The pathophysiology and clinical course of the normal coronary angina syndrome (cardiac syndrome X). Prog Cardiovasc Dis. 2008;50:294-310. [PMID: 18156008 DOI: 10.1016/j.pcad.2007.01.003]

Nonobstructive epicardial coronary artery disease: an evolving concept in need of diagnostic and therapeutic guidance

For decades, we have been treating patients presenting with angina and concerning electrocardiographic changes indicative of ischemia or injury, in whom no culprit epicardial coronary stenosis was found during diagnostic coronary angiography. Unfortunately, the clinical outcomes of these patients were not better than those with recognized obstructive coronary disease. Improvements in technology have allowed us to better characterize these patients. Consequently, an increasing number of patients with ischemia and no obstructive coronary artery disease (INOCA) or myocardial infarction in the absence of coronary artery disease (MINOCA) have now gained formal recognition and are more commonly encountered in clinical practice. Although both entities might share functional similarities at their core, they pose significant diagnostic and therapeutic challenges. Unless we become more proficient in identifying these patients, particularly those at higher risk, morbidity and mortality outcomes will not improve. Though this field remains in constant flux, data continue to become available. Therefore, we thought it would be useful to highlight important milestones that have been recognized so we can all learn about these clinical entities. Despite all the progress made regarding INOCA and MINOCA, many important knowledge gaps continue to exist. For the time being, prompt identification and early diagnosis remain crucial in managing these patients. Even though we are still not clear whether intensive medical therapy alters clinical outcomes, we remain vigilant and wait for more data.

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.

Role of different echocardiographic modalities in the assessment of microvascular function in women with ischemia and no obstructive coronary arteries

This review summarizes current knowledge about echocardiographic modalities used to assess microvascular function and left ventricular (LV) systolic function in women with ischemia and no obstructive coronary arteries (INOCA). Although the entire pathophysiological background of this clinical entity still remains elusive, it is primarily linked to microvascular dysfunction which can be assessed by coronary flow velocity reserve. Subtle impairments of LV systolic function in women with INOCA are difficult to assess by interpretation of wall motion abnormalities. LV longitudinal function impairment is considered to be an early marker of subclinical systolic dysfunction and can be assessed by global longitudinal strain quantification.

Risk Factors Predisposing to Angina in Patients with Non-Obstructive Coronary Arteries: A Retrospective Analysis

No hemodynamically significant atherosclerotic plaques are observed in up to 30% of patients reporting angina and undergoing coronary angiography. To investigate risk factors associated with non-obstructive coronary artery disease (NOCAD), we analyzed the medical records of, consecutively, 136 NOCAD subjects and 128 patients with significant stenosis in at least one coronary artery (the OCAD group). The blood concentrations of the TC (4.40 [3.78−5.63] mmol/L vs. 4.12 [3.42−5.01] mmol/L; p = 0.026), LDL-C (2.32 [1.80−3.50] mmol/L vs. 2.10 [1.50−2.70] mmol/L; p = 0.003), non-HDL-C (2.89 [2.29−4.19] mmol/L vs. 2.66 [2.06−3.39] mmol/L; p = 0.045), as well as the LDL-C/HDL-C ratio (1.75 [1.22−2.60] vs. 1.50 [1.10−1.95]; p = 0.018) were significantly increased in the NOCAD patients compared to the OCAD group due to the lower prevalence and intensity of the statin therapy in the NOCAD individuals (p < 0.001). Moreover, the abovementioned lipid parameters appeared to be valuable predictors of NOCAD, with the LDL-C (OR = 1.44; 95%CI = 1.14−1.82) and LDL-C/HDL-C (OR = 1.51; 95%CI = 1.13−2.02) showing the highest odds ratios. Furthermore, multivariable logistic regression models determined female sex as the independent risk factor for NOCAD (OR = 2.37; 95%CI = 1.33−4.20). Simultaneously, arterial hypertension substantially lowered the probability of NOCAD (OR = 0.21; 95%CI = 0.10−0.43). To conclude, female sex, the absence of arterial hypertension, as well as increased TC, LDL-C, non-HDL, and LDL-C/HDL-C ratio are risk factors for NOCAD in patients reporting angina, potentially as a result of poor hypercholesterolemia management.

