Spontaneous coronary artery spasm in variant angina is caused by a local hyperreactivity to a generalized constrictor stimulus

Noninvasive evaluation of dynamic microvascular dysfunction in ischemia and no obstructive coronary artery disease patients with suspected vasospasm

INTRODUCTION

In patients with ischemia and no obstructive coronary artery disease (INOCA), a dynamic coronary microvascular dysfunction (CMD) is frequent but difficult to capture by noninvasive means.The aim of our study was to assess dynamic CMD in INOCA patients with stress echocardiography after vasoconstrictive and vasodilator stimuli.

METHODS

In this prospective single-center study, we have enrolled 40 INOCA patients (age 56.3 ± 13 years, 32 women). All participants underwent stress echocardiography with hyperventilation (HYP), followed by supine bicycle exercise (HYP+EXE) and adenosine (ADO). Stress echocardiography included an assessment of regional wall motion abnormality (RWMA) and coronary flow velocity (CFV) in the distal left anterior descending (LAD) coronary artery.

RESULTS

HYP induced a 30% increase in rate pressure product (rest = 10 244 ± 2353 vs. HYP = 13 214 ± 3266 mmHg x bpm, P  < 0.001) accompanied by a paradoxical reduction in CFV (HYP< rest) in 21 patients (52%). HYP alone was less effective than HYP+EXE in inducing anginal pain (6/40, 15% vs. 10/40, 25%, P  = 0.046), ST segment changes (6/40, 15% vs. 24/40, 60%, P  < 0.001), and RWMA (6/40, 15% vs. 13/40, 32.5%, P  = 0.008). ADO-induced vasodilation was preserved (≥2.0) in all patients.

CONCLUSION

In patients with INOCA, a coronary vasoconstriction after HYP is common, in absence of structural CMD detectable with ADO. HYP+EXE test represents a more powerful ischemia inducer than HYP alone. Stress echocardiography with LAD-CFV may allow the noninvasive assessment of dynamic and structural coronary microcirculation during stress.

Vasospastic angina: Past, present, and future

Vasospastic angina (VSA) is characterized by episodes of rest angina that are responsive to short-acting nitrates and are attributable to coronary artery vasospasm. The condition is underdiagnosed as the provocation test is rarely performed. VSA, the most important component of non-obstructive coronary artery disease, can present with angina, be asymptomatic, or can even present with fatal arrhythmias and cardiac arrest. Although most patients with VSA respond well to vasodilating medications, prognosis does not improve as expected in most patients, suggesting the existence elusive prognostic factors and pathogenesis that warrant further exploration. Moreover, patients with either severe or refractory VSA barely respond to conventional treatment and may develop life-threatening arrhythmias or suffer sudden cardiac death during ischemic attacks, which are associated with immune-inflammatory responses and have been shown to achieve remission following glucocorticoid and immunoglobulin treatments. Our recent work revealed that inflammation plays a key role in the initiation and development of coronary spasms, and that inflammatory cytokines have predictive value for diagnosis. In contrast to the existing literature, this review both summarizes the theoretical and clinical aspects of VSA, and also discusses the relationship between inflammation, especially myocarditis and VSA, in order to provide novel insights into the etiology, diagnosis, and treatment of VSA.

Mechanisms of Coronary Artery Spasm

Recent clinical trials have highlighted that percutaneous coronary intervention in patients with stable angina provides limited additional benefits on top of optimal medical therapy. This has led to much more attention being paid to coronary vasomotion abnormalities regardless of obstructive or non-obstructive arterial segments. Coronary vasomotion is regulated by multiple mechanisms that include the endothelium, vascular smooth muscle cells (VSMCs), myocardial metabolic demand, autonomic nervous system and inflammation. Over the years, several animal models have been developed to explore the central mechanism of coronary artery spasm. This review summarises the landmark studies on the mechanisms of coronary vasospasm demonstrating the central role of Rho-kinase as a molecular switch of VSMC hypercontraction and the important role of coronary adventitial inflammation for Rho-kinase upregulation in VSMCs.

Management of vasospastic angina

Vasospastic angina is a well-established cause of chest pain that is caused by coronary artery spasm. It can be clinically diagnosed during a spontaneous episode by documenting nitrate-responsive rest angina with associated transient ischaemic ECG changes but more often requires provocative coronary spasm testing with acetylcholine during coronary angiography. Vasospastic angina may result in recurrent episodes of angina (including nocturnal angina), which can progress on to major adverse cardiac events. Calcium channel blockers are first-line therapy for this condition, given their anti-anginal and cardioprotective benefits. Despite an established diagnostic and therapeutic management pathway for vasospastic angina, this diagnosis is often overlooked in patients presenting with chest pain. Thus, there is need for increased clinical awareness of vasospastic angina to improve outcomes in affected patients.

