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

Quantitative Myocardial Perfusion Predicts Outcomes in Patients With Prior Surgical Revascularization

BACKGROUND

Patients with previous coronary artery bypass graft (CABG) surgery typically have complex coronary disease and remain at high risk of adverse events. Quantitative myocardial perfusion indices predict outcomes in native vessel disease, but their prognostic performance in patients with prior CABG is unknown.

OBJECTIVES

In this study, we sought to evaluate whether global stress myocardial blood flow (MBF) and perfusion reserve (MPR) derived from perfusion mapping cardiac magnetic resonance (CMR) independently predict adverse outcomes in patients with prior CABG.

METHODS

This was a retrospective analysis of consecutive patients with prior CABG referred for adenosine stress perfusion CMR. Perfusion mapping was performed in-line with automated quantification of MBF. The primary outcome was a composite of all-cause mortality and major adverse cardiovascular events defined as nonfatal myocardial infarction and unplanned revascularization. Associations were evaluated with the use of Cox proportional hazards models after adjusting for comorbidities and CMR parameters.

RESULTS

A total of 341 patients (median age 67 years, 86% male) were included. Over a median follow-up of 638 days (IQR: 367-976 days), 81 patients (24%) reached the primary outcome. Both stress MBF and MPR independently predicted outcomes after adjusting for known prognostic factors (regional ischemia, infarction). The adjusted hazard ratio (HR) for 1 mL/g/min of decrease in stress MBF was 2.56 (95% CI: 1.45-4.35) and for 1 unit of decrease in MPR was 1.61 (95% CI: 1.08-2.38).

CONCLUSIONS

Global stress MBF and MPR derived from perfusion CMR independently predict adverse outcomes in patients with previous CABG. This effect is independent from the presence of regional ischemia on visual assessment and the extent of previous infarction.

Fractal analysis of 4D dynamic myocardial stress-CT perfusion imaging differentiates micro- and macrovascular ischemia in a multi-center proof-of-concept study

Fractal analysis of dynamic, four-dimensional computed tomography myocardial perfusion (4D-CTP) imaging might have potential for noninvasive differentiation of microvascular ischemia and macrovascular coronary artery disease (CAD) using fractal dimension (FD) as quantitative parameter for perfusion complexity. This multi-center proof-of-concept study included 30 rigorously characterized patients from the AMPLIFiED trial with nonoverlapping and confirmed microvascular ischemia (n_micro = 10), macrovascular CAD (n_macro = 10), or normal myocardial perfusion (n_normal = 10) with invasive coronary angiography and fractional flow reserve (FFR) measurements as reference standard. Perfusion complexity was comparatively high in normal perfusion (FD_normal = 4.49, interquartile range [IQR]:4.46-4.53), moderately reduced in microvascular ischemia (FD_micro = 4.37, IQR:4.36-4.37), and strongly reduced in macrovascular CAD (FD_macro = 4.26, IQR:4.24-4.27), which allowed to differentiate both ischemia types, p < 0.001. Fractal analysis agreed excellently with perfusion state (κ = 0.96, AUC = 0.98), whereas myocardial blood flow (MBF) showed moderate agreement (κ = 0.77, AUC = 0.78). For detecting CAD patients, fractal analysis outperformed MBF estimation with sensitivity and specificity of 100% and 85% versus 100% and 25%, p = 0.02. In conclusion, fractal analysis of 4D-CTP allows to differentiate microvascular from macrovascular ischemia and improves detection of hemodynamically significant CAD in comparison to MBF estimation.

Plasma Ceramide Levels Are Elevated in Patients With Early Coronary Atherosclerosis and Endothelial Dysfunction

Background

Elevated plasma ceramides are independent predictors of cardiovascular disease and mortality in patients with advanced epicardial coronary artery disease. Our understanding of plasma ceramides in early epicardial coronary artery disease, however, remains limited. We examined the role of plasma ceramides in early coronary atherosclerosis characterized by coronary endothelial dysfunction.

Methods and Results

Participants presenting with chest pain and nonobstructive epicardial coronary artery disease underwent coronary endothelial function. Patients (n=90) demonstrated abnormal coronary endothelial function with acetylcholine (≥20% decrease in coronary artery diameter or ≤50% increase in coronary blood flow). A total of 30 controls had normal coronary endothelial function. Concentrations of plasma ceramide 18:0 (P=0.038), 16:0 (P=0.021), and 24:0 (P=0.019) differed between participants with normal and abnormal coronary endothelial function. Ceramide 24:0 (odds ratio [OR], 2.23 [95% CI, 1.07–4.66]; P=0.033) and 16:0 (OR, 1.91×10⁶ [95% CI, 11.93–3.07×10¹¹]; P=0.018) were independently associated with coronary endothelial dysfunction. Among participants with endothelium‐dependent coronary dysfunction (n=78), ceramides 16:0 (OR, 5.17×10⁵ [95% CI, 2.83–9.44×10¹⁰]; P=0.033), 24:0 (OR, 2.98 [95% CI, 1.27–7.00]; P=0.012), and 24:1/24:0 (OR, 4.39×10⁻⁴ [95% CI, 4×10⁻⁷–0.48]; P=0.030) were more likely to be elevated.

Conclusions

The current study demonstrated an association between increased circulating ceramide levels and coronary endothelial dysfunction in the absence of epicardial coronary artery disease. This study supports the role of plasma ceramides as a potential biomarker or a therapeutic target for early coronary atherosclerosis in humans.

Molecular mechanisms of coronary microvascular endothelial dysfunction in diabetes mellitus: focus on mitochondrial quality surveillance

Coronary microvascular endothelial dysfunction is both a culprit and a victim of diabetes, and can accelerate diabetes-related microvascular and macrovascular complications by promoting vasoconstrictive, pro-inflammatory and pro-thrombotic responses. Perturbed mitochondrial function induces oxidative stress, disrupts metabolism and activates apoptosis in endothelial cells, thus exacerbating the progression of coronary microvascular complications in diabetes. The mitochondrial quality surveillance (MQS) system responds to stress by altering mitochondrial metabolism, dynamics (fission and fusion), mitophagy and biogenesis. Dysfunctional mitochondria are prone to fission, which generates two distinct types of mitochondria: one with a normal and the other with a depolarized mitochondrial membrane potential. Mitochondrial fusion and mitophagy can restore the membrane potential and homeostasis of defective mitochondrial fragments. Mitophagy-induced decreases in the mitochondrial population can be reversed by mitochondrial biogenesis. MQS abnormalities induce pathological mitochondrial fission, delayed mitophagy, impaired metabolism and defective biogenesis, thus promoting the accumulation of unhealthy mitochondria and the activation of mitochondria-dependent apoptosis. In this review, we examine the effects of MQS on mitochondrial fitness and explore the association of MQS disorders with coronary microvascular endothelial dysfunction in diabetes. We also discuss the potential to treat diabetes-related coronary microvascular endothelial dysfunction using novel MQS-altering drugs.

Retinal microvasculature impairments in patients with coronary artery disease: An optical coherence tomography angiography study

PURPOSE

To investigate the association between retinal microvasculature and the presence and severity of coronary artery disease (CAD) using optical coherence tomography angiography (OCTA).