Overview of Microvascular Angina Pectoris and Discussion of Traditional Chinese Medicine Intervention

Previous research and treatment of coronary heart disease mostly focused on the large epicardial vessels, with limited research on the small endocardial coronary arteries or arterioles that could not be detected by coronary angiography, especially microvascular angina caused by microvascular stenosis or microcirculation dysfunction. Conventional Western medicine therapies have no specific efficacy, but traditional Chinese medicine has significant advantages in this regard. In particular, traditional Chinese medicine of supplementing Qi and activating blood circulation protects the vascular endothelium, relaxes coronary microvessels, reduces myocardial no-reflow after ischemia-reperfusion, increases myocardial hypoxia tolerance, constrains the aggregation of platelet, and increases the rate of blood flow. Moreover, these treatments can significantly improve patients' symptoms through multitarget comprehensive intervention. Here, we analyzed the pathogenesis of microvascular angina pectoris, the treatment status of modern medicine, and the research on the multitarget intervention of traditional Chinese medicine to provide new research ideas for correctly identifying the role of coronary microcirculation in coronary artery disease to solve clinical problems and prevent cardiovascular events.

Longitudinal myocardial function is more compromised in cardiac syndrome X compared to insignificant CAD: Role of stress echocardiography and calcium scoring

BACKGROUND AND AIM

The aim of this study was to assess the nature of myocardial dysfunction in the cardiac syndrome X (CSX) and insignificant coronary artery disease (ICAD) using dobutamine stress echocardiography (DSE) and coronary calcium scoring (CAC).

METHODS

We prospectively studied 35 consecutive patients who complained of exertional angina, had ≥1 mm ST shift on exercise stress test but normal or no obstructive CAD (<50%) on angiography. Patients were divided into CSX (n = 27) with normal arteries and ICAD (n = 8) with insignificant stenosis.

RESULTS

CSX patients had more females, lower calcium score and less prevalent cardiac risk factors compared to ICAD (p < 0.05 for all). At peak stress, MAPSE and TAPSE failed to increase in both groups. LV septal and lateral s' increased in the two groups but the increment increase was less in CSX than ICAD (p < 0.05) while other diastolic indices did not differ between groups (p > 0.05 for all). CAC correlated modestly with LV and RV systolic velocities: septal s' (r = -0.65, p < 0.001) lateral s' (r = -0.35, p = 0.04) and right s' (r = -0.53, p = 0.005) in CSX, while in ICAD patients only with RV s' (r = -0.58, p = 0.02). On multivariate model, only septal s' OR 1.816 (1.1090-3.820, p = 0.04) proved the most powerful independent predictor of CAC.

CONCLUSIONS

Compromised LV longitudinal systolic velocities were more pronounced and calcium score as a surrogate for atherosclerosis was lower in CSX than ICAD. These findings strengthen the evidence for different pathogenesis of CSX compared to ICAD, with microvascular disease in the former and calcification in the latter.

Effect of Chinese medicine for promoting blood circulation on microvascular angina: A systematic review and meta-analysis

BACKGROUND

Blood-activating drugs (BADs) are widely used to treat microvascular angina in China. This study aims to summarize relevant evidence from randomized controlled trials (RCTs) to assess the efficacy and safety of BADs in the treatment of microvascular angina.

METHODS

We searched for relevant studies before June 2019 from seven databases. Twenty-four studies were included of 1903 patients with microvascular angina. All studies compared the use of traditional Chinese medicine for activating blood circulation (BADs) and Western medicine (WM) with the use of Western medicine alone.