Phenotype-based management of coronary microvascular dysfunction

40-70% of patients undergoing invasive coronary angiography with signs and symptoms of ischemia are found to have no obstructive coronary artery disease (INOCA). When this heterogeneous group undergo coronary function testing, approximately two-thirds have demonstrable coronary microvascular dysfunction (CMD), which is independently associated with adverse prognosis. There are four distinct phenotypes, or subgroups, each with unique pathophysiological mechanisms and responses to therapies. The clinical phenotypes are microvascular angina, vasospastic angina, mixed (microvascular and vasospastic), and non-cardiac symptoms (reclassification as non-INOCA). The Coronary Vasomotor Disorders International Study Group (COVADIS) have proposed standardized criteria for diagnosis. There is growing awareness of these conditions among clinicians and within guidelines. Testing for CMD can be done using invasive or non-invasive modalities. The CorMicA study advocates the concept of 'functional angiography' to guide stratified medical therapy. Therapies broadly fall into two categories: those that modulate cardiovascular risk and those to alleviate angina. Management should be tailored to the individual, with periodic reassessment for efficacy. Phenotype-based management is a worthy endeavor for both patients and clinicians, aligning with the concept of 'precision medicine' to improve prognosis, symptom burden, and quality of life. Here, we present a contemporary approach to the phenotype-based management of patients with INOCA.

Inferior STEMI Electrocardiogram in a Young Postpartum Female with Sickle Cell Trait with Chest Pain - A Case Report

This is a case of a 35-year-old postpartum female presenting to the emergency department (ED) with acute onset chest pain and dyspnea with initial concern for acute ST-segment elevation myocardial infarct (STEMI). Her electrocardiogram (ECG) showed ST segment elevations in the lateral leads and inferior leads with depressions in the high lateral and septal leads. Given her post-partum status, spontaneous coronary artery dissection (SCAD) was part of the differential as well as other emergent processes. Upon cardiac catheterization, the patient was found to have 50% vasospasm in the left circumflex coronary artery. Her post-catheterization echocardiogram showed a normal ejection fraction (EF) without regional wall abnormalities. This is an interesting case of chest pain in a younger patient, without typical acute coronary syndrome (ACS) risk factors, presenting with a concerning ECG likely due to coronary vasospasm. We will discuss other atypical causes of STEMI patterns that should be considered in the differential and management of such patients.

Topics

Sickle cell trait, STEMI, postpartum, vasospasm, ECG, cardiology.

MINOCA: One Size Fits All? Probably Not—A Review of Etiology, Investigation, and Treatment

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a heterogeneous group of conditions that include both atherosclerotic (coronary plaque disruption) and non-atherosclerotic (spontaneous coronary artery dissection, coronary artery spasm, coronary artery embolism, coronary microvascular dysfunction, and supply–demand mismatch) causes resulting in myocardial damage that is not due to obstructive coronary artery disease. Failure to identify the underlying cause may result in inadequate and inappropriate therapy in these patients. The cornerstone of managing MINOCA patients is to identify the underlying mechanism to achieve the target treatment. Intravascular imaging is able to identify different morphologic features of coronary plaques, while cardiac magnetic resonance is the gold standard for detection of myocardial infarction in the setting of MINOCA. In this review, we summarize the relevant clinical issues, contemporary diagnosis, and treatment options of MINOCA.

Prognostic Impact of Chronic Vasodilator Therapy in Patients With Vasospastic Angina

Background

Chronic vasodilator therapy with long‐acting nitrate is frequently used to treat vasospastic angina. However, the clinical benefits of this approach are controversial. We investigated the prognostic impact of vasodilator therapy in patients with vasospastic angina from the multicenter, prospective VA‐KOREA (Vasospastic Angina in KOREA) registry.

Methods and Results

We analyzed data from 1895 patients with positive intracoronary ergonovine provocation test results. The patients were divided into 4 groups: no vasodilator (n=359), nonnitrate vasodilator (n=1187), conventional nitrate (n=209), and a combination of conventional nitrate and other vasodilators (n=140). The primary end point was a composite of cardiac death, acute coronary syndrome, and new‐onset arrhythmia at 2 years. Secondary end points were the individual components of the primary end point, all‐cause death, and rehospitalization due to recurrent angina.

The groups did not differ in terms of the risk of the primary end point. However, the acute coronary syndrome risk was significantly higher in the conventional nitrate (hazard ratio [HR], 2.49; 95% CI, 1.01–6.14; P=0.047) and combination groups (HR, 3.34; 95% CI, 1.15–9.75, P=0.027) compared with the no‐vasodilator group, as assessed using the inverse probability of treatment weights. Subgroup analyses revealed prominent adverse effects of nitrate in patients with an intermediate positive ergonovine provocation test result and in those with low Japanese Coronary Spasm Association scores.

Conclusions

Long‐acting nitrate‐based chronic vasodilator therapy was associated with an increased 2‐year risk of acute coronary syndrome in patients with vasospastic angina, especially in low‐risk patients.

