Spinal cord stimulation for chronic intractable angina pectoris: a unified theory on its mechanism

Spinal Cord Stimulation for Refractory Angina Pectoris: Current Status and Future Perspectives, a Narrative Review

Refractory angina pectoris (RAP) is a clinical syndrome characterized by persistent chest pain caused by myocardial ischemia that is unresponsive to optimal pharmacological therapy and revascularization procedures. Spinal cord stimulation (SCS) has emerged as a promising therapeutic option for managing RAP, offering significant symptom relief and improved quality of life. A systematic literature review was conducted to evaluate the clinical effectiveness, mechanisms of action, and safety profile of SCS in treating RAP. Comprehensive searches were performed in PubMed, Scopus, and Web of Science for studies published between 1990 and 2023. Of 328 articles identified, 6 met the inclusion and exclusion criteria for final analysis. The included studies consistently demonstrated that SCS significantly reduces the frequency of anginal episodes and nitroglycerin use while improving exercise capacity and quality of life. Proposed mechanisms include modulation of pain signals via the gate control theory, enhancement of autonomic balance, and redistribution of myocardial perfusion. Novel stimulation modalities, including high-frequency, Burst, and Differential Target Multiplexed (DTM), show potential advantages in enhancing patient comfort and clinical outcomes. Nevertheless, long-term studies are necessary to validate these findings and establish the comparative efficacy of these advanced technologies. SCS is a safe and effective therapy for patients with RAP who are unsuitable for surgical interventions. Innovations in neurostimulation, including closed-loop systems and personalized treatment strategies have the potential to further optimize outcomes. Rigorous clinical trials are needed to consolidate the role of SCS as a cornerstone therapy for the management of RAP.

Historical Perspective of the Cardiac Autonomic Nervous System

The contemporary history of the cardiac autonomic nervous system includes early descriptions of neuroanatomy in the 19th century, followed by an understanding of the physiologic determinants of neurocardiology in the 20th century. Neurology and cardiology preceded the arrival of clinical cardiac electrophysiology, a specialized field in medicine devoted to the diagnosis and treatment of cardiac arrhythmias. The rapid growth in pharmacology, ablation, pacing and defibrillation, associated with significant technological breakthroughs, have resulted in new opportunities for neuromodulation in the 21st century. Small changes in autonomic tone can potentially provide important therapeutic benefits for patients with cardiac and arrhythmia disorders.

Efficacy of spinal cord stimulation as an adjunctive therapy in heart failure: A systematic review

Neuromodulation therapy, like spinal cord stimulation (SCS), benefits individuals with chronic diseases, improving outcomes of patients with heart failure (HF). This systematic review aims to investigate the efficacy of SCS when used as an adjunctive therapy in HF. A systematic analysis of all studies that included SCS therapy in human participants with HF was conducted. After excluding studies not meeting specific criteria, 4 studies involving a total of 125 participants were selected. All participants had heart failure with the New York Heart Association (NYHA) classification ranging from 2.2 ± 0.4 to 3. The primary endpoints for assessment included the impact of SCS in HF-related symptoms, Left ventricular function, VO2 max, and NT-proBNP. All the studies could demonstrate safety and feasibility of SCS therapy, although the outcomes varied. Two studies reported improvement in NYHA classification, MLHFQ and QoL parameters after SCS. Concerning LVEF and VO2 max, only one study indicated positive changes. None of the studies found a significant change of NT-proBNP following SCS therapy. Given methodological variation, discrepancies in the results could be attributed to the diversity of the induction technique. Further studies are needed to develop a solid approach for employing SCS in human patients with HF.

Spinal cord stimulation for refractory pericarditis: a case report and a review of the mechanism of action

Background and objectives

In recent years, spinal cord stimulation (SCS) has emerged as a promising management option for chronic pain of multiple etiologies. While its effectiveness has been strongly suggested in many patients, the exact mechanism of action of SCS is incompletely understood. This article reviews the leading mechanisms underlying the analgesic and cardiovascular effects of SCS and reports its novel benefits in a case of recurrent pericarditis.

