Absence of myocardial dysfunction during stress in patients with syndrome X

Multiple Phenotypes of Chronic Coronary Syndromes Identified by ABCDE Stress Echocardiography

BACKGROUND

Regional wall motion abnormality is considered a sensitive and specific marker of ischemia during stress echocardiography (SE). However, ischemia is a multifaceted entity associated with either coronary artery disease (CAD) or angina with normal coronary arteries, a distinction difficult to make using a single sign. The aim of this study was to evaluate the diagnostic potential of the five-step ABCDE SE protocol for CAD detection.

METHODS

From the 2016-2022 Stress Echo 2030 study data bank, 3,229 patients were selected (mean age, 66 ± 12 years; 2,089 men [65%]) with known CAD (n = 1,792) or angina with normal coronary arteries (n = 1,437). All patients were studied using both the ABCDE SE protocol and coronary angiography, within 3 months. In step A, regional wall motion abnormality is assessed; in step B, B-lines and diastolic function; in step C, left ventricular contractile reserve; in step D, coronary flow velocity reserve in the left anterior descending coronary artery; and in step E, heart rate reserve.

RESULTS

SE response ranged from a score of 0 (all steps normal) to a score of 5 (all steps abnormal). For CAD, rates of abnormal results were 347 for step A (19.4%), 547 (30.5%) for step B, 720 (40.2%) for step C, 615 (34.3%) for step D, and 633 (35.3%) for step E. For angina with normal coronary arteries, rates of abnormal results were 81 (5.6%) for step A, 429 (29.9%) for step B, 432 (30.1%) for step C, 354 (24.6%) for step D, and 445 (31.0%) for step E. The dominant "solitary phenotype" was step B in 109 patients (9.1%).

CONCLUSIONS

Stress-induced ischemia presents with a wide range of diagnostic phenotypes, highlighting its complex nature. Using a comprehensive approach such as the advanced ABCDE score, which combines multiple markers, proves to be more valuable than relying on a single marker in isolation.

Clinical aspects of ischemia with no obstructive coronary artery disease (INOCA)

Ischemia with no obstructive coronary arteries (INOCA) is defined as patients with evidence of myocardial ischemia without obstructive coronary artery disease. About 3-4 million people in the United States have INOCA, more commonly affecting women, and carries adverse morbidity, mortality, and relatively high healthcare costs. The pathophysiology of INOCA appears to be multi-factorial with a variety of contributing mechanisms. Diagnosis of INOCA is suggested by non-invasive or invasive testing consistent with myocardial ischemia. Due to the high prevalence of coronary risk factors and atherosclerosis in the INOCA population, current treatment strategies target angina, coronary atherosclerosis, and atherosclerotic risk factors, as well as burgeoning treatment of coronary microvascular dysfunction (CMD). Ongoing clinical trials are assessing different options.

Global Longitudinal Strain as Predictor of Inducible Ischemia in No Obstructive Coronary Artery Disease in the CIAO-ISCHEMIA Study

BACKGROUND

Global longitudinal strain (GLS) is a sensitive marker for identifying subclinical myocardial dysfunction in obstructive coronary artery disease (CAD). Little is known about the relationship between GLS and ischemia in patients with myocardial ischemia and no obstructive CAD (INOCA).

OBJECTIVES

To investigate the relationship between resting GLS and ischemia on stress echocardiography (SE) in patients with INOCA.

METHODS

Left ventricular GLS was calculated offline on resting SE images at enrollment (n = 144) and 1-year follow-up (n = 120) in the CIAO-ISCHEMIA (Changes in Ischemia and Angina over One year in International Study of Comparative Health Effectiveness with Medical and Invasive Approaches trial screen failures with no obstructive CAD on computed tomography [CT] angiography) study, which enrolled participants with moderate or severe ischemia by local SE interpretation (≥3 segments with new or worsening wall motion abnormality and no obstructive (<50% stenosis) on coronary computed tomography angiography.

RESULTS

Global longitudinal strain values were normal in 83.3% at enrollment and 94.2% at follow-up. Global longitudinal strain values were not associated with a positive SE at enrollment (GLS = -21.5% positive SE vs GLS = -19.9% negative SE, P = .443) or follow-up (GLS = -23.2% positive SE vs GLS = -23.1% negative SE, P = .859). Significant change in GLS was not associated with positive SE in follow-up (P = .401). Regional strain was not associated with colocalizing ischemia at enrollment or follow-up. Changes in GLS and number of ischemic segments from enrollment to follow-up showed a modest but not clinically meaningful correlation (β = 0.41; 95% CI, 0.16, 0.67; P = .002).

CONCLUSIONS

In this cohort of INOCA patients, resting GLS values were largely normal and did not associate with the presence, severity, or location of stress-induced ischemia. These findings may suggest the absence of subclinical myocardial dysfunction detectable by echocardiographic strain analysis at rest in INOCA.

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.

Consistency of Positron Emission Tomography and Myocardial Contrast Echocardiography in Diagnosing Mental Stress-Induced Myocardial Ischemia: Study Protocol of a Prospective Study-Background, Design and Method

Mental stress-induced myocardial ischemia (MSIMI) has attracted increasing attention in the last 30 y. Positron emission tomography/computed tomography (PET/CT) is among the most accurate methods for evaluating myocardial perfusion. Even so, echocardiography seems to be a more harmless option when the radiation exposure and high expense of PET/CT are considered. To date, no previous studies have compared the consistency between echocardiography and PET/CT in the diagnosis of MSIMI. The primary aim of this research was to compare the consistency of myocardial contrast echocardiography and PET/CT in diagnosing MSIMI in women with angina symptom/ischemia but no obstructive coronary artery disease (INOCA). Fifty adult female patients with INOCA were recruited for a 12-min-long mental stress test. Each patient underwent both echocardiography and PET/CT at baseline and during mental stress testing; the interval between the two examinations was 1-3 d and the sequence was assigned naturally. MSIMI is defined by a summed difference score (SDS) ≥3 on PET-CT during mental stress testing. It is also defined by new abnormal wall motion, ejection fraction reduction ≥5%, and/or development of ischemic ST change on the electrocardiogram during mental stress testing. This study examined the consistency of PET/CT and myocardial contrast echocardiography in diagnosing MSIMI.

