Long-term follow-up of patients with cardiac syndrome X treated by spinal cord stimulation

Coronary microvascular disease in women: epidemiology, mechanisms, evaluation, and treatment

Coronary microvascular dysfunction (CMD) involves functional or structural abnormalities of the coronary microvasculature resulting in dysregulation of coronary blood flow (CBF) in response to myocardial oxygen demand. This perfusion mismatch causes myocardial ischemia, which manifests in patients as microvascular angina (MVA). CMD can be diagnosed non-invasively via multiple imaging techniques or invasively using coronary function testing (CFT), which assists in determining the specific mechanisms involving endothelium-independent and dependent epicardial and microcirculation domains. Unlike traditional coronary artery disease (CAD), CMD can often occur in patients without obstructive atherosclerotic epicardial disease, which can make the diagnosis of CMD difficult. Moreover, MVA due to CMD is more prevalent in women and carries increased risk of future cardiovascular events. Successful treatment of symptomatic CMD is often patient-specific risk factor and endotype targeted. This article aims to review newly identified mechanisms and novel treatment strategies for managing CMD, and outline sex-specific differences in the presentation and pathophysiology of the disease.

Chinese expert consensus on the diagnosis and treatment of coronary microvascular diseases (2023 Edition)

Since the four working groups of the Chinese Society of Cardiology issued first expert consensus on coronary microvascular diseases (CMVD) in 2017, international consensus documents on CMVD have increased rapidly. Although some of these documents made preliminary recommendations for the diagnosis and treatment of CMVD, they did not provide classification of recommendations and levels of evidence. In order to summarize recent progress in the field of CMVD, standardize the methods and procedures of diagnosis and treatment, and identify the scientific questions for future research, the four working groups of the Chinese Society of Cardiology updated the 2017 version of the Chinese expert consensus on CMVD and adopted a series of measures to ensure the quality of this document. The current consensus has raised a new classification of CMVD, summarized new epidemiological findings for different types of CMVD, analyzed key pathological and molecular mechanisms, evaluated classical and novel diagnostic technologies, recommended diagnostic pathways and criteria, and therapeutic strategies and medications, for patients with CMVD. In view of the current progress and knowledge gaps of CMVD, future directions were proposed. It is hoped that this expert consensus will further expedite the research progress of CMVD in both basic and clinical scenarios.

Cardiovascular Effects of Spinal Cord Stimulation: The Highs, the Lows, and the Don't Knows

BACKGROUND AND OBJECTIVES

There are many potential etiologies of impaired cardiovascular control, from chronic stress to neurodegenerative conditions or central nervous system lesions. Since 1959, spinal cord stimulation (SCS) has been reported to modulate blood pressure (BP), heart rate (HR), and HR variability (HRV), yet the specific stimulation sites and parameters to induce a targeted cardiovascular (CV) change for mitigating abnormal hemodynamics remain unclear. To investigate the ability and parameters of SCS to modulate the CV, we reviewed clinical studies using SCS with reported HR, BP, or HRV findings.

MATERIALS AND METHODS

A keyword-based electronic search was conducted through MEDLINE, Embase, and PubMed data bases, last searched on February 3, 2023. Inclusion criteria were studies with human participants receiving SCS with comparison with SCS turned off, with reporting of either HR, HRV, or BP findings. Non-English studies, conference abstracts, and studies not reporting standalone effects of SCS when comparing SCS with non-SCS interventions were excluded. Results were plotted for visual analysis. When available, participant-specific stimulation parameters and effects were extracted and quantitatively analyzed using ordinary least squares regression.

RESULTS

A total of 59 studies were included in this review; 51 studies delivered SCS invasively through implanted/percutaneous leads. Eight studies used noninvasive, transcutaneous electrodes. We found numerous reports of cervical, high thoracic, and mid-to-low thoracolumbar SCS increasing resting BP, and cervical/mid-to-low thoracolumbar SCS decreasing BP. The effect of SCS location on HR and HRV was equivocal. We were unable to analyze stimulation parameters owing to inadequate parameter reporting in many publications.