RESULTS

In all, 15 trials reported a significant effect of BADs on improving clinical symptoms compared with the control treatment (P < .00001), and 8 trials reported significant effects of BADs on reducing the frequency of angina pectoris attacks compared with Western medicine treatment (P < .00001). The pooled results also demonstrated that BADs provided a significant benefit in reducing the dosage of nitroglycerin required (P = .02), the maximum range of ST-segment depression (P = .003) and the descending degree of the ST-T segment of ECG (P = .0002); prolonging the total time of treadmill exercise (P < .00001) and the time of ST-segment depression of 1 mm (P = .002); enhancing the total effective rate of Traditional Chinese Medicine (TCM) syndromes (P < .00001); improving endothelial function (P < .00001); and reducing the levels of high-sensitivity C-reactive protein (hs-CRP) (P < .00001). BAD treatment showed no statistically significant effect on the levels of TNF-a (P = .8) or IL-6 (P = .13). No severe adverse events were reported.

CONCLUSION

This meta-analysis shows that BADs are effective for the treatment of microvascular angina. Although concerns regarding selective bias and low methodological quality were raised, our findings suggest that BADs are beneficial for patients with microvascular angina and should be given priority for future clinical studies.

Echocardiographic measurement of epicardial adipose tissue thickness in patients with microvascular angina

Introduction

Impaired coronary microcirculation, inflammation, and endothelial dysfunction were reported etiological factors for microvascular angina (MVA). Recently, increased epicardial adipose tissue (EAT) thickness has been associated with hypertension, metabolic syndrome, and coronary artery disease in general population. In this study, we aimed to evaluate the EAT thickness in patients with MVA.

Methods

This study enrolled 200 patients (83 males; mean age: 55.4 ± 8.2 years) who have been diagnosed with MVA and 200 controls (89 males; mean age: 54.4 ± 8.5 years). All patients underwent transthoracic echocardiography, and EAT thickness was measured from a parasternal long-axis view as the hypoechoic space on the right ventricular free wall.

Results

The mean EAT thickness was significantly higher in MVA patients than the controls (5.5 ± 1.1 vs. 4.9 ± 0.7 mm; p < 0.001). Multiple logistic regression analysis showed that increased EAT thickness was an independent predictor of MVA (OR = 1.183, 95% CI = 1.063-1.489; p = 0.023). In receiver operating characteristic curve analyses, EAT thickness above 5.3 mm predicted MVA with a sentivity of 68% and a specificity of 63% (AUC = 0.711, 95% CI = 0.659-0.762; p < 0.001).

Conclusions

The EAT thickness was observed significantly higher in MVA patients as compared to controls. Increased EAT thickness may be associated with mechanisms that play a major role in the pathogenesis of MVA.

Cardiovascular diseases in survivors of childhood cancer

Over the past few decades, the diagnosis and management of children with various malignancies have improved tremendously. As a result, there are an increasing number of children who are long-term cancer survivors. With improved survival, however, has come an increased risk of treatment-related cardiovascular complications that can appear decades after treatment. These problems are serious enough that all caregivers of childhood cancer survivors, including oncologists, cardiologists, and other health care personnel, must pay close attention to the short- and long-term effects of chemotherapy and radiotherapy on these children. This review discusses the effects of treatment-related cardiovascular complications from anthracyclines and radiotherapy and the methods for preventing, screening, and treating these complications.

Risk stratification for coronary artery disease in multi-ethnic populations: Are there broader considerations for cost efficiency?

Coronary artery disease (CAD) screening and diagnosis are core cardiac specialty services. From symptoms, autopsy correlations supported reductions in coronary blood flow and dynamic epicardial and microcirculatory coronaries artery disease as etiologies. While angina remains a clinical diagnosis, most cases require correlation with a diagnostic modality. At the onset of the evidence building process much research, now factored into guidelines were conducted among population and demographics that were homogenous and often prior to newer technologies being available. Today we see a more diverse multi-ethnic population whose characteristics and risks may not consistently match the populations from which guideline evidence is derived. While it would seem very unlikely that for the majority, scientific arguments against guidelines would differ, however from a translational perspective, there will be populations who differ and importantly there are cost-efficacy questions, e.g., the most suitable first-line tests or what parameters equate to an adequate test. This article reviews non-invasive diagnosis of CAD within the context of multi-ethnic patient populations.

