The functional assessment of patients with non-obstructive coronary artery disease: expert review from an international microcirculation working group

Living with myocardial ischaemia and no obstructive coronary arteries: a qualitative study

OBJECTIVE

To explore the lived experience of people with myocardial ischaemia with no obstructive arteries.

DESIGN

Qualitative study using semistructured interviews.

SETTING

Telephone interviews with 17 participants living in the UK.

PARTICIPANTS

17 people (2 males, 15 females; aged 31-69 years) with a presumed or confirmed diagnosis of myocardial ischaemia with no obstructive arteries, recruited via social media and online patient-led support forums.

RESULTS

Five themes were generated. Theme 1 describes the wide range of experiences that participants described, particularly the frequency and intensity of symptoms, and the uncertainty and fear that symptoms commonly provoked. Theme 2 describes the major impact on social relationships, employment and other aspects of everyday life. Theme 3 illustrates challenging and traumatising experiences participants described around pathways to diagnosis and accessing medical support. Theme 4 highlights the lack of consensus and clarity that participants had been confronted with around treatment and management. Theme 5 describes coping and supportive strategies valued by participants.

CONCLUSIONS

This study provides insight into the challenges of living with myocardial ischaemia with no obstructive arteries. Findings highlight the significant psychological impact on people living with these conditions and the need for improvements in diagnosis, support and long-term management.

INOCA/ANOCA: Mechanisms and novel treatments

Angina or ischemia with no obstructive coronary disease (ANOCA/INOCA) is a common but under-treated condition due to poorly understood pathophysiologic mechanisms, limited diagnostic tools, and lack of proven targeted therapy. Coronary microvascular dysfunction (CMD) occurs when the microvasculature inadequately perfuses the myocardium under stress, or at rest in the case of microvascular spasm resulting in ANOCA/INOCA. Coronary functional angiography (CFA) measures endothelial independent microvascular dysfunction (coronary flow reduction <2.5) in response to adenosine and endothelial dependent microvascular dysfunction (lack of dilation and/or constriction) to acetylcholine testing as well as epicardial and microvascular spasm. Current treatment for coronary microvascular dysfunction is limited to renin-angiotensin system (RAS) inhibitors and statins as well as antianginal medications. Novel therapies targeting the underlying pathology are under development and include the coronary sinus reducer, CD34+ stem cell therapy, and novel pharmacologic agents such as sGC stimulators or endothelin-receptor blockers. We review the current understanding of pathophysiology, diagnostic tools, and novel therapies for coronary microvascular dysfunction in ANOCA/INOCA.

Clonal Hematopoiesis of Indeterminate Potential Is Associated With Coronary Microvascular Dysfunction In Early Nonobstructive Coronary Artery Disease

BACKGROUND

Clonal hematopoiesis (CH) of indeterminate potential (CHIP) is a risk factor for cardiovascular disease. The relationship between CHIP and coronary microvascular dysfunction (CMD) is unknown. The current study examines the association between CHIP and CH with CMD and the potential relationships in risk for adverse cardiovascular outcomes.

METHODS

In this retrospective observational study, targeted next-generation sequencing was performed for 177 participants with no coronary artery disease who presented with chest pain and underwent routine coronary functional angiogram. Patients with somatic mutations in leukemia-associated driver genes in hematopoietic stem and progenitor cells were examined; CHIP was considered at a variant allele fraction ≥2%; CH was considered at a variant allele fraction ≥1%. CMD was defined as coronary flow reserve to intracoronary adenosine of ≤2. Major adverse cardiovascular events considered were myocardial infarction, coronary revascularization, or stroke.

RESULTS

A total of 177 participants were examined. Mean follow-up was 12±7 years. A total of 17 patients had CHIP and 28 had CH. Cases with CMD (n=19) were compared with controls with no CMD (n=158). Cases were 56±9 years, were 68% women, and had more CHIP (27%; P=0.028) and CH (42%; P=0.001) than controls. CMD was associated with independent risk for major adverse cardiovascular events (hazard ratio, 3.89 [95% CI, 1.21-12.56]; P=0.023), and 32% of this risk was mediated by CH. The risk mediated by CH was ≈0.5× as large as the direct effect of CMD on major adverse cardiovascular events.

