Index of microvascular resistance to assess the effect of rosuvastatin on microvascular function in women with chest pain and no obstructive coronary artery disease: A double-blind randomized study

Clinical implications of coronary microvascular dysfunction in patients with non-obstructive coronary artery disease and role of the thermodilution method

More than 60% of patients undergoing coronary angiography present no coronary artery disease (CAD). Angina and myocardial ischemia are classically determined by epicardial vascular obstruction, but coronary microvascular dysfunction (CMD) may also represent a possible cause for these phenomena. Two endotypes of CMD have been recognized, with two different pathophysiological mechanisms: structural CMD, characterized by low coronary flow reserve (CFR) and high microvascular resistance (MVR) values; and functional CMD, characterized by low CFR and normal MVR values. According to the present data, almost half of patients with non-obstructive CAD have shown signs of CMD. For this reason, further investigations for microvascular function assessment should be considered when evaluating no-CAD patients complaining of angina or presenting signs of myocardial ischemia. The thermodilution method is currently becoming a widespread invasive technique due to its feasibility and high reproducibility for coronary physiology evaluation. Furthermore, a recently introduced technique - called continuous thermodilution - allows for direct measurement of absolute coronary flow and resistances. The role of this brand-new technique in the clinical scenario is however still to be fully investigated and its use is at present limited to research purposes only. Among no-CAD patients, both structural and functional CMD are related to a worse prognosis in term of mortality and major adverse cardiovascular events (MACE). In this review, we will discuss the present evidence supporting the definition, prevalence and clinical implication of the different forms of CMD and the technical aspects of its invasive assessment.

Vascular endothelial cell injury: causes, molecular mechanisms, and treatments

Vascular endothelial cells form a single layer of flat cells that line the inner surface of blood vessels, extending from large vessels to the microvasculature of various organs. These cells are crucial metabolic and endocrine components of the body, playing vital roles in maintaining circulatory stability, regulating vascular tone, and preventing coagulation and thrombosis. Endothelial cell injury is regarded as a pivotal initiating factor in the pathogenesis of various diseases, triggered by multiple factors, including infection, inflammation, and hemodynamic changes, which significantly compromise vascular integrity and function. This review examines the causes, underlying molecular mechanisms, and potential therapeutic approaches for endothelial cell injury, focusing specifically on endothelial damage in cardiac ischemia/reperfusion (I/R) injury, sepsis, and diabetes. It delves into the intricate signaling pathways involved in endothelial cell injury, emphasizing the roles of oxidative stress, mitochondrial dysfunction, inflammatory mediators, and barrier damage. Current treatment strategies-ranging from pharmacological interventions to regenerative approaches and lifestyle modifications-face ongoing challenges and limitations. Overall, this review highlights the importance of understanding endothelial cell injury within the context of various diseases and the necessity for innovative therapeutic methods to improve patient outcomes.

A systematic review of enrolment criteria and treatment efficacy for microvascular angina

BACKGROUND

Microvascular angina (MVA) is an important contributor to morbidity and mortality in patients with non-obstructive coronary artery disease. Despite improvements in its recognition and diagnosis, uncertainty remains around the most effective treatment strategy, and more data are needed.

AIMS

We aimed to evaluate the quality of patient selection in treatment studies of MVA and provide a contemporary overview of the evidence base for the treatment of MVA.

METHODS

PubMed, the Cochrane Library and Google Scholar were searched from inception to 4 November 2023 for all treatment studies in patients with angina and non-obstructive coronary artery disease or coronary microvascular dysfunction. Populations with acute coronary syndrome were excluded (PROSPERO: CRD42023383075).

RESULTS

Forty-three studies were included. By contemporary definitions of MVA according to the Coronary Vasomotor Disorders International Study Group criteria, 11 (26%) studies enrolled patients with "definitive" MVA, 24 (56%) with "suspected" MVA, and 8 (19%) did not enrol patients who met the diagnostic criteria. A total of 24 unique treatment interventions were investigated. Most studies were observational and single armed (12/24, 50%) or had a single randomised study (9/24, 38%). Ranolazine is the most well-studied intervention drug. Double-blind randomised controlled trials of ranolazine (n=6) have shown inconsistent improvements in Seattle Angina Questionnaire scores and coronary flow reserve with short-term follow-up.