The Role of Antiplatelet Therapy in Patients With MINOCA

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

Inferior Myocardial Infarction Secondary to Coronary Artery Vasospasm Following Regadenoson Stress Imaging

Coronary artery vasospasm is a rare condition that is caused by hyperactive arterial smooth muscle vasoconstriction leading to reversible coronary artery occlusion. Patients that suffer from coronary artery vasospasm have the potential to develop life-threatening conditions such as myocardial infarction and fatal arrhythmias. ST-elevations are a rare complication that can occur in people with coronary vasospasm, and to the best of our knowledge there are no documented cases of ST-elevation myocardial infarction occurring in patients undergoing regadenoson stress test. We present a unique case of a patient with known coronary artery disease and catheter-induced coronary artery vasospasm who developed ST-segment elevations and typical angina immediately following the administration of regadenoson during an elective myocardial stress test.

Clinical presentation and management of myocardial infarction with nonobstructive coronary arteries (MINOCA): A literature review

Myocardial Infarction with Nonobstructive Coronary Arteries (MINOCA), as the name implies, is an acute myocardial infarction (MI) in the absence of significant coronary artery obstruction. Diagnosis and management of such cases have been challenging. There are many etiologies of MINOCA including coronary artery spasm, coronary microvascular dysfunction, plaque disruption, spontaneous coronary thrombosis or emboli, spontaneous coronary artery dissection, or cardiomyopathies. In this paper, the pathophysiology, diagnostic work-up, and clinical management for each subtype are described, and an overarching approach on how to evaluate and manage a patient presenting with MINOCA.

Pathophysiology and Diagnosis of Coronary Functional Abnormalities

Approximately one-half of patients undergoing diagnostic coronary angiography for angina have no significant coronary atherosclerotic stenosis. This clinical condition has recently been described as ischaemia with non-obstructive coronary arteries (INOCA). Coronary functional abnormalities are central to the pathogenesis of INOCA, including epicardial coronary spasm and coronary microvascular dysfunction composed of a variable combination of increased vasoconstrictive reactivity and/or reduced vasodilator function. During the last decade - in INOCA patients in particular - evidence for the prognostic impact of coronary functional abnormalities has accumulated and various non-invasive and invasive diagnostic techniques have enabled the evaluation of coronary vasomotor function in a comprehensive manner. In this review, the authors briefly summarise the recent advances in the understanding of pathophysiology and diagnosis of epicardial coronary artery spasm and coronary microvascular dysfunction.

Coronary Artery Spasm: New Insights

Coronary artery spasm (CAS) defined by a severe reversible diffuse or focal vasoconstriction is the most common diagnosis among INOCA (ischemia with no obstructive coronary artery disease) patients irrespective to racial, genetic, and geographic variations. However, the prevalence of CAS tends to decrease in correlation with the increasing use of medicines such as calcium channel blockers, angiotensin converting enzyme inhibitor, and statins, the controlling management of atherosclerotic risk factors, and the decreased habitude to perform a functional reactivity test in highly active cardiac catheterization centers. A wide spectrum of clinical manifestations from silent disease to sudden cardiac death was attributed to this complex entity with unclear pathophysiology. Multiple mechanisms such as the autonomic nervous system, endothelial dysfunction, chronic inflammation, oxidative stress, and smooth muscle hypercontractility are involved. Regardless of the limited benefits proffered by the newly emerged cardiac imaging modalities, the provocative test remains the cornerstone diagnostic tool for CAS. It allows to reproduce CAS and to evaluate reactivity to nitrates. Different invasive and noninvasive therapeutic approaches are approved for the management of CAS. Long-acting nondihydropyridine calcium channel blockers are recommended for first line therapy. Invasive strategies such as PCI (percutaneous coronary intervention) and CABG (coronary artery bypass graft) have shown benefits in CAS with significant atherosclerotic lesions. Combination therapies are proposed for refractory cases.

Diagnostic Utility and Pathogenic Role of Circulating MicroRNAs in Vasospastic Angina

We investigated the diagnostic value and pathophysiological role of circulating microRNA (miR) in vasospastic angina (VA). We enrolled patients who underwent coronary angiography for chest pain to explore the miR’s diagnostic utility. In addition, we investigated the role of miRs in regulating endothelial nitric oxide synthase (eNOS) expression in human coronary artery endothelial cells (hCAECs). Among the 121 patients, 46 were diagnosed with VA (VA group), 26 with insignificant coronary lesions (ICL group), and 49 with atherothrombotic angina (AA group). The VA group showed a significantly higher expression of miR-17-5p, miR-92a-3p, and miR-126-3p than the ICL group. In contrast, miR-221-3p and miR-222-3p were upregulated in the AA group compared to the VA group, and all levels of miR-17-5p, miR-92a-3p, miR-126-3p, miR-145-5p, miR-221-3p, and miR-222-3p differed between the AA group and the ICL group. In the hCAECs, transfection with mimics (pre-miR) of miR-17-5p, miR-92a-3p, and miR-126-3p was associated with eNOS suppression. Additionally, transfection with inhibitors (anti-miR) of miR-92a-3p significantly rescued the eNOS suppression induced by lipopolysaccharide. In conclusion, the circulating miRs not only proved to have diagnostic utility, but also contributed to pathogenesis by eNOS regulation.