CONCLUSIONS

In humans, we observe patients with CMD are more likely to have CHIP, and nearly one-third of major adverse cardiovascular events in CMD are mediated by CH.

Ischemia and no obstructive coronary arteries (INOCA): A narrative review

Myocardial ischemia with no obstructive coronary arteries (INOCA) is a chronic coronary syndrome condition that is increasingly being recognized as a substantial contributor to adverse cardiovascular mortality and outcomes, including myocardial infarction and heart failure with preserved ejection fraction (HFpEF). While INOCA occurs in both women and men, women are more likely to have the finding of INOCA and are more adversely impacted by angina, with recurrent hospitalizations and a lower quality of life with this condition. Abnormal epicardial coronary vascular function and coronary microvascular dysfunction (CMD) have been identified in a majority of INOCA patients on invasive coronary function testing. CMD can co-exist with obstructive epicardial coronary artery disease (CAD), diffuse non-obstructive epicardial CAD, and with coronary vasospasm. Epicardial vasospasm can also occur with normal coronary arteries that have no atherosclerotic plaque on intravascular imaging. While all predisposing factors are not clearly understood, cardiometabolic risk factors, and endothelium dependent and independent mechanisms that increase oxidative stress and inflammation are associated with microvascular injury, CMD and INOCA. Cardiac autonomic dysfunction has also been implicated in abnormal vasoreactivity and persistent symptoms. INOCA is under-recognized and under-diagnosed, partly due to the heterogenous patient populations and mechanisms. However, diagnostic testing methods are available to guide INOCA management. Treatment of INOCA is evolving, and focuses on cardiac risk factor control, improving ischemia, reducing atherosclerosis progression, and improving angina and quality of life. This review focuses on INOCA, relations to HFpEF, available diagnostics, current and investigational therapeutic strategies, and knowledge gaps in this condition.

Coronary endothelial dysfunction: from pathogenesis to clinical implications

Endothelial dysfunction (ED) has a substantial role in the pathogenesis of atherosclerosis and other vascular diseases. Multiple risk factors, including smoking, hyperlipiadaemia and diabetes, can have associated ED, which is correlated with cardiac events. Measurement of coronary artery endothelial function requires the use of invasive techniques to assess both epicardial coronary artery and microvascular beds. Peripheral vascular techniques and endothelial biomarkers can be used to indirectly assess coronary ED. In this review of coronary artery ED, we discuss the current state of the field, the techniques used to measure ED and its clinical implications.

Coronary functional assessment in non-obstructive coronary artery disease: Present situation and future direction

Non-obstructive coronary artery disease (CAD), which is defined as coronary stenosis <50%, has been increasingly recognized as an emerging entity in clinical practice. Vasomotion abnormality and coronary microvascular dysfunction are two major mechanisms contributing to the occur of angina with non-obstructive CAD. Although routine coronary functional assessment is limited due to several disadvantages, functional evaluation can help to understand the pathophysiological mechanism and/or to exclude specific etiologies. In this review, we summarized the potential mechanisms involved in ischemia with non-obstructive coronary arteries (INOCA) and myocardial infarction with non-obstructive coronary arteries (MINOCA), the two major form of non-obstructive CAD. Additionally, we reviewed currently available functional assessment indices and their use in non-obstructive CAD. Furthermore, we speculated that novel technique combined anatomic and physiologic parameters might provide more individualized therapeutic choice for patients with non-obstructive CAD.

Contemporary Management of Refractory Angina

Refractory angina (RA) is defined as chest pain caused by coronary ischemia in patients on maximal medical therapy and is not amenable to revascularization despite advanced coronary artery disease (CAD). The long-term prognosis has improved with optimal medical therapy including risk factor modification. Still, patients are left with major impairment in quality of life and have high resource utilization with limited treatment options. We review the novel invasive and noninvasive therapies under investigation for RA.

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.