METHODS

The cross-sectional study was conducted in Guangdong Provincial People's Hospital, China. Retinal microvasculature parameters were measured by OCTA of the optic disc, including the vessel density (VD) and retinal nerve fibre thickness of the radial peripapillary capillary. In terms of the entire macula, VD of the superficial capillary plexus (SCP), deep capillary plexus (DCP) and foveal density (FD-300) were included. The Gensini score was used to evaluate the severity of coronary artery obstructive lesions in CAD patients.

RESULTS

A total of 410 participants (270 CAD patients and 140 controls) were included. Overall, participants showed significantly greater odds of having CAD in the lower versus higher VD for mean SCP, OR = 2.33 (95% CI 1.49-3.65); in the parafoveal SCP, OR = 2.68 (95% CI 1.70-4.23); and in the perifoveal SCP, OR = 2.36 (95% CI 1.49-3.72). Additionally, participants showed significantly greater odds of having CAD in the lower versus higher VD for mean DCP, OR = 4.04 (95% CI 2.53-6.45); in the parafoveal DCP, OR = 4.08 (95% CI 2.54-6.55); and in the perifoveal DCP, OR = 3.88 (95% CI 2.43-6.19). Among CAD patients, lower VD of DCP was associated with significantly greater adjusted Gensini scores (p = 0.004 for mean DCP; p = 0.035 for parafoveal DCP; p = 0.006 for perifoveal DCP).

CONCLUSIONS

SCP and DCP were found to be associated with the presence of CAD among the whole population, while DCP was found to be associated with Gensini scores in CAD patients. Retinal microvasculature was associated with the presence and severity of coronary artery stenosis in CAD patients.

Ischemia preconditioning alleviates ischemia/reperfusion injury-induced coronary no-reflow and contraction of microvascular pericytes in rats

BACKGROUND

Ischemia preconditioning (IPC) ameliorates coronary no-reflow induced by ischemia/reperfusion (I/R) injury, and pericytes play an important role in microvascular function. However, it is unclear whether IPC exerts a protective effect on coronary microcirculation and regulates the pericytes.

OBJECTIVE

The purpose of this study was to assess whether IPC improves coronary microvascular perfusion and reduces pericyte constriction after myocardial I/R injury.

METHODS

Rats were randomly divided into three groups: the sham group, the I/R group, and the IPC + I/R group. The left anterior descending artery (LAD) of rats in the I/R group were ligated for 45 min, and the rats in the IPC + I/R group received 4 episodes of 6min occlusion followed by 6min reperfusion before the LAD was ligated. After 24 h of reperfusion, the area of no-reflow, and area at risk were evaluated with thioflavin-S and Evens blue staining, and infarct size with triphenyl tetrazolium chloride staining, respectively. Besides, fluorescent microspheres were perfused to enable visualization of the non-obstructed coronary vessels. Cardiac pericytes and microvascular were observed by immunofluorescence, and the diameter of microvascular at the site of the pericyte somata was analyzed.

RESULTS

The infarct size, and area of no-reflow in the IPC + I/R group were significantly reduced compared with the I/R group (infarct size, 33.5% ± 11.9% vs. 49.2% ± 9.4%, p = 0.021；no-reflow, 12.7% ± 5.2% vs. 26.6% ± 5.0%, p < 0.001). IPC improved microvascular perfusion and reduced the percentage of the blocked coronary capillary. Moreover, we found that cardiac pericytes were widely distributed around the microvascular in various regions of the heart, and expressed the contractile protein α-smooth muscle actin. The microvascular lumen diameter at pericyte somata was reduced after I/R (4.3 ± 1.0 μm vs. 6.5 ± 1.2 μm, p < 0.001), which was relieved in IPC + I/R group compared with the I/R group (5.2 ± 1.0 μm vs. 4.3 ± 1.0 μm, p < 0.001). Besides, IPC could reduce the proportion of apoptotic pericytes compared to the I/R group (22.1% ± 8.4% vs. 38.5% ± 7.5%, p < 0.001).

CONCLUSION

IPC reduced no-reflow and inhibited the contraction of microvascular pericytes induced by cardiac I/R injury, suggesting that IPC might play a protective role by regulating the pericyte function.

Clinical value of resting cardiac dual-energy CT in patients suspected of coronary artery disease

BACKGROUND

Rest/stress myocardial CT perfusion (CTP) has high diagnostic value for coronary artery disease (CAD), but the additional value of resting CTP especially dual-energy CTP (DE-CTP) beyond coronary CT angiography (CCTA) in chest pain triage remains unclear. We aimed to evaluate the diagnostic accuracy of resting myocardial DE-CTP, and additional value in detecting CAD beyond CCTA (obstructive stenosis: ≥ 50%) in patients suspected of CAD.

METHODS

In this prespecified subanalysis of 54 patients, we included patients suspected of CAD referred to invasive coronary angiography (ICA). Diagnostic accuracy of resting myocardial DE-CTP in detecting myocardial perfusion defects was assessed using resting ¹³N-ammonia positron emission tomography (PET) as the gold standard. Diagnostic accuracy of cardiac dual-energy CT in detecting flow-limiting stenoses (justifying revascularization) by CCTA combined with resting myocardial DE-CTP, using ICA plus resting ¹³N-ammonia PET as the gold standard. The CCTA and DE-CTP datasets derived from a single-phase scan performed with dual-energy mode.

RESULTS

For detecting myocardial perfusion defects, DE-CTP demonstrated high diagnostic accuracy with a sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) of 95.52%, 85.93%, and 0.907 on a per-segment basis. For detecting flow-limiting stenoses by CCTA alone, sensitivity, specificity, and AUC were 100%, 56.47%, and 0.777 respectively on a per-vessel basis. For detecting flow-limiting stenoses by CCTA combined with resting myocardial DE-CTP, sensitivity, specificity, and AUC were 96.10%, 95.29% and 0.956 respectively on a per-vessel basis. Additionally, CCTA combined with resting myocardial DE-CTP detected five patients (9%) with no obstructive stenosis but with myocardial perfusion defects confirmed by ICA plus ¹³N-ammonia PET.

CONCLUSIONS

Resting cardiac DE-CTP demonstrates a high diagnostic accuracy in detecting myocardial perfusion defects and provides an additional clinical value by reducing rates of false-positive and false-negative patients beyond CCTA in patients suspected of CAD.

In Vivo Imaging of Rat Vascularity with FDG-Labeled Erythrocytes

Microvascular disease is frequently found in major pathologies affecting vital organs, such as the brain, heart, and kidneys. While imaging modalities, such as ultrasound, computed tomography, single photon emission computed tomography, and magnetic resonance imaging, are widely used to visualize vascular abnormalities, the ability to non-invasively assess an organ’s total vasculature, including microvasculature, is often limited or cumbersome. Previously, we have demonstrated proof of concept that non-invasive imaging of the total mouse vasculature can be achieved with 18F-fluorodeoxyglucose (18F-FDG)-labeled human erythrocytes and positron emission tomography/computerized tomography (PET/CT). In this work, we demonstrate that changes in the total vascular volume of the brain and left ventricular myocardium of normal rats can be seen after pharmacological vasodilation using 18F-FDG-labeled rat red blood cells (FDG RBCs) and microPET/CT imaging. FDG RBC PET imaging was also used to approximate the location of myocardial injury in a surgical myocardial infarction rat model. Finally, we show that FDG RBC PET imaging can detect relative differences in the degree of drug-induced intra-myocardial vasodilation between diabetic rats and normal controls. This FDG-labeled RBC PET imaging technique may thus be useful for assessing microvascular disease pathologies and characterizing pharmacological responses in the vascular bed of interest.