Literature review

Throughout history, the analgesic properties of SCS were thought to arise via stimulation of the spinothalamic tract. Although this mechanism has been thoroughly reported, new research and patient outcomes from SCS have revealed various additional properties that cannot be fully explained by this mechanism alone. Evidence suggests that SCS enhances calcitonin gene-related peptide release and modulates inflammatory cytokine secretion, sympathetic tone, and inhibitory neurotransmitter secretion. These distinct mechanisms likely collectively contribute to the therapeutic effects of SCS on the cardiovascular system and pain management.

Case report

We report the case of a 48-year-old male patient with recurrent pericarditis, characterized by refractory angina-like pain and reduced left ventricular ejection fraction (LVEF). After 1 year of having a spinal cord stimulator implanted, the patient is free from pain and narcotics, with a reduction of 428 mg equivalent dose of morphine. The patient's LVEF increased from 40% to 45% without changes to his previous medical treatment. This is the first reported case of refractory pericarditis managed with spinal cord stimulation.

Conclusion

Recognizing the improved pain management, reduced narcotic usage, and improved LVEF in our patient following SCS is critical to paving the way toward a complete understanding of the mechanism of action of SCS. This case reveals the therapeutic potential of SCS for cardiovascular pathologies other than refractory angina pectoris.

Burst stimulation for refractory angina pectoris - A case report

BACKGROUND

Refractory angina pectoris (RAP) is a chronic, severe chest pain associated with coronary artery disease that cannot be resolved using optimal medical or surgical approaches. Spinal cord stimulation (SCS) is a suitable treatment option. Conventional waveforms of SCS have shown a potent effect on the tempering of RAP. However, SCS is associated with undesired paresthesia. The new burst SCS waveforms have been reported to have fewer adverse effects.

CASE

We reviewed a case in which RAP was successfully treated with burst SCS in a middle-aged male, with a tonic waveform employed for breakthrough pain as needed.

CONCLUSIONS

Appropriate use of tonic and burst stimulations according to the symptoms is expected to maximize the effect of relieving chest pain induced by RAP.

Long-term efficacy and safety of spinal cord stimulation in patients with refractory angina pectoris

Background

The number of patients with refractory angina pectoris (RAP), associated with poor quality of life, has been steadily increasing. Spinal cord stimulation (SCS) is a last resort treatment option leading to significant improvement in quality of life over a one year follow-up. The aim of this prospective, single-centre, observational cohort study is to determine the long-term efficacy and safety of SCS in patients with RAP.

Methods

All patients with RAP who received a spinal cord stimulator from the period July 2010 up to November 2019 were included. In May 2022 all patients were screened for long-term follow-up. If the patient was alive the Seattle Angina (SAQ) and RAND-36 questionnaire were completed and if the patient had passed away cause of death was determined. The primary endpoint is the change in SAQ summary score at long-term follow-up compared to baseline.

Results

From July 2010 up to November 2019 132 patients received a spinal cord stimulator due to RAP. The mean follow-up period was 65.2 ± 32.8 months. Seventy-one patients completed the SAQ at baseline and long-term follow-up. The SAQ SS showed an improvement of 24.32U (95% confidence interval [CI]: 18.71 – 29.93; p < 0.001).

Conclusions

The main findings of the study show that long-term SCS in patients with RAP leads to significant improvement in quality of life, significant reduction in angina frequency, significantly less use of short-acting nitrates and a low risk of spinal cord stimulator related complications over a mean follow-up period of 65.2 ± 32.8 months.

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.

Therapeutic Approaches for the No-Option Refractory Angina Patient

The combination of an aging population and improved survival rates among patients with coronary artery disease has resulted in an increase in the number of patients with refractory angina or anginal equivalent symptoms despite maximal medical therapy. Patients with refractory angina are often referred to the cardiac catheterization laboratory; however, they have often exhausted conventional revascularization options; thus, this population is often deemed as having "no options." We review the definition, prevalence, outcomes, therapeutic options, and treatment considerations for no-option refractory angina patients and focus on novel therapies for this complex and challenging population. We propose a multidisciplinary team approach for the evaluation and management of patients with refractory angina, ideally in a designated clinic. The severe limitations and symptomatology experienced by these patients highlight the need for additional research into the development of innovative treatments.