Gender-Related Differences in Clinical Presentation and Angiographic Findings in Patients with Ischemia and No Obstructive Coronary Artery Disease (INOCA): A Single-Center Observational Registry

Ischemia and no obstructive coronary arteries (INOCA) is a common clinical presentation, with a variety of causes that are often not fully investigated in routine clinical practice. The goal of our study was to characterize a real-world population of patients with INOCA, with a deeper focus on symptoms and stress test findings. The study population consisted of 435 patients who underwent diagnostic coronary angiography for anginal symptoms and/or evidence of myocardial ischemia at non-invasive imaging. In all patients angiography demonstrated nonobstructive coronary artery disease (CAD, less than 30% luminal diameter stenosis or fractional flow reserve > 0.8 and/or instantaneous wave-free ratio  > 0.89). Fifty-four percent of the patients were women. Atypical clinical presentation was more common in women (59.5 vs. 49.5%, p = 0.037). Women were more likely to have normal coronary arteries than men (41.8 vs. 16.2%, p < 0.001), and less likely than men to have hemodynamically non-significant CAD (32.1 vs. 55.1%, p < 0.001). No significant correlation between typicality of symptoms and evidence of ischemia was found in those patients (244/435, 56.1%) who had either dobutamine stress echocardiography or electrocardiogram stress test. INOCA is a common clinical condition, prevalent in women often presenting with atypical symptoms.

Coronary microvascular dysfunction in stable ischaemic heart disease (non-obstructive coronary artery disease and obstructive coronary artery disease)

Diffuse and focal epicardial coronary disease and coronary microvascular abnormalities may exist side-by-side. Identifying the contributions of each of these three players in the coronary circulation is a difficult task. Yet identifying coronary microvascular dysfunction (CMD) as an additional player in patients with coronary artery disease (CAD) may provide explanations of why symptoms may persist frequently following and why global coronary flow reserve may be more prognostically important than fractional flow reserve measured in a single vessel before percutaneous coronary intervention. This review focuses on the challenges of identifying the presence of CMD in the context of diffuse non-obstructive CAD and obstructive CAD. Furthermore, it is going to discuss the pathophysiology in this complex situation, examine the clinical context in which the interaction of the three components of disease takes place and finally look at non-invasive diagnostic methods relevant for addressing this question.

Mechanisms and diagnostic evaluation of persistent or recurrent angina following percutaneous coronary revascularization

Persistence or recurrence of angina after a percutaneous coronary intervention (PCI) may affect about 20-40% of patients during short-medium-term follow-up. This appears to be true even when PCI is 'optimized' using physiology-guided approaches and drug-eluting stents. Importantly, persistent or recurrent angina post-PCI is associated with a significant economic burden. Healthcare costs may be almost two-fold higher among patients with persistent or recurrent angina post-PCI vs. those who become symptom-free. However, practice guideline recommendations regarding the management of patients with angina post-PCI are unclear. Gaps in evidence into the mechanisms of post-PCI angina are relevant, and more research seems warranted. The purpose of this document is to review potential mechanisms for the persistence or recurrence of angina post-PCI, propose a practical diagnostic algorithm, and summarize current knowledge gaps.

Impairment of coronary flow velocity reserve and global longitudinal strain in women with cardiac syndrome X and slow coronary flow

BACKGROUND

Microvascular dysfunction (MVD) is associated with adverse prognosis and may account for abnormal stress tests and angina symptoms in women with cardiac syndrome X (CSX). The aim of our study was to assess MVD by coronary flow velocity reserve (CFVR) and left ventricular (LV) contractile function by LV global longitudinal strain (LVGLS) in CSX patients with respect to presence of slow coronary flow (SCF). It was of additional importance to evaluate clinical status of CSX patients using Seattle Angina Questionnaire.

METHODS AND RESULTS

Study population included 70 women with CSX (mean age 61 ± 7 years) and 34 age-matched controls. CSX group was stratified into two subgroups depending on SCF presence: CSX-Thrombolysis In Myocardial Infarction (TIMI) 3- normal flow subgroup (n = 38) and CSX-TIMI 2- SCF subgroup (n = 32) as defined by coronary angiography. LVGLS measurements and CFVR of left anterior descending (LAD) and posterior descending (PD) artery were performed. CFVR-LAD and PD were markedly impaired in CSX group compared to controls (2.34 ± 0.25 vs 3.05 ± 0.21, p < 0.001; 2.32 ± 0.24 vs 3.01 ± 0.13, p < 0.001), and furthermore decreased in CSX-TIMI 2 patients. Resting, peak, and ΔLVGLS were all significantly impaired in CSX group compared to controls (for all p < 0.001), and furthermore reduced in CSX-TIMI 2 subgroup. Strongest correlation was found between peak LVGLS and CFVR LAD (r = -0.784, p < 0.001) and PD (r = -0.772, p < 0.001). CSX-TIMI 2 subgroup had more frequent angina symptoms and more impaired quality of life.

CONCLUSIONS

MVD in CSX patients is demonstrated by reduction in CFVR and LVGLS values. SCF implies more profound impairment of microvascular and LV systolic function along with worse clinical presentation.

