Refractory angina pectoris in end-stage coronary artery disease: evolving therapeutic concepts

The Coronary Sinus Reducer Stent for the Treatment of Refractory Angina Pectoris: From the Conception of Innovation to Clinical Application

The Neovasc Coronary Sinus Reducer Stent (CSRS) was developed for the treatment of patients who continue to suffer from disabling symptoms despite optimal medical therapy. This patient population with refractory angina symptoms is expected to grow, since life expectancy of individuals with atherosclerotic coronary artery disease is increasing. In this paper, we discussed the development of a novel device the CSRS and the upside-down strategy to rebuild a retrograde coronary pressure that was attenuated by the atherosclerotic disease.

Autonomic Modulation by Electrical Stimulation of the Parasympathetic Nervous System: An Emerging Intervention for Cardiovascular Diseases

The cardiac autonomic nervous system has been known to play an important role in the development and progression of cardiovascular diseases. Autonomic modulation by electrical stimulation of the parasympathetic nervous system, which increases the parasympathetic activity and suppresses the sympathetic activity, is emerging as a therapeutic strategy for the treatment of cardiovascular diseases. Here, we review the recent literature on autonomic modulation by electrical stimulation of the parasympathetic nervous system, including vagus nerve stimulation, transcutaneous auricular vagal stimulation, spinal cord stimulation, and ganglionated plexi stimulation, in the treatment of heart failure, atrial fibrillation, and ventricular arrhythmias.

Remodelling of cardiac sympathetic re-innervation with thoracic spinal cord stimulation improves left ventricular function in a porcine model of heart failure

AIMS

Thoracic spinal cord stimulation (SCS) has been shown to improve left ventricular ejection fraction (LVEF) in heart failure (HF). Nevertheless, the optimal duration (intermittent vs. continuous) of stimulation and the mechanisms of action remain unclear.

METHODS AND RESULTS

We performed chronic thoracic SCS at the level of T1-T3 (50 Hz, pulse width 0.2 ms) in 30 adult pigs with HF induced by myocardial infarction and rapid ventricular pacing for 4 weeks. All the animals were treated with daily oral metoprolol succinate (25 mg) plus ramipril (2.5 mg), and randomized to a control group (n = 10), intermittent SCS (4 h ×3, n = 10) or continuous SCS (24 h, n = 10) for 10 weeks. Serial measurements of LVEF and +dP/dt and serum levels of norepinephrine and B-type natriuretic peptide (BNP) were measured. After sacrifice, immunohistological studies of myocardial sympathetic and parasympathetic nerve sprouting and innervation were performed. Echocardiogram revealed a significant increase in LVEF and +dP/dt at 10 weeks in both the intermittent and continuous SCS group compared with controls (P < 0.05). In both SCS groups, there was diffuse sympathetic nerve sprouting over the infarct, peri-infarct, and normal regions compared with only the peri-infarct and infarct regions in the control group. In addition, sympathetic innervation at the peri-infarct and infarct regions was increased following SCS, but decreased in the control group. Myocardium norepinephrine spillover and serum BNP at 10 weeks was significantly decreased only in the continuous SCS group (P < 0.05).

CONCLUSIONS

In a porcine model of HF, SCS induces significant remodelling of cardiac sympathetic innervation over the peri-infarct and infarct regions and is associated with improved LV function and reduced myocardial norepinephrine spillover.