CONCLUSIONS

Treatment studies of MVA enrolled a heterogeneous population, with only a quarter meeting contemporary diagnostic criteria for definitive MVA. There is a paucity of high quality, randomised data to support any specific treatment intervention. Larger studies with robust selection criteria, blinded patient-reported outcomes, and long-term follow-up are needed.

Beyond the Obstructive Paradigm: Unveiling the Complex Landscape of Nonobstructive Coronary Artery Disease

Traditionally focused on obstructive atherosclerosis, contemporary research indicates that up to 70% of patients undergoing coronary angiography for angina and ischemic symptoms do not exhibit significant stenoses. Nonobstructive coronary artery disease (CAD) has emerged as a prevalent phenotype among these patients. This review emphasizes the emerging understanding that nonobstructive coronary artery disease, encompassing conditions such as ANOCA (Angina with No Obstructive Coronary Artery Disease), INOCA (Ischemia with No Obstructive Coronary Artery Disease), and MINOCA (Myocardial Infarction with No Obstructive Coronary Arteries), represents the most prevalent phenotype in cardiac patients. It delves into the complex pathophysiology underlying these conditions, focusing on microvascular dysfunction and coronary vasoreactivity, which contribute to myocardial ischemia despite the absence of significant coronary obstructions. Additionally, the review critically examines the limitations of current treatments which primarily target obstructive lesions and underscores the necessity for tailored therapies that address the specific microvascular and immunoinflammatory pathways involved in nonobstructive CAD. The main focus of this review is to advocate for a shift in diagnostic and therapeutic strategies to better identify and manage this widely prevalent yet under-recognized subset of CAD.

Microvascular function and inflammatory activation in Takotsubo cardiomyopathy

AIMS

The aim of this study was to determine microvascular function in the acute phase of Takotsubo syndrome (TTS) and to identify inflammatory mediators that could reflect TTS-induced pathology.

METHODS AND RESULTS

The study included 20 females [median age 65 years; interquarile range (IQR) = 58-70 years] with TTS according to the Mayo diagnostic criteria. During heart catheterization, we determined the index of microvascular resistance (IMR) and drew blood samples almost simultaneously from the aorta and coronary sinus. Cardiac magnetic resonance imaging (MRI) was done in the acute phase. We present descriptive coronary physiology and cardiac MRI data and compare inflammatory biomarkers between samples from the aorta, coronary sinus, and venous samples after 3 months using the Wilcoxon signed-rank test. For comparison, we also analysed the actual biomarkers in venous blood from 15 healthy female controls. A supplementary analysis explored Spearman's rank correlation between the inflammatory biomarkers, IMR, MRI data, and cardiac biomarkers. The median IMR was 16.5 mmHg·s (IQR = 10.5-28.2 mmHg·s), which was only slightly higher than that in the reference populations. Seven (35%) of the study subjects had IMR > 25 mmHg·s, suggesting a microvascular dysfunction. IMR was not affected by time from symptom onset. According to MRI, the apical region of the left ventricle was affected in 65% of the subjects. The median ejection fraction was 41% (IQR = 31-48%). Biomarker analyses revealed elevation of markers for extracellular matrix remodelling and fibrosis, inflammation, immune activation, and upstream inflammation as compared with healthy controls. Only the levels of interleukin (IL)-1 receptor antagonist and soluble T-cell immunoglobulin mucin domain-3 (sTIM-3) were higher in the coronary sinus than in the aorta. No variable was significantly correlated with IMR. The IL-6 level in the aorta was inversely correlated with the left ventricular ejection fraction. Growth differentiation factor-15, osteoprotegerin, and von Willebrand factor levels in both aorta and coronary sinus were positively correlated with N-terminal-pro-brain-natriuretic peptide, while the correlations of IL-6 and sTIM-3 with N-terminal-pro-brain-natriuretic peptide were restricted to the aorta and coronary sinus, respectively. While most of the markers were within normal limits after 3 months, matrix metalloproteinase-9 increased during follow-up to reach levels higher than those in the healthy controls.