Update on Management of Cardiovascular Diseases in Women

Cardiovascular diseases (CVD) have a lower prevalence in women than men; although, a higher mortality rate and a poorer prognosis are more common in women. However, there is a misperception of CVD female risk since women have commonly been considered more protected so that the real threat is vastly underestimated. Consequently, female patients are more likely to be treated less aggressively, and a lower rate of diagnostic and interventional procedures is performed in women than in men. In addition, there are substantial sex differences in CVD, so different strategies are needed. This review aims to evaluate the main gender-specific approaches in CVD.

Evaluating the adverse outcome of subtypes of heart failure with preserved ejection fraction defined by machine learning: A systematic review focused on defining high risk phenogroups

The ability to distinguish clinically meaningful subtypes of heart failure with preserved ejection fraction (HFpEF) has recently been examined by machine learning techniques but studies appear to have produced discordant results. The objective of this study is to synthesize the types of HFpEF by examining their features and relating them to phenotypes with adverse prognosis. A systematic search was conducted using the search terms "Diastolic Heart Failure" OR "heart failure with preserved ejection fraction" OR "heart failure with normal ejection fraction" OR "HFpEF" AND "machine learning" OR "artificial intelligence" OR 'computational biology'. Ten studies were identified and they varied in their prevalence of ten clinical variables: age, sex, body mass index (BMI) or obesity, hypertension, diabetes mellitus, coronary artery disease, atrial fibrillation, chronic kidney disease, chronic obstructive pulmonary disease or symptom severity (NYHA class or BNP). The clinical findings associated with the different phenotypes in > 85 % of studies were age, hypertension, atrial fibrillation, chronic kidney disease and worse symptoms severity; an adverse outcome was in 65 % to 85 % of studies identified diabetes mellitus and female sex and in less than 65 % of studies was body mass index or obesity, and coronary artery disease. COPD was a relevant factor in only 33 % of studies. Adverse clinical outcome - death or admission to hospital (for heart failure) defined phenogroups with the worst outcome. Combining the 4 studies that calculated the MAGGIC score showed a significant (p<0.05) linear relationship between MAGGIC score and outcome, using the one-year event rate. A new score based on strength of the evidence of the HFpEF studies analyzed here, using 9 variables (eliminating COPD), showed a significant (p<0.009) linear relationship with one-year event rate. Three studies examined biomarkers in detail and the ones most prominently related to outcome or consistently found in the studies were GDF15, FABP4, FGF23, sST2, renin and TNF. The dominant factors that identified phenotypes of HFpEF with adverse outcome were hypertension, atrial fibrillation, chronic kidney disease and worse symptoms severity. A new simplified score, based on clinical factors, was proposed to assess prognosis in HFpEF. Several biomarkers were consistently elevated in phenogroups with adverse outcomes and may indicate the underlying mechanism or pathophysiology specific for phenotypes with an adverse prognosis.

Radiation-Induced Cardiovascular Disease: Mechanisms, Prevention, and Treatment

PURPOSE OF REVIEW

Despite the advancements of modern radiotherapy, radiation-induced cardiovascular disease (RICVD) remains a common cause of morbidity and mortality among cancer survivors.

RECENT FINDINGS

Proposed pathogenetic mechanisms of RICVD include endothelial cell damage with accelerated atherosclerosis, pro-thrombotic alterations in the coagulation pathway as well as inflammation and fibrosis of the myocardial, pericardial, valvular, and conduction tissues. Prevention of RICVD can be achieved by minimizing the exposure of the cardiovascular system to radiation, by treatment of underlying cardiovascular risk factors and cardiovascular disease, and possibly by prophylactic pharmacotherapy post exposure. Herein we summarize current knowledge on the mechanisms underlying the pathogenesis of RICVD and propose prevention and treatment strategies.

Coronary Arterial Function and Disease in Women With No Obstructive Coronary Arteries

Ischemic heart disease (IHD) is the leading cause of mortality in women. While traditional cardiovascular risk factors play an important role in the development of IHD in women, women may experience sex-specific IHD risk factors and pathophysiology, and thus female-specific risk stratification is needed for IHD prevention, diagnosis, and treatment. Emerging data from the past 2 decades have significantly improved the understanding of IHD in women, including mechanisms of ischemia with no obstructive coronary arteries and myocardial infarction with no obstructive coronary arteries. Despite this progress, sex differences in IHD outcomes persist, particularly in young women. This review highlights the contemporary understanding of coronary arterial function and disease in women with no obstructive coronary arteries, including coronary anatomy and physiology, mechanisms of ischemia with no obstructive coronary arteries and myocardial infarction with no obstructive coronary arteries, noninvasive and invasive diagnostic strategies, and management of IHD.

Updates in the Impact of Chronic Systemic Inflammation on Vascular Inflammation by Positron Emission Tomography (PET)

PURPOSE OF REVIEW

In this review, we focus on the clinical and epidemiological studies pertaining to systemic and vascular inflammation by positron emission tomography (PET) in patients with chronic inflammatory conditions such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), human immunodeficiency virus (HIV), and psoriasis to highlight the importance of chronic systemic inflammation on vascular inflammation by PET in these disease states.

RECENT FINDINGS

Recent clinical and translation advancements have demonstrated the durable relationship between chronic systemic inflammation and cardiovascular disease (CVD). In chronic inflammatory states, this relationship is robustly evident in the form of increased vascular inflammation, yet traditional risk estimates often underestimate the subclinical cardiovascular risk conferred by chronic inflammation. PET has emerged as a novel, non-invasive imaging modality capable of both quantifying the degree of systemic and vascular inflammation and detecting residual inflammation prior to cardiovascular events. We begin by demonstrating the role of inflammation in the pathogenesis of atherosclerosis, discussing how PET has been utilized to measure systemic and vascular inflammation and their effect on subclinical atherosclerosis, and finally reviewing recent applications of PET in constructing improved risk stratification for patients at high risk for stroke and CVD.

The Role of Antiplatelet Therapy in Patients With MINOCA

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogeneous group of clinical entities characterized by the common clinical evidence of myocardial infarction (MI) with non-obstructive coronary arteries on coronary angiography and without an overt cause for the MI. Platelets play a cornerstone role in the pathophysiology of MI with obstructive coronary arteries. Accordingly, antiplatelet therapy is recommended for treating patients with MI and obstructive coronary disease. However, the role of platelets in the pathophysiology of MINOCA patients is not fully defined, questioning the role of antiplatelet therapy in this setting. In this review, we will assess the role of antiplatelet therapy in MINOCA with a focus on the pathophysiology, therapeutic targets, current evidence, and future directions according to its different etiologies.

