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

Reappraisal of Ischemic Heart Disease

In recent years, it has become apparent that coronary microvascular dysfunction plays a pivotal pathogenic role in angina pectoris. Functional and structural mechanisms can affect the physiological function of the coronary microvasculature and lead to myocardial ischemia in people without coronary atheromatous disease and also in individuals with obstructive coronary artery disease. Abnormal dilatory responses of the coronary microvessels, coronary microvascular spasm, and extravascular compressive forces have been identified as pathogenic mechanisms in both chronic and acute forms of ischemic heart disease. The condition characterized by anginal symptoms and evidence of myocardial ischemia triggered by coronary microvascular dysfunction, in the absence of obstructive coronary disease, is known as microvascular angina. The concept of microvascular angina, however, may extend further to include patients with obstructive coronary artery disease and individuals with angina after coronary revascularization or heart transplantation because coronary microvascular dysfunction contributes to myocardial ischemia in many such patients. Patients with microvascular angina constitute a sizeable proportion of all cases of stable angina undergoing diagnostic coronary angiography and of those with persisting angina after successful coronary revascularization. Coronary microvascular dysfunction is also often responsible for angina in individuals with cardiomyopathy and heart valve disease as well as acute coronary syndrome cases such as Takotsubo syndrome and myocardial infarction with no obstructive coronary artery disease. Patients with stable microvascular angina present typically with effort or rest chest pain and a reduced coronary flow reserve or microvascular spasm. This condition, which affects women and men, can markedly impair quality of life and prognosis and represents a substantial cost burden to healthcare systems and individuals alike. In recent years, progress in the diagnosis of myocardial ischemia and the use of tests to investigate functional and structural causes for a reduced coronary flow reserve and microvascular spasm have allowed the identification of an increased number of cases of microvascular angina in everyday clinical practice. Although some of the available anti-anginal drugs may be helpful, treatment of coronary microvascular dysfunction remains a major challenge. The present article discusses the fundamental role that coronary microvascular dysfunction plays in the pathogenesis of ischemic heart disease, the clinical characteristics of patients presenting with microvascular angina, and possible diagnostic and therapeutic strategies.

Diagnosis of patients with angina and non-obstructive coronary disease in the catheter laboratory

Around 40% of all patients undergoing angiography are found to have normal coronary arteries or non-obstructive coronary artery disease (NOCAD). Despite the high prevalence, this is a group who rarely receive a definitive diagnosis, are frequently labelled and managed inappropriately and by and large, continue to remain symptomatic. Half of this group will have coronary microvascular dysfunction (CMD), associated with a higher rate of major adverse cardiovascular events; identifying CMD represents a therapeutic target of unmet need. As the pressure wire has revolutionised our ability to interrogate epicardial coronary disease during the time of angiography, measuring flow can similarly classify NOCAD during a single procedure. Assessment of flow is a function that is already integral to some pressure wires and furthermore, the familiarity and usage of the combined Doppler and pressure wire is rapidly increasing-these are techniques that readily lend themselves to the skillset of a practising interventional cardiologist. We present a structured algorithm designed for cardiologists who frequently encounter NOCAD in the catheter laboratory, identifying specific disease phenotypes within this heterogeneous population with linked therapy. This review paper clearly explains the rationale for this algorithm and outlines its applicability to routine clinical practice and also, the importance of phenotyping for future research. Ultimately, personalised therapy could improve outcomes for both patients and healthcare providers; while these approaches in turn will need robust evaluation to ensure that they improve both clinical outcomes and health economic benefits, this proposal will provide a framework for future trials and evaluations.

Debates over NICE Guideline Update: What Are the Roles of Nuclear Cardiology in the Initial Evaluation of Stable Chest Pain?

Recent clinical trials have demonstrated the values of cardiac computed tomography (CT) in the initial evaluation of stable chest pain which led to drastic changes in the National Institute for Health and Care Excellence (NICE) guidelines in 2016. According to the updated NICE guidelines, cardiac CT should be performed as the initial cardiac testing in stable chest pain regardless of pre-test probability (PTP) of coronary artery disease (CAD). As a result, cardiac CT is now considered as a validated gatekeeper for assessing stable chest pain, which precedes all the functional studies including nuclear myocardial perfusion imaging (MPI). Nuclear MPI, in contrast, has been assigned as one of the second-line studies, which is inevitably dependent on the results of cardiac CT. However, nuclear MPI has genuine values in the diagnosis, treatment decision, and prognostic stratification of stable chest pain, which cannot be replaced by cardiac CT. In this review, the updated NICE guidelines and related cardiac CT trials will be critically reviewed from the view of nuclear physicians and the exceptional values of nuclear MPI will be described along with the future perspectives.

Heart rate reserve is a long-term risk predictor in women undergoing myocardial perfusion imaging

BACKGROUND

Although women with cardiovascular disease experience relatively worse outcomes as compared to men, substantial knowledge gaps remain regarding the unique female determinants of cardiovascular risk. Heart rate (HR) responses to vasodilator stress mirror autonomic activity and may carry important long-term prognostic information in women.

METHODS AND RESULTS

Hemodynamic changes during adenosine stress were recorded in a total of 508 consecutive patients (104 women) undergoing clinically indicated 13N-ammonia Positron-Emission-Tomography (PET) at our institution. Following propensity matching, 202 patients (101 women, mean age 61.3 ± 12.6 years) were analyzed. During a median follow-up of 5.6 years, 97 patients had at least one cardiac event, including 17 cardiac deaths. Heart rate reserve (% HRR) during adenosine infusion was significantly higher in women as compared to men (23.8 ± 19.5 vs 17.3 ± 15.3, p = 0.009). A strong association between 10-year cardiovascular endpoints and a blunted HRR was observed in women, while this association was less pronounced in men. Accordingly, in women, but not in men, reduced HRR was selected as a strong predictor for adverse cardiovascular events in a Cox regression model fully adjusted for imaging findings and traditional risk factors (HR 2.41, 95% CI 1.23-4.75, p = 0.011). Receiver operating characteristics (ROC) curves revealed that a blunted HRR <21% was a powerful predictor for MACE in women with a sensitivity of 77% and a specificity of 68%.

CONCLUSION

Blunted HRR to adenosine stress adds incremental prognostic value for long-term cardiovascular outcomes in women beyond that provided by traditional risk factors and imaging findings.

