Direct myocardial revascularization and angiogenesis--how many patients might be eligible?

Intramyocardial transfer of hepatocyte growth factor as an adjunct to CABG: phase I clinical study

The purpose of this phase I clinical trial was to evaluate the safety, tolerability and potential efficacy of VM202, naked DNA expressing two isoforms of hepatocyte growth factor, as an adjunct therapy to coronary artery bypass grafting (CABG) in patients with ischemic heart disease (IHD). Nine patients were assigned to receive increasing doses (0.5 to 2.0 mg) of VM202 injected into the right coronary artery (RCA) territory following completion of CABG for the left coronary artery territory. Patients were evaluated for safety and tolerability, and changes in myocardial functions were monitored via echocardiography, cardiac magnetic resonance imaging and myocardial single photon emission computed tomography throughout 6-month follow-up period. No serious complication related to VM202 was observed throughout the 6-month follow-up period. Global myocardial functions (wall motion score index, P=0.0084; stress perfusion, P=0.0002) improved during the follow-up period. In the RCA region, there was an increase in the stress perfusion (baseline vs 3-month, P=0.024; baseline vs 6-month, P=0.024) and also in the wall thickness of the diastolic and systolic phases. Intramyocardial injection of VM202 can be safely used in IHD patients with the tolerable dose of 2.0 mg. In addition, VM202 might appear to have improved regional myocardial perfusion and wall thickness in the injected region.

Therapeutic angiogenesis for myocardial ischemia revisited: basic biological concepts and focus on latest clinical trials

Therapeutic angiogenesis is based on the premise that the development of new blood vessels can be augmented by exogenous administration of the appropriate growth factors. Over the last years, successful preclinical studies and promising results of early clinical trials have created great excitement about the potential of therapeutic angiogenesis for patients with advanced ischemic heart disease. The authors provide an overview of the biology of angiogenesis, the basic characteristics of angiogenic factors, and the different routes of their delivery. They discuss experimental studies in animal models of myocardial ischemia and outline available clinical studies on therapeutic angiogenesis for myocardial ischemia. Related safety issues are also addressed followed by a critical perspective about the future of proangiogenic therapies for ischemic cardiovascular disorders. Despite the established proof of concept and reasonable safety, however, results of the latest trials on therapeutic angiogenesis for myocardial ischemia have provided inconsistent results and the definite means of inducing clinically useful therapeutic angiogenesis remain elusive. More studies are required to gain further insights into the biology of angiogenesis and address pharmacological limitations of current approaches of angiogenic therapy. The authors hope and envisage that in the not-too-distant future, these investigative efforts will lead to important new strategies for treatment of myocardial ischemic syndromes. Means of non-invasive individualized pharmacological therapeutic neovascularization may be the next major advance in the treatment of ischaemic heart disease.

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.

Intramyocardial, autologous CD34+ cell therapy for refractory angina

RATIONALE

A growing number of patients with coronary disease have refractory angina. Preclinical and early-phase clinical data suggest that intramyocardial injection of autologous CD34+ cells can improve myocardial perfusion and function.

OBJECTIVE

Evaluate the safety and bioactivity of intramyocardial injections of autologous CD34+ cells in patients with refractory angina who have exhausted all other treatment options.

METHODS AND RESULTS

In this prospective, double-blind, randomized, phase II study (ClinicalTrials.gov identifier: NCT00300053), 167 patients with refractory angina received 1 of 2 doses (1×10(5) or 5×10(5) cells/kg) of mobilized autologous CD34+ cells or an equal volume of diluent (placebo). Treatment was distributed into 10 sites of ischemic, viable myocardium with a NOGA mapping injection catheter. The primary outcome measure was weekly angina frequency 6 months after treatment. Weekly angina frequency was significantly lower in the low-dose group than in placebo-treated patients at both 6 months (6.8±1.1 versus 10.9±1.2, P=0.020) and 12 months (6.3±1.2 versus 11.0±1.2, P=0.035); measurements in the high-dose group were also lower, but not significantly. Similarly, improvement in exercise tolerance was significantly greater in low-dose patients than in placebo-treated patients (6 months: 139±151 versus 69±122 seconds, P=0.014; 12 months: 140±171 versus 58±146 seconds, P=0.017) and greater, but not significantly, in the high-dose group. During cell mobilization and collection, 4.6% of patients had cardiac enzyme elevations consistent with non-ST segment elevation myocardial infarction. Mortality at 12 months was 5.4% in the placebo-treatment group with no deaths among cell-treated patients.