Contemporary Management of Stable Coronary Artery Disease

Coronary artery disease (CAD) continues to be the leading cause of mortality and morbidity in developed countries. Assessment of pre-test probability (PTP) based on patient's characteristics, gender and symptoms, help to identify more accurate patient's clinical likelihood of coronary artery disease. Consequently, non-invasive imaging tests are performed more appropriately to rule in or rule out CAD rather than invasive coronary angiography (ICA). Coronary computed tomography angiography (CCTA) is the first-line non-invasive imaging technique in patients with suspected CAD and could be used to plan and guide coronary intervention. Invasive coronary angiography remains the gold-standard method for the identification and characterization of coronary artery stenosis. However, it is recommended in patients where the imaging tests are non-conclusive, and the clinical likelihood is very high, remembering that in clinical practice, approximately 30 to 70% of patients with symptoms and/or signs of ischemia, referred to coronary angiography, have non obstructive coronary artery disease (INOCA). In this contest, physiology and imaging-guided revascularization represent the cornerstone of contemporary management of chronic coronary syndromes (CCS) patients allowing us to focus specifically on ischemia-inducing stenoses. Finally, we also discuss contemporary medical therapeutic approach for secondary prevention. The aim of this review is to provide an updated diagnostic and therapeutic approach for the management of patients with stable coronary artery disease.

Role of Exercise Treadmill Testing in the Assessment of Coronary Microvascular Disease

OBJECTIVES

The authors aimed to study the sensitivity and specificity of exercise treadmill testing (ETT) in the diagnosis of coronary microvascular disease (CMD), as well as the prognostic implications of ETT results in patients with CMD.

BACKGROUND

ETT is validated to evaluate for flow-limiting coronary artery disease (CAD), however, little is known about its use for evaluating CMD.

METHODS

We retrospectively studied 249 consecutive patients between 2006 and 2016 who underwent ETT and positron emission tomography within 12 months. Patients with obstructive CAD or left ventricular systolic dysfunction were excluded. CMD was defined as a coronary flow reserve <2. Patients were followed for the occurrence of a first major adverse event (composite of death or hospitalization for myocardial infarction or heart failure).

RESULTS

The sensitivity and specificity of a positive ETT to detect CMD were 34.7% (95% CI: 25.4%-45.0%) and 64.9% (95% CI: 56.7%-72.5%), respectively. The specificity of a positive ETT to detect CMD increased to 86.8% (95% CI: 80.3%-91.7%) when only classifying studies with ischemic electrocardiogram changes that lasted at least 1 minute into recovery as positive, although at a cost of lower sensitivity (15.3%; 95% CI: 8.8%-24.0%). Over a median follow-up of 6.9 years (IQR: 5.1-8.2 years), 30 (12.1%) patients met the composite endpoint, including 13 (13.3%) with CMD (n = 98). In patients with CMD, ETT result was not associated with the composite endpoint (P = 0.076).

CONCLUSIONS

Our data suggest limited sensitivity of ETT to detect CMD. However, a positive ETT with ischemic changes that persist at least 1 minute into recovery in the absence of obstructive CAD should raise suspicion for the presence of CMD given a high specificity. Further study is needed with larger patient sample sizes to assess the association between ETT results and outcomes in patients with CMD.

Effect of Polysaccharide Sulfate-Loaded Poly(lactic-co-glycolic acid) Nanoparticles on Coronary Microvascular Dysfunction of Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) mainly results from development of coronary microcirculatory dysfunction (CMD). Polysaccharide sulfate (PSS), as one heparin drug, has a variety of biological activities. This study examined the efficacy of a new type of PSS-loaded poly lactic-co-glycolic acid (PLGA) nanoparticles (PSS-NPs) on DCM, in finding a theoretical basis for CMD treatment. After establishment of DCM model, the animals were administrated with PSS, PSS-NPs, normal saline or poly(ethylene glycol)1 (PEG1) through intraperitoneal injection. 8 weeks after injection of streptozotocin (STZ), heart function of rats was assessed by echocardiography. The rat tissues were collected and detected by histological analysis. Quantitative reverse transcription PCR (RT-qPCR) and Western blot analyses determined the levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), and pro-inflammatory factors. PSS-NPs had a good protective effect on cardiac insufficiency in rats. Administration of PSS-NPs prolonged survival state, and enhanced cardiac function, thereby alleviating the symptoms, and inducing formation of micro vessels. Importantly, it improved the symptoms of DCM patients and their quality of life. Moreover, pro-inflammatory factor levels decreased upon the treatment, accompanied with inactivation of NF-κB signaling pathways, thereby improving DCM. This study demonstrated that the PSS-NPs significantly relieved DCM and restored cardiac function in rats through NF-κB signaling pathways, providing a theoretical basis for development of PSS-NPs, and new treatment ideas for CMD of DCM.

Myocardial Dysfunction and Heart Failure in Rheumatoid Arthritis

Rheumatoid arthritis (RA) patients have almost twice the risk of heart failure (HF) as individuals without RA, even with adjustment for the presence of ischemic heart disease. Moreover, RA patients remain at a 2-fold higher risk of mortality from HF compared to non-RA patients. These observations suggest that RA-specific inflammatory pathways are significant contributors to this increased risk of HF. Herein we summarize the epidemiology of HF in RA patients, the differences in myocardial structure or function between RA patients and non-RA patients without clinical signs of HF, and data on the role of systemic and local inflammation in RA HF pathophysiology. We also discuss the impact of subduing inflammation through the use of RA disease-modifying therapies on HF and myocardial structure and function, emphasizing gaps in the literature and areas needing further research.

COVID-19 vs. Classical Myocarditis Associated Myocardial Injury Evaluated by Cardiac Magnetic Resonance and Endomyocardial Biopsy

Background: Despite the ongoing global pandemic, the impact of COVID-19 on cardiac structure and function is still not completely understood. Myocarditis is a rare but potentially serious complication of other viral infections with variable recovery, and is, in some cases, associated with long-term cardiac remodeling and functional impairment.

Aim: To assess myocardial injury in patients who recently recovered from an acute SARS-CoV-2 infection with advanced cardiac magnetic resonance imaging (CMR) and endomyocardial biopsy (EMB).

Methods: In total, 32 patients with persistent cardiac symptoms after a COVID-19 infection, 22 patients with acute classic myocarditis not related to COVID-19, and 16 healthy volunteers were included in this study and underwent a comprehensive baseline CMR scan. Of these, 10 patients post COVID-19 and 13 with non-COVID-19 myocarditis underwent a follow-up scan. In 10 of the post-COVID-19 and 15 of the non-COVID-19 patients with myocarditis endomyocardial biopsy (EMB) with histological, immunohistological, and molecular analysis was performed.

Results: In total, 10 (31%) patients with COVID-19 showed evidence of myocardial injury, eight (25%) presented with myocardial oedema, eight (25%) exhibited global or regional systolic left ventricular (LV) dysfunction, and nine (28%) exhibited impaired right ventricular (RV) function. However, only three (9%) of COVID-19 patients fulfilled updated CMR–Lake Louise criteria (LLC) for acute myocarditis. Regarding EMB, none of the COVID-19 patients but 87% of the non-COVID-19 patients with myocarditis presented histological findings in keeping with acute or chronic inflammation. COVID-19 patients with severe disease on the WHO scale presented with reduced biventricular longitudinal function, increased RV mass, and longer native T1 times compared with those with only mild or moderate disease.

