Coronary Microvascular Disease in Contemporary Clinical Practice

Visual Estimates of Coronary Slow Flow Are Not Associated With Invasive Wire-Based Diagnoses of Coronary Microvascular Dysfunction

BACKGROUND

Coronary slow flow (CSF) by invasive coronary angiography is frequently understood to be an indicator of coronary microvascular dysfunction (CMD) in patients with ischemia with nonobstructive coronary arteries. However, the relationship between visual estimates of CSF and quantitative wire-based invasive diagnosis of CMD is uncertain.

METHODS

We prospectively enrolled adults aged ≥18 years with stable ischemic heart disease who were referred for invasive coronary angiography. Individuals with ≥50% epicardial coronary artery stenosis were excluded. Invasive coronary angiography was reviewed for CSF, defined as ≥3 cardiac cycles to opacify distal vessels with contrast. Coronary function testing was performed in the left anterior descending coronary artery using bolus coronary thermodilution techniques to measure coronary flow reserve (CFR) and the index of microcirculatory resistance (IMR). Invasively determined CMD was defined as abnormal CFR (<2.5), abnormal IMR (≥25), or both.

RESULTS

Among 104 participants, the median age was 61.5 years and 79% were female. The median CFR was 3.6 (interquartile range, 2.5-4.7) and the median IMR was 21 (interquartile range, 13.3-28.0). Overall, 24.0% of participants had abnormal CFR, 34.6% had abnormal IMR, and 48.1% had a final diagnosis of invasively determined CMD. CSF was present in 23 participants (22.1%). The proportions of patients with CMD (56.5% versus 45.7%; P=0.36), abnormal CFR (17.4% versus 25.9%; P=0.40), and abnormal IMR (43.5% versus 32.1%; P=0.31) were not different in patients with versus without CSF.

CONCLUSIONS

Among patients with ischemia with nonobstructive coronary artery, CSF was not associated with abnormal CFR, IMR, or either abnormal CFR or IMR. CSF is not a reliable angiographic surrogate of abnormal CFR or IMR as determined by invasive, wire-based physiology testing.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT03537586.

Coronary microvascular dysfunction and inflammation: Insights from the Coronary Microvascular Disease Registry

BACKGROUND

Coronary microvascular dysfunction (CMD) is associated with various inflammatory conditions that worsen endothelial dysfunction. This study aimed to investigate the relationship between CMD and inflammation using common inflammatory markers derived from complete blood count (CBC) analysis.

METHODS

Information was gathered from the Coronary Microvascular Disease Registry to examine the neutrophil-to-lymphocyte ratio (NLR), eosinophil-to-monocyte ratio (EMR), and monocyte-to-high-density lipoprotein ratio (MHR) in a cohort of patients with angina who showed non-obstructive coronary arteries and underwent invasive physiological assessments for CMD.

RESULTS

Of the 171 patients studied, 126 were CMD-negative and 45 were CMD-positive, constituting two groups of interest. The average age of all patients was 61.7 ± 11.1 years, and 63.7 % were female. No significant differences were observed between the two groups in terms of baseline characteristics, cardiovascular risk factors, or potential anti-inflammatory medications. Furthermore, there were no statistically significant differences in NLR (2.54 ± 3.71 vs. 2.52 ± 2.28, p = 0.97), EMR (0.3 ± 0.21 vs. 0.34 ± 0.29, p = 0.31), or MHR (0.02 ± 0.01 vs. 0.01 ± 0.01, p = 0.54) between CMD-positive and CMD-negative patients.

CONCLUSION

Our findings did not show a noteworthy connection between CMD and inflammation, as suggested by various simple CBC-based biomarkers.

Comprehensive Angiography-Derived Functional Assessment of Epicardial and Microvascular Coronary Disease. Correlation With Non-invasive Myocardial Stress Imaging