NONOBSTRUCTIVE CORONARY ARTERY DISEASE - CLINICAL RELEVANCE, DIAGNOSIS, MANAGEMENT AND PROPOSAL OF NEW PATHOPHYSIOLOGICAL CLASSIFICATION

SUMMARY – New data gathered from large clinical trials indicate that nonobstructive coronary artery disease (non-CAD) is a clinical entity that should not be ignored. It is estimated that 50% of female population undergoing coronarography are diagnosed with non-CAD. There is also an increase in the prevalence of non-CAD in both genders, which is probably due to gradual expanding of clinical indications for angiography in patients with angina. Furthermore, considering the increased mortality risk established recently, a prognosis of non-CAD is not benign as previously thought. However, the concept and definition of non-CAD remains elusive causing difficulties in diagnosis and treatment. One of the major shortcomings is the exclusion-based diagnosis of non-CAD. Furthermore, treatment of non-CAD still presents a great challenge and optimal therapy is yet to be determined. There are two major hypotheses explaining the pathophysiological mechanisms of non-CAD, i.e. ischemic hypothesis based on abnormal microvascular dysfunction and non-ischemic one based on altered pain perception. This review encompasses a broader spectrum of pathophysiological mechanisms of non-CAD, and proposes a new way of classification based on the major disorder involved: type I (ischemic mechanisms) and type II (non-ischemic mechanisms), depending on which mechanism predominates. Hopefully, this would provide new insights in the understanding of this disorder, thus leading to accurate and early diagnosis and successful treatment, especially considering the increased mortality risk in these patients.

Evaluation of the coronary flow by the coronary clearance time in patients with cardiac syndrome X

Objective

The vessels involved in the microcirculation are too small to be visualized by conventional angiography and no tools are currently available that can directly evaluate the coronary microcirculation. This study evaluated the coronary clearance frame count (CCFC) in patients with cardiac syndrome X (CSX).

Methods

The retrospective study enrolled patients with angina, who had a positive nuclear imaging test and normal coronary angiography; and a control group consisting of patients who underwent an angiogram to exclude coronary artery disease. Thrombosis in myocardial infarction frame count (TFC) and CCFC for each coronary artery (left anterior descending coronary artery [LAD], circumflex coronary artery [CFX] and right coronary artery [RCA]) were calculated offline.

Results

A total of 71 patients with CSX and 61 control patients were enrolled in the study. No significant differences were found between the two groups regarding the baseline demographic and clinical variables. The TFC of LAD, CFX and RCA were similar between the two groups. The mean CCFC-LAD, CCFC-CFX and CCFC-RCA were significantly longer in the CSX group compared with the control group.

Conclusion

CCFC is a simple, quantitative and highly reproducible method that might be used as a marker of coronary microvascular dysfunction.

Increased monocyte-to-HDL cholesterol ratio is related to cardiac syndrome X

OBJECTIVE

Cardiac syndrome X (CSX) is typically identified with ischaemia in treadmill exercise test or stress myocardial perfusion scintigraphy as well as angina-like chest pain without stenosis in coronary angiography. The purpose of the present study is to investigate the association between cardiac syndrome X and monocyte-to-HDL cholesterol ratio (MHR) which is a new marker associated with inflammation.

PATIENTS AND METHODS

A total of 230 patients (105 patients with cardiac syndrome X and 125 normal controls) were included in the study. Peripheral venous blood samples were drawn from all study population before coronary angiography for measuring MHR and other haematological parameters.

RESULTS

The patients with cardiac syndrome X were more likely to have higher platelet counts, plateletcrit (PCT), monocyte count and MHR values. Monocyte count and MHR of the CSX group were significantly higher than the control group [0.53 (0.35-1) vs. 0.49 (0.23-0.96); p = .002, .011 (0.006-0.038) vs. 0.010 (0.004-0.034); p < .001, respectively]. HDL-cholesterol levels of the CSX group were significantly lower than the control groups (46.3 ± 10.1 vs. 49.6 ± 11.6; p = .021). Higher MHR and PCT values were found to be associated with the presence of CSX by multivariate logistic regression analysis.