Physiology of spinal cord stimulation: review and update

Spinal cord stimulation (SCS) was an outgrowth of the well-known gate control theory presented by Melzack and Wall in 1965. Although the method has been used to treat chronic severe pain for more than three decades, very little was known about the physiological and biochemical mechanisms behind the beneficial effects until recently. We now know that SCS activates several different mechanisms to treat different types of pain such as neuropathic and ischemic. In general, these mechanisms seem most dependent on activation of only a few segments of the spinal cord. However, both animal studies and human observations have indicated that supraspinal circuits may contribute as well. In the treatment of neuropathic pain, intermittent SCS may give several hours of pain relief after cessation of the stimulation. This protracted effect indicates long-lasting modulation of neural activity involving changes in the local transmitter systems in the dorsal horns. In ischemic pain, animal experiments demonstrate that inhibition of afferent activity in the spinothalamic tracts, long-term suppression of sympathetic activity, and antidromic effects on peripheral reflex circuits may take part in the pain alleviation. Moderate SCS intensities seem to evoke sympathetic inhibition, but higher stimulation intensities may induce antidromically mediated release of vasoactive substances, eg, the calcitonin gene-related peptide (CGRP), resulting in peripheral vasodilation. The anti-ischemic effect of SCS in angina pectoris due to intermittent coronary ischemia probably occurs because application of SCS appears to result in a redistribution of cardiac blood supply, as well as a decrease in tissue oxygen demand. Recent studies indicate that SCS modulates the activity of cardiac intrinsic neurons thereby restricting the arrythmogenic consequences of intermittent local coronary ischemia. The present state of knowledge is briefly reviewed and recent research directions outlined.

Spinal cord stimulation for long-term treatment of severe angina pectoris: what does the evidence say?

Patients who continue to suffer from severe and disabling angina pectoris, despite optimum treatment in terms of conventional pharmacological therapy and/or revascularization procedures, have been termed as having refractory angina pectoris. The future group of patients with refractory angina pectoris will be different from today’s patients and represent a ‘moving target’ as risk factors, efficacy of treatment and indications continue to change. Spinal cord stimulation (SCS) is today considered as first-line treatment of refractory angina pectoris, by the European Society of Cardiology, with an anti-ischemic effect. There is strong evidence for SCS giving symptomatic benefits (decrease in anginal attacks), improved quality of life and improvement of functional status. In addition, SCS seems to be cost effective with a ‘break-even’ after approximately 15–16 months.

24. Chronic refractory angina pectoris

Angina pectoris, cardiac pain associated with ischemia, is considered refractory when optimal anti-anginal therapy fails to resolve symptoms. It is associated with a decreased life expectancy and diminishes the quality of life. Spinal cord stimulation (SCS) may be considered for patients who have also undergone comprehensive interventions, such as coronary artery bypass graft (CABG) and percutaneous transluminal coronary angioplasty (PTCA) procedures. The mechanism of action of SCS is not entirely clear. Pain reduction is related to the increased release of inhibitory neuropeptides as well as normalization of the intrinsic nerve system of the heart muscle, and may have a protective myocardial effect. SCS in patients with refractory angina pectoris results in reduced anginal attacks as well as improved rate pressure product prior to the occurrence of ischemic events. This may be the result of reduced Myocardial Volume Oxygen (MVO(2) ) and possibly the redistribution of the coronary blood flow to ischemic areas. There are a number of studies that demonstrate that SCS does not mask acute myocardial infarction. The efficacy of the treatment has been investigated in two prospective, randomized studies. The long-term results showed an improvement of the symptoms and of the quality of life. SCS can be an alternative to surgical intervention in a selected patient population. In addition, SCS is a viable option in patients in whom surgery is not possible. SCS is recommended in patients with chronic refractory angina pectoris that does not respond to conventional treatment and in whom revascularization procedures have been attempted or not possible, and who are optimized from a medical perspective.

Percutaneous coronary revascularization in patients with formerly "refractory angina pectoris in end-stage coronary artery disease" - not "end-stage" after all

Background

Patients with refractory angina pectoris in end-stage coronary artery disease represent a severe condition with a higher reduction of life-expectancy and quality of life as compared to patients with stable coronary artery disease. It was the purpose of this study to invasively re-evaluate highly symptomatic patients with formerly diagnosed refractory angina pectoris in end-stage coronary artery disease for feasible options of myocardial revascularization.