Treatment strategies in coronary microvascular dysfunction: A systematic review of interventional studies

CMD has been associated with a wide spectrum of diseases and conditions, and it has proven to be a strong prognostic marker of morbidity and mortality. Despite increased attention, guideline-based treatment recommendations are lacking. We performed a systematic review of pharmacological and nonpharmacological interventions to improve coronary perfusion, assessed by IC Doppler, TTDE, PET, CMRI, transthoracic contrast perfusion echocardiography, and dilution techniques. No restrictions were made regarding the study design (randomized, placebo-controlled/randomized with active comparators/nonrandomized with or without a control group), the cardiac condition studied, or the coronary microvascular function at baseline. An electronic database search yielded 4485 records of which 80 studies met our inclusion criteria. Included studies were sorted according to intervention and study design. Studies were small and heterogeneous in methodology, and only few were placebo-controlled. Although some treatments looked promising, we found that no specific treatment was sufficiently well documented to be recommended in any patient groups. There is a need for larger well-designed clinical trials, and we suggest that future studies stratify study populations according to pathogenic mechanisms, thereby investigating whether an individualized treatment approach would be more successful.

Detrimental effects of chemotherapy on human coronary microvascular function

Chemotherapy (CT) is a necessary treatment to prevent the growth and survival of cancer cells. However, CT has a well-established adverse impact on the cardiovascular (CV) system, even years after cessation of treatment. The effects of CT drugs on tumor vasculature have been the focus of much research, but little evidence exists showing the effects on the host microcirculation. Microvascular (MV) dysfunction is an early indicator of numerous CV disease phenotypes, including heart failure. The goal of this study was to evaluate the direct effect of doxorubicin (Dox) on human coronary MV function. To study the effect of CT on the cardiac MV function, flow-mediated dilation (FMD), pharmacologically-induced endothelial dependent dilation to acetylcholine (ACh), and smooth muscle-dependent dilation to papaverine were investigated. Vessels were freshly isolated from atrial appendages of adult patients undergoing cardiopulmonary bypass surgery or from cardiac tissue of pediatric patients, collected at the time of surgery to repair congenital heart defects. Isolated vessels were incubated in endothelial culture medium containing vehicle or Dox (100 nm, 15-20 h) and used to measure dilator function by video microscopy. Ex vivo treatment of adult human coronary microvessels with Dox significantly impaired flow-mediated dilation (FMD). Conversely, in pediatric coronary microvessels, Dox-induced impairment of FMD was significantly reduced in comparison with adult subjects. In both adult and pediatric coronary microvessels, ACh-induced constriction was reversed into dilation in the presence of Dox. Smooth muscle-dependent dilation remained unchanged in all groups tested. In vessels from adult subjects, acute treatment with Dox in clinically relevant doses caused significant impairment of coronary arteriolar function, whereas vessels from pediatric subjects showed only marginal impairment to the same stressor. This interesting finding might explain the delayed onset of future adverse CV events in children compared with adults after anthracycline therapy.NEW & NOTEWORTHY We have characterized, for the first time, human microvascular responses to acute ex vivo exposure to doxorubicin in coronary vessels from patients without cancer. Our data show an augmented impairment of endothelial function in vessels from adult subjects compared with pediatric samples.

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

AIMS

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

METHODS AND RESULTS

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

CONCLUSIONS

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

Non-invasive Risk Stratification for Coronary Artery Disease: Is It Time for Subclassifications?

PURPOSE OF REVIEW

Coronary artery disease (CAD) is the leading contributor to cardiovascular disease; it is the most prevalent non-communicable disease globally and has high morbidity, mortality and health care cost. Risk stratification is defined as prevention or containment of disease prior to it occurring or progressing, and non-invasive surrogates include history, examination, biomarkers and non-invasive imaging. This review aims to highlight advancement in current diagnostic strategies and explores gaps for CAD secondary to atherosclerosis and non-obstructive vascular diseases.

RECENT FINDINGS

Cardiac risk scores have largely proven inadequate in risk stratifying heterogeneous patient populations. Greater emphasis should also be provided to posttest risk stratification. Non-invasive imaging with MRI is the most accurate but least cost efficacious presently due to availability and expertise. Echocardiography and nuclear imaging have good accuracy, but radiation limits the latter. Novel echocardiographic technologies may increase its appeal. Cardiac CT angiography is increasingly promising. Non-invasive and minimally invasive imaging has significantly influenced the cost-efficacy trajectory of coronary artery disease diagnosis and management. Recent studies suggest that future guidelines will incorporate more subclassifications from the findings of these novel technologies and for more diverse patient demographics.

Asymmetric dimethylarginine predicts impaired epicardial coronary vasomotion in patients with angina in the absence of obstructive coronary artery disease

BACKGROUND

Impaired epicardial coronary vasomotion is a potential mechanism of angina and a predictor of adverse cardiovascular outcomes in patients without angiographic evidence of obstructive coronary artery disease (CAD). We sought to evaluate the association of asymmetric dimethylarginine (ADMA)-a marker of nitric oxide-mediated vascular dysfunction-with epicardial coronary vasomotor dysfunction in this select population.

METHODS

Invasive testing for epicardial vasomotor dysfunction was performed using intracoronary acetylcholine in the left anterior descending coronary artery. Impaired vasomotor response was defined as a luminal constriction of >20% on quantitative coronary angiography. Plasma ADMA levels were measured using high performance liquid chromatography. A robust multivariate linear mixed-effect model approach and Akaike information criterion were used to determine predictors of vasomotor dysfunction.

RESULTS

In 191 patients with angina in the absence of obstructive CAD, abnormal epicardial vasomotion was observed in 137 (71.7%) patients. Median ADMA rose as the extent of impairment progressed: none (0.48 [0.44-0.59] μM), any (0.51 [0.46-0.60] μM, p = 0.12), focal (0.54 [0.49,0.61] μM, p = 0.17), and diffuse (0.55 [0.49,0.63] μM, p = 0.02). In unadjusted analysis, ADMA was highly predictive of vasomotor dysfunction (χ²=15.1, p = 0.002). Notably, ADMA remained a significant predictor even after adjusting for other factors in the best fit model (χ²=10.0, p = 0.02).

CONCLUSIONS

ADMA is an independent predictor of epicardial coronary vasomotor dysfunction in patients with angina in the absence of obstructive CAD. These data support a very early mechanistic role of ADMA in the continuum of atherosclerotic heart disease.

Enhanced beta-1 adrenergic receptor responsiveness in coronary arterioles following intravenous stromal vascular fraction therapy in aged rats

Our past study showed that a single tail vein injection of adipose-derived stromal vascular fraction (SVF) into old rats was associated with improved dobutamine-mediated coronary flow reserve. We hypothesize that i.v. injection of SVF improves coronary microvascular function in aged rats via alterations in beta adrenergic microvascular signaling. Female Fischer-344 rats aged young (3 months, n=32) and old (24 months, n=30) were utilized, along with two cell therapies intravenously injected in old rats four weeks prior to sacrifice: 1x10⁷ green fluorescent protein (GFP+) SVF cells (O+SVF, n=21), and 5x10⁶ GFP+ bone-marrow mesenchymal stromal cells (O+BM, n=6), both harvested from young donors. Cardiac ultrasound and pressure-volume measurements were obtained, and coronary arterioles were isolated from each group for microvessel reactivity studies and immunofluorescence staining. Coronary flow reserve decreased with advancing age, but this effect was rescued by the SVF treatment in the O+SVF group. Echocardiography showed an age-related diastolic dysfunction that was improved with SVF to a greater extent than with BM treatment. Coronary arterioles isolated from SVF-treated rats showed amelioration of the age-related decrease in vasodilation to a non-selective β-AR agonist. I.v. injected SVF cells improved β-adrenergic receptor-dependent coronary flow and microvascular function in a model of advanced age.