Coronary Artery Spasm: The Interplay Between Endothelial Dysfunction and Vascular Smooth Muscle Cell Hyperreactivity

Patients with angina pectoris, the cardinal symptom of myocardial ischaemia, yet without significant flow-limiting epicardial artery stenosis represent a diagnostic and therapeutic challenge. Coronary artery spasm (CAS) is an established cause for anginal chest pain in patients with angiographically unobstructed coronary arteries. CAS may occur at the epicardial level and/or in the microvasculature. Although the underlying pathophysiological mechanisms of CAS are still largely unclear, endothelial dysfunction and vascular smooth muscle cell (VSMC) hyperreactivity seem to be involved as major players, although their contribution to induce CAS is still seen as controversial. This article will look at the role and possible mechanistic interplay between an impaired endothelial and VSMC function in the pathogenesis of CAS.

Severe Prinzmetal's Angina Inducing Ventricular Fibrillation Cardiac Arrest

Prinzmetal's angina is a vascular spasm of the coronary artery that can mimic acute coronary syndrome. It is rarely responsible for ventricular arrhythmias and cardiac arrest; however, survivors with these complications are at increased risk for recurrent ventricular arrhythmias and sudden cardiac death. This is true despite the presence of normal cardiac function and optimal medical therapy. Thus, this select population should be considered for an implantable cardioverter defibrillator (ICD). In this case vignette, we describe a healthy 48-year-old female with ventricular fibrillation arrest, followed by recurrent ventricular tachyarrhythmias caused by Prinzmetal's angina.

Vasospastic Angina and Role of Cardiac Catheterization

Prinzmetal angina, also known as vasospastic or variant angina, is defined as an intermittent focal coronary artery spasm often associated with an atherosclerotic lesion near the site of spasm. It is caused by a focal or diffuse spasm of the smooth layer of the arterial wall of an epicardial coronary artery. Acute infarctions or malignant arrhythmias may develop during spasm-induced ischemia. Evaluation includes observation of echocardiogram (EKG) for transient ST elevations during discomfort; diagnosis is confirmed with coronary angiography using provocative testing. We describe two cases of patients who presented for non-cardiac complaints, but had episodes of vasospastic angina during their hospitalization. Both underwent cardiac catheterization with differing results, demonstrating the importance of catheterization in patients who experience vasospastic angina.

Effect of sarpogrelate and high-dose statin on the reduction of coronary spasm in vasospastic angina: A two by two factorial, pilot randomized study

Background

Vasospastic angina (VSA) is characterized by coronary spasm, which can be aggravated by vasoactive substances such as serotonin. Hypothesis Sarpogrelate, a selective serotonin receptor antagonist, and high‐dose statin have some effects on the reduction of coronary spasm in patients with VSA.

Methods

We recruited 100 patients with angiographically confirmed VSA, and randomly assigned them into four groups: sarpogrelate with high‐dose statin (Group A, n = 25), sarpogrelate with low‐dose or no statin (Group B, n = 25), placebo with high‐dose statin (Group C, n = 25), and placebo with low‐dose or no statin (Group D, n = 25). The primary endpoint was the remission of coronary spasm on 1‐year follow‐up provocation test.

Results

The most common site of coronary spasm was left anterior descending artery (42%). Most patients (96%) took calcium channel blockers, and 46% were treated with vasodilators. Overall, 40% of patients reported no chest pain at 1 year, and 23% showed complete remission of coronary spasm on 1‐year follow‐up provocation test. No difference was observed in symptomatic and angiographically complete remission rate between the sarpogrelate and the placebo group. Although the apolipoprotein B level at the 1‐year follow‐up was significantly lower in the high‐dose statin group, symptomatic and angiographic outcomes were not different according to statin intensity. Distal thrombolysis in myocardial infarction (TIMI) flow on initial provocation test was independently associated with angiographically complete remission.

Conclusions

Sarpogrelate or high‐dose statin did not significantly improve the angiographic remission rate in patients with VSA. Distal TIMI flow on initial provocation test could predict the complete remission of coronary spasm at follow‐up.

Modeling the effects of muscle contraction on the mechanical response and circumferential stability of coronary arteries

Smooth muscle contraction regulates the size of the blood vessel lumen which directly affects the mechanical response of the vessel. Folding in arteries has been observed in arteries during excessive contraction, known as a coronary artery spasm. The interplay of muscle contraction, geometry, and material responses and their effects on stability can be understood through mathematical models. Here, we consider a three-layer cross-sectional model of a coronary artery with anisotropic properties and intimal thickening, and perform a linear stability analysis to investigate the circumferential folding patterns that emerge due to muscle contraction. Our model shows that a critical level of contractile activity yields a uniform strain distribution across the arterial wall. When the muscle is contracted above this critical level, the tissue behaves isotropically and it is more prone to circumferential instability. This theoretical framework could serve as a valuable tool to understand the relationship between arterial lumen morphology and wall contraction in health and disease.