Improvement in quality of life and angina pectoris: 1-year follow-up of patients with refractory angina pectoris and spinal cord stimulation

Aims

Spinal cord stimulation (SCS) is a treatment for patients with refractory angina pectoris (RAP) who remain symptomatic despite optimal medical therapy and without revascularisation options. Previous studies have shown that SCS improves the quality of life in this patient group and reduces the severity of the angina pectoris. The aim of this prospective, single-arm observational study is to show this effect in a single-centre cohort using a multidisciplinary team approach to the selection process, with a follow-up period of 1 year.

Methods and results

Between July 2010 and March 2017, 87 patients with RAP referred to our centre received SCS. The Seattle Angina Questionnaire (SAQ) and RAND 36-Item Health Survey (RAND-36) were completed at baseline, prior to implantation, and 1 year post-implantation. After 1 year of follow-up there was a statistically significant decrease in the frequency of angina pectoris attacks from more than 4 times a day to 1–2 times a week (p < 0.001). The SAQ showed statistically significant improvement in four of the five dimensions: physical limitation (p < 0.001), angina frequency (p < 0.001), angina stability (p < 0.001) and quality of life (p < 0.001). The RAND-36 showed statistically significant improvement in all nine dimensions: physical functioning (p = 0.001), role/physical (p < 0.001), social functioning (p = 0.03), role/emotional (p < 0.05), bodily pain (p < 0.001), general health (p < 0.001), vitality (p < 0.001), mental health (p = 0.02) and health change (p < 0.001).

Conclusion

This study showed a significant improvement in quality of life and reduction of angina pectoris severity after 1 year of follow-up in patients treated with SCS for RAP.

Electronic supplementary material

The online version of this article (10.1007/s12471-020-01422-0) contains supplementary material, which is available to authorized users.

Neuromodulation for Ventricular Tachycardia and Atrial Fibrillation: A Clinical Scenario-Based Review

Autonomic dysregulation in cardiovascular disease plays a major role in the pathogenesis of arrhythmias. Cardiac neural control relies on complex feedback loops consisting of efferent and afferent limbs, which carry sympathetic and parasympathetic signals from the brain to the heart and sensory signals from the heart to the brain. Cardiac disease leads to neural remodeling and sympathovagal imbalances with arrhythmogenic effects. Preclinical studies of modulation at central and peripheral levels of the cardiac autonomic nervous system have yielded promising results, leading to early stage clinical studies of these techniques in atrial fibrillation and refractory ventricular arrhythmias, particularly in patients with inherited primary arrhythmia syndromes and structural heart disease. However, significant knowledge gaps in basic cardiac neurophysiology limit the success of these neuromodulatory therapies. This review discusses the recent advances in neuromodulation for cardiac arrhythmia management, with a clinical scenario-based approach aimed at bringing neurocardiology closer to the realm of the clinical electrophysiologist.

The Effectiveness and Cost-Effectiveness of Spinal Cord Stimulation for Refractory Angina (RASCAL Study): A Pilot Randomized Controlled Trial

Background

Patients with “refractory angina” (RA) unsuitable for coronary revascularization experience high levels of hospitalization and poor health‐related quality of life. Randomized trials have shown spinal cord stimulation (SCS) to be a promising treatment for chronic stable angina and RA; however, none has compared SCS with usual care (UC). The aim of this pilot study was to address the key uncertainties of conducting a definitive multicenter trial to assess the clinical and cost‐effectiveness of SCS in RA patients, i.e., recruitment and retention of patients, burden of outcome measures, our ability to standardize UC in a UK NHS setting.

Methods

RA patients deemed suitable were randomized in a 1:1 ratio to SCS plus UC (SCS group) or UC alone (UC group). We sought to assess: recruitment, uptake, and retention of patients; feasibility and acceptability of SCS treatment; the feasibility and acceptability of standardizing UC; and the feasibility and acceptability of the proposed trial outcome measures. Patient outcomes were assessed at baseline (prerandomization) and three and six months postrandomization.