Coronary angiography (CA) is poorly correlated with non-invasive myocardial stress imaging (NSI) and myocardial ischemia is often observed in patients with unobstructed coronary arteries. Moreover, the diagnostic performance of combined epicardial and microcirculatory angiography-derived physiological assessment and its correlation with NSI remains unknown. A total of 917 coronary vessels in 319 patients who underwent both CA and NSI were included in this multicenter observational retrospective analysis. Quantitative flow ratio (QFR) and angiography-derived index of microcirculatory resistance (IMRangio) analyses were performed to estimate coronary epicardial and microcirculatory function respectively. NSI demonstrated evidence of myocardial ischemia in 76% of the cases. IMRangio (36 [22 to 50] vs 29 [21 to 41], p <0.001) was significantly higher and QFR (0.92 [0.78 to 0.99] vs 0.97 [0.91 to 0.99], p <0.001) was significantly lower in vessels subtending ischemic territories. Overall, the diagnostic accuracy of QFR was moderate (area under the curve of receiver operating characteristic [AUCROC] 0.632 [95% confidence interval [CI] 0.589 to 0.674], p <0.0001) but it was higher in patients with normal microcirculatory function (AUCROC = 0.726 [95% CI 0.669 to 0.784], p <0.0001, p Value for AUCROC comparison = 0.009). Combined QFR/IMRangio assessment provided incremental diagnostic performance compared with the evaluation of epicardial or microcirculatory districts in isolation (p Value for AUC comparison <0.0001) and it was able to identify the predominant mechanism of myocardial ischemia in 77% of the patients with positive NSI. Our study suggests the value of a combined angiography-derived assessment of epicardial and microvascular function for the definition of the predominant mechanism of myocardial ischemia in patients with suspected coronary artery disease.

Coronary microvascular dysfunction assessment: A comparative analysis of procedural aspects

BACKGROUND

Full adoption of coronary microvascular dysfunction (CMD) assessment faces challenges due to its invasive nature and concerns about prolonged procedure time and increased contrast and/or radiation exposure. We compared procedural aspects of CMD invasive assessment to diagnostic left heart catheterization (DLHC) in patients with chest pain who were not found to have obstructive coronary artery disease.

METHODS

A total of 227 patients in the Coronary Microvascular Disease Registry were compared to 1592 patients who underwent DLHC from August 2021 to November 2023. The two cohorts were compared using propensity-score matching; primary outcomes were fluoroscopy time and total contrast use.

RESULTS

The participants' mean age was 64.1 ± 12.6 years. CMD-assessed patients were more likely to be female (66.5% vs. 45.2%, p < 0.001) and have hypertension (80.2% vs. 44.5%, p < 0.001), history of stroke (11.9% vs. 6.3%, p = 0.002), and history of myocardial infarction (20.3% vs. 7.7%, p < 0.001). CMD assessment was safe, without any reported adverse outcomes. A propensity-matched analysis showed that patients who underwent CMD assessment had slightly higher median contrast exposure (50 vs. 40 mL, p < 0.001), and slightly longer fluoroscopy time (6.9 vs. 4.7 min, p < 0.001). However, there was no difference in radiation dose (209.3 vs. 219 mGy, p = 0.58) and overall procedure time (31 vs. 29 min, p = 0.37).

CONCLUSION

Compared to DLHC, CMD assessment is safe and requires only slightly additional contrast use (10 mL) and slightly longer fluoroscopy time (2 min) without clinical implications. These findings emphasize the favorable safety and feasibility of invasive CMD assessment.

Asymmetric Dimethylarginine Enables Depolarizing Spikes and Vasospasm in Mesenteric and Coronary Resistance Arteries

BACKGROUND

Increased vasoreactivity due to reduced endothelial NO bioavailability is an underlying feature of cardiovascular disease, including hypertension. In small resistance arteries, declining NO enhances vascular smooth muscle (VSM) reactivity partly by enabling rapid depolarizing Ca2+-based spikes that underlie vasospasm. The endogenous NO synthase inhibitor asymmetric dimethylarginine (ADMA) is metabolized by DDAH1 (dimethylarginine dimethylaminohydrolase 1) and elevated in cardiovascular disease. We hypothesized ADMA might enable VSM spikes and vasospasm by reducing NO bioavailability, which is opposed by DDAH1 activity and L-arginine.

METHODS

Rat isolated small mesenteric arteries and myogenic rat-isolated intraseptal coronary arteries (RCA) were studied using myography, VSM intracellular recording, Ca2+ imaging, and DDAH1 immunolabeling. Exogenous ADMA was used to inhibit NO synthase and a selective DDAH1 inhibitor, NG-(2-methoxyethyl) arginine, to assess the functional impact of ADMA metabolism.