CONCLUSION

The median IMR was only slightly elevated in this study, but about one-third of the patients had values indicating microvascular dysfunction. The present study supports the involvement of several inflammatory pathways in TTS, including monocyte/macrophage activation, with sTIM-3 as a potential novel marker.

Comprehensive Management of ANOCA, Part 2-Program Development, Treatment, and Research Initiatives: JACC State-of-the-Art Review

Centers specializing in coronary function testing are critical to ensure a systematic approach to the diagnosis and treatment of angina with nonobstructive coronary arteries (ANOCA). Management leveraging lifestyle, pharmacology, and device-based therapeutic options for ANOCA can improve angina burden and quality of life in affected patients. Multidisciplinary care teams that can tailor and titrate therapies based on individual patient needs are critical to the success of comprehensive programs. As coronary function testing for ANOCA is more widely adopted, collaborative research initiatives will be fundamental to improve ANOCA care. These efforts will require standardized symptom assessments and data collection, which will propel future large-scale clinical trials.

Statin withdrawal and health-related quality of life in a primary cardiovascular prevention cohort

PURPOSE

While some work has been done on Health-Related Quality of Life (HRQoL) in statin users, none has focused specifically on statin-associated muscle symptoms (SAMS) sufferers. The objective was to assess self-reported HRQoL, before and after statin withdrawal, in patients reporting SAMS. We hypothesized that the presence of SAMS associated with decreased self-reported physical and mental well-being.

METHODS

Patients (50 men/28 women [M/W], aged 49 ± 9 years [Mean ± SD]) in primary cardiovascular prevention were recruited into three cohorts: statin users with (SAMS, 29 M/18W) or without symptoms (No SAMS, 10 M/5W) and controls (11 M/5W). The Short Form 36 Health Survey (SF-36) was used to assess HRQoL. All variables were measured before and after 2 months of statin withdrawal, and repeated measures analyses were used to verify withdrawal and group effects as well as their interaction.

RESULTS

SF-36 physical and mental component scores (respectively, PCS and MCS) were lower in the SAMS group compared with other groups (both p < 0.01). Statin withdrawal led to an increase in LDL cholesterol for statin users (+69.0%, p < 0.01) and an improvement in well-being in the SAMS group, other groups showing no change. A time x category interaction (p = 0.02) was seen for PCS and post hoc analyses showed that statin withdrawal improved PCS and MCS (respectively, +12.5% [ES 0.77] and +5.1% [ES 0.27], both p < 0.05) in the SAMS group.

CONCLUSION

Patients self-reporting SAMS showed improved HRQoL following drug withdrawal, but this was mirrored by a rise in LDL cholesterol. These findings should be considered by clinicians in the evaluation and follow-up of treatment with statins.

Coronary Microvascular Dysfunction in Diabetes Mellitus: Pathogenetic Mechanisms and Potential Therapeutic Options

Diabetic patients are frequently affected by coronary microvascular dysfunction (CMD), a condition consisting of a combination of altered vasomotion and long-term structural change to coronary arterioles leading to impaired regulation of blood flow in response to changing cardiomyocyte oxygen requirements. The pathogenesis of this microvascular complication is complex and not completely known, involving several alterations among which hyperglycemia and insulin resistance play particularly central roles leading to oxidative stress, inflammatory activation and altered barrier function of endothelium. CMD significantly contributes to cardiac events such as angina or infarction without obstructive coronary artery disease, as well as heart failure, especially the phenotype associated with preserved ejection fraction, which greatly impact cardiovascular (CV) prognosis. To date, no treatments specifically target this vascular damage, but recent experimental studies and some clinical investigations have produced data in favor of potential beneficial effects on coronary micro vessels caused by two classes of glucose-lowering drugs: glucagon-like peptide 1 (GLP-1)-based therapy and inhibitors of sodium-glucose cotransporter-2 (SGLT2). The purpose of this review is to describe pathophysiological mechanisms, clinical manifestations of CMD with particular reference to diabetes, and to summarize the protective effects of antidiabetic drugs on the myocardial microvascular compartment.