Association between Ischemic Electrocardiographic Changes during Acetylcholine Provocation Test and Long-Term Clinical Outcomes in Patients with Vasospastic Angina

Objectives Intracoronary injection of acetylcholine (Ach) has been shown to induce significant coronary artery spasm (CAS) in patients with vasospastic angina. Clinical significance and angiographic characteristics of patients with ischemic electrocardiogram (ECG) changes during the Ach provocation test are not clarified yet. Methods A total 4,418 consecutive patients underwent coronary angiography with Ach provocation tests from 2004 to 2012 were enrolled. Ischemic ECG changes were defined as transient ST-segment depression or elevation ( &gt; 1 mm) and T inversion with/without chest pain. Finally, a total 2,293 patients (28.5% of total subjects) proven CAS were enrolled for this study. Results A total 119 patients (5.2%) showed ECG changes during Ach provocation tests. The baseline clinical and procedural characteristics are well balanced between the two groups. Ischemic ECG change group showed more frequent chest pain, higher incidence of baseline spasm, severe vasospasm, multi-vessel involvement, and more diffuse spasm ( &gt; 30 mm) than those without ischemic ECG changes. At 5 years, the incidences of death, major adverse cardiac events (MACE) and major adverse cardiac and cerebral events (MACCE) were higher in the ischemic ECG change group despite of optimal medical therapy. Conclusions The patients with ischemic ECG changes during Ach provocation tests were associated with more frequent chest pain, baseline spasm, diffuse, severe and multi-vessel spasm than patients without ischemic ECG changes. At 5-years, the incidences of death, MACE and MACCE were higher in the ischemic ECG change group, suggesting more intensive medical therapy with close clinical follow up will be required.

Clinical outcome according to spasm type of single coronary artery provoked by intracoronary ergonovine tests in patients without significant organic stenosis

BACKGROUND

This study aimed to evaluate clinical implications of single vessel coronary spasm provoked by intracoronary ergonovine provocation test in Korean population.

METHOD

A total of 1248 patients who presented with single vessel coronary artery spasm induced by intracoronary ergonovine provocation test, excluding 1712 with negative spasms, multiple and mixed coronary artery spasms and missing data among 2960 patients in the VA-KOREA (Vasospastic Angina in Korea) registry, were classified into diffuse (n=705) and focal (n=543) groups.

RESULTS

The 24-month incidences of a composite primary endpoints (cardiac death, new-onset arrhythmia, and acute coronary syndrome) were determined. Over a median follow-up of 30months, the composite primary end point occurred more frequently in the focal type patients than in the diffuse type patients (primary endpoint: adjusted hazard ratio [aHR], 1.658; 95% confidence interval [CI] 1.272 to 2.162, P<0.001). Especially, unstable angina in ACS components played a major role in this effect (hazard ratio [HR], 2.365; 95% confidence interval [CI] 1.100 to 5.087, P=0.028).

CONCLUSION

Focal type of single vessel coronary artery spasm in vasospastic angina (VSA) patients is found to be associated with worse clinical outcomes. It is thought that the effect is stemmed from unstable angina among ACS rather than the other components of primary endpoint. Therefore, focal type of single vessel coronary artery spasm in patients with VSA should be more carefully assessed and managed with appropriate medication.

Variant Angina and Aborted Sudden Cardiac Death

PURPOSE OF REVIEW

Variant angina, which is characterized by recurrent chest pain and transient ECG changes along with angiographic evidence of coronary artery spasm, generally has a favorable prognosis. However, episodes of ischemia caused by vasospasm may lead to potentially life-threatening ventricular arrhythmias and cardiac arrest, even in patients with no history of prior cardiac disease. This review describes the epidemiology, pathogenesis, clinical spectrum, and management of variant angina, as well as outcomes in patients who present with aborted sudden cardiac death (ASCD).

RECENT FINDINGS

Contrary to prior opinions, evidence from recent observational studies indicate that patients with variant angina presenting with ASCD face a worse prognosis than those without this type of presentation. Predictors of ASCD include age, hypertension, hyperlipidemia, family history of sudden cardiac death, multi-vessel spasm, and left anterior descending artery spasm. Medical therapy alone with calcium channel blockers and nitrates may not be sufficiently protective in these patients and there is lack of concrete data on the optimal management strategy. Current guidelines recommend implantable cardiac defibrillator (ICD) therapy in patients who are survivors of cardiac arrest caused by ventricular fibrillation or unstable ventricular tachycardia after reversible causes are excluded, and should strongly be considered in these patients. Although medical therapy is absolutely imperative for patients with variant angina and a history of ASCD, ICD therapy in these patients is justified. Further large-scale studies are required to determine whether ICD therapy can improve survival in this high-risk group of patients.