Diagnostic Approach to Patients with Stable Angina and No Obstructive Coronary Arteries

The diagnosis of microvascular angina (MVA) is usually considered in patients presenting with angina symptoms and evidence of MI on non-invasive stress tests but normal coronary arteries at angiography. A definitive diagnosis of MVA, however, would require the presence of coronary microvascular dysfunction. Several invasive (e.g. intracoronary Doppler wire recording and thermodilution) and non-invasive (e.g. PET, cardiac MRI, transthoracic Doppler echocardiography) methods can be applied to obtain a diagnosis. Both endothelium-dependent and -independent coronary microvascular dilator function, as well as increased microvascular constrictor activity, should be investigated. The main issues in the assessment of clinical and diagnostic findings in patients with suspected MVA are discussed and a diagnostic approach is suggested.

[The Clinical use of Stress Echocardiography in Ischemic Heart Disease Cardiovascular Ultrasound (2017)15:7. Translation authors: Arystan A.Zh., Fettser D.V.]

Stress echocardiography is an established technique for the assessment of extent and severity of coronary artery disease. The combination of echocardiography with a physical, pharmacological or electrical stress allows detecting myocardial ischemia with an excellent accuracy. A transient worsening of regional function during stress is the hallmark of inducible ischemia. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging or magnetic resonance, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. The evidence on its clinical impact has been collected over 35 years, based on solid experimental, pathophysiological, technological and clinical foundations. There is the need to implement the combination of wall motion and coronary flow reserve, assessed in the left anterior descending artery, into a single test. The improvement of technology and in imaging quality will make this approach more and more feasible. The future issues in stress echo will be the possibility of obtaining quantitative information translating the current qualitative assessment of regional wall motion into a number. The next challenge for stress echocardiography is to overcome its main weaknesses: dependence on operator expertise, the lack of outcome data (a widespread problem in clinical imaging) to document the improvement of patient outcomes. This paper summarizes the main indications for the clinical applications of stress echocardiography to ischemic heart disease.

'Primary' Microvascular Angina: Clinical Characteristics, Pathogenesis and Management

Microvascular angina (MVA), i.e. angina caused by abnormalities of the coronary microcirculation, is increasingly recognised in clinical practice. The pathogenetic mechanisms of MVA are heterogeneous and may involve both structural and functional alterations of coronary microcirculation, and functional abnormalities may variably involve an impairment of coronary microvascular dilatation and an increased microvascular constrictor activity. Both invasive and non-invasive diagnostic tools exist to identify patients with MVA in clinical practice. Prognosis has been reported to be good in primary MVA patients, although the prognostic implications of coronary microvascular dysfunction (CMVD) in more heterogeneous populations of angina patients need further assessment. Management of primary MVA can be challenging, but pharmacological and non-pharmacological treatments exist that allow satisfactory control of symptoms in most patients.

The clinical use of stress echocardiography in ischemic heart disease

Stress echocardiography is an established technique for the assessment of extent and severity of coronary artery disease. The combination of echocardiography with a physical, pharmacological or electrical stress allows to detect myocardial ischemia with an excellent accuracy. A transient worsening of regional function during stress is the hallmark of inducible ischemia. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging or magnetic resonance, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician.

The evidence on its clinical impact has been collected over 35 years, based on solid experimental, pathophysiological, technological and clinical foundations. There is the need to implement the combination of wall motion and coronary flow reserve, assessed in the left anterior descending artery, into a single test. The improvement of technology and in imaging quality will make this approach more and more feasible. The future issues in stress echo will be the possibility of obtaining quantitative information translating the current qualitative assessment of regional wall motion into a number. The next challenge for stress echocardiography is to overcome its main weaknesses: dependance on operator expertise, the lack of outcome data (a widesperad problem in clinical imaging) to document the improvement of patient outcomes. This paper summarizes the main indications for the clinical applications of stress echocardiography to ischemic heart disease.

Physical training improves myocardial perfusion but not left ventricular function response to exercise in patients with microvascular angina

BACKGROUND

Patients with primary microvascular angina (PMA) commonly exhibit abnormal left ventricular function (LVF) during exercise, potentially owing to myocardial ischemia. Herein, we investigated in PMA patients the effect of the reduction of myocardial perfusion disorders, by using aerobic physical training, upon LVF response to exercise.

METHODS

Overall, 15 patients (mean age, 53.7±8.9 years) with PMA and 15 healthy controls (mean age, 51.0±9.4 years) were studied. All subjects were subjected to baseline resting and exercise ventriculography, myocardial perfusion scintigraphy (MPS), and cardiopulmonary testing. PMA group members then participated in a 4-month physical training program and were reevaluated via the same methods applied at baseline.

RESULTS

Baseline left ventricular ejection fraction (LVEF) determinations by ventriculography were similar for both groups (PMA, 67.7±10.2%; controls, 66.5±5.4%; P=0.67). However, a significant rise in LVEF seen in control subjects during exercise (75.3±6.2%; P=0.0001) did not materialize during peak exercise in patients with PMA (67.7±10.2%; P=0.47). Of the 12 patients in the PMA group who completed the training program, 10 showed a significant reduction in reversible perfusion defects during MPS. Nevertheless, LVEF at rest (63.5±8.7%) and at peak exercise (67.3±15.9%) did not differ significantly (P=0.30) in this subset.

CONCLUSIONS

In patients with PMA, reduced left ventricular inotropic reserve observed during exercise did not normalize after improving myocardial perfusion through aerobic physical training.

Prevalence of Coronary Microvascular Dysfunction Among Patients With Chest Pain and Nonobstructive Coronary Artery Disease

OBJECTIVES

This study assessed the prevalence of coronary microvascular abnormalities in patients presenting with chest pain and nonobstructive coronary artery disease (CAD).