COlchicine to Prevent PeriprocEdural Myocardial Injury in Percutaneous Coronary Intervention (COPE-PCI): Coronary Microvascular Physiology Pilot Substudy

Aim

In this randomized pilot trial, we aimed to assess the anti-inflammatory effect of preprocedural colchicine on coronary microvascular physiology measurements before and after PCI.

Methods

Patients undergoing PCI for stable angina (SA) or non-ST-elevation myocardial infarction (NSTEMI) were randomized to oral colchicine or placebo, 6- to 24-hours before the procedure. Strict prespecified inclusion/exclusion criteria were set to ensure all patients were given the study medication, had a PCI, and had pre- and post-PCI culprit vessel invasive coronary physiology measurements. Fractional flow reserve (FFR), Index of Microvascular Resistance (IMR), Coronary Flow Reserve (CFR), and Resistive Reserve Ratio (RRR) were measured immediately before and after PCI. CMVD was defined as any one of post-PCI IMR >32 or CFR <2 or RRR <2. High-sensitive-(hs)-troponin-I, hsCRP, and leucocyte count were measured before and 24 hours after PCI.

Results

A total of 50 patients were randomized and met the strict prespecified inclusion/exclusion criteria: 24-colchicine and 26-placebo. Pre-PCI coronary physiology measurements, hs-troponin-I, and hsCRP were similar between groups. Although numerically lower in patients given colchicine, the proportion of patients who developed CMVD was not significantly different between groups (colchicine: 10 (42%) vs placebo: 16 (62%), p=0.16). Colchicine patients had higher post-PCI CFR and RRR vs placebo (respectively: 3.25 vs 2.00, p=0.03 & 4.25 vs 2.75, p < 0.01). Neutrophil count was lower after PCI in the colchicine arm (p=0.02), and hsCRP post-PCI remained low in both treatment arms (1.0 mg/L vs 1.7 mg/L, p=0.97). Patients randomized to colchicine had significantly less PCI-related absolute hs-troponin-I change (46 ng/L vs 152 ng/L, p=0.01).

Conclusion

In this pilot randomized substudy, colchicine given 6 to 24 hours before PCI did not statistically impact the post-PCI CMVD definition used in this study, yet it did improve post-PCI RRR and CFR measurements, with less procedure-related troponin release and less inflammation.

Mechanisms and clinical implications of endothelium-dependent vasomotor dysfunction in coronary microvasculature

Coronary microvascular disease (CMD), which affects the arterioles and capillary endothelium that regulate myocardial perfusion, is an increasingly recognized source of morbidity and mortality, particularly in the setting of metabolic syndrome. The coronary endothelium plays a pivotal role in maintaining homeostasis, though factors such as diabetes, hypertension, hyperlipidemia, and obesity can contribute to endothelial injury and consequently arteriolar vasomotor dysfunction. These disturbances in the coronary microvasculature clinically manifest as diminished coronary flow reserve, which is a known independent risk factor for cardiac death, even in the absence of macrovascular atherosclerotic disease. Therefore, a growing body of literature has examined the molecular mechanisms by which coronary microvascular injury occurs at the level of the endothelium and the consequences on arteriolar vasomotor responses. This review will begin with an overview of normal coronary microvascular physiology, modalities of measuring coronary microvascular function, and clinical implications of CMD. These introductory topics will be followed by a discussion of recent advances in the understanding of the mechanisms by which inflammation, oxidative stress, insulin resistance, hyperlipidemia, hypertension, shear stress, endothelial cell senescence, and tissue ischemia dysregulate coronary endothelial homeostasis and arteriolar vasomotor function.

Prevalence of Coronary Microvascular Disease and Coronary Vasospasm in Patients With Nonobstructive Coronary Artery Disease: Systematic Review and Meta-Analysis

Background

A relevant proportion of patients with suspected coronary artery disease undergo invasive coronary angiography showing normal or nonobstructive coronary arteries. However, the prevalence of coronary microvascular disease (CMD) and coronary spasm in patients with nonobstructive coronary artery disease remains to be determined. The objective of this study was to determine the prevalence of coronary CMD and coronary vasospastic angina in patients with no obstructive coronary artery disease.