Impact of invasive aortic pulse pressure on coronary microvascular endothelial-independent dysfunction and on mortality in non-obstructive coronary artery disease

Background

Pulse pressure (PP), a raw index of arterial stiffness, is inversely related to coronary microvascular function, even among patients with non-obstructive coronary artery disease (CAD), as per non-invasive studies. We aimed to determine whether invasive aortic PP is associated with coronary microvascular endothelial dysfunction (CMED) and/or coronary microvascular endothelial independent dysfunction (CMEID) in patients with non-obstructed CAD.

Methods

We retrospectively analysed a cohort of 1894 patients (mean age, 51.2 years; 1261 (66.6%) women) who presented with chest pain and non-obstructive CAD (angiographic stenosis <50%); coronary vasoreactivity was assessed in the mid-left anterior descending artery. The patients were classified based on whether aortic PP was high (≥50 mm Hg). CMEID was defined as abnormal coronary flow reserve (<2.5) or hyperaemic myocardial resistance (>2.0 mm Hg/cm/s), CMED was defined as abnormal acetylcholine-induced per cent change of coronary blood flow (≤50%).

Results

Patients with high aortic PP had a higher rate of CMEID than those with low aortic PP (40.9 vs 25.2%, p<0.001). Conversely, aortic PP was not associated with CMED. On multivariate analysis, high aortic PP was associated with CMEID occurrence (OR 1.42, 95% CI 1.13 to 1.78; p=0.003). On follow-up (median, 150 months), all-cause death was more frequent among patients with vs without high aortic PP (20.1% vs 7.3%, log-rank p<0.001) and HR was 2.08 (95% CI 1.34 to 3.32, p=0.002) on multivariate cox regression analysis. Furthermore, among patients with low aortic PP, CMEID was an independent risk factor for all-cause mortality (HR 2.04, 95% CI 1.01 to 4.16, p=0.048).

Conclusion

In patients with non-obstructive CAD, invasive aortic PP was significantly associated with CMEID, but not with CMED. High aortic PP was an independent predictor of all-cause mortality, but CMEID was an independent risk factor in patients with low aortic PP.

Ischemia and no obstructive coronary arteries in patients with stable ischemic heart disease

A large proportion of patients with suspected obstructive coronary artery disease (CAD) is found to have ischemia with no obstructive coronary artery disease (INOCA). Based on current evidence, these patients are at increased risk of adverse cardiovascular events, even though they have no obstructive CAD. Importantly, INOCA is associated with recurrent clinical presentations with chest pain, impaired functional capacity, reduced health-related quality of life, and high healthcare costs. Underlying coronary microvascular dysfunction (CMD), through endothelium-dependent and independent mechanisms contribute to these adverse outcomes in INOCA. While non-invasive and invasive diagnostic testing has typically focused on identification of obstructive CAD in symptomatic patients, functional testing to detect coronary epicardial and microvascular dysfunction should be considered in those with INOCA who have persistent angina. Current diagnostic methods to clarify functional abnormalities and treatment strategies for epicardial and/or microvascular dysfunction in INOCA are reviewed.

IMPROvE-CED Trial: Intracoronary Autologous CD34+ Cell Therapy for Treatment of Coronary Endothelial Dysfunction in Patients With Angina and Non-Obstructive Coronary Arteries

Background: Coronary endothelial dysfunction (CED) causes angina/ischemia in patients with no-obstructive CAD (NOCAD). Patients with CED have decreased number and function of CD34+ cells involved in normal vascular repair with microcirculatory regenerative potential and paracrine anti-inflammatory effects. We evaluated safety and potential efficacy of intracoronary (IC) autologous CD34+ cell therapy for CED.

Methods: Twenty NOCAD patients with invasively-diagnosed CED and persistent angina despite maximally-tolerated medical therapy (MTMT) underwent baseline exercise stress test (EST), GCSF-mediated CD34+ cell-mobilization, leukapheresis, and selective 1x105 CD34+ cells/kg infusion into LAD. Invasive CED evaluation and EST were repeated 6-months after cell infusion. Primary endpoints were safety and effect of IC autologous CD34+ cell therapy on CED at 6-months follow-up. Secondary endpoints were change in CCS angina class, as-needed sublingual nitroglycerin use/day, Seattle Angina Questionnaire (SAQ) scores, and exercise time at 6-months. Change in CED was compared to that of 51 historic-control NOCAD patients treated with MTMT alone.