Results

We failed to meet our planned recruitment target (45 patients) and randomized 29 patients (15 SCS group, 14 UC group) over a 42‐month period across four sites. None of the study participants chose to withdraw following consent and randomization. With exception of two deaths, all completed evaluation at baseline and follow‐up. Although the study was not formally powered to compare outcomes between groups, we saw a trend toward larger improvements in both primary and secondary outcomes in the SCS group.

Conclusions

While patient recruitment was found to be challenging, levels of participant retention, outcome completion, and acceptability of SCS therapy were high. A number of lessons are presented in order to take forward a future definitive pragmatic randomized trial.

Spinal cord stimulation is safe and feasible in patients with advanced heart failure: early clinical experience

AIMS

Pre-clinical work suggests that upper thoracic spinal cord stimulation (SCS) may have therapeutic effects in the treatment of heart failure (HF). We therefore aim to assess the safety and feasibility of SCS in HF patients.

METHODS AND RESULTS

A prospective, randomized, double-blind, crossover pilot study was conducted in symptomatic HF patients receiving optimal medical therapy. Patients were implanted with an SCS system and randomized to an SCS-ACTIVE, delivered at 90% paraesthesia threshold, or an SCS-INACTIVE phase for 3 months, followed by a 1-month washout period and crossover to the alternative phase. The safety of SCS therapy was assessed by death and cardiac events. Implantable cardioverter defibrillator (ICD) function in the presence of SCS was tested by defibrillation testing during SCS system implant and review of real-time and stored electrograms during follow-up. The efficacy of SCS therapy was assessed by changes in patient symptoms, LV function, and BNP level. Nine patients were investigated. In all cases, ICD sensing, detection, and therapy delivery were unaffected by SCS. During follow-up, one patient died and one was hospitalized for HF while in the SCS-INACTIVE phase, and two patients had HF hospitalizations during the SCS-ACTIVE phase. Symptoms were improved in the majority of patients with SCS, while markers of cardiac structure and function were, in aggregate, unchanged.

CONCLUSION

This study shows that an SCS system can be safely implanted in patients with advanced HF and that the SCS system does not interfere with ICD function.

Spinal cord stimulation: a 20-year retrospective analysis in 260 patients

Introduction. Spinal cord stimulation (SCS) is used clinically by many pain physicians and neurosurgeons alike without regard to their own outcome data. Methods. We reviewed our 20-year experience retrospectively of patients receiving SCS implants and analyzed our data by pain type and group. Results. We present 260 patients, 140 men and 120 women. The most frequent type of pain in our series was neuropathic pain in 44.25% and the most frequent diagnosis was peripheral vascular disease (PVD) with 98 cases. The second was failed back surgery syndrome (FBSS) with 65 cases and the third was complex regional pain syndrome type I (CRPS I), with 40 cases. In CRPS group, the mean visual analog scale (VAS) of this group was 77.89 ± 13.38. In total, 5% had no pain relief, 40% had poor pain relief, 47.5% had good pain relief, and 7.5% had excellent pain relief. In FBSS group, the mean VAS was 79.62 ± 11.69 mm. A total of 13.80% had no pain relief at all, 35.39% had poor pain relief, 50.76% had good pain relief, and there were no patients in this group who had complete pain relief. A total of 98 patients, 78 men and 20 women, were diagnosed with PVD. The mean VAS of this group was 69.75 ± 14.36 mm. A total of 11.22% had poor pain relief, 87.75% had good pain relief. One patient had complete pain relief and all patients in this group perceived at least some improvement in their symptoms. The rate of complications was close to 28% in our overall sample. Conclusions. In conclusion, we demonstrated the utility over time of this type of treatment is comparable with other series of efficacy of SCS. The analgesic efficacy was close to 65% in the overall group. The therapy was not free of complications. The preponderance of our patients was patients with the diagnosis of PVD and our results in this group of patients were excellent. These excellent results of more than 90% improvement suggest to us that SCS be considered as a first-line approach to the clinical management of patients with pain and ulcer of PVD.