Conclusions: In our cohort, CMR and EMB findings revealed that SARS-CoV-2 infection was associated with relatively mild but variable cardiac involvement. More symptomatic COVID-19 patients and those with higher clinical care demands were more likely to exhibit chronic inflammation and impaired cardiac function compared to patients with milder forms of the disease.

Deep Learning of the Retina Enables Phenome- and Genome-Wide Analyses of the Microvasculature

BACKGROUND

The microvasculature, the smallest blood vessels in the body, has key roles in maintenance of organ health and tumorigenesis. The retinal fundus is a window for human in vivo noninvasive assessment of the microvasculature. Large-scale complementary machine learning-based assessment of the retinal vasculature with phenome-wide and genome-wide analyses may yield new insights into human health and disease.

METHODS

We used 97 895 retinal fundus images from 54 813 UK Biobank participants. Using convolutional neural networks to segment the retinal microvasculature, we calculated vascular density and fractal dimension as a measure of vascular branching complexity. We associated these indices with 1866 incident International Classification of Diseases-based conditions (median 10-year follow-up) and 88 quantitative traits, adjusting for age, sex, smoking status, and ethnicity.

RESULTS

Low retinal vascular fractal dimension and density were significantly associated with higher risks for incident mortality, hypertension, congestive heart failure, renal failure, type 2 diabetes, sleep apnea, anemia, and multiple ocular conditions, as well as corresponding quantitative traits. Genome-wide association of vascular fractal dimension and density identified 7 and 13 novel loci, respectively, that were enriched for pathways linked to angiogenesis (eg, vascular endothelial growth factor, platelet-derived growth factor receptor, angiopoietin, and WNT signaling pathways) and inflammation (eg, interleukin, cytokine signaling).

CONCLUSIONS

Our results indicate that the retinal vasculature may serve as a biomarker for future cardiometabolic and ocular disease and provide insights into genes and biological pathways influencing microvascular indices. Moreover, such a framework highlights how deep learning of images can quantify an interpretable phenotype for integration with electronic health record, biomarker, and genetic data to inform risk prediction and risk modification.

Lycopene ameliorates skin aging by regulating the insulin resistance pathway and activating SIRT1

Lycopene could reverse insulin resistance through SIRT1 during skin aging and promotes microcirculation via the improvement of microvascular neovascularization to protect aging skin.

Prognostic impact of coronary microvascular dysfunction assessed by caIMR in overweight with chronic coronary syndrome patients

OBJECTIVE

Coronary microvascular dysfunction (CMD) may associate with adverse cardiovascular events in obese patients. Coronary angiography-derived index of microcirculatory resistance (caIMR) is proposed as a less-invasive and pressure-wire-free index to assess CMD. We aimed to investigate the impact of coronary microvascular function assessed by caIMR in patients with overweight and chronic coronary syndrome (CCS).

METHODS

CCS patients who underwent coronary angiography between 2015 to 2018 were included. Overweight was defined as BMI≥24.0kg/m². Impaired coronary microvascular function was defined as caIMR≥25U. The patients were classified according to BMI and caIMR. The primary endpoint was major adverse cardiac events (MACE). Kaplan-Meier and Cox regression analyses evaluated the association between caIMR and MACE.

RESULTS

Two hundred and eighty-two CCS patients were enrolled. Among these, 169 (59.93%) were overweight. Impaired coronary microvascular function was higher in overweight patients than in patients with normal weight (49.70% vs. 38.05%; P=0.035). During 35 months of follow-up, 33 MACE had occurred. Among the total CCS population, MACE was higher in patients with high caIMR than in low caIMR (18.11% vs. 6.45%, P=0.003). In subgroups analysis, MACE was higher in overweight patients with high caIMR than low caIMR (20.24% vs. 7.06%, P=0.014), while there were no significant differences in normal-weight patients. Multivariate Cox analysis demonstrated that caIMR≥25 was independently associated with MACE in overweight patients (HR, 2.87; 95% CI, 1.12-7.30; P=0.027) but not in the normal-weight patients. In addition, caIMR showed a significant predictive value for adverse outcomes in overweight patients and provided an incremental prediction when added to a prediction model with BMI.

CONCLUSIONS

Impaired coronary microvascular function assessed by caIMR was common and is an independent predictor of MACE in overweight patients with CCS.

Can EAT be an INOCA goalkeeper

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

Specialized Proresolving Mediators in Symptomatic Women With Coronary Microvascular Dysfunction (from the Women's Ischemia Trial to Reduce Events in Nonobstructive CAD [WARRIOR] Trial)

Resolvins and maresins, members of the specialized proresolving mediator (SPM) family, are omega-3 fatty acid-derived lipid mediators that attenuate inflammation. We hypothesized that they play a role in the pathophysiology of coronary microvascular dysfunction (CMD) in women with ischemia and no obstructive coronary disease. In a pilot study, we measured the D-series resolvins (D1, D2, D3, and D5), resolvin E1, maresin 1, docosahexaenoic acid, eicosapentaenoic acid (precursor of resolvin E1), and 18-hydroxyeicosapentaenoic acid by mass spectrometry in the peripheral blood of 31 women enrolled in the Women's Ischemia Trial to Reduce Events in Nonobstructive CAD (WARRIOR) trial who had confirmed CMD assessed by coronary flow reserve. We compared SPM levels with 12 gender and age-matched reference subjects. Compared with the reference subject group, those with CMD had significantly lower plasma concentrations of resolvin D1 and maresin 1 and significantly higher levels of docosahexaenoic acid and 18-hydroxyeicosapentaenoic acid. In conclusion, insufficient or ineffective SPM production may play a role in the pathophysiology of CMD. If our results are validated in a larger cohort, omega-3 fatty acid supplementation could be tested as a novel treatment for these patients.

Coronary Microvascular Dysfunction and Heart Failure with Preserved Ejection Fraction - implications for Chronic Inflammatory Mechanisms

Coronary Microvascular Dysfunction (CMD) is now considered one of the key underlying pathologies responsible for the development of both acute and chronic cardiac complications. It has been long recognized that CMD contributes to coronary no-reflow, which occurs as an acute complication during percutaneous coronary interventions. More recently, CMD was proposed to play a mechanistic role in the development of left ventricle diastolic dysfunction in heart failure with preserved ejection fraction (HFpEF). Emerging evidence indicates that a chronic low-grade pro-inflammatory activation predisposes patients to both acute and chronic cardiovascular complications raising the possibility that pro-inflammatory mediators serve as a mechanistic link in HFpEF. Few recent studies have evaluated the role of the hyaluronan-CD44 axis in inflammation-related cardiovascular pathologies, thus warranting further investigations. This review article summarizes current evidence for the role of CMD in the development of HFpEF, focusing on molecular mediators of chronic proinflammatory as well as oxidative stress mechanisms and possible therapeutic approaches to consider for treatment and prevention.

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

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

Tianxiangdan Improves Coronary Microvascular Dysfunction in Rats by Inhibiting Microvascular Inflammation via Nrf2 Activation

Background

Tianxiangdan (TXD) is used in traditional Chinese medicine because of its therapeutic and preventive effects in the treatment of coronary heart disease. However, the underlying mechanism of TXD in coronary microvascular disease (CMD) remains unclear.

