Microangiopathy Research Articles

Coronary microvascular disease (CMD) is an early complication of type 2 diabetes (T2D) involving adverse endothelial and smooth muscle function, vascular remodeling, and alterations in mechanics. These culminate in impaired coronary blood flow. To interrogate transcriptional differences potentially contributing to CMD, we tested the hypothesis that comprehensive single-cell and spatial transcriptomic profiling of the coronary microcirculation and surrounding myocardium will identify new pathways to target in CMD. We utilized an innovative combination of single-cell RNA profiling and spatial transcriptomics to examine transcriptional differences and molecular signatures of CMD in T2D mice. Single-cell RNA profiling and spatial transcriptomics revealed an upregulation of genes linked to adipogenesis, fatty acid metabolism, and oxidative phosphorylation in T2D cell clusters and coronary microvascular-enriched regions. In ECs, VSMCs, cardiomyocyte clusters, fibroblasts, and macrophages, the upregulation of adipogenesis was directed by Angplt4 and Ephx2, whereas Hmgcs2 and Acot2 were the key players in the upregulation of fatty acid metabolism, and Pdk4 and Ech1 were the drivers of oxidative phosphorylation upregulation. These intriguing data support the well-documented concept that cardiac metabolic inflexibility in T2D heart failure-characterized by reduced mitochondrial function, increased reliance on fatty acid oxidation, and impaired glucose utilization-contributes to oxidative stress and lipotoxicity. Our data unveiled novel and unique gene expression signatures of coronary microvessels in the presence and absence of diabetes.

Diabetic distal symmetric polyneuropathy (DDSP) is the most common form of diabetic neuropathy. DDSP, foot ulcerations, and lower limb amputation greatly increase mortality, which is 23% 2 years after a foot ulceration and rises to 71% after 10 years. DDSP is seen in patients with both type 1 and type 2 diabetes, but the clinical features and pathophysiology are distinctly different. DDSP also presents in patients with pre-diabetes and/or obesity alone, indicating that glycaemic control is not the sole contributor to the pathophysiology of DDSP. In the BARI 2D trial, 51% of those with type 2 diabetes had peripheral neuropathy at baseline. In the DCCT/EDIC trials, patients with type 1 diabetes had a 6% prevalence of diabetes on enrolment, which increased to 30% after 13-14 years of follow-up. In the lower limb, a combination of the components of sensory DDSP coupled with motor and autonomic components leads to an increased incidence of foot ulceration. The ADA 2025 Standard of Care recommends screening for diabetic neuropathy at the time of presentation for patients with type 2 diabetes and 5 years after diagnosis in patients with type 1 diabetes. Diagnostic techniques are discussed in this article. The basic pathological process in DDSP is oxidative and inflammatory stress due to diabetes and its associated metabolic abnormalities as well as microvascular disease. Therapy of symptomatic DDSP is less than satisfactory. Medications utilized for neuropathic pain are discussed as are the therapies to prevent and treat foot ulceration. It is important to recognize that DDSP in patients with diabetes may have other causes: particularly deficiencies of vitamins B12 and D, excessive alcohol intake, hypothyroidism, and paraproteinemias.

Type 2 diabetes mellitus (T2DM) and depression are significant global health problems. In particular, approximately 26–30 % of people with diabetes suffer from depression of varying severity, and T2DM doubles the risk of developing depression. The latter can be caused by behavioral factors, including unbalanced eating habits, obesity, physical inactivity, social instability, substance abuse, and sleep disturbances. Insulin resistance (IR), one of the leading signs of T2DM, has different forms specific to certain tissues. In particular, peripheral IR is manifested by reduced glucose uptake by skeletal muscles and adipose tissue due to defects in insulin receptor function and signaling pathways. IR of brain cells is associated with changes in insulin signaling in neurons and glial cells, with neurodegenerative processes, which links it to both cognitive decline and mood disorders. There are several hypotheses regarding common risk factors, such as the psychological impact of managing a chronic disease, potentially shared genetic predisposition, or pathophysiological disorders. The latter include dysregulation of the hypothalamic-pituitary-adrenal axis, activation of chronic low-grade inflammation, changes in the autonomic nervous system, dysfunction of the sympathoadrenal system, dysregulation of insulin signaling and neurotransmission, activation of oxidative stress processes and mitochondrial dysfunction, disturbance of intestinal microbiota homeostasis and dysfunction of the gut-brain axis, dysfunction of brain-derived neurotrophic factor, changes in synaptic plasticity of neurons, and disruption of autophagy. At the same time, it is reported that the relationship between T2DM and an increased risk of developing depressive symptoms is partly explained by increased levels of biomarkers of microvascular dysfunction, neurodegeneration, advanced glycation end products, and arterial stiffness. However, a significant impact of chronic low-grade inflammation processes has not been identified. The review aimed to examine the current state of research on the relationship between IR, depression, and T2DM, and to identify new trends and directions for future research. The search was conducted in Scopus, ScienceDirect (from Elsevier), and PubMed, including MEDLINE databases. The keywords used were “insulin resistance”, “depression”, “type 2 diabetes”, and “brain-derived neurotrophic factor”. A manual search for the bibliography of publications was used to identify research results that could not be found during the online search.