CONCLUSIONS

Patients with refractory angina who received intramyocardial injections of autologous CD34+ cells (10(5) cells/kg) experienced significant improvements in angina frequency and exercise tolerance. The cell-mobilization and -collection procedures were associated with cardiac enzyme elevations, which will be addressed in future studies.

Aging-induced collateral dysfunction: impaired responsiveness of collaterals and susceptibility to apoptosis via dysfunctional eNOS signaling

Despite positive animal studies, clinical angiogenesis trials have been disappointing, possibly due to risk factors present in humans but usually unexplored in animals. We recently demonstrated aging causes impaired collateral remodeling and collateral dropout; here, we investigate potential mechanisms responsible for these findings. Four-, 10-, and 18-month-C57BL/6J mice were subjected to femoral artery ligation; flow was measured using laser Doppler perfusion imaging. Endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS were measured in calf muscle. Apoptosis was assessed in endothelial (EC) and smooth muscle (SMC) cells isolated from young and old mice. Angiogenesis was measured using a Matrigel plug assay. Lethally irradiated young and old mice received bone marrow cells (BMC) from either young or old donors and were subjected to femoral artery ligation (FAL). BMC mobilization and homing were assessed. Flow recovery was impaired and less eNOS and phosphorylated eNOS was present in older vs. young mice (p < 0.001 and p = 0.015, respectively). ECs and SMCs from older mice were more sensitive to an apoptotic stimulus, but were rescued by NO-enhancing drugs. In older mice, angiogenesis (Matrigel plug assay) was impaired, as was mobilization and homing of BM progenitor cells following FAL. Although both mobilization and homing improved when older mice received BMC transplantation from young donors, flow recovery failed to improve. Aging impairs BMC mobilization and homing, collateral responsiveness to angiogenic stimuli, and increases EC and SMC susceptibility to apoptosis via dysfunctional eNOS signaling. The latter could contribute to impaired remodeling and collateral dropout. These finding identify potential obstacles to therapeutic interventions in elderly patients.

Effectiveness of percutaneous laser revascularization therapy for refractory angina

Refractory angina is a debilitating disease characterized by persistent cardiac pain resistant to all conventional treatments for coronary artery disease. Percutaneous myocardial laser revascularization (PMLR) has been proposed to improve symptoms in these patients. We used meta-analysis to assess the effectiveness of PMLR versus optimal medical therapy for improving angina symptoms, health-related quality of life (HRQL), and exercise performance; the impact on all-cause mortality was also examined. Seven trials, involving a total of 1,213 participants were included. Our primary analyses showed that at 12-month follow-up, those who had received PMLR had ≥2 Canadian Cardiovascular Society class angina symptom reductions, OR 2.13 (95% CI, 1.22 to 3.73), as well as improvements in aspects of HRQL including angina frequency, SMD = 0.29 (95% CI, 0.05 to 0.52), disease perception, SMD = 0.37 (95% CI, 0.14 to 0.61), and physical limitations, SMD = 0.29 (95% CI, 0.05 to 0.53). PMLR had no significant impact on all-cause mortality. Our secondary analyses, in which we considered data from one trial that featured a higher-dose laser group, yielded no significant overall impact of PMLR across outcomes. While PMLR may be effective for improving angina symptoms and related burden, further work is needed to clarify appropriate dose and impact on disease-specific mortality and adverse cardiac events.

Patients with coronary artery disease not amenable to traditional revascularization: prevalence and 3-year mortality

OBJECTIVES

To determine the contemporary prevalence of and mortality in patients with coronary artery disease (CAD) not amenable to revascularization.

BACKGROUND

A growing number of patients have severe CAD with ongoing angina despite optimal medical therapy which is not amenable to traditional revascularization. Limited data exist on contemporary prevalence and outcome for these patients.

METHODS

Clinical and angiographic data were reviewed for 493 consecutive patients undergoing coronary angiography and revascularization if indicated. Patients were categorized into six groups: (1) normal coronary arteries, (2) CAD <70%, (3) CAD >70% with complete revascularization by percutaneous intervention or coronary artery bypass grafting, (4) CAD >70% with partial revascularization, (5) CAD >70% treated medically, and (6) CAD >70% on optimal medical therapy with no revascularization option. All-cause mortality at 3 years was determined.

RESULTS

Prevalence for groups 1-6 was 14.8, 19.5, 36.9, 12.8, 9.3, and 6.7%, respectively. Three-year mortality increased with angiographic severity of CAD: 2.7, 6.3, 8.2, 12.7, 17.4, and 15.2%, respectively. Patients with incomplete revascularization (groups 4-6, n = 142) had higher mortality than completely revascularized patients (groups 1-3, n = 351): 14.8 vs. 6.6% (P = 0.004).