Methods

A rat model of CMD was developed to study the mechanism of TXD activity. Sodium laurate was injected into the left ventricle of Sprague–Dawley rats to induce CMD. The rats were divided into six groups: a sham-operated (sham) group, an untreated CMD group, a low-dose TXD group (0.81 g·kg⁻¹·d⁻¹), a mid-dose TXD (TXD-M) group (1.62 g·kg⁻¹·d⁻¹), a high-dose TXD (TXD-H) group (3.24 g·kg⁻¹·d⁻¹), and a nicorandil (NCR) group (1.35 mg·kg⁻¹·d⁻¹). The effect of TXD on rats with CMD was observed after four weeks, and the mechanism of TXD in lipopolysaccharide (LPS)-induced cardiac microvascular endothelial cells (CMECs) was explored through treatment with 50 μg/mL TXD.

Results

Compared with the rats in the untreated CMD group, rats in the TXD-M and TXD-H groups showed higher left ventricular ejection fraction values, improved pathological structures, decreased expressions of interleukin (IL)-1β, tumor necrosis factor-alpha (TNF-α), phosphorylated nuclear factor-κB inhibitor α (IκBα) and phosphorylated p65, and increased expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (P < 0.05). These effects were more pronounced in the TXD-H group than in the TXD-M group. In vitro experiments showed that TXD treatment increased the viability of LPS-induced CMECs and decreased the expression of IL-1β, TNF-α, phosphorylated IκBα, and phosphorylated p65 (P < 0.05). However, the effects of TXD on CMECs were markedly reversed upon treatment with ML385 (Nrf2 inhibitor).

Conclusion

The results showed that TXD exerts a protective effect on rats with CMD and related inflammatory injuries, and its anti-inflammatory mechanism is related to the activation of Nrf2 signalling.

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

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

Evaluation of cardiac allograft vasculopathy by positron emission tomography

Cardiac allograft vasculopathy (CAV) remains one of the most important late occurring complications in heart transplant (HT) recipients significantly effecting graft survival. Recently, there has been tremendous focus on the development of effective and safe non-invasive diagnostic strategies for the diagnosis of CAV employing a wide range of imaging technologies. During the past decade multiple studies have been published using positron emission tomography (PET) myocardial perfusion imaging, establishing the value of PET myocardial blood flow quantification for the evaluation of CAV. These independent investigations demonstrate that PET can be successfully used to establish the diagnosis of CAV, can be utilized for prognostication and may be used for serial monitoring of HT recipients. In addition, molecular imaging techniques have started to emerge as new tools to enhance our knowledge to better understand the pathophysiology of CAV.

Prognostic value of regional myocardial flow reserve derived from 13N-ammonia positron emission tomography in patients with suspected coronary artery disease

PURPOSE

To assess the prognostic value of regional quantitative myocardial flow measures as assessed by 13N-ammonia positron emission tomography (PET) myocardial perfusion imaging (MPI) in patients with suspected coronary artery disease (CAD).

METHODS

We retrospectively included 150 consecutive patients with suspected CAD who underwent clinically indicated 13 N-ammonia PET-MPI and who did not undergo revascularization within 90 days of PET-MPI. The presence or absence of a decreased global myocardial flow reserve (i.e., MFR < 2) as well as decreased regional MFR (i.e., ≥ 2 adjacent segments with MFR < 2) was recorded, and patients were classified as having preserved global and regional MFR (MFR group 1), preserved global but decreased regional MFR (MFR group 2), or decreased global and regional MFR (MFR group 3). We obtained follow-up regarding major adverse cardiac events (MACE, i.e., a combined endpoint including all-cause death, non-fatal myocardial infarction, and late revascularization) and all-cause death.

RESULTS

Over a median follow-up of 50 months (IQR 38-103), 30 events occurred in 29 patients. Kaplan-Meier analysis showed significantly reduced event-free and overall survival in MFR groups 2 and 3 compared to MFR group 1 (log-rank: p = 0.015 and p = 0.013). In a multivariable Cox regression analysis, decreased regional MFR was an independent predictor for MACE (adjusted HR 3.44, 95% CI 1.17-10.11, p = 0.024) and all-cause death (adjusted HR 4.72, 95% CI 1.07-20.7, p = 0.04).

CONCLUSIONS

A decreased regional MFR as assessed by 13 N-ammonia PET-MPI confers prognostic value by identifying patients at increased risk for future adverse cardiac outcomes and all-cause death.

Combining flow and reserve measurement during myocardial perfusion imaging: A new era for myocardial perfusion scintigraphy?

Myocardial flow reserve represents the ratio of myocardial blood flow between stress and rest, giving functional information about both macrocirculation and microcirculation; it has been reported extensively in positron emission tomography, with an increase in diagnostic performance, providing important prognostic information and being a powerful tool to guide therapy. Advances in single photon emission computed tomography, with the widespread availability of "cadmium zinc telluride" single photon emission computed tomography cameras, raise the question of myocardial flow reserve use in daily clinical practice. In this article, we review the pathophysiology of myocardial blood flow and myocardial flow reserve, and the initial data available from single photon emission computed tomography myocardial blood flow and myocardial flow reserve evaluation; we also discuss potential limitations to the wider implementation of flow evaluation in single photon emission computed tomography.

Coronary Vasculature and Myocardial Structure in HIV: Physiologic Insights From the Renin-Angiotensin-Aldosterone System

The landscape of HIV medicine dramatically changed with the advent of contemporary antiretroviral therapies, which has allowed persons with HIV (PWH) to achieve good virologic control, essentially eliminating HIV-related complications and increasing life expectancy. As PWH are living longer, noncommunicable diseases, such as cardiovascular disease (CVD), have become a leading cause of morbidity and mortality in PWH with rates that are 50% to 100% higher than in well-matched persons without HIV. In this review, we focus on disease of the coronary microvasculature and myocardium in HIV. We highlight a key hormonal system important to cardiovascular endocrinology, the renin-angiotensin-aldosterone system (RAAS), as a potential mediator of inflammatory driven-vascular and myocardial injury and consider RAAS blockade as a physiologically targeted strategy to reduce CVD in HIV.

Imaging techniques for the assessment of adverse cardiac remodeling in metabolic syndrome

Metabolic syndrome (MetS) includes different metabolic conditions (i.e. abdominal obesity, impaired glucose tolerance, hypertriglyceridemia, decreased HDL cholesterol, and/or hypertension) that concour in the development of cardiovascular disease and diabetes. MetS individuals often show adverse cardiac remodeling and myocardial dysfunction even in the absence of overt coronary artery disease or valvular affliction. Diastolic impairment and hypertrophy are hallmarks of MetS-related cardiac remodeling and represent the leading cause of heart failure with preserved ejection fraction (HFpEF). Altered cardiomyocyte function, increased neurohormonal tone, interstitial fibrosis, coronary microvascular dysfunction, and a myriad of metabolic abnormalities have all been implicated in the development and progression of adverse cardiac remodeling related to MetS. However, despite the enormous amount of literature produced on this argument, HF remains a leading cause of morbidity and mortality in such population. The early detection of initial adverse cardiac remodeling would enable the optimal implementation of effective therapies aiming at preventing the progression of the disease to the symptomatic phase. Beyond conventional imaging techniques, such as echocardiography, cardiac tomography, and magnetic resonance, novel post-processing tools and techniques provide information on the biological processes that underlie metabolic heart disease. In this review, we summarize the pathophysiology of MetS-related cardiac remodeling and illustrate the relevance of state-of-the-art multimodality cardiac imaging to identify and quantify the degree of myocardial involvement, prognosticate long-term clinical outcome, and potentially guide therapeutic strategies.