Methods

Thirty-four Patients formerly characterized as having end stage coronary artery disease with refractory angina pectoris were retrospectively followed for coronary interventions.

Results

Of those 34 patients 21 (61.8%) were eventually revascularized with percutaneous interventional revascularization (PCI). Due to complex coronary morphology (angulation, chronic total occlusion) PCI demanded an above-average amount of time (66 ± 42 minutes, range 25–206 minutes) and materials (contrast media 247 ± 209 ml, range 50–750 ml; PCI guiding wires 2.0 ± 1.4, range 1–6 wires). Of PCI patients 7 (33.3%) showed a new lesion as a sign of progression of atherosclerosis. Clinical success rate with a reduction to angina class II or lower was 71.4% at 30 days. Surgery was performed in a total of8 (23.5%) patients with a clinical success rate of 62.5%. Based on an intention-to-treat 2 patients of originally 8 (25%) demonstrated clinical success. Mortality during follow-up (1–18 months) was 4.8% in patients who underwent PCI, 25% in patients treated surgically and 25% in those only treated medically.

Conclusion

The majority of patients with end-stage coronary artery disease can be treated effectively with conventional invasive treatment modalities. Therefore even though it is challenging and demanding PCI should be considered as a first choice before experimental interventions are considered.

Spinal Cord Stimulation Improves Ventricular Function and Reduces Ventricular Arrhythmias in a Canine Postinfarction Heart Failure Model

Background— Spinal cord stimulation (SCS) reduces the incidence of ventricular tachyarrhythmias in experimental models. This study investigated the effects of long-term SCS on ventricular function in a postinfarction canine heart failure model.

Methods and Results— In stage 1, dogs underwent implantable cardioverter-defibrillator implantation and embolization of the left anterior descending artery followed by right ventricular pacing (240 ppm) for 3 weeks to produce heart failure. In stage 2, 28 surviving animals were assigned to the SCS (delivered at the T4/T5 spinal region for 2 hours 3 times a day), medicine (MED; carvedilol therapy at 12.5 mg PO BID), or control (CTRL; no therapy) group for the initial phase 1 study. In a subsequent phase 2 study, 32 stage 1 survivors were equally randomized to the SCS, MEDS (carvedilol plus ramipril 2.5 mg PO QD), SCS plus MEDS (concurrent therapy), or CTRL group. Animals were monitored for 5 weeks (phase 1) or 10 weeks (phase 2). In stage 3, all phase 1 animals underwent circumflex artery balloon occlusion for 1 hour. In the SCS group, left ventricular ejection fraction was 65±5% at baseline, 17±3% at the end of stage 1, and 47±7% at the end of stage 2. In the MED group, left ventricular ejection fraction was 61±4% at baseline, 18±3% at the end of stage 1, and 34±4% at the end of stage 2. In the CTRL group, left ventricular ejection fraction was 64±5% at baseline, 19±5% at the end of stage 1, and 28±3% at the end of stage 2. Left ventricular ejection fraction was significantly improved in the SCS compared with the MED and CTRL groups ( P <0.001 for both). The mean number of spontaneous nonsustained ventricular tachyarrhythmias during stage 2 and the occurrence of ischemic ventricular tachyarrhythmias during stage 3 also were significantly decreased in the SCS (27±17 and 27%, respectively; P <0.03) and MED (58±42 and 33%; P <0.05) versus CTRL (88±52 and 76%) group. After 10 weeks in the phase 2 studies, the greatest recovery in ejection fraction was noted in the SCS (52±5%) and SCS+MEDS (46±4%) groups compared with the MEDS (38±2%) and CTRL (31±4%) groups.

Conclusion— SCS significantly improved cardiac contractile function and decreased ventricular arrhythmias in canine heart failure.