CONCLUSIONS

Elevated MHR level independently was found in association with the presence of CSX. The value of MHR appears additive to conventional expensive methods commonly used in CSX prediction.

Tongxinluo Capsule () for Cardiac Syndrome X: A Systematic Review and Meta-Analysis

OBJECTIVE

To evaluate the efficacy and safety of Tongxinluo Capsule (, TXL) for patients with cardiac syndrome X (CSX).

METHODS

Randomized controlled trials (RCTs) regarding TXL in the treatment of CSX were searched in Chinese Biomedicine Literature Database, China National Knowledge Infrastructure, Chinese Scientific Journal Database, Wanfang Database, PubMed, EMBASE, Cochrane Central Register of Controlled Trial, websites of the Chinese and International Clinical Trial Registry platform up to June 30, 2015. The intervention was either TXL alone or TXL combined with conventional treatment, while the control intervention was conventional treatment with or without placebo. Data extraction, methodological quality assessment and data analyses were performed according to the Cochrane criteria. The primary outcome was a composite event of death, acute myocardial infarction (AMI), angina requiring hospitalization, revascularization, and heart failure. The secondary outcome measures were angina symptom improvement, electrocardiograph (ECG) improvement, and serum endothelin-1 (ET-1) level. The adverse events were also recorded. RevMan 5.3 software was applied for data analyses.

RESULTS

Twelve RCTs (696 patients) were included. Compared with conventional treatment, the addition of TXL to conventional treatment showed some benefits on relieving angina symptoms [risk ratio (RR): 1.46, 95% confidence interval (CI) (1.25, 1.71), P<0.01], and improving ECG [RR: 1.45, 95% CI (1.21, 1.74), P<0.01]. The pooled result did not support a benefit of TXL on reducing the incidence of primary outcome [RR: 0.20, 95% CI (0.02, 1.61), P=0.13]. In addition, TXL decreased serum ET-1 concentration of CSX patients [standardized mean number:-1.63, 95% CI (-2.29,-0.96), P<0.01]. No serious adverse events were reported.

CONCLUSIONS

TXL documents potential benefits on attenuating angina symptoms, improving ECG and decreasing serum ET-1 level for CSX patients. However, more rigorous RCTs with high quality are needed to confirm its efficacy and safety.

The influence of sex on microvascular function

A number of studies consistently report higher rates of all clinical outcomes including postinfarction mortality, need for repeat revascularization, and reinfarction in women with cardiovascular diseases than in men. As well, the gender gap in the prevalence of cardiovascular diseases decreases progressively with increasing age. Yet, the diagnosis and treatment of these diseases differ between genders and women remain underdiagnosed for coronary heart disease. In a recent retrospective analysis we showed that, along with vessel under study and age, gender is a determinant of adenosine responses during studies of fractional flow reserve, an effect that was probably due to differences in microvascular function and that influenced the interpretation of fractional flow reserve data. These data demonstrate that not only the clinical presentation is different, but also the diagnostic approach to coronary artery disease might differ between sexes.A gap still exists in the understanding of the mechanisms, awareness, and treatment of coronary artery disease in women, but also, as we show, in the application of diagnostic modalities that are well established in men.

Microvascular Coronary Artery Disease: Review Article

Recently it has become more apparent that microvascular dysfunction is responsible for morbidity and mortality in many different cardiovascular diseases. It is no longer felt to be benign, and besides accounting for angina symptoms, it likely plays a role in heart failure with preserved ejection fraction, as well as in Takotsubo syndrome and various inflammatory diseases associated with ischemia and atherosclerosis. Coronary microvascular disease can be diagnosed by means of invasive coronary reactivity testing and noninvasively by echocardiography, computerized tomography, magnetic resonance, and positron emission tomography. Unfortunately, treatment has been more empiric, and not as well evaluated by randomized trials as in other disease states. Beta blockers, nitrates, and calcium channel blockers have all been used with varying degrees of success. Given its prevalence, particularly among women, its increased recognition and importance mandates further research into prompt diagnosis and more robust studies of its treatment.