RESULTS

ADMA enhanced rat-isolated small mesenteric arteries vasoreactivity to the α1-adrenoceptor agonist, phenylephrine by enabling T-type voltage-gated calcium channel-dependent depolarizing spikes. However, some endothelium-dependent NO-vasorelaxation remained, which was sensitive to DDAH1-inhibition with NG-(2-methoxyethyl) arginine. In myogenically active RCA, ADMA alone stimulated depolarizing Ca2+ spikes and marked vasoconstriction, while NO vasorelaxation was abolished. DDAH1 expression was greater in rat-isolated small mesenteric arteries endothelium compared with RCA, but low in VSM of both arteries. L-arginine prevented depolarizing spikes and protected NO-vasorelaxation in rat-isolated small mesenteric artery and RCA.

CONCLUSIONS

ADMA increases VSM electrical excitability enhancing vasoreactivity. Endothelial DDAH1 reduces this effect, and low levels of DDAH1 in RCAs may render them susceptible to endothelial dysfunction contributing to vasospasm, changes opposed by L-arginine.

From chest pain to coronary functional testing: Clinical and economic impact of coronary microvascular dysfunction

BACKGROUND

Coronary functional testing to formally diagnose coronary microvascular dysfunction (CMD) reduces cardiovascular events and alleviates angina. This study aims to investigate the extensive and complex journey that patients with CMD undergo, from the onset of chest pain to eventual diagnosis.

METHODS

Data from the Coronary Microvascular Disease Registry (CMDR) were analyzed, including information on the date of first documentation of chest pain, number of non-invasive and invasive tests the patient underwent, emergency department visits, and hospitalizations. In addition, we estimated the total cost per patient. A total of 61 patients with CMD diagnosis were included in this analysis.

RESULTS

Most patients in our cohort were older than 50 years of age. The median time from initial chest pain symptoms to diagnosis was 0.62 (interquartile range [IQR]: 0.06-2.96) years. During this period, patients visited the emergency department a median of 1.0 (IQR: 0.0-2.0) times. Diagnostic tests included 3.0 (IQR: 2.0-6.0) electrocardiograms, 3.0 (IQR: 0.0-6.0) high-sensitivity troponin tests, and 1.0 (IQR: 1.0-2.0) echocardiograms. Prior to diagnosis of CMD, 13 (21.3 %) patients had left heart catheterization without coronary functional testing. Non-invasive testing for ischemia was conducted in 43 (70.5 %) patients. Alternative non-cardiac diagnoses were given to 11 (18.0 %) patients during the diagnostic process, with referrals made to gastroenterology for 16 (26.2 %) and pulmonology for 10 (16.4 %) patients. The cost was almost $2000/patient.

CONCLUSION

Timely identification of CMD offers promising opportunities for prompt symptom alleviation, accompanied by reduced visits to the emergency department, cardiovascular testing, invasive medical procedures, and consequently reduced healthcare expenses.

Coronary Microvascular Disease Registry (CMDR): Study design and rationale

BACKGROUND

Coronary microvascular dysfunction (CMD) is a prevalent condition among patients with cardiovascular risk factors, leading to a reduced quality of life and an increased risk of major adverse cardiovascular events. Novel invasive techniques have emerged to more accurately diagnose CMD. However, CMD's natural history remains poorly understood due to limited data. To address this knowledge gap, the Coronary Microvascular Disease Registry (CMDR) was established with the primary aim of standardizing comprehensive coronary functional testing and understanding of CMD.

DESIGN

CMDR is a prospective, multicenter registry enrolling an unlimited number of consecutive subjects who undergo comprehensive invasive hemodynamic assessment of the entire coronary arterial vasculature. Patients undergoing acetylcholine provocation test for coronary vasospasm will also be included. Follow-up assessments will be conducted at 30 days and annually for up to 5 years. The primary endpoint is Canadian Cardiovascular Society angina grade over time. Secondary endpoints, including all-cause mortality, cardiovascular death, acute myocardial infarction, stroke, hospitalizations, medication changes, and subsequent coronary interventions, will be analyzed to establish long-term safety and clinical outcomes in patients undergoing invasive CMD assessment.

SUMMARY

CMDR aims to characterize the clinical and physiologic profile of patients undergoing comprehensive invasive coronary functional testing, simultaneously providing crucial longitudinal information on the natural history and outcomes of these patients. This will shed light on CMD's course and clinical implications, which, in turn, holds the potential to significantly improve diagnostic and treatment strategies for CMD patients, ultimately leading to the enhancement of their overall prognosis and quality of life.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov, NCT05960474.

