the pathogenesis of both accelerated atherosclerosis and CMD in ARDs, especially in patients affected by SLE and RA. In this regard, some studies have highlighted the efficacy of immunosuppressants and/or biologics in restoring CMD in these patients. By contrast, the role of inflammation in the pathogenesis of CMD-SSc appears to be much less relevant compared to endothelial dysfunction and microvascular ischemia, with calcium-channel blockers providing some benefits. Few studies have endeavored to assess the occurrence of CMD in IIMs and systemic vasculitis, thus warranting further investigations. The present review summarizes the current evidence on the occurrence of CMD in ARDs, focusing on the role of inflammation and possible therapeutic approaches.

The role of coronary reactivity testing in women with no obstructive coronary artery disease

PURPOSE OF REVIEW

Two-thirds of women with signs and symptoms of ischemia and no obstructive coronary artery disease (INOCA) have abnormal coronary reactivity. These women are challenging to assess, diagnose and manage because of a lack of evidence-based guidelines. Furthermore, they are considered to be at 'low risk' by most physicians, often receive no specific therapy and tend to be dismissed from subspecialty care.

RECENT FINDINGS

Coronary reactivity testing (CRT) is considered the reference-standard for evaluation of epicardial and microvascular coronary function in response to various vasoactive agents. It provides a comprehensive vascular function assessment for diagnosis, a guide for management, and has prognostic benefit that outweighs the risk of the procedure. We recently demonstrated the prognostic value of assessing coronary vascular reactivity in women with signs and symptoms of ischemia, especially those with no obstructive coronary artery disease.

SUMMARY

Invasive CRT is a feasible, useful method to identify coronary microvascular dysfunction (CMD) and risk stratify women with INOCA. It has a comparable safety record with other invasive procedures. Future research is directed at optimizing patient selection, streamlining of invasive CRT methods using user-friendly catheters to enhance feasibility in the routine clinical setting, and optimizing treatment protocols, with clinical trials designed to evaluate outcomes.

Adenosine stress CMR perfusion imaging of the temporal evolution of perfusion defects in a porcine model of progressive obstructive coronary artery occlusion

Adenosine stress CMR perfusion imaging can quantify absolute perfusion and myocardial perfusion reserve (MPR) in coronary artery disease (CAD) with higher spatial resolution than positron emission tomography, the only clinically available technique for quantitative myocardial perfusion imaging. While porcine models of CAD are excellent for studying perfusion abnormalities in chronic CAD, to date there are a limited number of studies that use quantitative perfusion for evaluation. Therefore, we developed an adenosine stress CMR protocol to evaluate the temporal evolution of perfusion defects in a porcine model of progressive obstructive CAD. 10 Yucatan minipigs underwent placement of an ameroid occluder around the left circumflex artery (LCX) to induce a progressive chronic coronary obstruction. Four animals underwent a hemodynamic dose range experiment to determine the adenosine dose inducing maximal hyperemia. Each animal had a CMR examination, including stress/rest spiral quantitative perfusion imaging at baseline and 1, 3, and 6 weeks. Late gadolinium enhancement images determined the presence of myocardial infarction, if any existed. Pixelwise quantitative perfusion maps were generated using Fermi deconvolution. The results were statistically analyzed with a repeated mixed measures model to block for physiological variation between the animals. Five animals developed myocardial infarction by 3 weeks, while three developed ischemia without an infarction. The perfusion defects were located in the inferolateral myocardium in the perfusion territory of the LCX. Stress perfusion values were higher in remote segments than both the infarcted and ischemic segments (p < 0.01). MPR values were significantly greater in the remote segments than infarcted and ischemic segments (p < 0.01). While the MPR decreased in all segments, the MPR recovered by the sixth week in the remote regions. We developed a model of progressive CAD and evaluated the temporal evolution of the development of quantitative perfusion defects. This model will serve as a platform for understanding the development of perfusion abnormalities in chronic occlusive CAD.