CONCLUSIONS

Our findings suggest CV neuromodulation, particularly BP modulation, with SCS to be a promising frontier. Further research with larger randomized controlled trials and detailed reporting of SCS parameters will be necessary for appropriate evaluation of SCS as a CV therapy.

The Central Nervous System and Psychosocial Factors in Primary Microvascular Angina

Patients diagnosed with ischemia without obstructive coronary artery disease (INOCA) comprise the group of patients with primary microvascular angina (MVA). The pathophysiology underlying ischemia and angina is multifaceted. Differences in vascular tone, collateralization, environmental and psychosocial factors, pain thresholds, and cardiac innervation seem to contribute to clinical manifestations. There is evidence suggesting potential interactions between the clinical manifestations of MVA and non-cardiac conditions such as abnormal function of the central autonomic network (CAN) in the central nervous system (CNS), pain modulation pathways, and psychological, psychiatric, and social conditions. A few unconventional non-pharmacological and pharmacological techniques targeting these psychosocial conditions and modulating the CNS pathways have been proposed to improve symptoms and quality of life. Most of these unconventional approaches have shown encouraging results. However, these results are overall characterized by low levels of evidence both in observational studies and interventional trials. Awareness of the importance of microvascular dysfunction and MVA is gradually growing in the scientific community. Nonetheless, therapeutic success remains frustratingly low in clinical practice so far. This should promote basic and clinical research in this relevant cardiovascular field investigating, both pharmacological and non-pharmacological interventions. Standardization of definitions, clear pathophysiological-directed inclusion criteria, crossover design, adequate sample size, and mid-term follow-up through multicenter randomized trials are mandatory for future study in this field.

Management of ischaemia with non-obstructive coronary arteries (INOCA)

Up to half of patients undergoing elective coronary angiography for the investigation of chest pain do not present with evidence of obstructive coronary artery disease. These patients are often discharged with a diagnosis of non-cardiac chest pain, yet many could have an ischaemic basis for their symptoms. This type of ischaemic chest pain in the absence of obstructive coronary artery disease is referred to as INOCA (ischaemia with non-obstructive coronary arteries). This comprehensive review of INOCA management looks at why these patients require treatment, who requires treatment based on diagnostic evaluation, what clinical treatment targets should be considered, how to treat patients using a personalised medicine approach, when to initiate treatment, and where future research is progressing.

Spinal Cord Stimulation

Spinal cord stimulation (SCS) has been well established as a safe and effective treatment of pain derived from a wide variety of etiologies. Careful patient selection including a rigorous trial period and psychological evaluation are essential. When patients proceed to permanent implantation, various considerations should be made, such as the type of lead, type of anesthesia, and waveform patterns for SCS. This article discusses the common indications for SCS, patient selection criteria, and pertinent outcomes from randomized clinical trials related to common indications treated with SCS. Technical considerations, such as type of implant, anesthesia, and programming, are also discussed.

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.

'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.

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).

Management of microvascular angina pectoris

Microvascular angina (MVA) is defined as angina pectoris caused by abnormalities of small coronary arteries. In its most typical presentation, MVA is characterized by angina attacks mainly caused by effort, evidence of myocardial ischemia on non-invasive stress tests, but normal coronary arteries at angiography. Patients with stable MVA have excellent long-term prognoses, but often present with persistent and/or worsening of angina symptoms. Treatment of MVA is initially based on standard anti-ischemic drugs (beta-blockers, calcium antagonists, and nitrates), but control of symptoms is often insufficient. In these cases, several additional drugs, with different potential anti-ischemic effects, have been proposed, including ranolazine, ivabradine, angiotensin-converting enzyme (ACE) inhibitors, xanthine derivatives, nicorandil, statins, alpha-blockers and, in perimenopausal women, estrogens. In patients with 'refractory MVA', some further alternative therapies (e.g., spinal cord stimulation, pain-inhibiting substances such as imipramine, rehabilitation programs) have shown favorable results.