Update on sex specific risk factors in cardiovascular disease

Cardiovascular disease (CVD) is the leading cause of death worldwide and accounts for roughly 1 in 5 deaths in the United States. Women in particular face significant disparities in their cardiovascular care when compared to men, both in the diagnosis and treatment of CVD. Sex differences exist in the prevalence and effect of cardiovascular risk factors. For example, women with history of traditional cardiovascular risk factors including hypertension, tobacco use, and diabetes carry a higher risk of major cardiovascular events and mortality when compared to men. These discrepancies in terms of the relative risk of CVD when traditional risk factors are present appear to explain some, but not all, of the observed differences among men and women. Sex-specific cardiovascular disease research-from identification, risk stratification, and treatment-has received increasing recognition in recent years, highlighting the current underestimated association between CVD and a woman's obstetric and reproductive history. In this comprehensive review, sex-specific risk factors unique to women including adverse pregnancy outcomes (APO), such as hypertensive disorders of pregnancy (HDP), gestational diabetes mellitus, preterm delivery, and newborn size for gestational age, as well as premature menarche, menopause and vasomotor symptoms, polycystic ovarian syndrome (PCOS), and infertility will be discussed in full detail and their association with CVD risk. Additional entities including spontaneous coronary artery dissection (SCAD), coronary microvascular disease (CMD), systemic autoimmune disorders, and mental and behavioral health will also be discussed in terms of their prevalence among women and their association with CVD. In this comprehensive review, we will also provide clinicians with a guide to address current knowledge gaps including implementation of a sex-specific patient questionnaire to allow for appropriate risk assessment, stratification, and prevention of CVD in women.

Female-Specific Considerations in Aortic Health and Disease

The aorta plays a central role in the modulation of blood flow to supply end organs and to optimize the workload of the left ventricle. The constant interaction of the arterial wall with protective and deleterious circulating factors, and the cumulative exposure to ventriculoarterial pulsatile load, with its associated intimal-medial changes, are important players in the complex process of vascular aging. Vascular aging is also modulated by biomolecular processes such as oxidative stress, genomic instability, and cellular senescence. Concomitantly with well-established cardiometabolic and sex-specific risk factors and environmental stressors, arterial stiffness is associated with cardiovascular disease, which remains the leading cause of morbidity and mortality in women worldwide. Sexual dimorphisms in aortic health and disease are increasingly recognized and explain-at least in part-some of the observable sex differences in cardiovascular disease, which will be explored in this review. Specifically, we will discuss how biological sex affects arterial health and vascular aging and the implications this has for development of certain cardiovascular diseases uniquely or predominantly affecting women. We will then expand on sex differences in thoracic and abdominal aortic aneurysms, with special considerations for aortopathies in pregnancy.

Atherosclerosis in Systemic Lupus Erythematosus

PURPOSE OF THE REVIEW

Systemic lupus erythematosus (SLE) patients are at increased risk of cardiovascular disease (CVD) compared to the general population, despite most patients being young females, who are not classically considered to be at high risk for cardiovascular disease using traditional risk assessment tools. The purpose of this review is to discuss the pathophysiology of atherosclerosis in SLE and raise awareness of the relationship between SLE and CVD.

RECENT FINDINGS

The increased risk of CVD in SLE patients is multifactorial, due to proatherogenic lipid profiles, immune dysregulation and inflammation, side effects of lupus treatment, and microvascular dysfunction. Conventional CV risk models often underperform in the identification of SLE patients at high risk of atherosclerosis. The use of non-invasive imaging serves as a strategy to identify patients with evidence of subclinical CVD and in the evaluation of symptomatic patients. Identification of subclinical atherosclerosis allows for aggressive management of CV risk factors. SLE patients experience an increased risk of atherosclerotic CVD, which is not solely explained by traditional CV risk factors. It is imperative that clinicians are aware of this association to implement prompt detection and treatment of atherosclerotic CVD in SLE patients.

Endothelial cell dysfunction in cardiac disease: driver or consequence?

The vascular endothelium is a multifunctional cellular system which directly influences blood components and cells within the vessel wall in a given tissue. Importantly, this cellular interface undergoes critical phenotypic changes in response to various biochemical and hemodynamic stimuli, driving several developmental and pathophysiological processes. Multiple studies have indicated a central role of the endothelium in the initiation, progression, and clinical outcomes of cardiac disease. In this review we synthesize the current understanding of endothelial function and dysfunction as mediators of the cardiomyocyte phenotype in the setting of distinct cardiac pathologies; outline existing in vivo and in vitro models where key features of endothelial cell dysfunction can be recapitulated; and discuss future directions for development of endothelium-targeted therapeutics for cardiac diseases with limited existing treatment options.