Results: Mean age was 52{plus minus}13 years, 75% women. No death, myocardial infarction, or stroke occurred. IC CD34+ cell infusion improved microvascular CED [% acetylcholine-mediated coronary blood flow increased from 7.2 (-18.0-32.4) to 57.6 (16.3-98.3) %, p=0.014], decreased CCS angina class (3.7{plus minus}0.5 to 1.7{plus minus}0.9, Wilcoxon signed-rank test p=0.00018) and sublingual nitroglycerin use/day [1 (0.4-3.5) to 0 (0-1), Wilcoxon signed-rank test p=0.00047], and improved all SAQ scores with no significant change in exercise time at 6-months follow-up. Historic-control patients had no significant change in CED.

Conclusion: A single IC autologous CD34+ cell infusion was safe and may potentially be an effective disease-modifying therapy for microvascular CED in humans. Clinical Trial Registration: NCT03471611

Vasomotor Dysfunction in Patients with Ischemia and Non-Obstructive Coronary Artery Disease: Current Diagnostic and Therapeutic Strategies

Many patients who present with symptoms or objective evidence of ischemia have no or non-physiologically-significant disease on invasive coronary angiography. The diagnosis of ischemic heart disease is thus often dismissed, and patients receive false reassurance or other diagnoses are pursued. We now know that a significant proportion of these patients have coronary microvascular dysfunction and/or vasospastic disease as the underlying pathophysiology of their clinical presentation. Making the correct diagnosis of such abnormalities is important not only because they impact the quality of life, with recurring symptoms and unnecessary repeated testing, but also because they increase the risk for adverse cardiovascular events. The mainstay of diagnosis remains an invasive comprehensive physiologic assessment, which further allows stratifying these patients into appropriate “endotypes”. It has been shown that tailoring treatment to the patient’s assigned endotype improves symptoms and quality of life. In addition to the conventional drugs used in chronic stable angina, multiple newer agents are being investigated. Moreover, innovative non-pharmacologic and interventional therapies are emerging to provide a bail-out in refractory cases. Many of these novel therapies fail to show consistent benefits, but others show quite promising results.

Urine transferrin as an early endothelial dysfunction marker in type 2 diabetic patients without nephropathy: a case control study

BACKGROUND

Albumin, along with other proteins, is abnormally eliminated via the urine during early stages of diabetic nephropathy. Moreover, endothelial dysfunction (ED) accompanying early diabetic nephropathy may develop even before microalbuminuria is detectable. Transferrin has a molecular weight comparable to albumin, whereas transferrinuria and microalbuminuria in a 24-h urine sample may comparably reflect early diabetic nephropathy. Whereas transferrin metabolism is related with ED during very early diabetic nephropathy has not been elucidated yet. This case-control study aimed to evaluate the relation between ED and urine transferrin, even before early diabetic nephropathy is present.

METHODS

Patients were enrolled from two study sites in Mexico City: Ticomán General Hospital (healthy controls); and a Specialized Clinic for the Management of the Diabetic Patient (cases). All patients provided written informed consent. The primary endpoint was the correlation between urinary transferrin concentration and ED measured in type 2 diabetic patients without albuminuria. ED was evaluated by ultrasonographic validated measurements, which included carotid intima-media thickness (CIMT) and flow mediated dilation (FMD). Plasma biomarkers included glycated hemoglobin, creatinine, cholesterol and triglycerides, as well as urine albumin, transferrin and evidence of urinary tract infection.

RESULTS

Sixty patients with type 2 Diabetes Mellitus (t2DM; n = 30) or without t2DM (n = 30), both negative for microalbuminuria, were recruited. The group with t2DM were older, with higher values of HbA1c and higher ED. This group also showed significant differences in urine transferrin and urine/plasma transferrin ratio, as compared with healthy controls (14.4 vs. 18.7 mg/mL, p = 0.04, and 74.2 vs. 49.5; p = 0.01; respectively). Moreover, urine transferrin correlated with higher CIMT values (r = 0.37, p = 0.04), being particularly significant for t2DM population. CIMT also correlated with time from t2DM diagnosis (r = 0.48, p < 0.001) and HbA1c (r = 0.48; p < 0.001).