Hemorheological abnormalities and their associations with coronary blood flow in patients with cardiac syndrome X: a comparison between males and females

Aim:

The role of elevated whole blood viscosity (WBV) in the pathogenesis of atherosclerosis is well known. We sought to investigate the gender differences in the association between WBV, coronary blood flow and tissue oxygen delivery index (TODI) in cardiac syndrome X (CSX).

Methods:

Forty-six CSX patients and 14 healthy volunteers were enrolled. The coronary flow parameters were obtained with transthoracic Doppler echocardiography and WBV was measured (at high-shear and low-shear rates of 300s-1 and 5s-1, respectively) using a scanning capillary tube viscometer. TODI was determined from the ratio of hematocrit to WBV measured at a low-shear rate of 5s-1.

Results:

In male patients, the mean diastolic coronary flow velocity (CFV) and diastolic velocity time integral (VTI) were significantly decreased compared to control group (all p<0.05) and the WBV showed significant negative correlation with peak systolic CFV (r = −0.559 at 300s-1, r = −0.438 at 5s-1), mean systolic CFV (r = −0.577 at 300s-1, r = −0.488 at 5s-1), systolic VTI (r = −0.576 at 300s-1, r = −0.530 at 5s-1) and diastolic VTI (r = −0.553 at 300s-1, r = −0.551 at 5s-1) (all p<0.01). Meanwhile, although female patients showed no significant relationships between WBV and coronary flow parameters, TODI were significantly decreased compared to the control group (3.64 ± 0.34 vs. 4.07 ± 0.38%/centipoises (cP), respectively, p=0.008).

Conclusion:

Our study suggests that there are gender-related differences in the pathogenesis of microvascular angina and gender-specific approaches for CSX patients might be needed.

Cardiac Syndrome X: Update

Cardiac Syndrome X (CSX), characterized by angina-like chest discomfort, ST segment depression during exercise, and normal epicardial coronary arteries at angiography, is highly prevalent in women. CSX is not benign, and linked to adverse cardiovascular outcomes and a poor quality of life. Coronary microvascular and endothelial dysfunction and abnormal cardiac nociception have been implicated in the pathogenesis of CSX. Treatment includes life-style modification, anti-anginal, anti-atherosclerotic, and anti-ischemic medications. Non-pharmacological options include cognitive behavioral therapy, enhanced external counterpulsation, neurostimulation, and stellate ganglionectomy. Studies have shown the efficacy of individual treatments but guidelines outlining the best course of therapy are lacking.

Cardiac Syndrome X: update 2014

Cardiac Syndrome X (CSX), characterized by angina-like chest discomfort, ST segment depression during exercise, and normal epicardial coronary arteries at angiography, is highly prevalent in women. CSX is not benign, and linked to adverse cardiovascular outcomes and a poor quality of life. Coronary microvascular and endothelial dysfunction and abnormal cardiac nociception have been implicated in the pathogenesis of CSX. Treatment includes life-style modification, anti-anginal, anti-atherosclerotic, and anti-ischemic medications. Non-pharmacological options include cognitive behavioral therapy, enhanced external counterpulsation, neurostimulation, and stellate ganglionectomy. Studies have shown the efficacy of individual treatments but guidelines outlining the best course of therapy are lacking.

Women, cardiac syndrome X, and microvascular heart disease

New data suggest that persistent chest pain, despite normal coronary angiography, is less benign than previously thought. It has long been recognized that cardiac syndrome X (CSX) is associated with significant suffering, disability, and health care costs, but the biggest shift in thinking comes in terms of long-term risk. It is now recognized that the prognosis is not benign and that a significant proportion of patients are at increased cardiovascular disease risk. Of major debate is the question of whether the mechanisms that explain this chest pain are cardiac vs noncardiac. The most current definition of CSX is the triad of angina, ischemia, and normal coronary arteries, which is associated with an increased cardiovascular risk. This paper provides a review of CSX, epidemiology of the problem, proposed explanatory mechanisms, and important next steps in research. Central to this review is the proposition that new insights into CSX will be fostered by both clinical and scientific collaboration between cardiovascular and pain scientists.