CONCLUSIONS

In a contemporary series of patients undergoing coronary angiography, 28.8% (142/493) of patients had significant CAD and did not undergo complete revascularization, including 12.8% partially revascularized, 9.3% managed medically, and 6.7% with "no-option." These patients had higher mortality at 3 years (14.8 vs. 6.6%, P = 0.004) when compared with completely revascularized patients.

VEGF gene expression in adult human thymus fat: a correlative study with hypoxic induced factor and cyclooxygenase-2

It is well known that the adult human thymus degenerates into fat tissue; however, it has never been considered as a potential source of angiogenic factors. Recently, we have described that this fat (TAT) produces angiogenic factors and induces human endothelial cell proliferation and migration, indicating its potential angiogenic properties.

Design

Adult thymus fat and subcutaneous adipose tissue specimens were obtained from 28 patients undergoing cardiac surgery, making this tissue readily available as a prime source of adipose tissue. We focused our investigation on determining VEGF gene expression and characterizing the different genes, mediators of inflammation and adipogenesis, and which are known to play a relevant role in angiogenesis regulation.

Results

We found that VEGF-A was the isoform most expressed in TAT. This expression was accompanied by an upregulation of HIF-1α, COX-2 and HO-1 proteins, and by increased HIF-1 DNA binding activity, compared to SAT. Furthermore, we observed that TAT contains a high percentage of mature adipocytes, 0.25% of macrophage cells, 15% of endothelial cells and a very low percentage of thymocyte cells, suggesting the cellular variability of TAT, which could explain the differences in gene expression observed in TAT. Subsequently, we showed that the expression of genes known as adipogenic mediators, including PPARγ1/γ2, FABP-4 and adiponectin was similar in both TAT and SAT. Moreover the expression of these latter genes presented a significantly positive correlation with VEGF, suggesting the potential association between VEGF and the generation of adipose tissue in adult thymus.

Conclusion

Here we suggest that this fat has a potential angiogenic function related to ongoing adipogenesis, which substitutes immune functions within the adult thymus. The expression of VEGF seems to be associated with COX-2, HO-1 and adipogenesis related genes, suggesting the importance that this new fat has acquired in research in relation to adipogenesis and angiogenesis.

Electroporation-mediated delivery of a naked DNA plasmid expressing VEGF to the porcine heart enhances protein expression

Gene therapy is an attractive method for the treatment of cardiovascular disease. However, using current strategies, induction of gene expression at therapeutic levels is often inefficient. In this study, we show a novel electroporation (EP) method to enhance the delivery of a plasmid expressing an angiogenic growth factor (vascular endothelial growth factor, VEGF), which is a molecule previously documented to stimulate revascularization in coronary artery disease. DNA expression plasmids were delivered in vivo to the porcine heart with or without coadministered EP to determine the potential effect of electrically mediated delivery. The results showed that plasmid delivery through EP significantly increased cardiac expression of VEGF compared with injection of plasmid alone. This is the first report showing successful intracardiac delivery, through in vivo EP, of a protein expressing plasmid in a large animal.

Utility of telomerase-pot1 fusion protein in vascular tissue engineering

While advances in regenerative medicine and vascular tissue engineering have been substantial in recent years, important stumbling blocks remain. In particular, the limited life span of differentiated cells that are harvested from elderly human donors is an important limitation in many areas of regenerative medicine. Recently, a mutant of the human telomerase reverse transcriptase enzyme (TERT) was described, which is highly processive and elongates telomeres more rapidly than conventional telomerase. This mutant, called pot1-TERT, is a chimeric fusion between the DNA binding protein pot1 and TERT. Because pot1-TERT is highly processive, it is possible that transient delivery of this transgene to cells that are utilized in regenerative medicine applications may elongate telomeres and extend cellular life span while avoiding risks that are associated with retroviral or lentiviral vectors. In the present study, adenoviral delivery of pot1-TERT resulted in transient reconstitution of telomerase activity in human smooth muscle cells, as demonstrated by telomeric repeat amplification protocol (TRAP). In addition, human engineered vessels that were cultured using pot1-TERT-expressing cells had greater collagen content and somewhat better performance in vivo than control grafts. Hence, transient delivery of pot1-TERT to elderly human cells may be useful for increasing cellular life span and improving the functional characteristics of resultant tissue-engineered constructs.