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

The use of spinal cord stimulation (SCS) for chronic intractable anginal pain was first described in 1987. Numerous studies have demonstrated its efficacy in improving exercise tolerance, decreasing frequency of anginal episodes, and prolonging time to electrocardiographic signs of ischemia. This review will examine the potential mechanisms of this antianginal effect and propose a unified hypothesis explaining it. The effect of SCS involves a mutual interaction of decreased pain, decreased sympathetic tone, and a likely redistribution of myocardial blood flow to ischemic regions. Spinal cord stimulation reduces the transmission of nociceptive impulse via the spinothalamic tract due to an enhanced release of gamma aminobutyric acid (GABA) from dorsal horn interneurons. Improvement of myocardial blood flow at the microvascular level has been demonstrated by positron emission tomography (PET). A decreased sympathetic tone has been shown by norepinephrine kinetics, tests of sympathetic reflexes, and the use of ganglionic blockers. We hypothesize that SCS exerts its beneficial effects by decreasing pain and decreasing sympathetic tone, the result of which is decreased myocardial oxygen consumption along with an improved myocardial microcirculatory blood flow.

Angiogenic therapy for coronary artery and peripheral arterial disease

Neovascularization in chronically ischemic adult cardiac and skeletal muscle results from the processes of angiogenesis, arteriogenesis and vasculogenesis. Therapeutic angiogenesis describes an emerging field of cardiovascular medicine whereby new blood vessels are induced to grow to supply oxygen and nutrients to cardiac or skeletal muscle rendered ischemic as a result of progressive atherosclerosis. Various techniques have been utilized to promote new blood vessel growth in the heart and extremities, including mechanical means such as surgical or percutaneous myocardial laser revascularization, angiogenic growth factor therapies involving members of the vascular endothelial growth factor and fibroblast growth factor families, and more recently, cellular-based therapies using stem cells known as endothelial progenitor cells or angioblasts. The following review discusses each of these treatment strategies in detail including both preclinical and clinical data for their use in peripheral arterial and coronary artery disease.

Enhancing myocardial plasmid expression by retrograde coronary venous delivery

Myocardial delivery of genes holds great promise for treating many heart diseases; however, the optimal delivery technique, which maximizes safety and efficacy, has not been established. Two delivery techniques were evaluated in swine; percutaneous retrograde coronary venous delivery (RCVD) and direct intramyocardial injection (IM). RCVD was performed in the anterior interventricular vein (AIV) with an end-hole occlusion balloon catheter. The plasmid gWiz, encoding beta-galactosidase (10 ml; 1 mg/ml), was injected using either manual high pressure (HP-RCVD; n = 5) or pressure wire-guided low pressure (LP-RCVD; n = 4). For the IM group (n = 4), beta-Gal plasmid (5 mg/ml) was injected at 10 sites (200 microl/site) in the anterior left ventricular wall. Animals were euthanized after 5 days. The percentage of beta-Gal expressing cells in the delivered region was higher in the HP-RCVD (0.26% +/- 0.05%) than the LP-RCVD (0.05% +/- 0.03%; P = 0.07) and IM groups (0.02% +/- 0.01%; P = 0.01). Myocardium from the HP-RCVD group contained 7- and 17-fold higher levels of beta-Gal activity than either LP-RCVD and IM groups, respectively (P = 0.05 for both). The results of this study confirm the safety and efficacy of RCVD for myocardial gene delivery.

Thoracic spinal cord stimulation reduces the risk of ischemic ventricular arrhythmias in a postinfarction heart failure canine model

BACKGROUND

Thoracic spinal cord stimulation (SCS) is a promising therapy in treating refractory angina. This study was designed to investigate SCS with regard to the risk of arrhythmias during myocardial ischemia and its cardiac electrophysiological effects.