Spinal cord stimulation has proven benefit on pain and quality of life in patients with angina pectoris when less invasive therapies have failed

Background.  Since 1988, spinal cord stimulation (SCS) has been used at Odense University Hospital for patients with refractory angina pectoris. The aim of our prospective study was to evaluate the long-term effects of SCS on pain, activities of daily living (ADLs), quality of life (QOL), sleep hygiene, and physical functioning for patients with angina pectoris. Methods.  Before and after placement of SCS for patients with intractable angina pectoris, we performed structured telephone interviews questioning for pain relief, ADLs (Nottingham Health Profile), physical functioning (Seattle Angina Questionnaire) and sleep hygiene. Results.  Out of 150 patients with SCS over 15 years, 41 patients had died, 46 patients had their devices explanted, and four patients did not participate or could not be reached. Three patients had less than 6 months of follow-up and were therefore not included in our analysis. The beneficial effects of SCS treatment for intractable angina pectoris were reduction in pain and improvement in QOL. Sleep pattern and physical functioning were not improved to the same extent as reduction in pain or improvement in QOL. Almost all of our SCS-treated patients did recommend SCS for intractable angina pectoris. About 30% of patients discontinued treatment, the most common cause being electrode displacement and malfunction of the system. Other reasons for discontinued therapy were the evolvement of invasive treatment options such as coronary artery bypass graft and PTCA and use of such options in some patients during our prolonged observation period. Conclusion.  This survey shows that SCS leads to a 70-80% improvement in pain, which, in turn, leads to improvement in QOL, whereas, physical condition and sleep pattern did not improve to the same extent.

Myocardial sympathetic innervation in patients with symptomatic coronary artery disease: follow-up after 1 year with neurostimulation

In both diabetic and nondiabetic patients, there is a loose correlation between coronary flow reserve (CFR) and sympathetic innervation in viable myocardial segments. The loose correlation implies that sympathetic innervation may be preserved even with major impairment of myocardial blood supply. In some patients, denervation is due to repetitive episodes of ischemia in areas with severely reduced CFR. We investigated the long-term effect of reduced CFR on myocardial sympathetic innervation in diabetic and nondiabetic patients with spinal cord stimulation.

METHODS

We analyzed 23 patients (10 diabetic and 13 nondiabetic) with coronary artery disease and without known cardiac autonomic neuropathy. At baseline, we determined quantitative myocardial blood flow using (13)N-ammonia PET, myocardial viability using (18)F-FDG PET, and cardiac innervation using (11)C-hydroxyephedrine (HED) PET. At the 1-y follow-up we measured CFR and (11)C-HED retention. During follow-up, no cardiac intervention was performed and no myocardial infarction occurred. In all patients, spinal cord stimulation was performed for relief of angina.

RESULTS

There was no significant difference in segmental (11)C-HED retention between baseline and follow-up in the whole patient group. In diabetic patients, as well as in segments with severely reduced CFR (<1.5), (11)C-HED retention showed a small but significant decrease (P<0.05). Linear regression of segmental (11)C-HED retention between baseline and follow-up was high (r(2)=0.81), confirming good reproducibility of the investigation on the one hand and little change in regional sympathetic innervation on the other hand.

CONCLUSION

In patients with stable chronic coronary artery disease, sympathetic innervation of the myocardium is almost unchanged in both diabetic and nondiabetic patients in a 1-y follow-up. In myocardial segments with severely altered blood supply, a small but significant decrease in (11)C-HED retention most probably reflects ischemic neuronal damage. The prognostic relevance of sympathetic denervation in viable myocardium still has to be determined.

Spinal cord stimulation in treatment of chronic benign pain: challenges in treatment planning and present status, a 22-year experience

OBJECTIVE

To present an in-depth analysis of clinical predictors of outcome including age, sex, etiology of pain, type of electrodes used, duration of pain, duration of treatment, development of tolerance, employment status, activities of daily living, psychological status, and quality of life. Suggestions for treatment of low back pain with a predominant axial component are addressed. We analyzed the complications and proposed remedial measures to improve the effectiveness of this modality.