BACKGROUND

Coronary microvascular abnormalities mediate ischemia and can lead to an increased risk of cardiovascular events.

METHODS

Using an intracoronary Doppler guidewire, endothelial-dependent microvascular function was examined by evaluating changes in coronary blood flow in response to acetylcholine, whereas endothelial-independent microvascular function was examined by evaluating changes in coronary flow velocity reserve in response to intracoronary adenosine. Patients were divided into 4 groups depending on whether they had a normal (+) or abnormal (-) coronary blood flow (CBF) in response to acetylcholine (Ach) and a normal (+) or abnormal (-) coronary flow velocity reserve (CFR) in response to adenosine (Adn): CBFAch+, CFRAdn+ (n = 520); CBFAch-, CFRAdn+ (n = 478); CBFAch+, CFRAdn- (n = 173); and CBFAch-, CFRAdn- (n = 268).

RESULTS

Two-thirds of all patients had some sort of microvascular dysfunction. Women were more prevalent in each group (56% to 82%). Diabetes was uncommon in all groups (7% to 12%), whereas hypertension and hyperlipidemia were relatively more prevalent in each group, although rates for most conventional cardiovascular risk factors did not differ significantly between groups. There were no significant differences in the findings of noninvasive functional testing between groups. In a multivariable analysis, age was the only variable that independently predicted abnormal microvascular function.

CONCLUSIONS

Patients with chest pain and nonobstructive CAD have a high prevalence of coronary microvascular abnormalities. These abnormalities correlate poorly with conventional cardiovascular risk factors and are dissociated from the findings of noninvasive functional testing.

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.

Diagnosis of coronary microvascular dysfunction - Present status

Definite clinical diagnosis of microvascular angina is not possible with the existing knowledge. Resting electrocardiogram may be normal, and exercise electrocardiogram may be unremarkable. Echocardiography usually does not show regional wall motion abnormalities. Transthoracic Doppler echocardiography can satisfactorily evaluate only left anterior descending coronary artery and that too in some patients. Radio-isotope imaging can detect only severe localized disease. Noninvasive diagnosis needs high index of suspicion. At present, definite diagnosis is based on documentation of normal epicardial coronaries, coronary flow reserve less than 2.5 on adenosine induced hyperemia, and absence of spasm of epicardial coronaries on acetylcholine provocation. Invasive evaluation is costly, needs sophisticated equipments and expertise. Therapeutic and prognostic implications of various parameters remains to be evaluated. At present invasive evaluation is recommended only for patients with intractable symptoms with unconfirmed diagnosis, requiring repeated hospitalization and evaluation with failure of empirical therapy.

Assessment of the left ventricular systolic function in cardiac syndrome X using speckle tracking echocardiography

OBJECTIVE

The aim of this study was to evaluate left ventricular (LV) systolic strain by speckle tracking echocardiography (STE) and real-time three-dimensional echocardiography (3-DE) for the early detection of myocardial dysfunction in patients with cardiac syndrome X (CSX).

METHODS

We compared 34 patients with CSX (18 females, mean age 47.9±10.0 years) with 41 healthy persons as a control group (23 females, mean age 50.6±9.9 years). Inclusion criteria for CSX were typical angina, a positive exercise ECG stress test, and angiographically documented normal coronary arteries. Exclusion criteria for both groups were hypertension, valvular heart disease, cardiomyopathies, inflammatory diseases, myocarditis, vasculitis, arthropathies, Tietze's syndrome, gastrointestinal diseases, aortic diseases, hormone replacement therapy, arrhythmias, liver diseases, and alcohol use. All subjects underwent two-dimensional STE and 3-DE to assess resting LV function. STE measures were taken from the basal septum, mid-septum, apical septum, apex, apicolateral, mid-lateral, basal lateral, anteroseptal, anterior, anterolateral, inferolateral, inferior, and inferoseptal walls. Student's t-test, Mann-Whitney U test, and chi-square test were used to statistically analyze data.

RESULTS

LV echo ejection fraction (EF) and systolic wave peak velocity were similar for both groups. Regional mean longitudinal strain (-17.7±2.5% vs. -19.8±1.8%; p<0.0001) was significantly lower in patients with CSX than in healthy control patients. However, regional mean circumferential strain values (-22.0±1.6% vs. -22.2±2.3%; p=0.78) did not differ significantly between the two groups.

CONCLUSION

Significant impairment of LV longitudinal myocardial systolic function was detected with STE in patients with CSX, although normal 3-D EF and tissue Doppler imaging systolic parameters were observed. Arteriosclerosis of small coronary arteries and microvascular dysfunction may affect myocardial longitudinal strain.

Cardiac magnetic resonance myocardial perfusion reserve index is reduced in women with coronary microvascular dysfunction. A National Heart, Lung, and Blood Institute-sponsored study from the Women's Ischemia Syndrome Evaluation

BACKGROUND

Women with signs and symptoms of ischemia and no obstructive coronary artery disease often have coronary microvascular dysfunction (CMD), diagnosed by invasive coronary reactivity testing (CRT). Although traditional noninvasive stress imaging is often normal in CMD, cardiac MRI may be able to detect CMD in this population.

METHODS AND RESULTS

Vasodilator stress cardiac MRI was performed in 118 women with suspected CMD who had undergone CRT and 21 asymptomatic reference subjects. Semi-quantitative evaluation of the first-pass perfusion images was completed to determine myocardial perfusion reserve index (MPRI). The relationship between CRT findings and MPRI was examined by Pearson correlations, logistic regression, and sensitivity/specificity. Symptomatic women had lower mean pharmacological stress MPRI compared with reference subjects (1.71±0.43 versus 2.23±0.37; P<0.0001). Lower MPRI was predictive of ≥1 abnormal CRT variables (odds ratio =0.78 [0.70, 0.88], P<0.0001, c-statistic 0.78 [0.68, 0.88]). An MPRI threshold of 1.84 predicted CRT abnormality with sensitivity 73% and specificity 74%.