METHODS AND RESULTS

We studied 22 dogs with healed anterior myocardial infarction (MI) and superimposed heart failure (HF) induced by rapid ventricular pacing. SCS was applied at the dorsal T1-T2 segments of the spinal cord (at 50 Hz, 0.2 ms) for 15 minutes. Transient (2-minute) myocardial ischemia was induced on 2 separate occasions (no SCS and SCS) to provoke ventricular arrhythmias (ventricular tachycardia/ventricular fibrillation; VT/VF). Ischemic episodes were separated by 90 minutes, and dogs were randomly assigned to receive SCS or no SCS before the first or second ischemic episode. SCS reduced the occurrence of VT/VF from 59% to 23% when SCS was applied during transient myocardial ischemia (odds ratio, 0.36; 95% confidence interval, 0.1626 to 0.5646; P=0.0009). SCS also decreased sinus rate by 7.5+/-14 bpm (P=0.048), increased the PR interval by 11.1+/-14.7 ms (P=0.009), and reduced systolic blood pressure by 9.8+/-13.6 mm Hg (P=0.02).

CONCLUSIONS

Thoracic SCS appears to protect against ischemic VT/VF in a canine model of healed MI and HF. SCS reduced sinus rate and systolic blood pressure, changes consistent with the previously known antisympathetic effect of SCS, which may have contributed to the antiarrhythmic benefits.

Translational physiology: porcine models of human coronary artery disease: implications for preclinical trials of therapeutic angiogenesis

"Therapeutic angiogenesis" describes an emerging field of cardiovascular medicine whereby new blood vessels are induced to grow to supply oxygen and nutrients to ischemic cardiac or skeletal muscle. Various methods of producing therapeutic angiogenesis have been employed, including mechanical means, gene therapy, and the use of growth factors, among others. The use of appropriate large-animal models is essential if these therapies are to be critically evaluated in a preclinical setting before their use in humans, yet little has been written comparing the various available models. Over the past decade, swine have been increasingly used in studies of chronic ischemia because of their numerous similarities to humans, including minimal preexisting coronary collaterals as well as similar coronary anatomy and physiology. Consequently, this review describes the most commonly used swine models of chronic myocardial ischemia with special attention to regional myocardial blood flow and function and critically evaluates the strengths and weaknesses of each model in terms of utility for preclinical trials of angiogenic therapies.

A randomized trial of aggressive lipid reduction for improvement of myocardial ischemia, symptom status, and vascular function in patients with coronary artery disease not amenable to intervention

PURPOSE

To determine the effects of aggressive lipid lowering on markers of ischemia, resistance vessel function, atherosclerotic burden, and symptom status in patients with symptomatic coronary artery disease.

METHODS

Sixty consecutive patients with coronary artery disease that was unsuitable for revascularization were assigned randomly to either usual therapy of lipids for patients with a low-density lipoprotein (LDL) cholesterol target level <116 mg/dL, or to a more aggressive lipid-lowering strategy involving up to 80 mg/d of atorvastatin, with a target LDL cholesterol level <77 mg/dL. The extent and severity of inducible ischemia (by dobutamine echocardiography), vascular function (brachial artery reactivity), atheroma burden (carotid intima-media thickness), and symptom status were evaluated blindly at baseline and after 12 weeks of treatment.

RESULTS

After 12 weeks of treatment, patients in the aggressive therapy group had a significantly greater decrease in mean (+/- SD) LDL cholesterol level than those in the usual care group (29 +/- 38 mg/dL vs. 7 +/- 24 mg/dL, P = 0.03). Patients in the aggressive therapy group had a reduction in the number of ischemic wall segments (mean between-group difference of 1.3; 95% confidence interval: 0.1 to 2.0; P = 0.04), flow-mediated dilatation (mean between-group difference of 5.9%; 95% confidence interval: 2.5% to 9.4%; P = 0.001), and angina score after 12 weeks. There were no significant changes in atherosclerotic burden in either group.

CONCLUSION

Patients with symptomatic coronary artery disease who are treated with aggressive lipid lowering have improvement of symptom status and ischemia that appears to reflect improved vascular function but not atheroma burden.

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.