METHODS

Study group consists of 410 patients (252 men, 58 women) with a mean age of 54 years and a mean follow-up period of 97.6 months. All patients were gated through a multidisciplinary pain clinic. The study was conducted over 22 years.

RESULTS

The early success rate was 80% (328 patients), whereas the long-term success rate of internalized patients was 74.1% (243 patients) after the mean follow-up period of 97.6 months. Hardware-related complications included displaced or fractured electrodes, infection, and hardware malfunction. Etiologies demonstrating efficacy included failed back syndrome, peripheral vascular disease, angina pain, complex regional pain syndrome I and II, peripheral neuropathy, lower limb pain caused by multiple sclerosis. Age, sex, laterality of pain or number of surgeries before implant did not play a role in predicting outcome. The percentage of pain relief was inversely related to the time interval between pain onset and time of implantation. Radicular pain with axial component responded better to dual Pisces electrode or Specify-Lead implantation.

CONCLUSION

Spinal cord stimulation can provide significant long-term pain relief with improved quality of life and employment. Results of this study will be effective in better defining prognostic factors and reducing complications leading to higher success rates with spinal cord stimulation.

Current medical management of chronic stable angina

Severe atherosclerotic narrowing of one or more coronary arteries is responsible for myocardial ischemia and angina pectoris in most patients with stable angina. The coronary arteries of patients with stable angina also contain many more non-obstructive plaques, which are prone to rupture resulting in acute coronary syndrome (unstable angina, myocardial infarction, sudden ischemic death). Therefore, the medical management must use strategies which not only relieve symptoms and prolong angina free walking but also reduce the incidence of adverse clinical outcomes. Whether any of the approved antianginal drugs, nitrates, beta-blockers, and calcium channel blockers reduce the incidence of adverse clinical outcomes in patients with stable angina has not been studied to date. Published data shows that percutaneous coronary revascularization procedures and coronary bypass surgery are effective in relieving angina but these procedures do not reduce mortality or the incidence of myocardial infarction compared to anti-anginal drug therapy. From the available data, an initial trial of medical treatment with anti-anginal drugs and strategies to reduce adverse clinical outcomes (smoking cessation, daily aspirin, treatment of dyslipidemias and hypertension) is indicated in most patients with stable angina pectoris. The initial choice of drug will depend on the presence or absence of comorbid conditions. Patients who do not respond to medical therapy or do not wish to take anti-anginal drugs and whose life style is limited because of anginal symptoms should be offered percutaneous revascularization procedures with or without stent placement or coronary bypass surgery. New drug-coated stents hold promise but long-term data and large-scale trials assessing the continued long-term improvement in symptoms and reduction of adverse outcomes is needed before offering such devices to all patients with stable angina. Newer medical therapies such as metabolic modulators and sinus rate lowering drugs also hold promise but need further evaluation. Patients who have refractory angina despite optimal medical therapy and are not candidates for revascularization procedures may be candidates for some new techniques of enhanced external Counterpulsation, Spinal Cord Stimulation, sympathectomy or direct transmyocardial revascularization. The usefulness of these techniques, however, needs to be confirmed in large randomized trials.

Spinal cord stimulation for the treatment of angina pectoris

Spinal cord stimulation (SCS) has been demonstrated to cause clinical improvement in patients with refractory angina pectoris in the number of anginal episodes, in nitroglycerin consumption, in maximal exercise time, in exercise time until angina, in the number of episodes of myocardial ischemia, in the duration of episodes of myocardial ischemia, and in ischemic ST-segment depression at a comparable workload. Double-blind, randomized, placebo-controlled studies have not been performed with SCS. The clinical improvement from SCS occurred despite no improvement in measured regional myocardial blood flow during exercise or in myocardial oxygen consumption as assessed by the heart rate times systolic pressure product at maximal exercise. The mechanisms of clinical improvement by SCS are unclear. SCS must be considered experimental at this time, and it remains a potential therapeutic option for the treatment of refractory angina pectoris in patients unable to have coronary revascularization or at very high risk for coronary revascularization.