CONCLUSIONS

Noninvasive cardiac MRI MPRI can detect CMD defined by invasive CRT. Further work is aimed to optimize the noninvasive identification and management of CMD patients.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00832702.

Role of echocardiography in the management of cardiac disease in women

The widespread use of echocardiography has contributed to the early recognition of several distinct cardiac diseases in women. During pregnancy, safe monitoring of the disease process, as well as a better understanding of hemodynamics, is possible. During the use of potentially cardiotoxic drugs for breast cancer chemotherapy, echocardiographic patient monitoring is vital. Compared to men, the addition of an imaging modality to routine electrocardiogram monitoring during stress testing is more informative for diagnosing coronary disease in women. This review briefly discusses the role of echocardiography in the management of several women-specific cardiac diseases where echocardiography plays a pivotal role in disease management.

Abnormal left ventricular contractile response to exercise in the absence of obstructive coronary artery disease is associated with resting left ventricular long-axis dysfunction

BACKGROUND

The etiology of reduced left ventricular (LV) ejection fraction after exercise, without obstructive coronary artery disease or other established causes, is unclear. The aims of this study were to determine whether patients undergoing treadmill stress echocardiography with this abnormal LV contractile response to exercise (LVCRE) without established causes have resting LV long-axis dysfunction or microvascular dysfunction and to determine associations with this abnormal LVCRE.

METHODS

Of 5,275 consecutive patients undergoing treadmill stress echocardiography, 1,134 underwent cardiac computed tomography angiography or invasive angiography. Having excluded patients with obstructive coronary artery disease, hypertensive response, submaximal heart rate response, resting LV ejection fraction < 50%, and valvular disease, 110 with "abnormal LVCRE" and 212 with "normal LVCRE" were analyzed. Resting mitral annular velocities were measured to assess LV long-axis function. Myocardial blush grade and corrected Thrombolysis In Myocardial Infarction frame count were determined angiographically to assess microvascular function.

RESULTS

Comparing normal LVCRE with abnormal LVCRE, age (mean, 59.7 ± 11.1 vs 61.4 ± 10.0 years), hypertension (53% vs 55%), diabetes (16% vs 20%), and body mass index (mean, 29.1 ± 5.4 vs 29.5 ± 6.4 kg/m(2)) were similar (P > .05). Abnormal LVCRE had reduced resting LV long-axis function with lower septal (mean, 6.1 ± 1.9 vs 7.7 ± 2.2 cm/sec) and lateral (mean, 8.1 ± 2.9 vs 10.4 ± 3.0 cm/sec) e' velocities (P < .001) and larger resting left atrial volumes (mean, 37.3 ± 10.1 vs 31.1 ± 7.2 mL/m(2), P < .001). On multivariate analysis, female gender (odds ratio [OR], 1.21; 95% confidence interval [CI], 1.15-1.99; P < .001), exaggerated chronotropic response (OR, 1.49; 95% CI, 1.09-2.05; P < .001), resting left atrial volume (OR, 2.38; 95% CI, 1.63-3.47; P < .001), and resting lateral e' velocity (OR, 1.70; 95% CI, 1.22-2.49; P = .003) were associated with abnormal LVCRE, but not myocardial blush grade or corrected Thrombolysis In Myocardial Infarction frame count.

CONCLUSIONS

An abnormal LVCRE in the absence of established causes is associated with resting LV long-axis dysfunction and is usually seen in women.

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.

Sex-specific factors in microvascular angina

In women presenting for evaluation of suspected ischemic symptoms, a diagnosis of normal coronary arteries is 5 times more common than it is in men. These women are often labelled as having cardiac syndrome X, and a subset of them have microvascular angina caused by microvascular coronary dysfunction (MCD). MCD is not benign and is associated with an annual 2.5% cardiac event rate. Noninvasive testing for MCD remains insensitive, although newer imaging modalities, such as adenosine cardiac magnetic resonance imaging, appear promising. The gold standard for diagnosis of MCD is coronary reactivity testing, an invasive technique that is not available in many countries. With regard to treatment, large-scale trials are lacking. Although research is ongoing, the current platform of therapy consists of antiangina, antiplatelet, and endothelium-modifying agents (primarily angiotensin-converting enzyme inhibitors and statins).

Altered transmural contractility in postmenopausal women affected by cardiac syndrome X

BACKGROUND

Cardiac syndrome X (CSX) is characterized by typical angina and abnormal exercise test results, with normal coronary arteries. Cardiovascular magnetic resonance imaging has shown subendocardial hypoperfusion in patients with CSX after adenosine. The aim of this study was to investigate the contribution of separate myocardial layers to global function under stress in women with CSX.

METHODS

Twenty-two postmenopausal women with CSX were studied and compared with 20 healthy women matched for age and body mass index. All subjects underwent clinical evaluations and exercise echocardiography. Left ventricular systolic and diastolic parameters were evaluated at rest and at peak exercise. Layer-specific global longitudinal strain (GLS) and strain rate (SR) were assessed from the endocardium, midmyocardium, and epicardium using two-dimensional speckle-tracking echocardiography.

RESULTS

All subjects showed normal contractile function at rest and at peak exercise. Significant increases in GLS and SR in all myocardial layers were observed at peak exercise in the control group, whereas patients with CSX showed significantly lower increases in endocardial GLS and SR compared with the control group (endocardial ΔSR, 0.17 ± 0.19 vs 0.33 ± 0.13 [P < .01]; endocardial ΔGLS, 1.33 ± 2.93 vs 6.64 ± 2.62 [P < .001]). Moreover, significantly impaired diastolic function (ΔE', 1.1 ± 3.3 vs 4.0 ± 2.03) was observed in patients with CSX.