Minimally invasive coronary artery bypass grafting for the left anterior descending coronary artery

OBJECTIVE

A single surgeon conducted One hundred and twelve patients underwent minimally invasive direct coronary artery bypass grafting for the left anterior descending coronary artery 112 patients at Yamato Seiwa Hospital from September 1996 until August 1999.

METHODS

All procedures were performed via left anterior short thoracotomy using a stabilizer during graft anastomosis.

RESULTS

No operative deaths occurred but 3 patients died while hospitalized due to noncardiac events. Graft occlusion was seen in 3 patients early postoperatively. Other angiography graft failure such as stenosis was seen in 11 patients. Occlusive lesions of other coronary arteries occurred in 77 patients (69%) and 53 patients underwent percutaneous transluminal coronary angioplasty the pre/postoperatively for those lesions.

CONCLUSIONS

These results suggest that minimally invasive direct coronary artery bypass grafting is seen by cardiologists as a reasonable form of revascularization in conditioned patients having left anterior descending artery lesion, and that minimally invasive direct coronary artery bypass grafting has a spectrum of candidates different from that of conventional surgical revascularization for the coronary artery.

Chest pain and the treatment of psychosocial/emotional distress in CAD patients

Treatment of psychosocial/emotional distress as a strategy for diminishing chest pain in such patients remains entirely unutilized in standard care. Sixty-three patients with known or suspected CAD were entered in an aggressive lifestyle modification program. Patients completed the Symptom Checklist 90-Revised (SCL90R) at the diagnostic interview session, at 3 and at 12 months. Statistically significant drops were observed on multiple scales of the SCL90R at both 3 and 12 months. An item from the SCL90R was used as a proxy for angina. Multiple measures of emotional distress at baseline were found to correlate with chest pain at baseline, but not a number of traditional cardiovascular risk factors. The chest pain item displayed improvement at both 3 and 12 months. Improvement on all scales of the SCL90R correlated with improvement in chest pain. It may be possible to control chest pain in some CAD patients with psychosocial interventions.

Video-assisted thoracoscopic sympathectomy for severe intractable angina

OBJECTIVE

Endoscopic trans-thoracic sympathectomy is a well documented, safe and successful treatment for palmar and axillary hyperhidrosis. This may also be helpful in the management of patients with intractable angina and advanced coronary disease unsuitable for coronary artery bypass graft (CABG) or percutaneous transluminal coronary angioplasty (PTCA). We evaluated video assisted thoracoscopic sympathectomy (VATS) in such patients with the aim of improving symptoms and quality of life.

METHODS

Video assisted thoracoscopic sympathectomy, a minimally invasive procedure, was performed under general anaesthesia with alternating single lung ventilation. Three stab incisions were made at the level of the fourth intercostal space in the anterior and posterior axillary lines, and at the fifth intercostal space in the mid-axillary line through which an extensive thoracic sympathectomy was performed to include second to the fourth ganglia, bilaterally.

RESULTS

A total of 16 patients aged 46-76 (mean 61) years were assessed for VATS. Of these 10 patients had the procedure performed; nine with previous CABG and one with diffuse coronary disease. Six patients were excluded because of an evolving MI (n = 1), left ventricular ejection fraction (LVEF) < 30% (n = 2), and chronic stable angina with no objective evidence of ischaemia (n = 3). All 10 patients had marked symptomatic improvement with reduction of both angina frequency and intensity of attacks. Mean follow-up period 11.5 months. Exercise tolerance and time to onset of angina measured on exercise treadmill was significantly increased post-VATS (P = 0.028) and maintained 1 year post-operative.

CONCLUSION

VATS was associated with both reduction in angina symptoms and an increase in exercise time to onset of angina. An improved quality of life was evident.

Clinical outcome of patients treated with spinal cord stimulation for therapeutically refractory angina pectoris. The Working Group on Neurocardiology

OBJECTIVE

To determine morbidity and mortality characteristics in patients treated with electrical neuromodulation for refractory angina pectoris.