Acute Coronary Syndromes: The Way Forward From Mechanisms to Precision Treatment

Well into the 21st century, we still triage acute myocardial infarction on the basis of the presence or absence of ST-segment elevation, a century-old technology. Meanwhile, we have learned a great deal about the pathophysiology and mechanisms of acute coronary syndromes (ACS) at the clinical, pathological, cellular, and molecular levels. Contemporary imaging studies have shed new light on the mechanisms of ACS. This review discusses these advances and their implications for clinical management of the ACS for the future. Plaque rupture has dominated our thinking about ACS pathophysiology for decades. However, current evidence suggests that a sole focus on plaque rupture vastly oversimplifies this complex collection of diseases and obscures other mechanisms that may mandate different management strategies. We propose segmenting coronary artery thrombosis caused by plaque rupture into cases with or without signs of concomitant inflammation. This distinction may have substantial therapeutic implications as direct anti-inflammatory interventions for atherosclerosis emerge. Coronary artery thrombosis caused by plaque erosion may be on the rise in an era of intense lipid lowering. Identification of patients with of ACS resulting from erosion may permit a less invasive approach to management than the current standard of care. We also now recognize ACS that occur without apparent epicardial coronary artery thrombus or stenosis. Such events may arise from spasm, microvascular disease, or other pathways. Emerging management strategies may likewise apply selectively to this category of ACS. We advocate this more mechanistic approach to the categorization of ACS to provide a framework for future tailoring, triage, and therapy for patients in a more personalized and precise manner.

Echocardiographic Epicardial Adipose Tissue Thickness Is Associated with Symptomatic Coronary Vasospasm during Provocative Testing

BACKGROUND

Epicardial adipose tissue (EAT) is the ectopic visceral fat surrounding the heart, which plays an important role in atherosclerosis of the coronary arteries via endothelial damage. Several studies have also suggested that vasospasm with angina (VSA) causes endothelial dysfunction in the coronary arteries. The aim of this study was to evaluate the thickness of EAT in the anterior interventricular groove (EAT-AIG) using echocardiography in patients who had no obstructive coronary artery disease and were suspected of having VSA.

METHODS

Sixty-five patients who underwent intracoronary acetylcholine provocation testing for clinical indications were prospectively enrolled. VSA was diagnosed by coronary artery stenosis increase of >90% and the presentation of chest pain with ischemic changes on electrocardiography.

RESULTS

Subjects were divided into two groups, with and without significant coronary spasm (VSA group, 30 patients; non-VSA group, 35 patients), consistent with acetylcholine provocation testing. EAT-AIG thickness was significantly greater in the VSA group than in the non-VSA group (8.2 ± 2.7 vs 6.1 ± 2.5 mm, P = .002). By receiver operating characteristic analysis, EAT-AIG thickness had a high C statistic (area under the curve = 0.81, P < .001) after adjustment for conventional risk factors (smoking, diabetes mellitus, and dyslipidemia). EAT-AIG thickness had incremental diagnostic value over other conventional risk factors (area under the curve = 0.81 vs 0.64, P for comparison = .020).

CONCLUSIONS

EAT-AIG thickness, which is noninvasively and easily measured using transthoracic echocardiography, can be one of multiple clinical variables associated with VSA.

Management standards for stable coronary artery disease in India

Coronary artery disease (CAD) is one of the important causes of cardiovascular morbidity and mortality globally, giving rise to more than 7 million deaths annually. An increasing burden of CAD in India is a major cause of concern with angina being the leading manifestation. Stable coronary artery disease (SCAD) is characterised by episodes of transient central chest pain (angina pectoris), often triggered by exercise, emotion or other forms of stress, generally triggered by a reversible mismatch between myocardial oxygen demand and supply resulting in myocardial ischemia or hypoxia. A stabilised, frequently asymptomatic phase following an acute coronary syndrome (ACS) is also classified as SCAD. This definition of SCAD also encompasses vasospastic and microvascular angina under the common umbrella.

Phosphorylated Myosin Light Chain 2 (p-MLC2) as a Molecular Marker of Antemortem Coronary Artery Spasm

Background

It is not uncommon that only mild coronary artery stenosis is grossly revealed after a system autopsy. While coronary artery spasm (CAS) is the suspected mechanism of these deaths, no specific biomarker has been identified to suggest antemortem CAS.

Material/Methods

To evaluate the potential of using phosphorylated myosin light chain 2 (p-MLC2) as a diagnostic marker of antemortem CAS, human vascular smooth muscle cells (VSMCs) were cultured and treated with common vasoconstrictors, including prostaglandins F2α (PGF2α), acetylcholine (ACh), and 5-hydroxy tryptamine (5-HT). The p-MLC2 level was examined in the cultured cells using Western blot analysis and in a rat model of spasm provocation tests using immunohistochemistry (IHC). Effects of increased p-MLC2 level on VSMCs contractile activities were assessed in vitro using confocal immunofluorescence assay. Four fatal cases with known antemortem CAS were collected and subject to p-MLC2 detection.