Coronary microvascular dysfunction: an update

Many patients undergoing coronary angiography because of chest pain syndromes, believed to be indicative of obstructive atherosclerosis of the epicardial coronary arteries, are found to have normal angiograms. In the past two decades, a number of studies have reported that abnormalities in the function and structure of the coronary microcirculation may occur in patients without obstructive atherosclerosis, but with risk factors or with myocardial diseases as well as in patients with obstructive atherosclerosis; furthermore, coronary microvascular dysfunction (CMD) can be iatrogenic. In some instances, CMD represents an epiphenomenon, whereas in others it is an important marker of risk or may even contribute to the pathogenesis of cardiovascular and myocardial diseases, thus becoming a therapeutic target. This review article provides an update on the clinical relevance of CMD in different clinical settings and also the implications for therapy.

Effects of ivabradine and ranolazine in patients with microvascular angina pectoris

Patients with microvascular angina (MVA) often have persistence of symptoms despite full classical anti-ischemic therapy. In this study, we assessed the effect of ivabradine and ranolazine in MVA patients. We randomized 46 patients with stable MVA (effort angina, positive exercise stress test [EST], normal coronary angiography, coronary flow reserve <2.5), who had symptoms inadequately controlled by standard anti-ischemic therapy, to ivabradine (5 mg twice daily), ranolazine (375 mg twice daily), or placebo for 4 weeks. The Seattle Angina Questionnaire (SAQ), EuroQoL scale, and EST were assessed at baseline and after treatment. Coronary microvascular dilation in response to adenosine and to cold pressor test and peripheral endothelial function (by flow-mediated dilation) were also assessed. Both drugs improved SAQ items and EuroQoL scale compared with placebo (p <0.01 for all), with ranolazine showing some more significant effects compared with ivabradine, on some SAQ items and EuroQoL scale (p <0.05). Time to 1-mm ST-segment depression and EST duration were improved by ranolazine compared with placebo. No effects on coronary microvascular function and on flow-mediated dilation were observed with drugs or placebo. In conclusion, ranolazine and ivabradine may have a therapeutic role in MVA patients with inadequate control of symptoms in combination with usual anti-ischemic therapy.

Long-term prognosis of patients with cardiac syndrome X: a review

Aims

Follow-up studies of patients with cardiac syndrome X (CSX) generally report good prognosis. However, some recent studies report an adverse outcome for women.

Methods and results

Structured literature search and meta-analysis for studies regarding prognosis of cardiac syndrome X patients. We identified 85 studies, ultimately selecting 16 for inclusion. Meta-analysis yielded a pooled major cardiac event percentage of 1.5% per 5 years and a pooled vascular event percentage of 4.8% per 5 years (n = 16 studies, n = 1694 patients). Fourteen studies reported upon the recurrence rate of angina pectoris: the pooled percentage of angina recurrence was 55% (n = 1336 patients).

Conclusion

The present review of recent archival literature demonstrates an overall major cardiac event rate of 1.5% per 5 years. Although this is an excellent prognosis for CSX patients, the quality of life is impaired because of the high recurrence rate of angina pectoris (55%).

Technological innovation in spinal cord stimulation: use of a newly developed delivery device for introduction of spinal cord stimulation leads

OBJECTIVE

The use of multiple cylindrical leads and multicolumn and single column paddle leads in spinal cord stimulation offers many advantages over the use of a single cylindrical lead. Despite these advantages, placement of multiple cylindrical leads or a paddle lead requires a more invasive surgical procedure. Thus, the ideal situation for lead delivery would be percutaneous insertion of a paddle lead or multiple cylindrical leads. This study evaluated the feasibility and safety of percutaneous delivery of S-Series paddle leads using a new delivery device called the Epiducer lead delivery system (all St. Jude Medical Neuromodulation Division, Plano, TX, USA).

MATERIALS AND METHODS

This uncontrolled, open-label, prospective, two-center study approved by the AZ St. Lucas (Ghent) Ethics Committee evaluated procedural aspects of implantation of an S-Series paddle lead using the Epiducer lead delivery system and any adverse events relating to the device. Efficacy data during the patent's 30-day trial also were collected.