DESIGN

A retrospective multicentre study of patients treated with spinal cord stimulation between 1987 and 1997; 21 centres were contacted and 14 responded.

SETTING

Specialist centres worldwide.

PATIENTS

Questionnaires were returned on 517 patients, of whom 71% were male. One was lost to follow up. Mean (SD) age was 63.9 (10.1) years. Duration of angina pectoris was 8.1 (6.3) years.

RESULTS

Before spinal cord stimulation, 66% of the patients had experienced myocardial infarction, 68% had three vessel disease, and in 24% the left ventricular ejection fraction (LVEF) was </= 40%. Percutaneous transluminal coronary angioplasty and bypass surgery were performed in 17% and 58% of the subjects, respectively. During a median follow up of 23 months (range 0 to 128), 103 patients died (52 from a cardiac cause, 25 from a non-cardiac cause, and 26 from an unknown cause). Annual all cause mortality was 7-8%; annual cardiovascular fatality was 3.5-5%. Mortality was univariately related to sex, number of diseased vessels, number of revascularisation procedures, previous myocardial infarction, LVEF, insulin dependent diabetes, beta blocking agents, and angiotensin converting enzyme inhibitors. Multiple variate analysis showed that LVEF, sex, beta blockers, and age >/= 71 years were independent predictors of mortality. During spinal cord stimulation, New York Heart Association functional class improved from 3.5 to 2.1 (p < 0.01); 25 of the deceased patients (24%) and 32 survivors (8%) experienced myocardial infarction; hospital admissions were significantly (p < 0.001) more common in the deceased group (66% v 37%).

CONCLUSIONS

The clinical outcome of patients with intractable angina is not adversely affected by the chronic use of neurostimulation.

Transmyocardial and percutaneous myocardial revascularization: current and future role in the treatment of coronary artery disease

Transmyocardial revascularization (TMR) is a new treatment modality under evaluation in patients with severely symptomatic, diffuse coronary artery disease, in whom the potential for medical or interventional management has been exhausted. Preliminary clinical trials show improved ischemic symptoms within the first 3 months in about 70% of TMR-treated patients. The original proposed mechanism of surgical or catheter-based TMR (percutaneous myocardial revascularization [PMR]) was that channels mediate direct blood flow between the left ventricular cavity and ischemic myocardium. However, several alternative explanations for the clinical success of TMR have recently been suggested, including improved perfusion by angiogenesis, an anesthetic effect by nerve destruction, and a potential placebo effect. This article reviews the clinical role of TMR/PMR, its possible pathophysiologic mechanisms, and its controversies. It provides an overview of the actual scientific and clinical status of TMR and details future directions.

Long-term Urokinase Therapy and Isovolemic Hemodilution: A Clinical and Hemodynamic Comparison in Patients with Refractory Angina Pectoris