Microcirculation function assessed by adenosine triphosphate stress myocardial contrast echocardiography and prognosis in patients with nonobstructive coronary artery disease

BACKGROUND

Recent studies have demonstrated that coronary microcirculation dysfunction (CMVD) is closely correlated with adverse clinical outcomes. In this study, quantitative stress myocardial contrast echocardiography (MCE) was used to evaluate the CMVD and to investigate its association with the prognosis of patients with nonobstructive coronary artery disease (CAD).

MATERIAL AND METHODS

From 2006 to 2014, 227 consecutive patients with chest pain and a diagnostic coronary angiography without significant coronary artery stenosis (<50%) who underwent adenosine triphosphate disodium (ATP) stress MCE were enrolled. Quantitative MCE measurements were analyzed using replenishment curves.

RESULTS

Median follow-up time of this study was 5.3 years. Predictors of impaired coronary flow reserve (CFR) were smoking, diabetes, high apolipoprotein B, high low-density lipoprotein, serum uric acid, and low apolipoprotein A. During follow-up, 22 patients were reported to have 30 cardiac events (21 unstable angina, 3 nonfatal myocardial infarctions, 6 percutaneous coronary interventions). Using multivariate analysis, abnormal β reserve (≤1.6), impaired CFR (≤2.0), and diabetes were independent predictors of primary endpoint events in patients with nonobstructive CAD (P < .05). Multivariate analysis showed that CFR ≤2.0 (odds ratio [OR] =  25.21, 95% confidence interval [CI]: 3.01-182.32; P = .003), β reserve ≤1.6 (OR = 29.96, 95% CI: 3.5-241.27; P = .002), and diabetic (OR = 33.11, 95% CI: 3.65-300.02; P = .002) significantly increased the risk of the primary endpoint events.

CONCLUSIONS

ATP stress quantitative MCE is a feasible and effective method to evaluate microcirculation abnormalities in human coronary arteries and it can be used for the clinical analysis, risk stratification, and treatment of early CAD.

Coronary Microvascular Dysfunction by Myocardial Contrast Echocardiography in Nonelderly Patients Referred for Computed Tomographic Coronary Angiography

BACKGROUND

Microvascular dysfunction (MVD) is a potential cause of chest pain in younger individuals. The authors hypothesized that nonelderly patients referred for computed tomographic angiography (CTA) but without significant stenosis would have a high prevalence of MVD by myocardial contrast echocardiography (MCE). Secondary aims were to test whether the presence of nonobstructive coronary artery disease (CAD) or reduced brachial flow-mediated dilation (FMD) predicted MVD.

METHODS

Subjects ≤60 years of age undergoing CTA were recruited if they had either no evidence of coronary plaque or evidence of mild CAD (<50% stenosis) and at least one high-risk plaque feature. Subjects underwent quantitative perfusion imaging using MCE at rest and during regadenoson vasodilator stress. MVD was defined as global or segmental delay of microvascular refill (≥2 sec) during regadenoson. FMD of the brachial artery was also performed.

RESULTS

Of the 29 patients in whom MCE could be performed, 12 (41%) had MVD. These subjects, compared with those with normal microvascular function, had lower hyperemic perfusion (mean, 236 ± 68 vs 354 ± 161 intensity units/sec; P = .02) and microvascular flux rate (mean, 1.6 ± 0.4 vs 2.5 ± 0.9 sec-1; P = .002) on quantitative MCE. The degree of FMD was not significantly different in those with or without MVD (mean, 11 ± 4% vs 9 ± 4%; P = .32), and there was a poor correlation between results on stress MCE and FMD. Only eight of the 29 subjects were classified as having nonobstructive CAD. There were no groupwise differences in the prevalence of MVD function in those with versus without CAD (43% vs 38% for negative and positive findings on CTA, respectively, P = .79).

CONCLUSIONS

MVD is a common finding in the nonelderly population referred for CTA for evaluation of possible CAD but without obstructive stenosis. Neither the presence of noncritical atherosclerotic disease nor abnormal FMD increases the likelihood for detecting MVD in this population.

Assessing Coronary Microvascular Dysfunction in Ischaemic Heart Disease: Little Things Can Make a Big Difference

The role of coronary microvascular dysfunction (CMD) in the pathogenesis of ischaemic heart disease and in determining long-term prognosis is increasingly recognised. In selected patients, a comprehensive coronary assessment including an assessment of microvascular function may help refine risk stratification and improve patient outcomes. Various non-invasive and invasive techniques have been developed to assess the coronary microcirculation. Many of these tests utilise the indicator-dilution principle to determine coronary or myocardial blood flow. However, these techniques are often limited by their variability and lack of specificity for the coronary microvasculature. Consequently, there is still paucity of data on targeted therapies for CMD and their implications on long-term clinical outcomes, particularly in the setting of non-ST elevation acute coronary syndromes. Recent technical advancements, such as the index of microcirculatory resistance, have largely overcome these limitations and are able to provide novel insights into the assessment and treatment of CMD. This review summarises the currently available techniques for the assessment of CMD and provides an overview of its clinical implications.

Sex Differences in 1-Year Rehospitalization for Heart Failure and Myocardial Infarction After Primary Percutaneous Coronary Intervention

It is unclear whether universal access to primary percutaneous coronary intervention (pPCI) may reduce sex differences in 1-year rehospitalization for heart failure (HF) and myocardial infarction (MI) after ST-elevation myocardial infarction (STEMI). We studied 7,597 consecutive STEMI patients (13.8% women, n = 1,045) who underwent pPCI from January 2007 to December 2013. Cox regression models adjusted for competing risk from death were used to assess sex differences in rehospitalization for HF and MI within 1 year from discharge. Compared with men, women were older (median age 67.6 vs 56.0 years, p < 0.001) with higher prevalence of co-morbidities and multivessel disease. Women had longer median door-to-balloon time (76 vs 66 minutes, p < 0.001) and were less likely to receive drug-eluting stents (19.5% vs 24.1%, p = 0.001). Of the medications prescribed at discharge, fewer women received aspirin (95.8% vs 97.6%, p = 0.002) and P2Y₁₂ antagonists (97.6% vs 98.5%, p = 0.039), but there were no significant sex differences in other discharge medications. After adjusting for differences in baseline characteristics and treatment, sex differences in risk of rehospitalization for HF attenuated (hazard ratio [HR] 1.05, 95% confidence interval [CI] 0.79 to 1.40), but persisted for MI (HR 1.68, 95% CI 1.22 to 2.33), with greater disparity in patients aged ≥60 years (HR 1.83, 95% CI 1.18 to 2.85) than those aged <60 years (HR 1.45, 95% CI 0.84 to 2.50). In conclusion, in a setting of universal access to pPCI, the adjusted risk of 1-year rehospitalization for HF was similar in both sexes, but women had significantly higher adjusted risk of 1-year rehospitalization for MI, especially older women.