Bolus thermodilution is the most commonly used invasive assessment for coronary microvascular dysfunction (CMD). However, variability in thermodilution transit time measurements (TTM) affects calculated Coronary Flow Reserve (CFR) and Index of Microvascular Resistance (IMR) values. This study determined variables associated with transit time variability and quantified confidence intervals for the range of measured CFR and IMR values. The CoroFlow Cardiovascular System (Coroventis, Sweden) and PressureWire™ X Guidewire (Abbott) were used to collect 2541 TTM from 259 vessels at 14 US sites included in the FlowLab Study. Correlations with baseline patient and procedural variables were determined by both linear and mixed linear models. Mixed linear models with the physician or vessel as the random effect were computed. Monte Carlo simulations of CFR and IMR were performed to determine 95% confidence intervals for thresholds of 2.5 for CFR and 25 for IMR. Mixed linear analysis with vessel as the random effect provided the best model fit (R2 = 0.948). In this model, RCA vessel location (p < 0.001) and pressure sensor distance < 5 cm (p < 0.005) were significantly associated with transit time. Monte Carlo simulations identified a "gray zone" range of 2.1-3.1 for CFR and 19-31 for IMR. Minimizing variability in invasive CMD assessment is essential for improving diagnostic accuracy and guiding clinical decision-making as testing becomes more widespread. In this study, target vessel choice (RCA) and pressure sensor placement were identified as key modifiable sources of transit time variability. Clinically applicable confidence intervals around CFR and IMR values were defined.

Endothelial cells regulate vascular tone by releasing nitric oxide (NO) and prostacyclin (PGI2), as well as by initiating hyperpolarization of vascular smooth muscle cells through K+ channels and myoendothelial coupling. This review highlights the therapeutic potential of targeting endothelium-dependent hyperpolarization (EDH) to address unmet needs in microvascular disorders such as cerebral small vessel disease, an important cause of stroke and dementia, and preeclampsia, a major pregnancy complication associated with maternal and fetal morbidity. Oxidative stress, connexin dysfunction, and impaired K+ channel signalling disrupt electrical coupling between endothelium and smooth muscle cells, leading to loss of vascular homeostasis. Building on this mechanistic convergence, we propose a multimodal therapeutic strategy to restore EDH in concert with the NO and PGI2 pathways. Within this framework, human tissue kallikrein-1 (KLK1) exemplifies an integrated therapeutic approach by simultaneously engaging multiple endothelial vasodilator mechanisms. Through bradykinin B2 receptor signalling, KLK1 enhances NO and PGI2 production while also promoting EDH via K+ channel activation. Its recombinant form, rinvecalinase alfa (DM199), has demonstrated consistent benefit in early-phase clinical trials, supporting its potential to restore endothelial balance. By reactivating these complementary vasodilatory pathways, DM199 improves microvascular perfusion and endothelial resilience, positioning it as a prototype multimodal therapy for microvascular diseases.

Introduction: Persistent COVID-19 is associated with microvascular dysfunction, with retinal vessels as potential early biomarkers. Obesity, particularly visceral adiposity, contributes to this dysfunction; however, the body mass index (BMI) is limited in its ability to assess it. Therefore, more precise alternative anthropometric indices have been proposed, although their relationship with retinal vascular caliber in persistent COVID-19 has not been studied. Objective: To analyze the relationship between different anthropometric measurements and the caliber of retinal vessels in an adult population with persistent COVID-19. Materials and Methods: This was an observational, descriptive, and cross-sectional study and included individuals diagnosed with persistent COVID-19. Retinal images were obtained using a non-mydriatic retinograph. The anthropometric variables used included: waist and hip circumference, BMI, waist-to-height ratio (WHtR), Body Roundness Index (BRI), Abdominal Volume Index (AVI), and body composition parameters measured by bioelectrical impedance analysis. Results: The sample included 284 participants (mean age: 52.7 years; 31.8% men). Men exhibited greater general and abdominal adiposity. The AV Index was negatively associated with various anthropometric indicators (BMI, BRI, waist circumference, and AVI), while venular caliber showed positive associations with all these indices, except for BMI (p &lt; 0.05 for all). No significant correlations were found between anthropometric values and arteriolar caliber. These associations persisted after adjusting for age, sex, and pharmacological treatment. Conclusions: Individuals with obesity are associated with alterations in retinal vessels in patients with persistent COVID-19, evidenced by an increase in venous caliber and a decrease in the AV Index. However, these findings should be interpreted cautiously.