Aspirin plus verapamil relieves angina and perfusion abnormalities in patients with coronary microvascular dysfunction and Chagas disease: a pilot non-randomized study

INTRODUCTION

Most patients with chronic cardiomyopathy of Chagas disease (CCCD) harbor a secondary cause of coronary microvascular dysfunction (CMD), for which there is no evidence-based therapy. We evaluated the impact of verapamil plus aspirin on symptoms and perfusion abnormalities in patients with CCCD and CMD.

METHODS

Consecutive patients with angina pectoris, who had neither coronary artery obstructions nor moderate-severe left ventricular dysfunction (left ventricular ejection fraction > 40%) despite showing wall motion abnormalities on ventriculography, were referred for invasive angiography and tested for Chagas disease. Thirty-two patients with confirmed CCCD and ischemia on stress-rest SPECT myocardial perfusion scintigraphy (MPS) were included. Clinical evaluation, quality of life (EQ-5D/ Seattle Angina Questionnaire), and MPS were assessed before and after 3 months of treatment with oral verapamil plus aspirin (n=26) or placebo (n=6).

RESULTS

The mean patient age was 64 years, and 18 (56%) were female. The ischemic index summed difference score (SDS) in MPS was significantly reduced by 55.6% after aspirin+verapamil treatment. A decrease in SDS was observed in 20 (77%) participants, and in 10 participants, no more ischemia could be detected. Enhancements in quality of life were also detected. No change in symptoms or MPS was observed in the placebo group.

CONCLUSIONS

This low-cost 3-month treatment for patients diagnosed with CCCD and CMD was safe and resulted in a 55.6% reduction in ischemic burden, symptomatic improvement, and better quality of life.

Coronary artery spasm and impaired myocardial perfusion in patients with ANOCA: Predictors from a multimodality study using stress CMR and acetylcholine testing

BACKGROUND

Functional coronary disorders such as coronary spasm and microvascular dysfunction (including microvascular spasm and impaired microvascular dilatation) are frequent findings among patients with angina and non-obstructed coronary arteries (ANOCA). In this study, we investigated a potential association of coronary spasm and myocardial perfusion abnormalities as well as predictors of such functional coronary disorders in ANOCA patients using a multimodality diagnostic strategy including adenosine stress CMR and intracoronary acetylcholine testing.

METHODS

We enrolled 129 patients with ANOCA who underwent acetylcholine testing and adenosine stress perfusion CMR. Patients were allocated to 3 groups according to their spasm testing result with regard to standardized COVADIS criteria: 1) epicardial spasm, 2) microvascular spasm, and 3) no spasm. The myocardial perfusion reserve index (MPRI) was semiquantitatively determined from adenosine stress perfusion CMR. Multivariate regression analyses were performed to identify predictors of coronary functional disorders.

RESULTS

Patients with epicardial spasm had lower MPRI than patients without, whereas MPRI was preserved in patients with microvascular spasm. Multivariate analyses revealed age, previous myocardial infarction, LVEF and epicardial spasm as independent predictors of diminished MPRI, whereas previous PCI was associated with epicardial spasm, and female sex was a strong predictor of microvascular spasm.

CONCLUSIONS

Our results demonstrate coexistence of different functional coronary disorder endotypes involving the macro- and microvascular level of the coronary circulation in patients with ANOCA. We demonstrate that epicardial spasm is associated with diminished myocardial perfusion reserve and report further predictors of coronary functional disorders.

Impaired perfusion in the myocardial microcirculation in asymptomatic patients with Stages 1-4 chronic kidney disease with intrarenal arterial lesions

BACKGROUND

Even mild renal disease is a powerful cardiovascular risk factor. However, the association between these pathophysiologic processes (especially in the early asymptomatic stage) is not known.

METHODS

We recruited 243 asymptomatic patients with Stages 1-4 chronic kidney disease (CKD) without obstructive coronary artery disease (CAD). We distinguished different degrees of severity of intrarenal arterial lesions (IALs) according to the Oxford classification. Myocardial microcirculation perfusion was measured using single-photon emission computed tomography (SPECT). Summed scores of 17 stress and rest image segments produced the summed stress score (SSS) and summed rest score (SRS), respectively. The summed difference score (SDS) was calculated as the difference between the SSS and SRS. Coronary microvascular disease (CMD) was defined as abnormal SPECT (SSS ≥4 or SDS ≥2) in the absence of obstructive CAD.

RESULTS

Participants showed a stepwise increase in CMD severity with IAL aggravation. SSS of no/mild/moderate/severe IALs was 1.64 ± 1.08, 2.56 ± 1.35, 4.42 ± 2.17 and 6.48 ± 3.52, respectively (P < 0.05 for all). SDS of no/mild/moderate/severe IALs was 1.29 ± 0.49, 1.75 ± 0.56, 3.06 ± 1.12 and 4.16 ± 1.85, respectively (P < 0.05 for all). The percentage of subclinical CMD in CKD patients with IALs was significantly higher than in those without IALs (69.57% versus 14.71%; P = 0.01). Multiple regression analysis showed that renal arteriolar hyalinization (odds ratio = 1.578, P = 0.009) was associated independently with subclinical CMD.

CONCLUSIONS

We demonstrated, for the first time, that impaired perfusion in the myocardial microcirculation in asymptomatic patients with Stages 1-4 CKD with IALs. Renal arteriolar hyalinization may be a useful marker of CMD in CKD.

Inflammation in Metabolic Cardiomyopathy

Overlapping pandemics of lifestyle-related diseases pose a substantial threat to cardiovascular health. Apart from coronary artery disease, metabolic disturbances linked to obesity, insulin resistance and diabetes directly compromise myocardial structure and function through independent and shared mechanisms heavily involving inflammatory signals. Accumulating evidence indicates that metabolic dysregulation causes systemic inflammation, which in turn aggravates cardiovascular disease. Indeed, elevated systemic levels of pro-inflammatory cytokines and metabolic substrates induce an inflammatory state in different cardiac cells and lead to subcellular alterations thereby promoting maladaptive myocardial remodeling. At the cellular level, inflammation-induced oxidative stress, mitochondrial dysfunction, impaired calcium handling, and lipotoxicity contribute to cardiomyocyte hypertrophy and dysfunction, extracellular matrix accumulation and microvascular disease. In cardiometabolic patients, myocardial inflammation is maintained by innate immune cell activation mediated by pattern recognition receptors such as Toll-like receptor 4 (TLR4) and downstream activation of the NLRP3 inflammasome and NF-κB-dependent pathways. Chronic low-grade inflammation progressively alters metabolic processes in the heart, leading to a metabolic cardiomyopathy (MC) phenotype and eventually to heart failure with preserved ejection fraction (HFpEF). In accordance with preclinical data, observational studies consistently showed increased inflammatory markers and cardiometabolic features in patients with HFpEF. Future treatment approaches of MC may target inflammatory mediators as they are closely intertwined with cardiac nutrient metabolism. Here, we review current evidence on inflammatory processes involved in the development of MC and provide an overview of nutrient and cytokine-driven pro-inflammatory effects stratified by cell type.