Recognition and treatment of ischemic heart diseases in women

Heart disease is the leading cause of death among women in the industrialized world. However, women after myocardial infarctions (MIs) are less likely to receive preventive medications or revascularization and as many as 47% experience heart failure, stroke or die within 5 years. Premenopausal women with MIs frequently have coronary plaque erosions or dissections. Women under 50 years with angina and nonobstructive epicardial coronary artery disease often have coronary microvascular dysfunction (CMD) with reductions in coronary flow reserve that may require nontraditional therapies. In women with coronary artery disease treated with stents, the 3-year incidence of recurrent MI or death is 9.2%. Coronary bypass surgery operative mortality averages 4.6% for women compared with 2.4% in men. Addition of internal mammary artery and radial artery coronary grafts in women does not increase operative survival but improves 5-year outcome to greater than 80%.

Heart rate reserve during pharmacological stress is a significant negative predictor of impaired coronary flow reserve in women

PURPOSE

Evidence to date has failed to adequately explore determinants of cardiovascular risk in women with coronary microvascular dysfunction (CMVD). Heart rate responses to adenosine mirror autonomic activity and may carry important prognostic information for the diagnosis of CMVD.

METHODS

Hemodynamic changes during adenosine stress were analyzed in a propensity-matched cohort of 404 patients (202 women, mean age 65.9 ± 11.0) who underwent clinically indicated myocardial perfusion 13N-ammonia Positron-Emission-Tomography (PET) at our institution between September 2013 and May 2017.

RESULTS

Baseline heart rate (HR) was significantly higher in patients with abnormal coronary flow reserve (CFR, p < 0.001 vs normal CFR). Accordingly, a blunted HR response to adenosine (=reduced heart rate reserve, %HRR) was seen in patients with abnormal CFR, with a most pronounced effect being observed in female patients free of myocardial ischemia (45.9 ± 34.9 vs 26.5 ± 18.0, p < 0.001 in women and 29.1 ± 16.9 vs 24.3 ± 21.7, p = 0.15 in men). Hence, a fully-adjusted multivariate logistic regression model identified HRR as the strongest negative predictor of reduced CFR in women free of myocardial ischemia, but not in men. Accordingly, receiver operating characteristics (ROC) curves for the presence of reduced CFR revealed that a %HRR <35 was a powerful predictor for abnormal CFR with a sensitivity of 81% and a specificity of 60% in women.

CONCLUSION

A blunted HRR <35% is associated with abnormal CFR in women. Taking into account HR responses during stress test in women may help to risk stratify the heterogeneous female population of patients with non-obstructive coronary artery disease (CAD).

Coexistence of obstructive sleep apnea and telomerase activity, concentration of selected adipose tissue hormones and vascular endothelial function in patients with arterial hypertension

AIM

The aim of the present study was to determine the effect of obstructive sleep apnea (OSA) with hypertension on telomerase activity, visfatin and adipsine concentration in the blood and vascular endothelial function assessed by ultrasound measured flow-mediated dilatation of the brachial artery (FMD).

MATERIAL AND METHODS

The study involved a group of 106 people (average age: 54.79 years). The determination of telomerase activity and blood visfatin and adipsine concentrations, brachial artery ultrasound examination with endothelium-dependent dilatation evaluation (FMD) and polysomnography were carried out.

RESULTS

Patients with hypertension without OSA were characterized by significantly greater FMD in comparison to patients with arterial hypertension and OSA (8.13 ± 5.12 %vs. 6.82 ± 5.36%; p < 0.05). Negative linear relationship between apnea-hypopnea index (AHI) and FMD (r = -0.22, p < 0.05) has been demonstrated. Negative linear relationship between adipsine concentration in the blood and length of REM (Rapid Eye Movement) sleep (r = -0.21, p < 0.05) was found. Positive linear relationship between the concentration of visfatin in the blood and the length of REM sleep (r = 0.22, p < 0.05) was also observed. Higher body mass index, higher total cholesterol, triglyceride and glucose levels have been shown to be independent predictors of higher AHI values, while greater telomerase activity, greater FMD and use of angiotensin converting enzyme inhibitors are independent predicators for lower AHI values.

CONCLUSION

Higher values of AHI index in polysomnography in hypertensive patients can be related to lower telomerase activity in the blood and impaired function of vascular endothelial function assessed using ultrasound.

Biopsy-confirmed endothelial cell activation in patients with coronary microvascular dysfunction

BACKGROUND

Patients with angina yet having unobstructed coronaries are found in ∼50% of cases undergoing invasive angiography. Coronary spasm and microvascular dysfunction can be responsible for the clinical presentation in ∼60% of cases. However, little is known about structural changes in the myocardium. The aim of this study was to describe findings in endomyocardial biopsies of symptomatic patients with unobstructed coronaries.

PATIENTS AND METHODS

We retrospectively analyzed a cohort of 1416 consecutive patients who underwent endomyocardial biopsy sampling and coronary angiography between 2002 and 2016 for various clinical indications. Of them, 309 patients had also undergone intracoronary acetylcholine testing (ACH-test). To be eligible for the study, patients had to have normal left ventricular ejection fraction, unobstructed coronaries and absence of viral genomes in the myocardium.

RESULTS

Among the final cohort of 33 (70% female, mean age 53) patients, the ACH-test revealed coronary microvascular spasm in 11 (33.3%) patients. Twelve (36.4%) patients had epicardial spasm and 10 (30.3%) had an uneventful ACH-test. Immunohistology revealed activated macrophages in 10 (30%) cases and activated endothelial cells as well as perivascular or interstitial fibrosis in 17 (52%). Myocardial hypertrophy was seen in nine (27%) patients, and smooth muscle cell proliferation was present in 11 (33%) cases. Compared with the rest of the cohort, patients with microvascular spasm significantly more often had activated endothelial cells (P=0.003).

CONCLUSION

This study gives unique insights into structural myocardial alterations in patients with angina, unobstructed coronaries and abnormal coronary vasomotion, suggesting that a combination of both structural and functional alterations is frequent.