RESULTS

  Data from 34 patients were collected from two investigational sites. There were no adverse events related to the Epiducer lead delivery system. The device was inserted at an angle of either 20°-30° or 30°-40° and was entered into the epidural space at T12/L1 in most patients. The S-Series paddle lead was advanced four vertebral segments in more than 50% of patients. The average (±standard deviation [SD]) time it took to place the Epiducer lead delivery system was 8.7 (±5.0) min. The average (+SD) patient-reported pain relief was 78.8% (+24.1%).

CONCLUSIONS

This study suggests the safe use of the Epiducer lead delivery system for percutaneous implantation and advancement of the S-Series paddle lead in 34 patients.

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.

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.

Contemporary treatment of Western and Chinese medicine for cardiac syndrome X

Clinical reports on cardiac syndrome X (CSX) have been increasing in recent years. In general, CSX does not increase the cardiovascular mortality, but it can affect the patient's quality of life (QOL) and increase the incidence rates of cardiovascular and cerebrovascular events. Although a variety of drugs and therapies have been utilized in the clinical treatment, the management of CSX still represents a major challenge due to its unclear pathogenesis. It is necessary to explore more effective treatment programs. Many attempts have been made on trials of the Chinese medicine (CM) treatment for CSX and proved that CM has a certain advantage in efficacy to improve clinical symptoms and QOL. CM may provide a new approach for the effective treatment of CSX.

Usefulness of impairment of cardiac adrenergic nerve function to predict outcome in patients with cardiac syndrome X

Patients with cardiac syndrome X (CSX) have an excellent long-term prognosis, but a significant number show worsening angina over time. Previous studies have found a significant impairment of cardiac uptake of iodine-123-meta-iodobenzylguanidine (MIBG) on myocardial scintigraphy, indicating abnormal function of cardiac adrenergic nerve fibers. The aim of this study was to assess whether cardiac MIBG results can predict symptomatic outcome in patients with CSX. Cardiac MIBG scintigraphy was performed in 40 patients with CSX (mean age 58 ± 5 years, 14 men). Cardiac MIBG uptake was measured by the heart/mediastinum uptake ratio and a single photon-emission computed tomographic regional uptake score (higher values reflected lower uptake). Clinical findings, exercise stress test parameters, sestamibi stress myocardial scintigraphy, and C-reactive protein serum levels were also assessed. At an average follow-up of 79 months (range 36 to 144), no patient had died or developed acute myocardial infarction. Cardiac MIBG defect score was significantly lower in patients with worsening versus those without worsening of angina status (13 ± 7 vs 38 ± 28, p = 0.001), in those with versus those without hospital readmission because of recurrent chest pain (15 ± 9 vs 35 ± 29, p = 0.01), and in those who underwent versus those who did not undergo repeat coronary angiography (11 ± 7 vs 36 ± 27, p = 0.001). Significant correlations were found between quality of life (as assessed by the EuroQoL scale) and heart/mediastinum ratio (r = 0.48, p = 0.002) and cardiac MIBG uptake score (r = -0.69, p <0.001). No other clinical or laboratory variable showed a significant association with clinical end points. In conclusion, in patients with CSX, abnormal function of cardiac adrenergic nerve fibers, as assessed by an impairment of cardiac MIBG uptake, identifies those with worse symptomatic clinical outcomes.

Definitions and incidence of cardiac syndrome X: review and analysis of clinical data

There is no consensus regarding the definition of cardiac syndrome X (CSX). We systematically reviewed recent literature using a standardized search strategy. We included 57 articles. A total of 47 studies mentioned a male/female distribution. A meta-analysis yielded a pooled proportion of females of 0.56 (n = 1,934 patients, with 95% confidence interval: 0.54-0.59). As much as 9 inclusion criteria and 43 exclusion criteria were found in the 57 articles. Applying these criteria to a population with normal coronary angiograms and treated in 1 year at a general hospital, the attributable CSX incidence varied between 3 and 11%. The many inclusion and exclusion criteria result in a wide range of definitions of CSX and these have large effects on the incidence. This shows the need for a generally accepted definition of CSX.

Autogenic training to manage symptomology in women with chest pain and normal coronary arteries

OBJECTIVES

To explore autogenic training (AT) as a treatment for psychological morbidity, symptomology, and physiological markers of stress among women with chest pain, a positive exercise test for myocardial ischemia, and normal coronary arteries (cardiac syndrome X).