Relative Prognostic Significance of Positron Emission Tomography Myocardial Perfusion Imaging Markers in Cardiomyopathy

BACKGROUND

Rubidium-82 positron emission tomography myocardial perfusion imaging provides measurements of perfusion, myocardial blood flow and reserve (MBFR), and changes in left ventricular ejection fraction (LVEF) at rest and peak stress. Although all of these variables are known to provide prognostic information, they have not been well studied in patients with heart failure due to reduced LVEF.

METHODS

Between 2010 and 2016, 1255 consecutive unique patients with LVEF≤40% were included in this study who underwent rubidium-82 positron emission tomography myocardial perfusion imaging and did not have subsequent revascularization within 90 days. Perfusion assessment was scored semiquantitatively, and LVEF reserve (stress-rest LVEF) and global MBFR (stress/rest MBF) were quantified using automated software. Cox proportional hazards models adjusted for 14 clinical and 7 test characteristics were used to define the independent prognostic significance of MBFR on all-cause mortality.

RESULTS

Of 1255 patients followed for a mean of 3.2 years, 454 (36.2%) died. After adjusting for clinical variables, the magnitude of fixed and reversible perfusion defects was prognostic of death (P=0.02 and 0.01, respectively), while the rest LVEF was not (P=0.18). The addition of LVEF reserve did not add any incremental value, while the addition of MBFR revealed incremental prognostic value (hazard ratio per 0.1 unit decrease in MBFR=1.08 [95% CI, 1.05-1.11], P<0.001) with fixed and reversible defects becoming nonsignificant (P=0.07 and 0.29, respectively). There was no interaction between MBFR and cause of cardiomyopathy (ischemic versus nonischemic).

CONCLUSIONS

In patients with a known cardiomyopathy who did not require early revascularization, reduced MBFR as obtained by positron emission tomography myocardial perfusion imaging is associated with all-cause mortality while other positron emission tomography myocardial perfusion imaging measures were not.

Coronary Artery Disease in Women: A Comprehensive Appraisal

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

Microvascular Resistance Reserve for Assessment of Coronary Microvascular Function: JACC Technology Corner

The need for a quantitative and operator-independent assessment of coronary microvascular function is increasingly recognized. We propose the theoretical framework of microvascular resistance reserve (MRR) as an index specific for the microvasculature, independent of autoregulation and myocardial mass, and based on operator-independent measurements of absolute values of coronary flow and pressure. In its general form, MRR equals coronary flow reserve (CFR) divided by fractional flow reserve (FFR) corrected for driving pressures. In 30 arteries, pressure, temperature, and flow velocity measurements were obtained simultaneously at baseline (BL), during infusion of saline at 10 mL/min (rest) and 20 mL/min (hyperemia). A strong correlation was found between continuous thermodilution-derived MRR and Doppler MRR (r = 0.88; 95% confidence interval: 0.72-0.93; P < 0.001). MRR was independent from the epicardial resistance, the lower the FFR value, the greater the difference between MRR and CFR. Therefore, MRR is proposed as a specific, quantitative, and operator-independent metric to quantify coronary microvascular dysfunction.

The association between markers of inflammation and retinal microvascular parameters: A systematic review and meta-analysis

BACKGROUND AND AIMS

Adverse changes to the microcirculation play an important role in the pathogenesis of cardiovascular disease (CVD), and inflammation is a key causal mechanism. We investigated the relationship between inflammatory markers and retinal microvascular parameters.

METHODS

Studies up to April 2021 were identified in Medline, Embase and PubMed with the following terms: retinal microvascular parameters, inflammatory markers, and observational studies. Correlation coefficients of inflammatory markers and retinal vascular caliber were pooled using the random-effects model.

RESULTS

Of 4783 studies identified, 36 met the inclusion criteria (general population 26, patients with diseases 10). C-reactive protein (CRP) and white blood cell count (WBC) were most frequently reported. We conducted meta-analysis with 12 CRP studies (22422 participants) and six WBC studies (15209 participants), and also performed a narrative review of all studies. There was consistent evidence of a modest association between CRP and venular caliber (r = 0.09, 95%CI 0.05 to 0.12), but little evidence of an association between CRP with retinal arteriolar caliber (r = 0.00, 95%CI -0.02 to 0.02). Similarly, WBC had stronger associations with venular (r = 0.18, 95%CI 0.05 to 0.31) than arteriolar caliber (r = 0.05, 95%CI 0.01 to 0.09). Narrative review of other inflammatory markers showed consistent findings. There was little evidence of associations between inflammation markers and other microvascular parameters, fractal dimension and tortuosity.

CONCLUSIONS

There was more evidence for an association of inflammation with retinal venular than with arterial caliber. The findings suggest a potential druggable mechanism contributing to microvascular damage that has been relatively overlooked in CVD pathogenesis and treatment.

Coronary CT Fractional Flow Reserve before Transcatheter Aortic Valve Replacement: Clinical Outcomes

Background The role of CT angiography-derived fractional flow reserve (CT-FFR) in pre-transcatheter aortic valve replacement (TAVR) assessment is uncertain. Purpose To evaluate the predictive value of on-site machine learning-based CT-FFR for adverse clinical outcomes in candidates for TAVR. Materials and Methods This observational retrospective study included patients with severe aortic stenosis referred to TAVR after coronary CT angiography (CCTA) between September 2014 and December 2019. Clinical end points comprised major adverse cardiac events (MACE) (nonfatal myocardial infarction, unstable angina, cardiac death, or heart failure admission) and all-cause mortality. CT-FFR was obtained semiautomatically using an on-site machine learning algorithm. The ability of CT-FFR (abnormal if ≤0.75) to predict outcomes and improve the predictive value of the current noninvasive work-up was assessed. Survival analysis was performed, and the C-index was used to assess the performance of each predictive model. To compare nested models, the likelihood ratio χ² test was performed. Results A total of 196 patients (mean age ± standard deviation, 75 years ± 11; 110 women [56%]) were included; the median time of follow-up was 18 months. MACE occurred in 16% (31 of 196 patients) and all-cause mortality in 19% (38 of 196 patients). Univariable analysis revealed CT-FFR was predictive of MACE (hazard ratio [HR], 4.1; 95% CI: 1.6, 10.8; P = .01) but not all-cause mortality (HR, 1.2; 95% CI: 0.6, 2.2; P = .63). CT-FFR was independently associated with MACE (HR, 4.0; 95% CI: 1.5, 10.5; P = .01) when adjusting for potential confounders. Adding CT-FFR as a predictor to models that include CCTA and clinical data improved their predictive value for MACE (P = .002) but not all-cause mortality (P = .67), and it showed good discriminative ability for MACE (C-index, 0.71). Conclusion CT angiography-derived fractional flow reserve was associated with major adverse cardiac events in candidates for transcatheter aortic valve replacement and improved the predictive value of coronary CT angiography assessment. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Choe in this issue.