Spinal cord stimulation for angina pectoris and peripheral vascular disease

SCS is a viable option for treating angina pectoris and inoperable PVD. Its mechanism of action remains controversial, but successful pain relief has been consistently reported in various studies. Many clinicians are foregoing a formal trial, choosing instead to obtain an adequate area of paresthesia and implant in one session. Long-term follow-up of SCS patients treated for angina pectoris shows continued pain relief, increase in activities, and decreased use of medications. Emerging literature supports the finding that SCS is cost-effective in this patient population relative to CABG. SCS does not mask the ischemic pain that signals impending further damage of the myocardium. In patients with inoperable PVD, SCS relieves pain and improves microcirculatory blood flow. Quality of life and mobility can be improved with SCS. The beneficial effects of SCS on ulcer healing are controversial, and evidence suggests that the best candidates for the procedure are those with ischemic rest pain without tissue loss. Patients with diabetes mellitus and hypertension may have the least favorable outcomes with regard to limb salvage. No convincing data have been published on the cost-effectiveness of SCS in this patient population. SCS is a safe procedure that is minimally invasive, reversible, and associated with only infrequent side effects, the most common of which include lead migration and infection. SCS is clearly an option for the improvement of pain and the quality of life in this carefully selected subset of patients.

Refractory angina pectoris: mechanism and therapeutic options

As the survival of patients with primary coronary events continues to increase, the number of patients presenting with coronary artery disease unsuitable to further revascularization techniques and symptoms refractory to medical therapy also continues to rise. The aims of this review were to define the population of patients with refractory angina pectoris and to present the therapeutic options currently available for this condition. Refractory angina pectoris is defined, and traditional medical therapies are discussed. Then, current therapeutic options for patients with refractory angina are extensively reviewed. A multitude of therapeutic options exist for patients with refractory angina pectoris. Small, uncontrolled studies have shown a potential benefit for additional antiplatelet and antithrombotic therapy. In randomized trials, neurostimulation has been shown to be effective in reducing angina symptoms. Enhanced external counterpulsation is a viable treatment option for select patients with refractory angina. In many randomized trials, laser revascularization has been shown to diminish angina symptoms, although no placebo-controlled studies exist to date. Gene therapy is a promising area of research in this field. Percutaneous in situ coronary venous arterialization is in its infancy, but may be able to treat many patients if proved successful. No data support the role of chelation therapy in this population. Heart transplantation remains a final option for these patients. Further research of the techniques mentioned in this review is warranted. The importance of randomized, double-blinded, placebo-controlled trials cannot be overemphasized, as the placebo effect of these therapies is probably marked.

Spinal Cord Stimulation: A Comparison of Efficacy versus Other Novel Treatments for Refractory Angina Pectoris

Recently much attention has been directed toward novel treatment alternatives for refractory angina pectoris. Refractory angina is persistent stable class III or IV angina despite maximally tolerated medical treatment in patients with end-stage coronary artery disease. Transmyocardial laser revascularization (TMLR), gene therapy, intermittent urokinase therapy, enhanced external balloon counterpulsation, and spinal cord stimulation have all been employed to treat refractory angina pectoris. TMLR and gene therapy are invasive open-chest procedures that have yielded controversial results. Intermittent urokinase and enhanced external balloon counterpulsation studies have limited follow-up times and require multiple clinic visits for treatment. Spinal cord stimulation has a proven short- and long-term efficacy and cost-effectiveness in the treatment of refractory angina. When compared to coronary artery bypass grafting (CABG), it has been shown to decrease the frequency of anginal attacks and consumption of short-acting nitrates to the same extent in refractory angina. Spinal cord stimulation's safety profile has also been well established and it can be used concurrently with cardiac pacemakers or MRI systems, provided the proper precautions are taken. Since spinal cord stimulation is a minimally invasive procedure with a favorable efficacy and safety profile, it should be considered as a valid treatment alternative after medical management has failed in refractory angina prior to implementing invasive modalities such as TMLR or gene therapy.