Peripheral Microvascular Function Reflects Coronary Vascular Function

Objectives- Coronary endothelial dysfunction is a precursor of atherosclerosis and adverse outcomes. Whether endothelial dysfunction is a localized or generalized phenomenon in humans remains uncertain. We simultaneously measured femoral and coronary vascular function with the hypothesis that peripheral vascular endothelial function will be reflective of coronary endothelial function. Approach and Results- Eighty-five subjects underwent coronary angiography for evaluation of chest pain or abnormal stress tests. Endothelium-dependent and -independent vascular function were measured using intracoronary and intrafemoral infusions of acetylcholine and sodium nitroprusside, respectively. Coronary flow reserve was assessed using intracoronary adenosine infusion. Flow velocity was measured in each circulation using a Doppler wire (FloWire, EndoSonics). Coronary vascular resistance and femoral vascular resistance were calculated as mean arterial pressure (mm Hg)/coronary blood flow (mL/min) and mean arterial pressure (mm Hg)/femoral average peak velocity (cm/s), respectively. Mean age was 53±11 years, 37% were female, 44% had hypertension, 12% had diabetes mellitus, and 38% had obstructive coronary artery disease. There was a correlation between the change in femoral vascular resistance with acetylcholine and acetylcholine-mediated changes in both the coronary vascular resistance ( r=0.27; P=0.014) and in the epicardial coronary artery diameter ( r=-0.25; P=0.021), indicating that subjects with normal endothelial function in the femoral circulation had normal endothelial function in the coronary epicardial and microcirculation and vice versa. The coronary vasodilator response to adenosine also correlated with the femoral vasodilatation with acetylcholine ( r=0.4; P=0.0002). There was no correlation between the coronary and femoral responses to sodium nitroprusside. Conclusions- Endothelial functional changes in the peripheral and coronary circulations were modestly correlated. Thus, peripheral microvascular endothelial function reflects endothelium-dependent coronary epicardial and microvascular function and the coronary flow reserve. Visual Overview- An online visual overview is available for this article.

Elevated renalase levels in patients with acute coronary microvascular dysfunction - A possible biomarker for ischemia

AIMS

We explored the relationship between inflammation, renalase an anti-inflammatory protein, and acute chest pain with coronary microvascular dysfunction (CMD).

METHODS AND RESULTS

We used cardiac Rb-82 PET/CT imaging to diagnose coronary artery disease (CAD/CALC) (defect or coronary calcification) and CMD (depressed coronary flow reserve without CAD) in patients with chest pain in an emergency department (ED). Blood samples were collected pre-imaging within 24 h of ED presentation and were analyzed for renalase and inflammatory markers including C-reactive protein, interleukins, interferon gamma, tumor necrosis factor, vascular endothelial growth factor, and metalloproteinases. Exclusions were age ≤30 years, myocardial infarction, hemodynamic instability, hypertensive crisis, heart failure or dialysis. Between 6/2014 and 11/2015, 80 patients undergoing PET/CT provided blood and were categorized as normal (18%), CAD/CALC (27%) and CMD (55%). Median renalase values were highest in patients with CMD (5503 ng/ml; IQR 3070) compared to patients with normal flows (4266 ng/ml; IQR 1503; p = 0.02) or CAD/CALC (4069 ng/ml IQR 1850; p = 0.004). CMD patients had similar median values for inflammatory markers as normal patients (p > 0.05). Renalase remained an independent predictor of CMD (OR 1.34; 95% CI = 1.1-1.7, per 1000 ng/ml) after adjustment for smoking, family history, obesity and Framingham risk score. In a model for CMD diagnosis with Framingham risk score, typical angina history and CRP, renalase improved discrimination from C-statistic = 0.60 (95% CI 0.47, 0.73) to 0.70 (95% CI, 0.59-0.82).

CONCLUSION

We found elevated renalase in response to ischemia from acute CMD. Its role as a biomarker needs validation in larger trials.

Prevalence of Coronary Endothelial and Microvascular Dysfunction in Women with Symptoms of Ischemia and No Obstructive Coronary Artery Disease Is Confirmed by a New Cohort: The NHLBI-Sponsored Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction (WISE-CVD)

OBJECTIVE

In a separate, contemporary cohort, we sought to confirm findings of the original Women's Ischemia Syndrome Evaluation (WISE).

BACKGROUND

The original WISE observed a high prevalence of both invasively determined coronary endothelial and coronary microvascular dysfunction (CMD) that predicted adverse events in follow-up.

METHODS

We comparatively studied the WISE-Coronary Vascular Dysfunction (CVD) cohort (2009-2011), with signs and symptoms of ischemia but without significant CAD, to the original WISE (1997-2001) cohort. CMD was defined as coronary flow reserve (CFR) ≤2.5, or endothelial dysfunction as epicardial coronary artery constriction to acetylcholine (ACH), or <20% epicardial coronary dilation to nitroglycerin (NTG).

RESULTS

In WISE (n=181) and WISE-CVD (n=235) women, mean age in both was 54 years, and 83% were white (WISE) vs 74% (WISE-CVD, p=0.04). Use of hormone replacement therapy was less frequent in WISE-CVD vs WISE (46% vs 57%, p=0.026) as was presence of hypertension (40% vs 52%, p=0.013), hyperlipidemia (20% vs 46%, p<0.0001), and smoking (46% vs 56%, p=0.036). Similar rates were observed in WISE-CVD and WISE cohorts for CMD (mean CFR 2.7±0.6 vs 2.6±0.8, p=0.35), mean change in diameter with intracoronary ACH (0.2±10.0 vs 1.6±12.8 mm, p=0.34), and mean change in diameter with intracoronary NTG (9.7±13.0 vs 9.8±13.5 mm, p=0.94), respectively.

CONCLUSIONS

This study confirms prevalence of CMD in the contemporary WISE-CVD cohort similar to that of the original WISE cohort, despite a lower risk factor burden in WISE-CVD. Because these coronary functional abnormalities predict major adverse cardiac events, clinical trials of therapies targeting these abnormalities are indicated.

Sex-Specific Physiology and Cardiovascular Disease

Sex differences in cardiovascular diseases can be classified as those which are specific to one sex and those that differ in incidence, prevalence, etiology, symptomatology, response to treatment, morbidity, and mortality in one sex compared to the other. All sex differences in cardiovascular conditions have their basis in the combined expression of genetic and hormonal differences between women and men. This chapter addresses how understanding basic mechanisms of hormone responses, imaging diagnostics, and integration of genomics and proteomics has advanced diagnosis and improved outcomes for cardiovascular conditions, apart from those related to pregnancy that are more prevalent in women. These conditions include obstructive coronary artery disease, coronary microvascular dysfunction, spontaneous coronary artery dissection, diseases of the cardiac muscle including heart failure and takotsubo cardiomyopathy, and conditions related to neurovascular dysregulation including hot flashes and night sweats associated with menopause and effects of exogenous hormones on vascular function. Improvement in technologies allowing for noninvasive assessment of neuronally mediated vascular reactivity will further improve our understanding of the basic etiology of the neurovascular disorders. Consideration of sex, hormonal status, and pregnancy history in diagnosis and treatment protocols will improve prevention and outcomes of cardiovascular disease in women as they age.