DESIGN

Fifty-three women with cardiac syndrome X (mean +/- SD age, 57.1 +/- 8 years) were randomized to an 8-week AT program or symptom diary control. Symptom severity and frequency, Hospital Anxiety and Depression Scale, Spielberger State-Trait Anxiety Inventory, Cardiac Anxiety Questionnaire (CAQ), and Ferrans and Powers Quality of Life Index (QLI), blood pressure, heart rate, electrocardiogram, and plasma catecholamines were measured before and after intervention and at the 8-week follow-up.

RESULTS

Women who underwent AT had improved symptom frequency (8.04 +/- 10.08 vs 1.66 +/- 2.19, P < 0.001) compared with control women and reduced symtom severity (2.08 +/- 1.03 vs 1.23 +/- 1.36, P = 0.02) and frequency (6.11 +/- 3.17 vs 1.66 +/- 2.19, P < G 0.001) post-AT compared with baseline within group. Within-group improvements among women who underwent AT include QLI health functioning (17.80 +/- 5.74 vs 19.41 +/- 5.19, P = 0.04) and CAQ fear (1.53 +/- 0.61 vs 1.35 +/- 0.56, P = 0.02) post-AT and QLI health functioning (17.80 +/- 5.74 vs 20.09 +/- 5.47, P = 0.01), CAQ fear (1.53 +/- 0.61 vs 1.30 +/- 0.67, P = 0.002), CAQ total (1.42 +/- 0.54 vs 1.29 +/- 0.475, P = 0.04), Spielberger State-Trait Anxiety Inventory trait anxiety (42.95 +/- 11.19 vs 38.68 +/- 11.47, P = 0.01), and QLI quality of life (20.67 +/- 5.37 vs 21.9 +/- 4.89, P = 0.02) at follow-up.

CONCLUSION

An 8-week AT program improves symptom frequency, with near-significant improvements in symptom severity in women with cardiac syndrome X.

Cardiac rehabilitation for the treatment of women with chest pain and normal coronary arteries

OBJECTIVE

To explore cardiac rehabilitation (CR) as a treatment for psychological and physiological morbidity in women with chest pain and normal coronary arteries (cardiac syndrome X).

DESIGN

Sixty-four women aged 57.3+/-8.6 years (mean +/- SD) with cardiac syndrome X were randomly assigned to an 8-week phase III CR exercise program or symptom monitoring control. All women completed the Hospital Anxiety and Depression Scale, Health Anxiety Questionnaire, and Short Form-36 before and after intervention and at the 8-week follow-up. CR patients underwent physical assessment before and after CR.

RESULTS

After CR, patients demonstrated improved symptom severity (2.0+/-0.8 vs 1.26+/-1.1, P=0.009), Hospital Anxiety and Depression Scale depression score (8.0+/-3.4 vs 6.4+/-3.1, P=0.04), total Health Anxiety Questionnaire score (12.0+/-5.5 vs 9.5+/-6.0, P=0.008), health worry (4.5+/-3.1 vs 3.52+/-2.4, P=0.025) and interference (2.4+/-1.8 vs 1.6+/-1.8, P=0.004), SF-36 physical functioning (53.1+/-20.4 vs 62.3+/-23.9, P = 0.006), energy (36.3+/-20.7 vs 49.8+/-19.1, P<0.001), pain (49.9+/-20.7 vs 58.1+/-22.9, P=0.028), and general health (48.8+/-17.9 vs 57.6+/-17.0, P=0.01) not found among the control women. Improvements were maintained at follow-up. CR patients showed significant improvements in Shuttle Walk Test performance (326.8+/-111.0 vs 423.6+/-133.2 m, P<0.001), diastolic blood pressure (84.7+/-9.4 vs 79.7+/-7.3 mm Hg, P=0.007), and body mass index (29.1+/-6.0 vs 28.4+/-6.17 kg/m2, P=0.003).

CONCLUSIONS

An 8-week phase III CR program improves exercise tolerance, quality of life, psychological morbidity, symptom severity, and cardiovascular risk factors in women with cardiac syndrome X.

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.