Angiogenic properties of adult human thymus fat

The endogenous proangiogenic properties of adipose tissue are well recognized. Although the adult human thymus has long been known to degenerate into fat tissue, it has never been considered as a potential source of angiogenic factors. We have investigated the expression of diverse angiogenic factors, including vascular endothelial growth factor A and B, angiopoietin 1, and tyrosine-protein kinase receptor-2 (an angiopoietin receptor), and then analyzed their physiological role on endothelial cell migration and proliferation, two relevant events in angiogenesis. The detection of the gene and protein expression of the various proteins has been performed by immunohistochemistry, Western blotting, and quantitative real-time polymerase chain reaction. We show, for the first time, that adult thymus fat produces a variety of angiogenic factors and induces the proliferation and migration of human umbilical cord endothelial cells. Based on these findings, we suggest that this fat has a potential angiogenic function that might affect thymic function and ongoing adipogenesis within the thymus.

Nonrevascularizable coronary artery disease following coronary artery bypass graft surgery: a population-based study in Olmsted County, Minnesota

AIMS

Therapeutic options for patients with recurrent cardiac ischemia after coronary artery bypass surgery may be limited and some patients may be considered nonrevascularizable. To further the understanding of this patient cohort, we performed a population-based study of post-coronary bypass patients who developed recurrent angina.

METHODS AND RESULTS

Patients who underwent coronary artery and bypass graft angiography at Mayo Clinic from 2001 to 2005 were identified. Medical records were reviewed to determine indication for angiography, and angiographic analysis was performed in all patients. Among 133 000 residents of Olmsted County, Minnesota, 347 post-bypass patients with angina underwent coronary angiography from 2001 to 2005. Of these, 177 patients received further revascularization (145 percutaneous coronary intervention and 32 redo coronary artery bypass grafting) and the remaining 170 patients were managed medically. Revascularization was not associated with improvement in all-cause or cardiac mortality. Multivariate analysis identified renal dysfunction, diabetes, and severe left ventricular dysfunction but not the lack of revascularization as predictors of mortality.

CONCLUSION

In this population-based study, we identified a yearly incidence range of 17.9-33.2 patients with nonrevascularizable angina after coronary artery bypass grafting per 100 000 population. Further revascularization was not associated with improved mortality or morbidity. Attempts to develop therapeutics for this population must consider the incidence and outcomes of this cohort.

Spinal cord stimulation in the treatment of refractory angina: systematic review and meta-analysis of randomised controlled trials

Background

The aim of this paper was undertake a systematic review and meta-analysis of the use of spinal cord stimulation (SCS) in the management of refractory angina.

Methods

We searched a number of electronic databases including Medline, Embase and Cochrane Library up to February 2008 to identify randomised controlled trials (RCTs) reporting exercise capacity, ischemic burden, functional class, quality of life, usage of anti-anginal medication, costs and adverse events including mortality. Results were reported both descriptively for each study and using random effects meta-analysis. Given the variety in outcomes reported, some outcome results were pooled as standardised mean differences (SMD) and reported in standard deviation units.

Results

Seven RCTs were identified in a total of 270 refractory angina patients. The outcomes of SCS were found to be similar when directly compared to coronary artery bypass grafting (CABG) and percutaneous myocardial laser revascularisation (PMR). Compared to a 'no stimulation' control, there was some evidence of improvement in all outcomes following SCS implantation with significant gains observed in pooled exercise capacity (SMD: 0.76, 0.07 to 1.46, p = 0.03) and health-related quality of life (SMD: 0.83, 95% CI: 0.32 to 1.34, p = 0.001). Trials were small and were judged to range considerably in their quality. The healthcare costs of SCS appeared to be lower than CABG at 2-years follow up.

Conclusion

SCS appears to be an effective and safe treatment option in the management of refractory angina patients and of similar efficacy and safety to PMR, a potential alternative treatment. Further high quality RCT and cost effectiveness evidence is needed before SCS can be accepted as a routine treatment for refractory angina.

Transmyocardial laser revascularization versus medical therapy for refractory angina

BACKGROUND

Chronic angina and advanced forms of coronary disease are increasingly more frequent. Although the improved efficacy of available revascularization treatments, a subgroup of patients present with refractory angina. Transmyocardial laser revascularization (TMLR) has been proposed to improve the clinical situation of these patients.

OBJECTIVES

To assess the efficacy and safety of TMLR versus optimal medical treatment in patients with refractory angina in alleviating the severity of angina and improving survivorship and heart function.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials on The Cochrane Library (Issue 2 2007), MEDLINE (January 2006 to June 2007), EMBASE ( 2004 to June 2007) and ongoing studies were sought using the metaRegister of Controlled Trials database (mRCT) and ClinicalTrials.gov databases. No languages restrictions were applied. Reference lists of relevant papers were also checked.