Antiischemic effectiveness of long-term urokinase therapy and isovolemic hemodilution therapy has been reported in patients with symptomatic coronary artery disease, but both interventions have never been compared. In patients with refractory angina pectoris and end-stage coronary artery disease (clinical functional class III), isovolemic hemodilution (n = 9) (hydroxyethyl starch solution 6%, 1-2 times/week), and urokinase therapy (n = 11) (500,000 U urokinase per i.v. injection, 3 times a week) were performed over a period of 12 weeks, each additionally to maximal conventional treatment. Apart from the assessment of clinical symptoms and rheologic parameters, invasive hemodynamic measurements were carried out at rest and during exercise testing before and after treatment. After treatment with urokinase, patients showed a significant reduction of clinical symptoms (from 19.8 +/- 6.5 to 5.0 +/- 4.3 anginal events/week, p < 0.001), fibrinogen (from 410 +/- 88 to 238 +/- 40 mg/dl, p < 0.001), plasma viscosity (from 1.45 +/- 0.10 to 1.33 +/- 0.03 mPa x s-1, p < 0.01), and no changes of hematocrit (from 0.45 +/- 0.02 to 0.45 +/- 0.02) and whole blood viscosity (from 4.7 +/- 0.5 to 4.4 +/- 0.7 mPa x s-1); however, hemodilution resulted in a decrease of hematocrit (from 0.46 +/- 0.01 to 0.39 +/- 0.01, p < 0.001) and whole blood viscosity (from 4.7 +/- 0.5 to 4.0 +/- 0.3 mPa x s-1, p < 0.001) and no changes of initially comparable levels of clinical symptoms, fibrinogen, and plasma viscosity. Hemodynamic parameters at rest improved after urokinase therapy with a reduction of pulmonary capillary wedge pressure (from 9.1 +/- 5.1 to 5.5 +/- 2.8 mmHg, p < 0.05) at comparable levels of systemic vascular resistance (from 1510 +/- 340 to 1420 +/- 510 dyn x s x cm-5). Hemodilution did not result in any significant hemodynamic changes. Apart from clinical symptoms, long-term intermittent urokinase therapy reduces pulmonary capillary wedge pressure at rest. This may reflect an improved diastolic function due to a rheological enhancement of myocardial perfusion at the level of the coronary microcirculation. Isovolemic hemodilution seems to be of no benefit.

Long-term outcome of spinal cord electrical stimulation in patients with refractory chest pain

BACKGROUND AND HYPOTHESIS

Treatment of patients with refractory chest pain remains a challenge. In this study, the long-term clinical effects of spinal cord electrical stimulation were evaluated in 10 consecutive male patients (mean age 53.7 years) with chronic chest pain in a prospective observational study.

METHODS

After placement of the electrode in an epidural position and before implantation of the device, patients were subjected to clinical evaluation, including atrial pacing, in order to document significant antianginal effects.

RESULTS

Spinal cord electrical stimulation abolished or improved pacing time to angina by more than 50% in seven of the patients who subsequently had the device implanted. In three of these patients, the system was ineffective after a period of 3-9 months despite paresthesia in the area of anginal pain with electrical stimulation. The effects of treatment remained satisfactory in the remaining patients (40%) after a mean follow-up of 60 (45-72) months. Thus, a long-lasting clinical response was able to be predicted in 57% of the patients.

CONCLUSION

Spinal cord electrical stimulation is one of the few therapeutic options in inoperable patients with refractory chest pain.

[Conservative therapeutic approaches in terminal coronary heart disease. Chronic intermittent urokinase therapy]

Despite progress in the invasive revascularization procedures and even though conventional antianginal treatment has improved the quality of life in patients with symptomatic coronary artery disease considerably, an increasing number of patients suffers from end-stage coronary artery disease and refractory angina pectoris. For these refractory patients long-term intermittent urokinase therapy was developed as an antithrombotic intervention, which is based on its capacity to enhance thrombolysis and blood rheology, and may possibly lead to plaque regression. The coronary syndrome of refractory angina pectoris is characterized by a mismatch of severe coronary insufficiency and a relatively large amount of viable myocardium as indicated by an only moderately impaired left ventricular function. Prior to initiation of long-term intermittent urokinase therapy all potential measures to improve myocardial perfusion have to be considered in each patient. These supportive measures include rigorous reduction of LDL-cholesterol, which has proven antiischemic properties due to an improved endothelial function of epicardial conductance vessels possibly resulting in an antianginal effect. Apart from the proven antiischemic properties of long-term intermittent urokinase therapy in patients with refractory angina pectoris, objective signs of ischemic myocardial heart failure improve. Follow-up studies demonstrated a significant increase of left ventricular ejection fraction as evaluated with multi-gated blood pool analysis. Furthermore, left ventricular diastolic function normalized after a treatment period of 12 weeks. As the clinical effects last well beyond the actual treatment period and as they are accompanied by a remarkable increase in the quality of life, a complex approach as this one is justified in this highly symptomatic patient group.