Coronary microvascular dysfunction is associated with poor glycemic control amongst female diabetics with chest pain and non-obstructive coronary artery disease

Background

Patients with type 2 diabetes mellitus are at an increased risk of adverse cardiovascular events compared to those without diabetes. The timing, relative to disease onset, and degree of glycemic control that reduces the risk of adverse cardiovascular events remains uncertain. Coronary microvascular dysfunction is prevalent in patients with type 2 diabetes mellitus and is linked to adverse cardiovascular events. We assessed the association between endothelial-dependent and endothelial-independent coronary microvascular dysfunction and glycemic control in patients presenting with chest pain and nonobstructive coronary disease at angiography.

Methods

Patients presenting with chest pain and found to have non-obstructive CAD (stenosis < 40%) at angiography underwent an invasive assessment of endothelial-independent and endothelial –dependent microvascular function. Endothelial-independent microvascular function was assessed by comparing the coronary flow velocity, measured using a Doppler guidewire, in response to intracoronary infusion of adenosine to calculate the coronary flow reserve ratio in response to adenosine (CFRAdn Ratio). A CFRAdn Ratio ≤ 2.5 was considered abnormal. Endothelial-dependent microvascular function was assessed by measuring the percent change in coronary blood flow in response to intracoronary infusions of acetylcholine (%ΔCBFAch), and microvascular endothelial dysfunction defined as a %ΔCBFAch of ≤ 50%. Patients were classified by normal versus abnormal CFRAdn Ratio and %ΔCBFAch. Measurements of HbA1c and fasting serum glucose were obtained prior to catheterization and compared between groups.

Results

Between 1993 and 2012, 1469 patients (mean age 50.4 years, 35% male) underwent coronary angiography and invasive testing for coronary microvascular dysfunction, of which 129 (8.8%) had type 2 diabetes. Fifty-one (39.5%) had an abnormal %ΔCBFAch and 49 (38.0%) had an abnormal CFRAdn Ratio. Conventional cardiovascular risk factors and cardiovascular or diabetic medication use did not vary significantly between groups. Females with an abnormal CFRAdn Ratio or abnormal %ΔCBFAch had a significantly higher HbA1c compared to patients with a normal CFRAdn Ratio or %ΔCBFAch respectively: HbA1c % (standard deviation) 7.4 (2.1) vs. 6.5 (1.1), p = 0.035 and 7.3 (1.9) vs. 6.4 (1.2), p = 0.022, respectively. Female patients with an abnormal CFRAdn Ratio had significantly higher fasting serum glucose concentrations compared to those with a normal CFRAdn Ratio: fasting serum glucose mg/dL (standard deviation) 144.4 (55.6) vs. 121.9 (28.1), p = 0.035. This was not observed in men. Amongst female diabetics, a higher HbA1c was significantly associated with any coronary microvascular dysfunction both in a univariate and multivariate analysis: odds ratio (95% confidence interval) 1.69 (1.01–2.86) p = 0.049; and a fasting serum glucose > 140 mg/dL was significantly associated with an abnormal CFRAdn Ratio, 4.28 (1.43–12.81).

Conclusion

Poor glycemic control is associated with coronary microvascular dysfunction amongst female diabetics presenting with chest pain and non-obstructive CAD. These findings highlight the importance of sex specific risk stratification models and treatment strategies when managing cardiovascular risk amongst diabetics. Further studies are required to identify additional risk prevention tools and therapies targeting microvascular dysfunction as an integrated index of cardiovascular risk.

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0833-1) contains supplementary material, which is available to authorized users.

Molecular Imaging of Factor XIII Activity for the Early Detection of Mouse Coronary Microvascular Disease

Coronary microvascular disease (MVD) remains a major clinical problem due to limited mechanistic understanding and a challenging diagnosis. In the present study we evaluated the utility of targeted imaging of active factor XIII (FXIII) for detection of coronary MVD associated with thrombus. We hypothesized that a high specificity and sensitivity FXIII targeted radiolabeled probe can serve as a biomarker for cross-linked thrombi in the microvasculature, and thus an indicator for underlying coronary MVD. To evaluate this approach, a coronary MVD model was established for local induction of singlet oxygen and reactive oxygen species (ROS) via a photochemical reaction (PCR).

Methods: PCR was used to induce endothelial injury and microthrombi via focal over-production of ROS only in the coronary microvasculature. Oxidative stress was initially evaluated in primary coronary endothelial cells to optimize parameters of PCR, which were then translated to in vivo experiments. To develop the coronary MVD model, 64 mice were assigned to one of four groups after thoracotomy: 1) sham control; 2) rose bengal; 3) green light; or 4) their combination. Following interventions, the mice underwent transmission electron microscopy, fluorescent myocardial perfusion, coronary angiography, and immunohistochemical staining. Echocardiography (n = 12) and gene expression (n = 10) studies were also performed after MVD induction to monitor serial changes in cardiac function and explore possible mechanisms. To diagnose early onset MVD, FXIII radioactivity was assessed in 104 mice using ex vivo gamma well counting (GWC) and in 14 mice using in vivo serial single photon emission computed tomography / computed tomography (SPECT/CT) imaging of a FXIII targeted technetium-labeled probe (^99mTc-NC100668).

Results:In vitro experiments demonstrated that photosensitizer concentration and light illumination time were critical parameters for PCR. In vivo experiments demonstrated manifestations of clinical MVD, including endothelial damage, a “no flow zone,” arteriole rarefaction with patent epicardial coronary arteries, infiltration of inflammatory cells in the PCR-treated region, and preserved cardiac function. Gene expression also demonstrated a pro-thrombotic and impaired fibrinolytic status. In the early stages of MVD, enhanced FXIII activity was confirmed within the MVD region using GWC and in vivo SPECT/CT imaging.

Conclusion: Our results demonstrate that molecular imaging of FXIII activity may allow for early detection of coronary MVD associated with thrombus, in a novel pre-clinical model.

Impact of Abnormal Coronary Reactivity on Long-Term Clinical Outcomes in Women

BACKGROUND

Currently as many as one-half of women with suspected myocardial ischemia have no obstructive coronary artery disease (CAD), and abnormal coronary reactivity (CR) is commonly found.

OBJECTIVES

The authors prospectively investigated CR and longer-term adverse cardiovascular outcomes in women with and with no obstructive CAD in the National Heart, Lung, and Blood Institute-sponsored WISE (Women's Ischemia Syndrome Evaluation) study.

METHODS

Women (n = 224) with signs and symptoms of ischemia underwent CR testing. Coronary flow reserve and coronary blood flow were obtained to test microvascular function, whereas epicardial CR was tested by coronary dilation response to intracoronary (IC) acetylcholine and IC nitroglycerin. All-cause mortality, major adverse cardiovascular events (MACE) (cardiovascular death, myocardial infarction, stroke, and heart failure), and angina hospitalizations served as clinical outcomes over a median follow-up of 9.7 years.