CONCLUSIONS

The results of this study show subendocardial impairment of contractile function during exercise in patients with CSX, confirming the existence of reduced myocardial perfusion reserve in patients with CSX and suggesting layer-targeted exercise echocardiography as a sensitive diagnostic tool in the assessment of suspected CSX.

Role of inflammation and endothelial dysfunction in the pathogenesis of cardiac syndrome X

Chest pain with normal coronary arteriograms represents a major diagnostic and therapeutic challenge to contemporary cardiology. Cardiac syndrome X (CSX), defined as typical angina-like chest pain, a positive response to exercise stress testing and normal coronary arteriograms, encompasses patients with a variety of pathogenic mechanisms. Cardiac ischemia has been documented in approximately 25% of CSX patients and is associated with endothelial dysfunction and microvascular vasodilator abnormalities. Increased endothelin-1, a powerful vasoconstrictor, has been suggested to play a pathogenic role. There is a high prevalence of postmenopausal women with CSX and thus estrogen deficiency has also been proposed to represent a possible pathogenic mechanism. Inflammatory mechanisms and endothelial dysfunction at the coronary microvascular level appear to be important in the pathogenesis of CSX. Treatment with agents that have protective effects on the vasculature and also anti-inflammatory properties, such as statins and angiotensin-converting enzyme inhibitors have been effective in improving both symptoms and electrocardiographic signs of myocardial ischemia in patients with CSX. This review discusses the roles for endothelial dysfunction and inflammation in the pathogenesis of CSX, as well as the potential therapeutic implications of these mechanisms.

Coronary microvascular dysfunction in the clinical setting: from mystery to reality

Far more extensive than the epicardial coronary vasculature that can be visualized angiographically is the coronary microcirculation, which foregoes routine imaging. Probably due to the lack of techniques able to provide tangible evidence of its crucial role, the clinical importance of coronary microvascular dysfunction is not fully appreciated. However, evidence gathered over the last several decades indicates that both functional and structural abnormalities of the coronary microvasculature can lead to myocardial ischaemia, often comparable with that caused by obstructive coronary artery disease. Indeed, a marked increase in coronary microvascular resistance can impair coronary blood flow and trigger angina pectoris, ischaemic ECG shifts, and myocardial perfusion defects, and lead to left ventricular dysfunction in patients who otherwise have patent epicardial coronary arteries. This condition--often referred to as 'chest pain with normal coronary arteries' or 'cardiac syndrome X'--encompasses several pathogenic mechanisms involving the coronary microcirculation. Of importance, coronary microvascular dysfunction can occur in conjunction with several other cardiac disease processes. In this article, we review the pathogenic mechanisms leading to coronary microvascular dysfunction and its diagnostic assessment, as well as the different clinical presentations and prognostic implications of microvascular angina. As such, this review aims to remove at least some of the mystery surrounding the notion of coronary microvascular dysfunction and to show why it represents a true clinical entity.

From heart to brain: the genesis and processing of cardiac pain

Angina pectoris is important because of its association with heart disease and risk of death. Historically after Heberden's account of angina in 1772, the association of pain with coronary artery disease quickly followed. Within a few years, Burns suggested an etiological role for ischemia. Subsequently, theories of differential myocardial stretch dominated thinking until Lewis' chemical hypothesis in 1932, in which the local release of chemical substances during ischemia was seen as the cause of pain. This review considers how ischemia at the tissue level triggers activation of afferent nociceptive pain fibres. The afferent projections of sympathetic and vagal afferent fibres are described, with a number of methodologies cited (eg, injection of pseudorabies virus into the heart with mapping of the retrograde viral transport pathways; and elevation of neuronal c-fos synthesis in brain regions activated by capsaicin application to the heart). Our own functional neuroimaging studies of angina are also reviewed. There are 2 intriguing features of angina. The first is the poor correlation between symptoms and extent of coronary disease. The spectrum ranges from entirely silent myocardial ischemia to that of a functional pain syndrome--the 'sensitive heart'--of cardiac syndrome X. An even more difficult aspect is the wide variability in symptoms experienced by an individual patient. A new paradigm is presented which, besides considering myocardial oxygen supply/demand imbalance, also draws insights from the broader field of pain research. Neuromodulation applies at multiple levels of the neuraxis--peripheral nerves, spinal cord, and brain--and it invites exploitation, whether pharmacological or electrical, for the benefit of the cardiac patient in pain.

Patients with syndrome X have normal transmural myocardial perfusion and oxygenation: a 3-T cardiovascular magnetic resonance imaging study

BACKGROUND

The pathophysiology of chest pain in patients with cardiac syndrome X remains controversial. Advances in perfusion imaging with cardiovascular magnetic resonance (CMR) now enable absolute quantification of regional myocardial blood flow (MBF). Furthermore, blood oxygen level-dependent (BOLD) or oxygenation-sensitive CMR provides the unprecedented capability to assess regional myocardial oxygenation. We hypothesized that the combined assessment of regional perfusion and oxygenation with CMR could clarify whether patients with syndrome X show evidence of myocardial ischemia (reduced perfusion and oxygenation) during vasodilator stress compared with normal volunteers.