CONCLUSION

Urine transferrin correlated with subclinical atherogenesis in patients with t2DM without renal failure, suggesting its potential to identify cardiovascular risk in patients at very early nephropathy stage without microalbuminuria.

Machine learning aids clinical decision-making in patients presenting with angina and non-obstructive coronary artery disease

Aims

The current gold standard comprehensive assessment of coronary microvascular dysfunction (CMD) is through a limited-access invasive catheterization lab procedure. We aimed to develop a point-of-care tool to assist clinical guidance in patients presenting with chest pain and/or an abnormal cardiac functional stress test and with non-obstructive coronary artery disease (NOCAD).

Methods and results

This study included 1893 NOCAD patients (<50% angiographic stenosis) who underwent CMD evaluation as well as an electrocardiogram (ECG) up to 1-year prior. Endothelial-independent CMD was defined by coronary flow reserve (CFR) ≤2.5 in response to intracoronary adenosine. Endothelial-dependent CMD was defined by a maximal percent increase in coronary blood flow (%ΔCBF) ≤50% in response to intracoronary acetylcholine infusion. We trained algorithms to distinguish between the following outcomes: CFR ≤2.5, %ΔCBF ≤50, and the combination of both. Two classes of algorithms were trained, one depending on ECG waveforms as input, and another using tabular clinical data. Mean age was 51 ± 12 years and 66% were females (n = 1257). Area under the curve values ranged from 0.49 to 0.67 for all the outcomes. The best performance in our analysis was for the outcome CFR ≤2.5 with clinical variables. Area under the curve and accuracy were 0.67% and 60%. When decreasing the threshold of positivity, sensitivity and negative predictive value increased to 92% and 90%, respectively, while specificity and positive predictive value decreased to 25% and 29%, respectively.

Conclusion

An artificial intelligence-enabled algorithm may be able to assist clinical guidance by ruling out CMD in patients presenting with chest pain and/or an abnormal functional stress test. This algorithm needs to be prospectively validated in different cohorts.

Prognostic impact and clinical outcomes of coronary flow reserve and hyperaemic microvascular resistance

BACKGROUND

Most studies dichotomise indices of coronary microvascular function to assess their prognostic values.

AIMS

We aimed to investigate whether coronary flow reserve (CFR) and hyperaemic microvascular resistance (HMR) as continua predict major adverse cardiovascular events (MACE), comprising all-cause death, myocardial infarction, revascularisation, and stroke in patients with ischaemia and non-obstructive coronary artery disease.

METHODS

A total of 610 patients were included and followed up over a median of 8.0 years (199 individual MACE in 174 patients).

RESULTS

Both CFR and HMR as continua predicted MACE with an odds ratio (OR) of 0.70 (per 1-unit increase, 95% confidence interval [CI]: 0.53, 0.92; p=0.01) and 1.63 (per 1 mmHg/cm/s, 95% CI: 1.20, 2.21; p=0.002), respectively. This relationship remained significant after adjustment for age and sex with an adjusted OR of 0.66 (per 1 unit increase, 95% CI: 0.49, 0.89; p=0.01) and 1.42 (per 1 mmHg/cm/s, 95% CI: 1.03, 1.94; p=0.03). HMR added prognostic value to CFR in predicting MACE (net reclassification index 0.17, 95% CI: 0.02, 0.31; p=0.03; integrated discrimination improvement 0.01, 95% CI: 0.0001, 0.02; p=0.046).

CONCLUSIONS

Both CFR and HMR as continuous variables predict future risk of MACE.

Diagnostic pathways in myocardial infarction with non-obstructive coronary artery disease (MINOCA)

When acute myocardial injury is found in a clinical setting suggestive of myocardial ischaemia, the event is labelled as acute myocardial infarction (AMI), and the absence of coronary stenosis angiographically 50% or greater leads to the working diagnosis of myocardial infarction with non-obstructive coronary arteries (MINOCA). The initial diagnosis of MINOCA can be confirmed or ruled out based on the results of subsequent investigations. This narrative review discusses the downstream diagnostic approaches to MINOCA, and appraises strengths and limitations of invasive and non-invasive investigations for this condition. The aim of this article is to increase the awareness that establishing the underlying cause of a MINOCA is possible in the vast majority cases. Determining the cause of MINOCA and excluding other possible causes for cardiac troponin elevation has notable implications for tailoring secondary prevention measures aimed at improving the overall prognosis of AMI.