Myopia represents a growing global public health challenge, characterized by increasing prevalence and associated complications such as myopic macular degeneration and retinal detachment. Although genetic and environmental factors are well-recognized contributors, emerging evidence supports a pathological link between inflammation and myopia progression. Epidemiological studies indicate a higher incidence of myopia among individuals with systemic or ocular inflammatory conditions. Inflammation perturbs the ocular immune microenvironment by upregulating pro-inflammatory cytokines and matrix metalloproteinase-2, thereby accelerating extracellular matrix (ECM) degradation and scleral remodeling, which culminates in axial elongation. Conversely, excessive axial elongation in high myopia triggers choroidal microvascular dysfunction, tissue hypoxia, and disruption of the blood-retinal barrier, leading to elevated inflammatory cytokines in the aqueous humor and vitreous, thereby raising the possibility of a self-perpetuating loop. Anti-inflammatory agents, including diacerein, resveratrol, and lactoferrin, have demonstrated therapeutic potential in experimental models by modulating inflammatory pathways, reducing pro-inflammatory cytokines, and preserving ECM integrity. However, their clinical efficacy and long-term safety require further validation. Elucidating the complex interplay between inflammation and myopia is pivotal for the development of targeted interventions, moving the focus of myopia management beyond optical correction towards disease-modifying strategies.

Introduction: Alzheimer’s Disease (AD) is associated with cerebral microvascular dysfunction and metabolic alterations. We hypothesized that activation/overproduction of PKC contributes to AD related cerebral microvascular endothelial dysfunction. The objective of this study was to investigate whether inhibition of PKC protects against cerebral microvascular endothelial dysfunction in the setting of Streptozotocin (STZ)-Induced AD mice. Methods: Mice (C57BL/6J, 10–12-month-old, male) received a single dose of STZ (3mg/kg, 3μl) intracerebroventricular (ICV) injection or citric buffer (control group). After one week of STZ-ICV injection (AD), some of the mice received the selective PKC inhibitor LY333531 (LY) treatment (10mg/kg, oral gavage). The control (n=6), STZ-AD (n =6) and the STZ-AD + LY (n =6) mice then underwent the Morris Water Maze test for assessing spatial learning and memory and in-vitro cerebral microvascular (pial arterioles) myography for examining microvascular reactivity. Mouse brain tissue samples were also harvested for protein analysis and mouse brain microvascular endothelial cells (MBMECs)were isolated/cultured for ion channel recording via whole cell patch clamp methods. Results: Increased phospho-PKCβ and phospho-Tau (S202/T205), partially impaired spatially learning/memory and reduced cerebral microvascular relaxation were observed in mice with STZ-AD. Chronic treatment with LY partially reversed STZ-AD-impaired spatial learning and memory by showing a significant decrease in escape latency of STZ-AD mice over time compared with STZ-AD alone (P&lt;0.05). Furthermore, treatment with LY significantly improved cerebral microvascular relaxation in response to the endothelium-dependent vasodilator NS309 as compared to STZ-AD alone (P&lt;0.05). There were no significant differences in response to the endothelium-independent vasodilator SNP among the three groups, control, STZ-AD and STZ-AD +LY. Treatment with LY significantly improved MBMECs’ endothelial SK channel currents. Conclusions: Our research presents novel findings which investigate the role of PKC inhibition in restoring cerebral microvascular function and in improving endothelial SK channel function in AD in the STZ-AD mice.

Background: Angina with non-obstructive coronary artery disease (ANOCA) prognosis requires improved prediction tools. The prognostic role of coronary angiography-derived index of microvascular resistance (caIMR) remains underexplored. Research Question: Does elevated caIMR correlate with worse clinical outcomes in ANOCA patients and improve prognostic prediction? Methods: ANOCA patients were selected from a prospective coronary artery disease registry (NCT05337319). Computational fluid dynamics analyzed angiography images to quantify caIMR. Patients were stratified by caIMR &gt;25 (microvascular dysfunction) or ≤25 (non-dysfunction). Inverse probability of treatment weighting adjusted baseline differences. The primary endpoint was the 18-month patient-oriented composite outcome (POCO): cardiovascular death, heart failure hospitalization, or rehospitalization for ischemic symptoms. Results: Among 917 ANOCA patients, 608 (66.3%) had microvascular dysfunction. Fifty-five POCO events occurred over median 483-day follow-up. After adjustment, the high caIMR group had significantly higher POCO risk (adjusted hazard ratio [HR] 2.78, 95% confidence interval [CI] 1.20-6.46) and higher rehospitalization risk (adjusted HR 2.98, 95% CI 1.06-8.38) versus low caIMR. Continuous caIMR independently predicted POCO risk (adjusted HR 1.03 per unit, 95% CI 1.01-1.05, p=0.002). Adding caIMR to clinical models improved prediction: net reclassification improvement 0.027 (95% CI 0.004-0.051, p=0.025); integrated discrimination improvement 0.317 (95% CI 0.054-0.580, p=0.018). Conclusions: Elevated caIMR independently predicts increased POCO risk in ANOCA patients, showing a dose-response relationship. Incorporating caIMR enhances traditional prognostic models, providing objective quantitative data for risk stratification and treatment decisions.