METHODS AND RESULTS

Eighteen patients with syndrome X (chest pain, abnormal exercise treadmill test, normal coronary angiogram without other causes of microvascular dysfunction) and 14 controls underwent CMR scanning at 3 T. Myocardial function, scar, perfusion (2-3 short-axis slices), and oxygenation were assessed. Absolute MBF was measured during adenosine stress (140 μg/kg per minute) and at rest by model-independent deconvolution. For oxygenation, using a T2-prepared BOLD sequence, signal intensity was measured at adenosine stress and rest in the slice matched to the midventricular slice of the perfusion scan. There were no significant differences in MBF at stress (2.35 versus 2.37 mL/min per gram; P=0.91), BOLD signal change (17.3% versus 17.09%; P=0.91), and coronary flow reserve measurements (2.63 versus 2.53; P=0.60) in patients with syndrome X and controls, respectively. Oxygenation and perfusion measurements per coronary territory were also similar between the 2 groups. More patients with syndrome X (17/18 [94%]) developed chest pain during adenosine stress than controls (6/14 [43%]; P=0.004).

CONCLUSIONS

Patients with syndrome X show greater sensitivity to chest pain compared with controls but no evidence of deoxygenation or hypoperfusion during vasodilatory stress.

Microvascular coronary dysfunction in women: pathophysiology, diagnosis, and management

Women exhibit a greater symptom burden, more functional disability, and a higher prevalence of no obstructive coronary artery disease compared to men when evaluated for signs and symptoms of myocardial ischemia. Microvascular coronary dysfunction (MCD), defined as limited coronary flow reserve and/or coronary endothelial dysfunction, is the predominant etiologic mechanism of ischemia in women with the triad of persistent chest pain, no obstructive coronary artery disease, and ischemia evidenced by stress testing. Evidence shows that approximately 50% of these patients have physiological evidence of MCD. MCD is associated with a 2.5% annual major adverse event rate that includes death, nonfatal myocardial infarction, nonfatal stroke, and congestive heart failure. Although tests such as adenosine stress cardiac magnetic resonance imaging may be a useful noninvasive method to predict subendocardial ischemia, the gold standard test to diagnose MCD is an invasive coronary reactivity testing. Early identification of MCD by coronary reactivity testing may be beneficial in prognostication and stratifying these patients for optimal medical therapy. Currently, understanding of MCD pathophysiology can be used to guide diagnosis and therapy. Continued research in MCD is needed to further advance our understanding.

Tissue Doppler echocardiography reveals impaired cardiac function in patients with reversible ischaemia

AIMS

To determine if echocardiographic tissue Doppler imaging (TDI) performed at rest detects reduced myocardial function in patients with reversible ischaemia.

METHODS AND RESULTS

Eighty-four patients with angina pectoris, no previous history of ischaemic heart disease and normal left ventricular ejection fraction were examined with colour TDI, single-photon emission computed tomography (SPECT), and coronary angiography (CAG). Patients with a normal SPECT (n= 42) constituted the control group and patients with a positive SPECT (n= 42) were divided into patients with (true-positive SPECT, n= 30) or without (false-positive SPECT, n= 12) significant coronary stenoses assessed by CAG. Regional longitudinal systolic (s'), early diastolic (e'), and late diastolic (a') myocardial velocities were measured by colour TDI at six mitral annular sites and averaged to provide global estimates. In patients with reversible ischaemia both global systolic and diastolic function were impaired in terms of reduced average s' (5.6 ± 0.9 vs. 6.1 ± 1.1 cm/s; P< 0.05), reduced average e' (5.9 ± 1.8 vs. 7.0 ± 1.7 cm/s; P< 0.01) and increased average E/e' (14.2 ± 5.0 vs. 11.5 ± 3.9; P< 0.01). This impairment of the cardiac function was even more evident in patients with a true-positive SPECT with reduced average s' (5.5 ± 0.8 vs. 6.1 ± 1.1 cm/s; P< 0.01), reduced average e' (5.2 ± 1.5 vs. 7.0 ± 1.7 cm/s; P< 0.001), and increased average E/e' (15.5 ± 5.2 vs. 11.5 ± 3.9; P< 0.001), whereas no difference in myocardial velocities could be demonstrated in patients with a false-positive SPECT compared with controls.

CONCLUSION

In patients with stable angina pectoris, preserved ejection fraction, and reversible ischaemia assessed by SPECT, echocardiographic colour TDI performed at rest reveals impaired cardiac function. The impairment of the cardiac function seems to be evident only in patients with a true-positive SPECT and colour TDI may therefore increase its diagnostic value.

Gender and microvascular angina

There are gender differences in the presentation, diagnosis, and treatment of chest pain. When compared to men, women may have more atypical presentations of chest pain. In addition, current diagnostic tools are often not definitive regarding cardiac etiology for chest pain in women. The current diagnostic model of chest pain focuses on significant obstructions within the large coronary arteries as the cause for angina. Microvascular angina (MVA) represents an under-recognized pathophysiologic mechanism that may explain the apparent disparities and elucidate an etiology for the common finding in women of chest pain, ischemia on stress testing, and no obstructive coronary artery disease (CAD) on angiography in the presence of abnormal coronary reactivity testing. Endothelial dysfunction, estrogen deficiency, and abnormal nociception play a role in the pathophysiology of MVA. Treatments are targeted toward these underlying mechanisms. Recognizing the role gender and other pathophysiologic models of chest pain can play in the work-up and treatment of angina may identify a treatable cardiac condition, that would otherwise be discounted as non-cardiac in origin.

Microvascular angina and the continuing dilemma of chest pain with normal coronary angiograms

Since initial reports over 4 decades ago, cases of patients with angina-like chest pain whose coronary angiograms show no evidence of obstructive coronary artery disease and who have no structural heart disease continue to be a common occurrence for cardiologists. Many features of this patient population have remained constant with successive reports over time: a female predominance, onset of symptoms commonly between 40 and 50 years of age, pain that is severe and disabling, and inconsistent responses to conventional anti-ischemic therapy. Because patients may have had abnormal noninvasive testing that led to performance of coronary angiography, investigators have sought to show an association of this syndrome with myocardial ischemia. Abnormalities in coronary flow and metabolic responses to stress have been reported by several groups, findings consistent with a microvascular etiology for ischemia and symptoms, but others have questioned the presence of ischemia, even in patients selected for abnormal noninvasive testing. Despite considerable efforts by many groups over 4 decades, the syndrome remains controversial with regard to pathophysiology, diagnosis, and management.