RESULTS

The authors identified 129 events during the follow-up period. Low coronary flow reserve was a predictor of increased MACE rate (hazard ratio [HR]: 1.06; 95% confidence interval [CI]: 1.01 to 1.12; p = 0.021), whereas low coronary blood flow was associated with increased risk of mortality (HR: 1.12; 95% CI: 1.01 to 1.24; p = 0.038) and MACE (HR: 1.11; 95% CI: 1.03 to 1.20; p = 0.006) after adjusting for cardiovascular risk factors. In addition, a decrease in cross-sectional area in response to IC acetylcholine was associated with higher hazard of angina hospitalization (HR: 1.05; 95% CI: 1.02 to 1.07; p < 0.0001). There was no association between epicardial IC-nitroglycerin dilation and outcomes.

CONCLUSIONS

On longer-term follow-up, impaired microvascular function predicts adverse cardiovascular outcomes in women with signs and symptoms of ischemia. Evaluation of CR abnormality can identify those at higher risk of adverse outcomes in the absence of significant CAD. (Women's Ischemia Syndrome Evaluation [WISE]; NCT00000554).

Late sodium channel blockade improves angina and myocardial perfusion in patients with severe coronary microvascular dysfunction: Women's Ischemia Syndrome Evaluation-Coronary Vascular Dysfunction ancillary study

BACKGROUND

In a prior trial of late sodium channel inhibition (ranolazine) among symptomatic subjects without obstructive coronary artery disease (CAD) and limited myocardial perfusion reserve index (MPRI), we observed no improvement in angina or MPRI, overall. Here we describe the clinical characteristics and myocardial perfusion responses of a pre-defined subgroup who had coronary flow reserve (CFR) assessed invasively.

METHODS

Symptomatic patients without obstructive CAD and limited MPRI in a randomized, double-blind, crossover trial of ranolazine vs. placebo were subjects of this prespecified substudy. Because we had previously observed that adverse outcomes and beneficial treatment responses occurred in those with lower CFR, patients were subgrouped by CFR <2.5 vs ≥2.5. Symptoms were assessed using the Seattle Angina Questionnaire and the SAQ-7, and left-ventricular volume and MPRI were assessed by magnetic resonance imaging (MRI). Coronary angiograms, CFR, and MRI data were analyzed by core labs masked to treatment and patient characteristics.

RESULTS

During qualifying coronary angiography, 81 patients (mean age 55 years, 98% women) had invasively determined CFR 2.69 ± 0.65 (mean ± SD; range 1.4-5.5); 43% (n = 35) had CFR <2.5. Demographic and symptomatic findings did not differ comparing CFR subgroups. Those with low CFR had improved angina (p = 0.04) and midventricular MPRI (p = 0.03) with ranolazine vs placebo. Among patients with low CFR, reduced left-ventricular end-diastolic volume predicted a beneficial angina response.

CONCLUSIONS

Symptomatic patients with CFR <2.5 and no obstructive CAD had improved angina and myocardial perfusion with ranolazine, supporting the hypothesis that the late sodium channel is important in management of coronary microvascular dysfunction.

TRIAL REGISTRATION

clinicaltrials.gov Identifier NCT01342029.

Clinical and coronary haemodynamic determinants of recurrent chest pain in patients without obstructive coronary artery disease - A pilot study

BACKGROUND

Coronary haemodynamic testing frequently identifies abnormal pathophysiological parameters in patients with angina and non-obstructed coronaries on angiography (NoCAD) but the clinical utility of these measures has received limited attention.

OBJECTIVE

This study aims to identify the clinical and coronary haemodynamic determinants of recurrent chest pain at one month in patients with NoCAD.

METHODS

Patients with angina, NoCAD (<50% stenosis) and normal LV systolic function underwent invasive coronary haemodynamic testing involving: (1) angiographic TIMI frame and opacification rate, (2) microvascular functional measures including coronary flow reserve (CFR) and hyperaemic microvascular resistance (HMR), (3) coronary endothelial function assessment with low dose intracoronary acetylcholine (IC-ACh) infusions (0.18 μg/min & 1.8 μg/min over 2 min), and (4) Provocative spasm testing with high dose IC-ACh boluses (25, 50 and 100 μg). Clinical and health status were assessed at baseline and one month.

RESULTS

In the 49 NoCAD patients (78% female, mean age of 54 ± 11) undergoing comprehensive coronary haemodynamic testing, 33 (67%) continued to experience chest pain at one month. Determinants of recurrent chest pain on univariate analysis included baseline chest pain status or a HMR > 1.9. Multivariate logistic regression analysis identified frequent angina at baseline (OR: 68.9 [4.1, 1165.0], p = 0.003), previous unstable angina admission (OR: 43.9 [3.5, 547.9], p = 0.003) and a HMR > 1.9 (OR: 15.6 [2.1, 114.0], p = 0.007) as independent predictors of recurrent chest pain.

CONCLUSION

In this small pilot study, an abnormal HMR was the only coronary haemodynamic parameter that was a determinant of ongoing angina at short-term follow-up.

Sex-Specific Association Between Coronary Artery Disease Severity and Myocardial Ischemia Induced by Mental Stress

OBJECTIVE

It is unclear whether mental stress-induced myocardial ischemia (MSIMI) is related to obstructive coronary artery disease (CAD). We examined this question and contrasted results with ischemia induced by conventional stress testing (CSIMI). Because women are more susceptible to ischemia without coronary obstruction than men, we examined sex differences.

METHODS

We studied 276 patients 61 years and younger with recent myocardial infarction. CAD severity was quantified using the log-transformed Gensini Score (lnGS) and the Sullivan Stenosis Score. Patients underwent myocardial perfusion imaging with mental stress (public speaking) and conventional (exercise or pharmacological) stress testing. MSIMI and CSIMI were defined as a new or worsening perfusion defect.

RESULTS

The prevalence of MSIMI was 15% in men and 20% in women. The median GS for patients with MSIMI was 65.0 in men and 28.5 in women. In logistic regression models adjusted for demographic and cardiovascular risk factors, CAD severity was associated with CSIMI in the full sample (odds ratio [OR] = 1.49, 95% [CI], 1.14-1.95, per 1-unit increase in lnGS), with no significant difference by sex. Although CAD severity was not associated with MSIMI in the entire sample, results differed by sex. CAD severity was associated with MSIMI among men (OR = 1.95, 95% CI, 1.13-3.36, per 1-unit increase in lnGS), but not among women (OR = 1.02, 95% CI, 0.74-1.42, p = .042 for interaction). Analysis using Sullivan Stenosis Score yielded similar results.

CONCLUSIONS

Findings suggest that CAD severity is related to MSIMI in men but not women. MSIMI in women may therefore be driven by alternative mechanisms such as coronary microvascular disease.