Background: Endometriosis increases risk of cognitive impairment, coagulopathy, and ischemic and hemorrhagic stroke. Endometriosis affects ~10% of reproductive-age women globally, with little known regarding its link to cerebrovascular disease. Cerebrovascular outcomes in endometriosis overlap with those related to cerebral small vessel disease (CSVD). However, potential biological mechanisms linking endometriosis and CSVD have not yet been explored. Purpose: We assessed transcriptomic and genetic data of menstrual fluid from women with or without endometriosis to identify differentially expressed genes (DEGs) and pathways associated with CSVD. Approach: We analyzed publicly available RNA-sequencing data of menstrual fluid samples from women with (n=11) or without (n=9) endometriosis. DEGs that met Bonferroni-adjusted significance were then selected as exposure variables in Mendelian randomization (MR) analyses. Two-sample MR analyses using publicly available summary statistics from genome-wide association studies. For the exposures, we identified whole-blood expression quantitative trait loci (eQTL, n=943) associated with the significant DEGs selected from the analysis of menstrual fluid samples. The outcomes were derived from summary statistics for three markers of CSVD: white matter hyperintensity volume (WMH, n=18381), perivascular space burden (PVS, n=40095), and cerebral microbleeds (CMB, n=25862). MR analyses were conducted with inverse-weighted variance or Wald ratio methods. Results are presented as odds ratios (OR) and 95% confidence intervals (95%CI). Results: Menstrual fluid of women with or without endometriosis revealed 119 DEGs at a threshold of p&lt;0.05, with 16 meeting corrected statistical significance. All 16 DEGs were upregulated in endometriosis, and associated with ceramide metabolism ( Asah1 , Gla , Hexb ) and lysosome pathways ( Asah1 , Atp6ap1 , Mcoln1 ). MR revealed greater expression of Asah1 was associated with a greater risk of CMBs (OR 1.32, 95%CI: 1.18-1.49, p&lt;0.001). Expression of Zfand5 was associated with greater PVS burden (OR 1.07, 95%CI: 1.01-1.13, p=0.03), though only the Asah1 -CMBs association remained significant after correction for multiple testing. Conclusions: Our findings identify a potential biological pathway linking endometriosis and CSVD. Specifically, involvement of Asah1 may implicate acid ceramidase pathways which have previously been associated with endothelial and microvascular dysfunction.

Introduction: Hypoxic-ischemic brain injury after cardiac arrest (CA) results from both the primary insult of cerebral hypoperfusion and secondary injury mechanisms post–return of spontaneous circulation (ROSC), such as microvascular dysfunction, cerebral edema, and impaired autoregulation. Despite improved resuscitation protocols, neurological outcomes remain poor. Interventions like targeted temperature management and MAP optimization have yielded inconsistent results, prompting a shift toward phenotyping cardiac arrest patients using clinical examination, biomarkers, and imaging. This study aimed to identify comorbidities and biomarkers associated with mortality and motor outcomes to aid in future phenotypic classification. Method: A retrospective cohort study was conducted at an urban academic center, analyzing health records of patients treated for in-hospital and out-of-hospital CA between 2015-2025. Patients were divided into deceased and survivor groups. Data abstraction from the EMR was completed for variables including comorbidities, post-arrest biomarkers (pH, lactate, and MAP), and neurologic status (GCS). In a subgroup analysis, motor outcomes were compared between those with good (GCS M4–6) and poor (GCS M1–3) function. Results: Among 1,086 CA patients, compared to survivors, mortality was significantly associated with acute kidney injury (79.4% vs. 61.2%), cirrhosis (39.4% vs. 16.4%), malignancy (35.0% vs. 21.8%), arrhythmia (45.5% vs. 38.8%), myocardial infarction (43.8% vs. 36.0%), and atrial fibrillation (41.8% vs. 30.6%) (all p&lt;0.05). A history of drug use was more common in survivors (25.2% vs. 18.6%, p=0.011). Non-survivors had higher lactate (4.01 vs. 3.44 mmol/L, p=0.025), lower arterial pH (7.29 vs. 7.32, p=0.049), and consistently lower MAP at 24, 48, and 72 hours post-ROSC. In the motor outcome subset, patients with better function (GCS M4–6) had lower rates of AKI and cirrhosis, lower lactate (3.21 vs. 4.69 mmol/L), higher pH (7.32 vs. 7.28), and higher post-ROSC GCS scores (12.5 vs. 10.24, p&lt;0.0001). Conclusion: Comorbidities such as AKI, cirrhosis, malignancy, arrhythmias, prior MI, and AF are associated with mortality and should be considered in phenotyping post-ROSC patients. Drug use may define a distinct subgroup with a different risk profile. Biomarkers, including pH, lactate, and MAP, reflecting early brain injury severity and hemodynamic status, are strongly associated with both survival and motor outcomes.