Angina in Women without Obstructive Coronary Artery Disease

Angina in the absence of obstructive coronary artery disease, sometimes referred to as cardiac syndrome X (CSX), is a debilitating condition that disproportionately affects women. More than 50% of women evaluated for angina have non-obstructive disease by cardiac catheterization, although the total numbers of women affected by CSX are unknown. Varying clinical definitions and the lack of large scale epidemiologic studies focusing on this illness have resulted in limited knowledge about its risk factors, although there appears to be an association with black race, estrogen deficiency, and insulin resistance. Contrary to prior beliefs about the benign nature of this entity, these women suffer considerable morbidity with costly economic implications that approach the lifetime costs of healthcare utilization for those with obstructive coronary disease. Two prevailing hypotheses have emerged to explain CSX: the ischemic hypothesis detailing abnormal coronary microvascular function and the non-ischemic hypothesis describing altered pain perception and myocardial hypersensitivity. Treatment strategies have focused on both of these pathways with the main goal of improving symptoms. Beta blockers provide the most convincing evidence for benefit, with other antianginals having secondary roles. Other promising pharmacologic therapies include xanthine derivatives, estrogen replacement therapy, ACE inhibitors, and statin medications, among other emerging treatment options. Neurostimulation and lifestyle factors including exercise can also be beneficial in reducing symptoms. However, managing patients with CSX can be frustrating for both patients and physicians, as there is a lack of data regarding an optimal treatment algorithm including few large-scale randomized controlled trials to clarify effective therapies.

Two coronary "orphan" diseases in search of clinical consideration: coronary syndromes x and y

We set out to describe the clinical characteristics of patients presenting with acute or stable coronary syndromes and no stenosis in epicardial coronaries. Although the existence of patients who experience typical angina and who have intact epicardial coronaries is well accepted, the pathophysiology of cardiac ischemia in this setting remains poorly understood. In typical coronary syndrome X, it is believed that at least two components play a role: the first is the incapacity of coronary resistance vessels to adapt to situations of increased blood demand, resulting in demand ischemia; the second is an inappropriate transduction or generation or pain stimuli within the central nervous system. These two mechanisms concur to determine episodes of precordial pain and electrocardiogram (ECG) evidence of ischemia during exercise. In contrast, the coronary slow-flow phenomenon, or syndrome Y, is an angiographic finding that is characterized by delayed progression of the contrast medium during coronary angiography. Although the mechanism of this phenomenon remains largely unknown, it has been proposed that it might depend on the presence of inappropriately high resting coronary resistances, causing reduced blood flow and therefore low-flow ischemia and unstable angina. Importantly, the prognosis of many of the patients presenting with coronary slow-flow does not appear to be favorable, with recurrence of acute coronary syndromes and life-threatening arrhythmias. In the present article, we revise the current evidence regarding these two phenomena, and propose that syndrome Y should be considered a separate clinical entity.

Sudden adult death

In the investigation of sudden death in adults, channelopathies, such as long QT syndrome, have risen to the fore in the minds of forensic pathologists in recent years. Examples of these disorders are touched upon in this review as an absence of abnormal findings at postmortem examination is characteristic and the importance of considering the diagnosis lies in the heritable nature of these conditions. Typically, a diagnosis of a possible channelopathy is evoked as an explanation for a 'negative autopsy' in a case of apparent sudden natural death. However, the one potential adverse effect of this approach is that subtle causes of sudden death may be overlooked. The intention of this article is to review and discuss potential causes of sudden adult death (mostly natural) that should be considered before resorting to a diagnosis of possible channelopathy. Nonetheless, it becomes apparent that many of the potential causes of sudden death can have a genetic basis. Thus, it becomes an important consideration that there may be a genetic basis to sudden death that extends beyond the negative autopsy.