An EAPCI Expert Consensus Document on Ischaemia with Non-Obstructive Coronary Arteries in Collaboration with European Society of Cardiology Working Group on Coronary Pathophysiology & Microcirculation Endorsed by Coronary Vasomotor Disorders International Study Group

This consensus document, a summary of the views of an expert panel organized by the European Association of Percutaneous Cardiovascular Interventions (EAPCI), appraises the importance of ischaemia with non-obstructive coronary arteries (INOCA). Angina pectoris affects approximately 112 million people globally. Up to 70% of patients undergoing invasive angiography do not have obstructive coronary artery disease, more common in women than in men, and a large proportion have INOCA as a cause of their symptoms. INOCA patients present with a wide spectrum of symptoms and signs that are often misdiagnosed as non-cardiac leading to under-diagnosis/investigation and under-treatment. INOCA can result from heterogeneous mechanism including coronary vasospasm and microvascular dysfunction and is not a benign condition. Compared to asymptomatic individuals, INOCA is associated with increased incidence of cardiovascular events, repeated hospital admissions, as well as impaired quality of life and associated increased health care costs. This consensus document provides a definition of INOCA and guidance to the community on the diagnostic approach and management of INOCA based on existing evidence from research and best available clinical practice; noting gaps in knowledge and potential areas for further investigation.

Angiogenic CD34 Stem Cell Therapy in Coronary Microvascular Repair-A Systematic Review

Ischemia with non-obstructive coronary arteries (INOCA) is an increasingly recognized disease, with a prevalence of 3 to 4 million individuals, and is associated with a higher risk of morbidity, mortality, and a worse quality of life. Persistent angina in many patients with INOCA is due to coronary microvascular dysfunction (CMD), which can be difficult to diagnose and treat. A coronary flow reserve <2.5 is used to diagnose endothelial-independent CMD. Antianginal treatments are often ineffective in endothelial-independent CMD and thus novel treatment modalities are currently being studied for safety and efficacy. CD34+ cell therapy is a promising treatment option for these patients, as it has been shown to promote vascular repair and enhance angiogenesis in the microvasculature. The resulting restoration of the microcirculation improves myocardial tissue perfusion, resulting in the recovery of coronary microvascular function, as evidenced by an improvement in coronary flow reserve. A pilot study in INOCA patients with endothelial-independent CMD and persistent angina, treated with autologous intracoronary CD34+ stem cells, demonstrated a significant improvement in coronary flow reserve, angina frequency, Canadian Cardiovascular Society class, and quality of life (ESCaPE-CMD, NCT03508609). This work is being further evaluated in the ongoing FREEDOM (NCT04614467) placebo-controlled trial.

Pathobiology and evolving therapies of coronary artery vasospasm

Coronary artery vasospasm is a known cause of chest pain and requires a high level of clinical suspicion for diagnosis. It also remains in the differential diagnosis for patients presenting with type 2 myocardial infarction. There are few randomized controlled trials for guideline-based prevention and treatment for coronary artery vasospasm. In this article, we review updated concepts in coronary artery vasospasm. Specifically, our aim is to provide current evidence of pathophysiology, identify the risk factors, propose a diagnostic algorithm, review available evidence of evolving therapies, and identify patients who would benefit from automatic implantable cardioverter defibrillators.

An EAPCI Expert Consensus Document on Ischaemia with Non-Obstructive Coronary Arteries in Collaboration with European Society of Cardiology Working Group on Coronary Pathophysiology & Microcirculation Endorsed by Coronary Vasomotor Disorders International Study Group