Introduction: Cardiogenic shock (CS) is a life-threatening condition characterized by reduced tissue perfusion due to cardiac pump failure. In patients with diabetes mellitus (DM), the incidence and severity of CS are heightened due to accelerated atherosclerosis, microvascular dysfunction, and impaired myocardial recovery. Although sex-based differences in cardiovascular disease are increasingly recognized, their specific impact on outcomes in diabetic patients with CS remains largely understudied. Addressing these disparities is essential for improving outcomes and promoting equity in care. Hypothesis: This systematic review evaluates whether sex-based differences exist in the presentation, management, and outcomes of CS in patients with type 2 DM. We hypothesize that women experience worse outcomes and receive less aggressive treatment than men. Methods: A systematic search of PubMed was conducted following PRISMA guidelines. Studies published from January 2000 to March 2025 were screened. Inclusion criteria: adults (≥18 years) with type 2 DM and CS, and outcomes reported by sex. Extracted data included study design, population details, interventions, and sex-stratified outcomes. Risk of bias was evaluated using the Newcastle-Ottawa Scale. Due to heterogeneity, a descriptive synthesis was performed. Results: Twelve studies involving 25,000 patients met criteria. Women with CS and DM presented later, experienced longer delays in treatment, and were less likely to receive percutaneous coronary intervention (PCI) or mechanical circulatory support (MCS). In-hospital mortality among women ranged from 34% to 62%, compared to 28% to 55% in men. Six studies identified female sex as an independent predictor of mortality. Use of advanced hemodynamic monitoring and timely revascularization was lower in women. Conclusion: Notable sex-specific disparities exist in CS outcomes among diabetic patients. Women face delayed care, reduced access to life-saving interventions, and higher mortality. These gaps reflect a mix of biological, clinical, and systemic factors. Future efforts should include more women in CS research, perform sex-stratified analyses, and develop tailored treatment strategies to reduce disparities.

Background: The management of coronary artery anomalies (CAA) remains a clinical dilemma as the prognostic implications are poorly understood. The presence of ischemia and CAA does not establish causality. We report the first documented case of hereditary transthyretin cardiac amyloidosis (ATTR-CA) in a patient with CAA, highlighting the diagnostic and therapeutic complexity of this dual pathology. Case: A 65-year-old man with a history of carpal tunnel syndrome, hypertension, and CAA presented with exertional dyspnea. Family history included a brother with hypertrophic cardiomyopathy. Stress testing noted ischemia in the left anterior descending (LAD) and left circumflex (LCX) territories. Invasive angiography and cardiac computed tomography (CT) confirmed an anomalous LAD arising from the right coronary cusp with an interarterial course and a retroaortic LCX arising from the ostium of the right coronary artery without obstructive disease ( Figure 1 ). Echocardiography revealed concentric LV thickening, severe diastolic dysfunction, an apical sparing strain pattern, and dynamic left ventricular outflow tract obstruction ( Figure 2 ). Light-chain amyloidosis was excluded, and cardiac scintigraphy confirmed ATTR-CA ( Figure 3 ). Genetic testing revealed a rare TTR variant of previously uncertain significance (p.Val113Leu), prompting cascade screening. Discussion: The diagnosis of ATTR-CA reframed the patient’s ischemia and prompted reevaluation of the family’s cardiac history. ATTR-CA likely contributed to ischemia through microvascular dysfunction and supply-demand mismatch rather than epicardial coronary obstruction. Surgical reimplantation of CAA was deferred in favor of aggressive medical management resulting in symptomatic improvement. Subsequent testing of the patient’s sibling identified ATTR-CA with the same mutation (p.Val113Leu), supporting reclassification of the variant as likely pathogenic. Conclusion: This case underscores the importance of an integrated anatomic and functional assessment of ischemia in patients with CAA. The presence of infiltrative disease, specifically ATTR-CA, may amplify the ischemic potential of CAA. Furthermore, the identification of ATTR-CA redefined a presumed familial diagnosis and provides compelling evidence supporting reclassification of the rare TTR genetic variant (p.Val113Leu) as likely pathogenic. This finding carries significant implications for genetic counseling and management strategies of affected families.

Background: Carotid ultrasound is convenient and widely used for CVD risk assessment. Plaques—especially in the internal carotid artery (ICA) or bulb—predict atherosclerotic cardiovascular disease (ASCVD) events, but plaque burden alone may miss vascular vulnerability or microvascular disease; additional biomarkers are needed to refine risk prediction. Hypothesis: We hypothesized that coronary artery calcium score (CACS) and a deep learning–based retinal biomarker (Dr.Noon CVD) would each associate with carotid plaque and predict ASCVD events, independently and in combination. Methods: We analyzed 1,075 high-risk adults from the CMERC-HI cohort with carotid ultrasound, CACS, and Dr.Noon CVD scores. Plaque was defined as any ICA/bulb lesion. ASCVD events (nonfatal or fatal) included stroke, heart failure, and myocardial infarction, and cardiovascular deaths. Age- and sex-adjusted logistic regression assessed associations of plaque with CACS (low: 0; moderate: 1–99; high: 100-400, very high: ≥400) and Dr.Noon CVD (low: &lt;31; moderate: 31-40; high: 41-50; very high: ≥51). For ASCVD event prediction, Cox models compared high and very high vs. low+moderate for CACS and Dr.Noon CVD, and plaque presence vs. absence. Performance was evaluated using hazard ratios (HRs), C-indices, and Kaplan–Meier curves. Results: Plaque was present in 719 (66.8%) participants. Over 8.8 years (median), 72 ASCVD events occurred. Incidence rates ranged from 0–14.6 per 1,000 PYs (Dr.Noon CVD), 2.6–19.7 per 1,000 PYs (CACS), and 5.6–9.3 per 1,000 PYs (plaque). Each 1-point Dr.Noon CVD increase was associated with plaque (OR 1.06; 95% CI 1.04–1.08; p&lt;0.001). Participants at moderate, high, and very high Dr.Noon CVD risk had ORs of 2.21, 3.71, and 7.01 for plaque (all p&lt;0.001). Similar trends were seen for CACS: moderate, high, and very high categories had ORs of 2.65, 3.91, and 5.17, respectively (all p&lt;0.001). In Cox models, the C-index was 0.680 for Dr.Noon CVD, 0.676 for CACS, and 0.661 for plaque alone. Combining plaque with Dr.Noon CVD or with CACS improved the C-index by Δ +0.060 and +0.038 versus plaque only (both p&lt;0.001). Kaplan–Meier curves confirmed clear risk stratification (log-rank p&lt;0.001). Conclusion: Dr.Noon CVD and CACS each associate with carotid plaque and predict ASCVD events. The greatest improvement in discrimination occurred when combining Dr.Noon CVD with plaque, underscoring its potential for practical vascular risk stratification.