Rationale and design of the Coronary Microvascular Angina Cardiac Magnetic Resonance Imaging (CorCMR) diagnostic study: the CorMicA CMR sub-study

Introduction

Angina with no obstructive coronary artery disease (ANOCA) is a common syndrome with unmet clinical needs. Microvascular and vasospastic angina are relevant but may not be diagnosed without measuring coronary vascular function. The relationship between cardiovascular magnetic resonance (CMR)-derived myocardial blood flow (MBF) and reference invasive coronary function tests is uncertain. We hypothesise that multiparametric CMR assessment will be clinically useful in the ANOCA diagnostic pathway.

Methods/analysis

The Stratified Medical Therapy Using Invasive Coronary Function Testing In Angina (CorMicA) trial is a prospective, blinded, randomised, sham-controlled study comparing two management approaches in patients with ANOCA. We aim to recruit consecutive patients with stable angina undergoing elective invasive coronary angiography. Eligible patients with ANOCA (n=150) will be randomised to invasive coronary artery function-guided diagnosis and treatment (intervention group) or not (control group). Based on these test results, patients will be stratified into disease endotypes: microvascular angina, vasospastic angina, mixed microvascular/vasospastic angina, obstructive epicardial coronary artery disease and non-cardiac chest pain. After randomisation in CorMicA, subjects will be invited to participate in the Coronary Microvascular Angina Cardiac Magnetic Resonance Imaging (CorCMR) substudy. Patients will undergo multiparametric CMR and have assessments of MBF (using a novel pixel-wise fully quantitative method), left ventricular function and mass, and tissue characterisation (T1 mapping and late gadolinium enhancement imaging). Abnormalities of myocardial perfusion and associations between MBF and invasive coronary artery function tests will be assessed. The CorCMR substudy represents the largest cohort of ANOCA patients with paired multiparametric CMR and comprehensive invasive coronary vascular function tests.

Ethics/dissemination

The CorMicA trial and CorCMR substudy have UK REC approval (ref.16/WS/0192).

Trial registration number

NCT03193294.

Cardiac implications of thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a multisystem disorder that essentially can affect any organ in the human body. The hallmark of the pathogenesis in TTP is the large von Willebrand factor multimers on platelet-mediated micro-thrombi formation, leading to microvascular thrombosis. Autopsy studies showed that cardiac arrest and myocardial infarction are the most common immediate causes of death in these patients. Clinical manifestations of cardiac involvement in TTP vary dramatically, from asymptomatic elevation of cardiac biomarkers, to heart failure, MI and sudden cardiac death. There is limited knowledge about optimal cardiac evaluation and management in patients with TTP. The absence of typical cardiac symptoms, combined with complicated multi-organ involvement in TTP, may contribute to the under-utilization of cardiac evaluation and treatment. Prompt diagnosis and timely initiation of effective therapy could be critically important in selected cases. Based on our experience and this review of the literature, we developed several recommendations for focused cardiac evaluation for patients with acute TTP: (1) patients with suspected or confirmed TTP should be screened for the potential presence of cardiac involvement with detailed history and physical, electrocardiogram and cardiac enzymes; (2) clinical deterioration of TTP patients warrants immediate cardiac reevaluation; (3) TTP patients with clinical evidence of cardiac involvement should be monitored for telemetry, cardiac biomarkers and evaluated with transthoracic echocardiography. These patients require urgent targeted TTP treatment as well as cardiac-specific treatment. Aspirin therapy is indicated for all TTP patients. Since epicardial coronary artery involvement is rare, cardiac catheterization is usually not required, given the high risk for hemorrhage and kidney injury; (4) we recommend evidence-based medical therapy for ischemic symptoms and heart failure. TTP patients with evidence of cardiac involvement would also benefit from routine cardiology follow up during remission.

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.

Lower Circulating Omega-3 Polyunsaturated Fatty Acids Are Associated with Coronary Microvascular Dysfunction Evaluated by Hyperemic Microvascular Resistance in Patients with Stable Coronary Artery Disease

The consumption of omega-3 polyunsaturated fatty acids (PUFAs) reduces the incidence of cardiovascular events and sudden cardiac death. Coronary microvascular dysfunction (CMD) is a predictor of cardiac mortality, but little information is known on the relationship between CMD and omega-3 PUFAs. This study aimed to identify the relationship between the serum levels of omega-3 PUFAs and the CMD evaluated by the hyperemic microvascular resistance index (hMVRI) to assess coronary microvascular function in patients with stable coronary artery disease (CAD).Intracoronary physiological variables (fractional flow reserve (FFR), hMVRI, mean distal coronary pressure (Pd), and average peak velocity (APV)) were measured in 108 patients. These parameters were evaluated in 150 coronary arteries with stenosis of intermediate severity and without significant ischemia (FFR > 0.80). The PUFA levels and atherosclerotic risk factors were also measured. Univariate analysis shows that hMVRI was negatively correlated with eicosapentaenoic acid (EPA)/arachidonic acid (AA) ratio (β = -0.31, P = 0.001) and EPA (β = -0.25, P = 0.009) and was positively correlated with dihomo-γ-linolenic acid (β = 0.26, P = 0.006). Multivariate regression analysis shows that the EPA/AA ratio was the only independent determinant of hMVRI (β = -0.234, SE = 0.231, P = 0.024). Furthermore, hMVRI decreased significantly from the lowest to highest tertiles of the EPA/AA ratio (P = 0.007). The EPA/AA ratio was positively correlated with APV at hyperemia (β = 0.26, P = 0.008) but not with Pd at hyperemia.A lower serum EPA/AA ratio may cause CMD in patients with stable CAD.

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.

The association of 18F-FDG PET/CT and biomarkers in confirming coronary microvascular dysfunction

Objective

The purpose of this study is to evaluate the association between PET/CT CFR and biomarkers combined in confirming the diagnosis of coronary microvascular dysfunction.

Results

A total of 28 patients (21 males and 7 females) were included in this descriptive observational study (both qualitative and quantitative). The mean patient age was 55.50 ± 10.21 years (range 27–70 years) and the median was 56.5 years (range 49–63 years). All patients underwent Echo, CAG and PET/CT scan. Chest tightness was the most common symptom in our study. Most patients had normal blood pressure (n = 18, 64.3%) while only (n = 10, 37.5%) had hypertension, and (n = 1, 3.6%) had diabetes mellitus. The mean HDL in CMVD (n = 25) and non-CMVD (n = 3) were 1.30 ± 0.39 and 1.08 ± 0.95, respectively, indicating that the difference between the groups was statistically significant (p = 0.04). Similarly, the mean HBA1c- (glycated haemoglobin) in CMVD (n = 25) and non-CMVD (n = 3) were 5.6 ± 0.53 and 5.0 ± 0.26, respectively, with (p = 0.03). Our findings managed to show the association between biomarkers and PET/CT CFR in confirming the diagnosis of coronary microvascular dysfunction.