Results

The p-MLC2 was significantly increased in VSMCs after treatments with vasoconstrictors and in the spasm provocation tests. Myofilament was well-organized and densely stained in VSMCs with high p-MLC2 level, but disarrayed in VSMCs with low p-MLC2 level. Three of the 4 autopsied cases showed strongly positive staining of p-MLC2 at the stenosed coronary segment and the adjacent interstitial small arteries. The fourth case was autopsied at the 6th day after death and showed negative-to-mild positive staining of p-MLC2.

Conclusions

p-MLC2 might be a useful marker for diagnosis of antemortem CAS. Autopsy should be performed as soon as possible to collect coronary arteries for detection of p-MLC2.

Vasotonic Angina as a Cause of Myocardial Ischemia in Women

The frequency, presentation, prognosis, and treatment of myocardial ischemia differ in men and women. A large proportion of women who have "normal" coronary arteries on angiography without any significant evidence of flow-limiting disease also have biochemical or imaging evidence of myocardial ischemia. In these women it is believed to be a dysfunction of coronary microcirculation and/or macrocirculation, or vasotonic angina (VA), that leads to abnormal vasoconstriction, and potentially to myocardial infarction, ventricular arrhythmias, and sudden death. Despite having a "normal" or near normal coronary angiography, these women should therefore undergo additional testing with acetylcholine to assess endothelial function. Long-term survival is believed to be relatively good. Predictors of poorer prognosis include documentation of severe endothelial dysfunction and presence of concurrent angiographycally visible coronary atherosclerosis. Because atherosclerosis is common in patients with VA, medical and lifestyle interventions for preventing or treating atherosclerosis should be implemented when appropriate. Angiotensin converting enzyme inhibitors are the mainstays of medical therapy for VA. Other agents have been tried with variable success, including beta-blockers. There are no available data on any specific treatment of VA in women (versus men).

Coronary artery spasm: Is ST-elevation key for diagnosis?

Coronary vasospasm is uncommon during pregnancy and the postpartum period. We present a very rare case of an acute coronary vasospasm in a 36-year-old woman who was two weeks postpartum. The coronary arteriograms showed a coronary vasospasm in the distal left anterior descending and circumflex coronary arteries. Electrocardiogram (ECG) presentation was atypical, with T-wave inversions in leads I, aVL, and V2 to V6. To our knowledge, this is the first case with a well-documented coronary artery vasospasm in a postpartum woman without the classic ST elevation on ECG. Management should follow the usual principles of care for acute coronary vasospasm.

Evaluation of Coronary Artery Status by Coronary Angiography after First Survival of Acute Myocardial Infarction

INTRODUCTION

Acute Myocardial Infarction (AMI) is a life threatening medical emergency which needs urgent medical attention. It is one of the major cause of mortality and morbidity throughout the world.

AIM

The aim of the present study was to assess the coronary artery status by Coronary Angiography (CAG) after first survival of the Acute Myocardial Infarction (AMI) and to correlate the CAG findings with Coronary Artery Disease (CAD) Risk Factor (RF) and effect of early thrombolysis.

MATERIALS AND METHODS

CAG was done on 870 patients consecutively from June 2013 to May 2015. Age, Gender, Body Mass Index (BMI), CAD risk factors (RF) such as Type 2 diabetes mellitus (T2 DM), hypertension, dyslipidaemia, smoking status and history of thrombolyctic status were recorded. The correlation between the CAD risk factors (RF) and the CAG findings were statistically analyzed.

RESULTS

Coronary heart disease risk factors analysis revealed ≥ three RF in 23.88%, two RF in 29.88% and one RFin 45.86% of patients. CAG showed Single Vessel Disease (SVD) in 236 (27.1%) patients, double vessel disease (DVD) in 220(25.2%) patients, Triple Vessel Disease (TVD) in 252 (28.9%) patients. Multiple coronary artery involvement were found in the high risk group patients, which was found statistically significant (p-value<0.0001). A total of 348/870 (40%) patients were thrombolysed amongst them 80 (22.9%) revealed minimal and/or normal coronary artery which was found statistically significant (p-value<0.0001).

CONCLUSION

Higher the coronary risk factors, more the chance of the multiple coronary arteries involvement. All AMI patients should be thrombolysed as early as possible to get the benefit of recanalization of the culprit vessel.

Coronary artery spasm: Current knowledge and residual uncertainties

Myocardial ischaemia results from a direct mismatch between oxygen supply and demand, commonly arising as a result of coronary atherosclerosis, microvascular dysfunction or acute thrombosis and luminal obstruction. However, transient ischaemia may also occur due to coronary spasm leading to acute and unexpected myocardial ischaemia without obvious visible coronary pathology. Aside from symptoms of chest pain, coronary spasm can cause infarction, LV impairment, promote life threatening arrhythmias and ultimately sudden cardiac death. While therapeutic options are available, controversies exist around diagnosis, pathology, management and prognosis. This review summarises some of the common questions in this area. In particular we explore and discuss the available evidence for the pharmacological treatment of coronary spasm, and strategies for identification and management of very high risk patients to try and reduce the incidence of sudden premature death.

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Myocardial ischaemia results from a mismatch between oxygen supply and demand.