Background: Microvascular endothelial dysfunction is a key contributor to cardiac injury in cardiovascular diseases. Plasmalemma vesicle-associated protein (PLVAP) is a structural component of endothelial diaphragms and is essential for vascular development. In murine models, disruption of the PLVAP gene leads to embryonic lethality, marked by edema, hemorrhage, and significant structural defects in subcutaneous capillaries; however, its upstream regulation and role in cardiac endothelial barrier function remain poorly understood. HIF2A/ARNT heterodimers are essential regulators of endothelial cell (EC) behavior, affecting their barrier function. Given the central role of endothelial dysfunction in various diseases, defining the ARNT-PLVAP pathway may reveal new therapeutic targets for cardiac and vascular complications Methods and Results: We used tamoxifen-inducible, endothelial-specific knockout mice lacking either HIF-2α or ARNT ( Hif2α flox/flox or ARNT flox/flox driven by Cdh5-CreERT2 ). Primary cardiac microvascular endothelial cells (CMVECs) were isolated from these mice, and human CMVECs were transfected with siRNA targeting HIF2A, ARNT, or PLVAP to assess gene regulation and endothelial barrier function. Loss of either HIF2A or ARNT significantly reduced PLVAP expression at both mRNA and protein levels (n = 6, p &lt; 0.001) and increased cardiac vascular leakage in an LPS-induced endotoxemia model compared to wild-type controls (LPS 10mg/kg body weight) (n = 10–12, p &lt; 0.05). Mechanistic studies using ChIP, Co-IP, and luciferase assays demonstrated that ARNT directly regulates PLVAP transcription via promoter binding. PLVAP deletion impaired endothelial glycocalyx and reduced VE-cadherin and Occludin expression, suggesting its essential role in maintaining vascular barrier function. Furthermore, LPS treatment (500ng/ml) in human CMVECs suppressed PLVAP expression, while lentivirus-mediated overexpression of ARNT restored PLVAP expression and rescued endothelial resistance, as measured by ECIS, confirming ARNT’s protective role in inflammatory injury. Conclusion: PLVAP is a key transcriptional target of the HIF-2α/ARNT pathway and is essential for maintaining cardiac endothelial barrier integrity, especially under inflammatory conditions. Disruption of this axis leads to vascular leakage, while its restoration reverses barrier dysfunction, highlighting the ARNT-PLVAP pathway as a potential therapeutic target in cardiovascular disease.

Background: Approximately 50% of patients with angina who undergo invasive coronary angiography (ICA) do not exhibit obstructive epicardial coronary artery disease. A significant subset of these patients has coronary microvascular dysfunction (CMD). The current gold standard for diagnosing CMD is the invasive Index of Microcirculatory Resistance (IMR), which requires administration of adenosine and pressure wire instrumentation, carrying procedural risks. Angiography-derived IMR (Angio-IMR) is a novel, non-invasive, machine learning-based method that applies computational fluid dynamics to standard ICA images to emulate hyperemic microvascular assessment. Hypothesis: Angio-IMR is an accurate predictor of CMD when compared with invasively measured IMR. Methods: This prospective, multicentre study was conducted across three tertiary Australian hospitals. Patients undergoing ICA were assessed using both invasive IMR and Angio-IMR. Angio-IMR analyses were performed centrally and blinded, using manual frame counting with Medis QFR software (version 3.1). Patients were stratified into derivation and validation cohorts. Diagnostic performance of Angio-IMR was assessed using ROC analysis, with invasive IMR &gt; 25 was used as the threshold for significant CMD. Results: A total of 335 patients (63 ± 10.6 years; 56% male), encompassing 394 vessels, were included. In the derivation (n = 124) and validation (n = 124) cohorts, significant CMD (IMR &gt; 25) was present in 27% and 23% of vessels respectively. Angio-IMR showed moderate correlation with invasive IMR (r = 0.47 in derivation; r = 0.33 in validation). Angio-IMR predicted significant CMD with an area under the ROC curve (AUC) of 0.82 and 0.76 (both p &lt; 0.001) in the derivation and validation cohorts, respectively. An Angio-IMR threshold of &gt; 21 optimized sensitivity and specificity. At this cutoff, sensitivity and negative predictive value (NPV) were 94.9% and 95.9% in the derivation cohort, and 89.0% and 92.0% in the validation cohort, respectively. Conclusion: Angio-IMR is a promising non-invasive tool for the detection of CMD, demonstrating strong diagnostic performance, particularly in ruling out disease. Its high sensitivity and NPV support its use as a gatekeeper to invasive IMR, potentially reducing need for pressure wire-based assessments in low-risk patients. This study establishes Angio-IMR as a clinically valuable adjunct in the assessment of microvascular coronary disease.