Stress echocardiography expert consensus statement: European Association of Echocardiography (EAE) (a registered branch of the ESC)

Stress echocardiography is the combination of 2D echocardiography with a physical, pharmacological or electrical stress. The diagnostic end point for the detection of myocardial ischemia is the induction of a transient worsening in regional function during stress. Stress echocardiography provides similar diagnostic and prognostic accuracy as radionuclide stress perfusion imaging, but at a substantially lower cost, without environmental impact, and with no biohazards for the patient and the physician. Among different stresses of comparable diagnostic and prognostic accuracy, semisupine exercise is the most used, dobutamine the best test for viability, and dipyridamole the safest and simplest pharmacological stress and the most suitable for combined wall motion coronary flow reserve assessment. The additional clinical benefit of myocardial perfusion contrast echocardiography and myocardial velocity imaging has been inconsistent to date, whereas the potential of adding - coronary flow reserve evaluation of left anterior descending coronary artery by transthoracic Doppler echocardiography adds another potentially important dimension to stress echocardiography. New emerging fields of application taking advantage from the versatility of the technique are Doppler stress echo in valvular heart disease and in dilated cardiomyopathy. In spite of its dependence upon operator's training, stress echocardiography is today the best (most cost-effective and risk-effective) possible imaging choice to achieve the still elusive target of sustainable cardiac imaging in the field of noninvasive diagnosis of coronary artery disease.

Spinal cord stimulation normalizes abnormal cortical pain processing in patients with cardiac syndrome X

Cardiac syndrome X (CSX) is characterized by effort angina, ST-segment depression during stress tests and normal coronary arteries. Abnormal nociception was suggested in these patients by studies showing a reduced cardiac pain threshold; furthermore, we recently found a lack of habituation to pain stimuli using recording of laser evoked potentials (LEPs). In CSX patients with severe angina, spinal cord stimulation (SCS) was shown to improve symptoms. In this study we investigated whether, in these patients, SCS has any effects on the excitability of the nociceptive system, assessed by LEPs recording. We studied 16 CSX patients (61.6+/-7 years; 4 men) who underwent SCS for refractory angina. Cortical LEPs were recorded during stimulation of the chest and right-hand during active SCS (SCS-ON) and in the absence of SCS (SCS-OFF), using a randomized cross-over design. Three sequences of painful stimuli were applied at each site during each test. During the first sequence of chest stimuli, the N2/P2 LEP amplitude was higher during the SCS-ON, compared to the SCS-OFF phase (18.2+/-7.8 vs. 11.5+/-4.4 microV, P=0.006). The N2/P2 amplitude did not change significantly across the three stimulation sequences during the SCS-OFF phase (P=0.22), whereas it decreased progressively during the second and third sequence (to 87.1+/-29.5% and 76.4+/-24.1%, respectively) compared with the first sequence, during the SCS-ON phase (P=0.014). Similar results were observed during right-hand stimulation. Our study shows that in CSX patients SCS is able to restore habituation to peripheral pain stimuli. This effect might contribute to restore the ability of CSX patients to better tolerate cardiac pain.

Relation between stress-induced myocardial perfusion defects on cardiovascular magnetic resonance and coronary microvascular dysfunction in patients with cardiac syndrome X

OBJECTIVES

The purpose of this study was to investigate whether a direct relation can be demonstrated between myocardial perfusion defects detected during dobutamine stress test (DST) by cardiovascular magnetic resonance (CMR) and impairment of coronary microvascular dilatory function in patients with cardiac syndrome X (CSX).

BACKGROUND

Despite the fact that coronary microvascular dysfunction has been shown in most patients with CSX, the ischemic origin of CSX remains debated. No previous study assessed whether a strict relation exists between abnormalities in myocardial perfusion and coronary microvascular dysfunction in CSX patients.

METHODS

Eighteen CSX patients (mean age 58 +/- 7 years, 7 men) and 10 healthy control subjects (mean age 54 +/- 8 years, 4 men) underwent myocardial perfusion study by gadolinium-enhanced CMR at rest and at peak DST (maximal dose 40 microg/kg/min). Coronary flow response (CFR) to adenosine (140 microg/kg/min in 90 s) in the left anterior descending (LAD) coronary artery was assessed by high-resolution transthoracic echo-Doppler and expressed as the ratio between coronary flow velocity at peak adenosine and at rest.

RESULTS

At peak DST, reversible perfusion defects on CMR were found in 10 CSX patients (56%) but in none of the control subjects (p = 0.004). The CFR to adenosine in the LAD coronary artery was lower in CSX patients than in control subjects (2.03 +/- 0.63 vs. 3.29 +/- 1.0, p = 0.0004). The CSX patients with DST-induced myocardial perfusion defects in the LAD territory on CMR had a lower CFR to adenosine compared with those without perfusion defects in the LAD territory (1.69 +/- 0.5 vs. 2.31 +/- 0.6, p = 0.01). A significant correlation was found in CSX patients between CFR to adenosine and a DST perfusion defect score on CMR in the LAD territory (r = -0.45, p = 0.019).

CONCLUSIONS

Our data concurrently show DST-induced myocardial perfusion defects on CMR and reduced CFR in the LAD coronary artery territory in CSX patients, thus giving strong evidence that a dysfunction of coronary microcirculation resulting in myocardial perfusion abnormalities is present in these patients.