This consensus document, a summary of the views of an expert panel organized by the European Association of Percutaneous Cardiovascular Interventions (EAPCI), appraises the importance of ischaemia with non-obstructive coronary arteries (INOCA). Angina pectoris affects approximately 112 million people globally. Up to 70% of patients undergoing invasive angiography do not have obstructive coronary artery disease, more common in women than in men, and a large proportion have INOCA as a cause of their symptoms. INOCA patients present with a wide spectrum of symptoms and signs that are often misdiagnosed as non-cardiac leading to under-diagnosis/investigation and under-treatment. INOCA can result from heterogeneous mechanism including coronary vasospasm and microvascular dysfunction and is not a benign condition. Compared to asymptomatic individuals, INOCA is associated with increased incidence of cardiovascular events, repeated hospital admissions, as well as impaired quality of life and associated increased health care costs. This consensus document provides a definition of INOCA and guidance to the community on the diagnostic approach and management of INOCA based on existing evidence from research and best available clinical practice; noting gaps in knowledge and potential areas for further investigation.

Coronary microvascular dysfunction is associated with exertional haemodynamic abnormalities in patients with heart failure with preserved ejection fraction

AIMS

This study uniquely explored the relationship between coronary microvascular function and exercise haemodynamics using concurrent invasive testing.

METHODS AND RESULTS

Fifty-one consecutive patients with unexplained cardiac exertion symptoms, non-obstructive coronary artery disease and normal left ventricular ejection fraction (>50%) underwent haemodynamic exercise assessment and concurrent coronary reactivity testing. Heart failure with preserved ejection fraction (HFpEF) was defined as a pulmonary arterial wedge pressure (PAWP) ≥15 mmHg at rest and/or ≥25 mmHg at peak exercise. Endothelium-independent coronary microvascular dysfunction (CMD) was defined as a coronary flow reserve (CFR) ≤2.5, while endothelium-dependent CMD was defined as ≤50% increase in coronary blood flow (CBF) in response to intracoronary acetylcholine infusions. Patients with HFpEF (n = 22) had significantly lower CFR (2.5 ± 0.6 vs. 3.2 ± 0.7; P = 0.0003) and median %CBF increase in response to intracoronary acetylcholine [1 (-35; 34) vs. 64 (-4; 133); P = 0.002] compared to patients without HFpEF (n = 29). PAWP was significantly higher in patients with endothelium-independent CMD compared to controls during both rest and exercise. This significant elevation was only present during exercise in patients with endothelium-dependent CMD compared to controls. CFR had significant inverse correlations with PAWP at rest (r = -0.31; P = 0.03) and peak exercise (r = -0.47, P = 0.001). CFR also had positive correlations with maximal exercise capacity (in W/kg) (r = 0.33, P = 0.02).

CONCLUSIONS

Coronary microvascular function is inversely associated with filling pressures, particularly during exercise. Both types of CMD are associated with higher filling pressures at peak exercise. These findings underscore the potential mechanism and therapeutic target for CMD and HFpEF.

Coronary Microvascular Endothelial Dysfunction in Patients With Angina and Nonobstructive Coronary Artery Disease Is Associated With Elevated Serum Homocysteine Levels

Background

Elevated levels of serum homocysteine, via impaired nitric oxide production, and coronary microvascular dysfunction are associated with increased risk of major adverse cardiovascular events. However, whether serum homocysteine levels and coronary microvascular endothelial dysfunction (CMED) are linked remains unknown.

Methods and Results

This study included 1418 patients with chest pain or an abnormal functional stress test and with nonobstructive coronary artery disease (<40% angiographic stenosis), who underwent CMED evaluation with functional angiography and had serum homocysteine levels measured. Patients were classified as having normal microvascular function versus CMED. Patients in the CMED group (n=743; 52%) had higher mean age (52.1±12.2 versus 50.0±12.4 years; P<0.0001), higher body mass index (29.1 [25.0–32.8] versus 27.5 [24.2–32.4]; P=0.001), diabetes mellitus (12.5% versus 9.4%; P=0.03), and fewer women (63.5% versus 68.7%; P=0.04) compared with patients in the normal microvascular function group. However, they had lower rates of smoking history, and mildly lower low‐density lipoprotein cholesterol levels. Serum homocysteine levels were significantly higher in patients with CMED, and the highest quartile of serum homocysteine level (>9 µmol/L) was an independent predictor of CMED (odds ratio, 1.34 [95% CI, 1.03–1.75]; P=0.03) after adjustment for age; sex; body mass index; chronic kidney disease (CKD); diabetes mellitus; smoking exposure; low‐density lipoprotein cholesterol; high‐density lipoprotein cholesterol and triglycerides; and aspirin, statin, and B vitamin use.