Background: Approximately 50% of women with ischemia but no obstructive coronary artery disease have coronary microvascular dysfunction (CMD), a condition associated with adverse cardiovascular outcomes. Postmenopausal women with CMD experience recurrent chest pain, reduced functional capacity, fatigue, and impaired quality of life (QoL), but direct comparisons of women with obstructive coronary disease (oCAD) or healthy controls are lacking. We therefore examined angina-related physical limitations and QoL across these three groups. Methods: A total of 48 postmenopausal women were grouped as follows: CMD (n=14, CFR or MFR ≤2.5), oCAD (n=12, &gt;50% stenosis), and Controls (n=22, normal stress tests, no cardiac history or medications). Demographics, cardiac risk factors, and subscale scores from the validated Seattle Angina Questionnaire (SAQ)—including physical limitation, angina stability, angina frequency, treatment satisfaction, and QoL—were assessed. The Duke Activity Status Index (DASI) was used to assess functional capacity and a score ≤34 is prognostic of major adverse cardiac events. Total step counts for 7 days were measured by Actiwatch wrist actigraphy. Descriptive statistical analysis and Spearman rank correlations were performed for data analysis. Results: Baseline characteristics and cardiovascular risk factors were comparable among all three groups. However, there was a higher percentage of hypertension among CMD and a higher percentage of hyperlipidemia in oCAD as opposed to the other groups. The treatment satisfaction SAQ subscale demonstrated a lower satisfaction score in the CMD group compared to the oCAD group (p=0.012). Despite similar angina burden compared to oCAD, DASI score was significantly lower in CMD (20.5±14.0) as opposed to oCAD (37.1±14.3) with p=0.013, even after BMI adjustment. A positive correlation was observed between DASI scores and step counts in the CMD group ( R = 0.84, p =0.0045), but not in oCAD. Conclusion: Postmenopausal women with CMD exhibit physical limitation and reduced functional capacity compared to other groups. These impairments are associated with lower treatment satisfaction, physical activity, and QoL. Tailored exercise and rehabilitation strategies targeting physical function may improve both functional capacity and QoL in this at-risk CMD population.

Background: Tumor necrosis factor (TNF) receptor-associated periodic syndrome (TRAPS) is a rare autoinflammatory condition associated with recurrent episodes of fever, chest pain, and serositis responsive to anti-inflammatory therapies. We present a case of COVID-induced TRAPS with clinical and radiographic resolution of coronary microvascular dysfunction (CMD) from anti-interleukin-1 (IL-1) treatment. Case: A previously healthy 40-year-old male marathon runner developed COVID infection in 2022 followed by recurrent episodes of fevers, myalgias, and arthralgias. In March 2023, rheumatology diagnosed him with an unspecified autoinflammatory disorder due to elevated inflammatory markers with a negative infectious and autoimmune workup. He had mild relief with prednisone and hydroxychloroquine but then developed dyspnea and chest pain in July 2023. Echocardiogram showed a newly reduced ejection fraction to 35-40%. Stress cardiac magnetic resonance imaging (cMRI) revealed a localized perfusion defect concerning for ischemia with globally abnormal stress perfusion curves suggestive of multivessel obstructive epicardial diseases versus CMD. Coronary angiogram revealed only luminal irregularities. Cardiac positron emission tomography (cPET) findings were consistent with CMD. Given the patient's refractoriness to antianginal and anti-inflammatory therapies with TRAPS phenotype, he was initiated on anakinra, an IL-1 receptor antagonist. His angina resolved within 1 month, as well as normalization of myocardial perfusion on cPET and cMRI at 3 and 4 months, respectively. Discussion: Due to the patient’s angina and new cardiomyopathy in the setting of a prior viral infection, a stress cMRI was pursued to evaluate for inflammatory and ischemic etiologies; findings were concerning for ischemia. cPET raised the likelihood of CMD given the absence of obstructive disease on the coronary angiogram. The patient met clinical criteria for TRAPS, likely triggered by COVID infection, with angina refractory to standard medical therapy, so he was trialed on anakinra with remarkable clinical response and radiographic evidence of CMD resolution. Conclusion: TRAPS is due to an enhanced inflammatory response that can be triggered by viral infections, but, to date, no known cases have been reported of COVID-induced TRAPS in adults. TRAPS can cause chronic inflammation that predisposes individuals to CMD with resultant angina, which can be treated by targeting the systemic inflammation.