Methods and Results

A systematic review and meta‐analysis of studies assessing the prevalence of CMD and vasospastic angina in patients with no obstructive coronary artery disease was performed. Random‐effects models were used to determine the prevalence of these 2 disease entities. Fifty‐six studies comprising 14 427 patients were included. The pooled prevalence of CMD was 0.41 (95% CI, 0.36–0.47), epicardial vasospasm 0.40 (95% CI, 0.34–0.46) and microvascular spasm 24% (95% CI, 0.21–0.28). The prevalence of combined CMD and vasospastic angina was 0.23 (95% CI, 0.17–0.31). Female patients had a higher risk of presenting with CMD compared with male patients (risk ratio, 1.45 [95% CI, 1.11–1.90]). CMD prevalence was similar when assessed using noninvasive or invasive diagnostic methods.

Conclusions

In patients with no obstructive coronary artery disease, approximately half of the cases were reported to have CMD and/or coronary spasm. CMD was more prevalent among female patients. Greater awareness among physicians of ischemia with no obstructive coronary arteries is urgently needed for accurate diagnosis and patient‐tailored management.

Comprehensive treatment of microvascular angina in overweight women - a randomized controlled pilot trial

AIMS

Coronary microvascular dysfunction (CMD) carries a poor cardiovascular prognosis and may explain angina in women without obstructive coronary artery disease (CAD). Currently, no evidence-based treatment for CMD exists. We investigated whether reducing cardiovascular risk factors improves symptoms and microvascular function in women with non-endothelial dependent CMD and no obstructive CAD.

METHODS

We randomized 62 women aged 40-75, with body mass index (BMI) >25 kg/m2, angina ≥monthly, and coronary flow velocity reserve (CFVR) ≤2.5 to a 24-week intervention comprising low energy diet, exercise training, and optimized treatment of hypertension, dyslipidemia and diabetes or to control. Patients were assessed before randomization and after 24 weeks. Primary outcomes were CFVR assessed by transthoracic Doppler stress-echocardiography and angina burden by Seattle Angina Questionnaire (SAQ). Secondary outcomes were exercise capacity, body composition, glycemic control, myocardial function, and anxiety and depression symptoms.

RESULTS

Fifty-six participants (90%) completed the study. Median (IQR) age was 65.2 (57.1;70.7) years, BMI was 30.1 (28.4;32.7) kg/m2. The intervention resulted in relevant improvement in angina symptoms (9-21-point increase on SAQ-scales (all p<0.01)) but had no effect on CFVR (p = 0.468). Mean (CI) weight loss was 9.6 (7.80;11.48) kg, (p<0.0001). There was a significant mean (CI) decrease in depression symptoms = 1.16 (0.22;2.12), triglycerides = 0.52 (0.25;0.78) mmol/L, total cholesterol = 0.55 (0.12;0.98) mmol/L, and HbA1c in diabetics = 27.1 (1.60;52.6) mmol/mol but no effect on other secondary outcomes.

CONCLUSION

A major weight loss and intensified risk factor control resulted in significantly improved angina burden but no improvement of coronary microvascular function among women with microvascular angina.

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

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

Rosuvastatin alters the genetic composition of the human gut microbiome

The gut microbiome contributes to the variation of blood lipid levels, and secondary bile acids are associated with the effect of statins. Yet, our knowledge of how statins, one of our most common drug groups, affect the human microbiome is scarce. We aimed to characterize the effect of rosuvastatin on gut microbiome composition and inferred genetic content in stool samples from a randomized controlled trial (n = 66). No taxa were significantly altered by rosuvastatin during the study. However, rosuvastatin-treated participants showed a reduction in the collective genetic potential to transport and metabolize precursors of the pro-atherogenic metabolite trimethylamine-N-oxide (TMAO, p < 0.01), and an increase of related metabolites betaine and γ-butyrobetaine in plasma (p < 0.01). Exploratory analyses in the rosuvastatin group showed that participants with the least favorable treatment response (defined as < median change in high-density/low-density lipoprotein (HDL/LDL) ratio) showed a marked increase in TMAO-levels compared to those with a more favorable response (p < 0.05). Our data suggest that while rosuvastatin has a limited effect on gut microbiome composition, it could exert broader collective effects on the microbiome relevant to their function, providing a rationale for further studies of the influence of statins on the gut microbiome.