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Spasm might lead to myocardial ischaemia without visible coronary pathology.

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Coronary spasm can cause infarction, LV impairment and sudden cardiac death.

Ventricular fibrillation due to coronary vasospasm

A 43-year-old woman developed a sudden-onset severe chest pain and breathlessness at home. She collapsed within minutes and received bystander cardiopulmonary resuscitation from her husband. On arrival, the paramedics identified ventricular fibrillation requiring defibrillation. She was admitted to the intensive care unit for observation. A coronary angiogram performed at our hospital demonstrated non-obstructive disease of the right coronary artery. Her antidepressant medications were discontinued and she was discharged. No specific cause was found for the arrhythmia and collapse. One week later, she developed similar chest pain. An ECG showed transient ST-elevation in the inferior leads. Symptoms and ECG changes resolved with sublingual nitroglycerin. During the course of a repeat coronary angiogram the patient developed severe spasm of the right coronary artery associated with typical chest pain and ST-elevation in the inferior leads. She was treated with insertion of a drug-eluting stent and a cardiac defibrillator.

Provocative testing for coronary reactivity and spasm

Coronary spasm is an important and often overlooked etiology of chest pain. Although coronary spasm, or Prinzmetal's angina, has been thought of as benign, contemporary studies have shown serious associated adverse outcomes, including acute coronary syndrome, arrhythmia, and death. Definitive diagnosis of coronary spasm can at times be difficult, given the transience of symptoms. Numerous agents have been historically described for provocative testing. We provide a review of published data for the role of provocation testing in the diagnosis of coronary spasm.

Coronary artery spasm: review and update

Coronary artery spasm (CAS), an intense vasoconstriction of coronary arteries that causes total or subtotal vessel occlusion, plays an important role in myocardial ischemic syndromes including stable and unstable angina, acute myocardial infarction, and sudden cardiac death. Coronary angiography and provocative testing usually is required to establish a definitive diagnosis. While the mechanisms underlying the development of CAS are still poorly understood, CAS appears to be a multifactorial disease but is not associated with the traditional risk factors for coronary artery disease. The diagnosis of CAS has important therapeutic implications, as calcium antagonists, not β-blockers, are the cornerstone of medical treatment. The prognosis is generally considered benign; however, recurrent episodes of angina are frequently observed. We provide a review of the literature and summarize the current state of knowledge regarding the pathogenesis of CAS.

Significant Response to Lower Acetylcholine Dose Is Associated with Worse Clinical and Angiographic Characteristics in Patients with Vasospastic Angina

Background and Objectives

Subjects and Methods

Results

Conclusion

A series of unfortunate events: prinzmetal angina culminating in transmural infarction in the setting of acute gastrointestinal hemorrhage

Prinzmetal angina or vasospastic angina is a clinical phenomenon that is often transient and self-resolving. Clinically it is associated with ST elevations on the electrocardiogram, and initially it may be difficult to differentiate from an acute myocardial infarction. The vasospasm induced in this setting occurs in normal or mildly to moderately diseased vessels and can be triggered by a number of etiologies including smoking, changes in autonomic activity, or drug ingestion. While the ischemia induced is usually transient, myocardial infarction and life-threatening arrhythmias can occur in 25% of cases. We present the case of a 65-year-old female where repetitive intermittent coronary vasospasm culminated in transmural infarction in the setting of gastrointestinal bleeding. This case highlights the mortality associated with prinzmetal angina and the importance of recognizing the underlying etiology.

Impairment of the extrusion transporter for asymmetric dimethyl-L-arginine: a novel mechanism underlying vasospastic angina

A 37-year old male patient presented with frequent angina attacks (up to 40/day) largely resistant to classical vasodilator therapy. The patient showed severe coronary and peripheral endothelial dysfunction, increased platelet aggregation and increased platelet-derived superoxide production. The endothelial nitric oxide synthase (eNOS)-inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME) reduced superoxide formation in platelets identifying "uncoupled" eNOS as a superoxide source. Oral L-arginine normalized coronary and peripheral endothelial dysfunction and reduced platelet aggregation and eNOS-derived superoxide production. Plasma concentrations of the endogenous NOS inhibitor asymmetric dimethyl-L-arginine (ADMA), representing an independent risk factor for cardiovascular disease, were normal in the patient. However, immediately after oral administration of cationic amino acid (CAA), plasma ADMA levels rose markedly, demonstrating increased ADMA efflux from intracellular stores. ADMA efflux from mononuclear cells of the patient was accelerated by CAA, but not neutral amino acids (NAA) demonstrating impairment of y(+)LAT (whose expression was found reduced in these cells). These data suggest that impairment of y(+)LAT may cause intracellular (endothelial) ADMA accumulation leading to systemic endothelial dysfunction. This may represent a novel mechanism underlying vasospastic angina and vascular dysfunction in general. Moreover, these new findings contribute to the understanding of the l-arginine paradox, the improvement of eNOS activity by oral L-arginine despite sufficient cellular l-arginine levels to ensure proper function of this enzyme.