Background: Myocardial ischemia in the absence of obstructive coronary artery disease along with diminished coronary flow reserve is diagnostic for coronary microvascular dysfunction (CMD). Studies implicate vasoconstriction by endothelin-1 (ET-1) or through protein kinase C (PKC) activation in CMD development. However, the molecular signaling in coronary microvascular constriction to ET-1 and PKC is incompletely understood. Herein, coronary arteriolar constrictions to a clinical level of ET-1 and PKC activator phorbol 12,13-dibutyrate (PDBu) were directly characterized in vitro. Aim: Determine roles of ET-1 receptors, extracellular Ca 2+ , Rho kinase isoforms, PKC, and myosin light chain phosphatase subunit MYPT1 in coronary arteriolar constrictions to ET-1 and PDBu. Methods: The vasomotor response and signaling pathway of isolated and pressurized (60 cmH 2 O) pig coronary arterioles (&lt;100 µm maximal diameter) to vasoconstrictors were studied using videomicroscopic, pharmacologic, and molecular tools. Results: Coronary arterioles developed basal tone with resting diameters (40-50 µm) about 50% of maximal diameters. ET-1 (0.1 nM) and PDBu (0.1 µM) evoked comparable degree of constriction. Without crossover effects, ROCK inhibitor H-1152 and broad-spectrum PKC inhibitor bisindolylmaleimide XI, abolished constriction to ET-1 and PDBu, respectively. Expression of ROCK2 was greater than ROCK1 in arterioles, and ROCK2 but not ROCK1 siRNA attenuated ET-1-induced constriction. Increased pMYPT1 (Thr850) was detected in ET-1-constricted but not PDBu-constricted arterioles. In the absence of extracellular Ca 2+ , arterioles lost basal tone and did not constrict to ET-1 and PDBu. In the presence of extracellular Ca 2+ , L-type voltage-operated Ca 2+ channel (L-VOCC) blocker nifedipine abolished both basal tone and constriction to PDBu but did not alter constriction to ET-1. ET A receptor antagonist BQ123 but not ET B receptor antagonist BQ788 inhibited constriction to ET-1. Conclusions: Our findings indicate divergent mechanisms for ET-1- and PKC-induced constriction of coronary arterioles. ET-1 binds to arteriolar ET A receptors and triggers extracellular Ca 2+ entry. Subsequent activation of ROCK2 phosphorylates MYPT1 independent of PKC. By contrast, PKC activation linked to L-VOCCs independent of ROCK and MYPT1 elicits constriction. These insights suggest that ROCK2 and L-VOCCs may provide druggable targets in CMD associated with elevated ET-1 and PKC activation, respectively.

Coronary microcirculation is essential to maintaining normal cardiac function. When the cardiac metabolic demand increases (e.g., exercise or stress), coronary blood flow increases accordingly to meet the needs. However, when coronary vasodilation is impaired or coronary microvascular dysfunctions, the balance of supply and demand breaks. Deficiency of myocardial blood flow causes myocardial ischemia. Coronary microvascular dysfunction (CMD) is associated with diabetic cardiomyopathy and heart failure with preserved ejection fraction (HFpEF), but detailed mechanisms have yet to be elucidated. Nuclear Sirtuin 6 (SIRT6) plays essential roles in cardiovascular homeostasis; however, the mechanisms by which SIRT6 regulates coronary microvascular function remain poorly understood. This study will investigate how Sirt6 regulates coronary vasodilation and coronary blood flow in physiological and pathological conditions (diabetes and aging). Global Sirt6 knockout mice are perinatally lethal because of hypoglycemia, which limits to explore the roles of Sirt6 in vivo. We generated inducible global Sirt6 knockout mice (Sirt6 f/f mice,CAG-cre , Sirt6 iD ), and the mice were viable after tamoxifen induction at 6 weeks. The Sirt6 iD mice and their littermate controls were fed with a chow or a high-fat, high-sugar (HFHS) diet. We isolated coronary arterioles to measure endothelial-dependent dilation (EDD) by myography (DMT) and measured myocardial blood flow (MBF) and coronary flow reserve (CFR), an index clinically used to diagnose CMD. To study the role of Sirt6 in coronary microcirculation in diabetes, we treated the diabetic mice (Tallyho), which were reported to have impaired coronary vasodilation, with Sirt6 activator MDL-800 and overexpressed Sirt6. Moreover, we included 24-month-old mice. Our preliminary data showed that Sirt6 is downregulated in diabetes, a deficiency of Sirt6 impaired coronary EDD, switched the mediator of vasodilation from NO to H 2 O 2 when mice were fed a chow diet, and impaired coronary flow reserve (CFR). The phenotype was more severe when the mice were fed with an HFHS diet, accompanied by severe hyperglycemia and insulin resistance. Interestingly, the Sirt6 activator ameliorated coronary EDD and CFR in diabetic mice, suggesting the therapeutic roles of Sirt6 in CMD in diabetes. Moreover, the aging mice showed impaired coronary vasodilation and CFR. The underlying mechanism and the pathways involved will be further elucidated.