Conclusions

Patients with CMED have significantly higher levels of serum homocysteine. Elevated serum homocysteine levels were associated with a significantly increased odds of an invasive diagnosis of CMED. The current study supports a potential role for homocysteine for diagnosis and target treatment in the patients with early coronary atherosclerosis.

Assessment of Vascular Dysfunction in Patients Without Obstructive Coronary Artery Disease: Why, How, and When

Ischemic heart disease secondary to coronary vascular dysfunction causes angina and impairs quality of life and prognosis. About one-half of patients with symptoms and signs of ischemia turn out not to have obstructive coronary artery disease, and coronary vascular dysfunction may be relevant. Adjunctive tests of coronary vasomotion include guidewire-based techniques with adenosine and reactivity testing, typically by intracoronary infusion of acetylcholine. The CorMicA (Coronary Microvascular Angina) trial provided evidence that routine management guided by an interventional diagnostic procedure and stratified therapy improves angina and quality of life in patients with angina but no obstructive coronary artery disease. In this paper, the COVADIS study group provide a comprehensive review of why, how, and when coronary vascular dysfunction should be assessed invasively. They discuss the rationale through a shared understanding of vascular pathophysiology and clinical evidence. They propose a consensus approach to how an interventional diagnostic procedure is performed with focus on practical aspects. Finally, the authors discuss the clinical scenarios in patients with stable and acute coronary syndromes in which measurement of coronary vascular function may be helpful for patient care.

Incidental Anomalous Left Coronary Artery in a Transplanted Heart

Anomalous coronary artery is an uncommon congenital cardiac anomaly that is often detected incidentally on coronary angiography. It has rarely been reported in the donor heart of patients who have undergone cardiac transplantation. Here, we report a case of a 72-year-old patient who received a second heart transplant and has been identified to have an anomalous left main coronary artery originating from the right coronary sinus on postoperative coronary angiography.

Endothelium-dependent and independent coronary microvascular dysfunction in patients with heart failure with preserved ejection fraction

BACKGROUND

Coronary microvascular inflammation is hypothesized to play a fundamental role in the pathophysiology of heart failure with preserved ejection fraction (HFpEF). No study has directly evaluated both endothelium-dependent and independent coronary microvascular function in HFpEF.

METHODS AND RESULTS

Consecutive patients with HFpEF undergoing invasive coronary physiologic testing and echocardiography were examined. Endothelial function was quantified by the increase in coronary blood flow in response to intracoronary infusion of acetylcholine (10^-6 -10^-4  mol/L) using a Doppler flow wire with quantitative angiography. Endothelium-independent coronary microvascular function was assessed by the hyperaemic increase in coronary flow reserve in response to adenosine infusion. Among 162 HFpEF patients (67% women), coronary microvascular function was abnormal in 117 (72%). Isolated endothelium-dependent microvascular dysfunction was present in 47 patients (29%), isolated endothelium-independent microvascular dysfunction in 53 patients (33%), and combined microvascular dysfunction in 17 patients (10%). The presence of coronary microvascular dysfunction was not identifiable from medical co-morbidities or other clinical characteristics. As compared to patients with normal endothelium-independent function, HFpEF patients with endothelium-independent coronary microvascular dysfunction displayed lower diastolic relaxation velocities (7.0 ± 1.8 vs. 8.4 ± 2.9 cm/s, P = 0.002) and higher estimated filling pressures (E/e' 13.1 ± 4.1 vs. 9.6 ± 3.4, P < 0.001). There were no relationships between left ventricular structure, function, or haemodynamics and endothelium-dependent coronary vasodilatation. Endothelium-independent microvascular dysfunction was associated with increased mortality.

CONCLUSIONS

Coronary microvascular dysfunction is common in patients with HFpEF and is caused equally by endothelium-dependent and independent mechanisms, but the presence of microvascular dysfunction cannot be identified from clinical markers and co-morbidities alone. Patients with HFpEF and endothelium-independent microvascular dysfunction display worse diastolic dysfunction and outcomes.