SELECTION CRITERIA

Studies were selected if they fulfilled the following criteria: randomized controlled trials of TMLR, by thoracotomy, in patients with angina grade III-IV who were excluded from other revascularization procedures. From a total of 181 references, 20 papers were selected, reporting data from seven studies.

DATA COLLECTION AND ANALYSIS

Two reviewers abstracted data from selected papers; . The reviewers performed independently both quality assessment and data extraction. Selected studies present methodological weaknesses. None of them fulfilled all the quality criteria.

MAIN RESULTS

Seven studies (1137 participants of which 559 randomized to TMLR) were included. Overall, 43.8 % of patients in the treatment group decreased two angina classes as compared with 14.8 % in the control group, odds ratio (OR) of 4.63 (95% confidence interval (CI) 3.43 to 6.25), and heterogeneity was statistically significant. Mortality by intention-to-treat analysis at both 30 days (4.0 % in the TMLR group and 3.5 % in the control group) and 1 year (12.2 % in the TMLR group and 11.9 % in the control group) was similar in both groups. The 30-days mortality as treated was 6.8% in TMLR group and 0.8% in the control group, showing a statistically significant difference. The pooled OR was 3.76 (95% CI 1.63 to 8.66), because of the higher mortality in patients crossing from standard treatment to TMLR.

AUTHORS' CONCLUSIONS

There is insufficient evidence to conclude that the clinical benefits of TMLR outweigh the potential risks. The procedure is associated with a significant early mortality.

Spinal cord stimulation in severe angina pectoris--a systematic review based on the Swedish Council on Technology assessment in health care report on long-standing pain

Patients who continue to suffer from lasting and severely disabling angina pectoris despite optimum drug treatment and who are not suitable candidates for invasive procedures, suffer from a condition referred to as "chronic refractory angina pectoris". Based on the available data, spinal cord stimulation, SCS, is considered as the first-line additional treatment for these patients by the European Society of Cardiology. However, no systematic review of randomised controlled studies has yet been published. A systematic literature research, 1966-2003, as part of the Swedish Board of Health and Welfare (SBU) report on long-standing pain, and an additional research covering the years 2003-2007, were carried out. Acute studies, case reports and mechanistic reviews were excluded, and the remaining 43 studies were graded for study quality according to a modified Jadad score. The eight medium- to high-score studies formed the basis for conclusions regarding the scientific evidence (strong, moderately strong or limited) for the efficacy of SCS. There is strong evidence that SCS gives rise to symptomatic benefits (decrease in anginal attacks) and improved quality of life in patients with severe angina pectoris. There is also a strong evidence that SCS can improve the functional status of these patients, as illustrated by the improved exercise time on treadmill or longer walking distance without angina. In addition, SCS does not seem to have any negative effects on mortality in these patients (limited scientific evidence). The complication rate was found to be acceptable.

Trans-Coronary-Venous Interventions

The coronary venous system is routinely targeted during electrophysiological measurements or cardiac resynchronization therapy. However, several novel interventional techniques require coronary venous catheterization and visualization as well as transvenous delivery of devices and/or therapeutic agents. Recent reports suggest the possibility of a transvenous approach for the interventional treatment of refractory angina and mitral valve regurgitation. In addition, the coronary venous system has been used as a route for the delivery of stem cells in patients with left ventricular dysfunction due to ischemic heart disease. We review the potential value of using a coronary venous approach in association with recent therapeutic developments in the interventional treatment of structural and ischemic heart disease. We will also discuss techniques related to coronary venous catheterization.

Transmyocardial laser revascularization: from randomized trials to clinical practice. A review of techniques, evidence-based outcomes, and future directions

Cardiac surgeons are increasingly faced with a more complex patient who has developed a pattern of diffuse coronary artery disease that cannot be completely revascularized by CAGB alone. Considering the increased operative and long-term cardiac risks predicted by incomplete revascularization, and the documented operative and long-term benefits associated with sole therapy and adjunctive TMR in randomized patients with diffuse coronary artery disease, increased use of sole therapy and adjunctive TMR therapy is warranted.

Clinical and research issues regarding chronic advanced coronary artery disease: part I: Contemporary and emerging therapies

The following report is based on a working group meeting about advanced coronary artery disease for patients with refractory ischemia who cannot receive revascularization. The aims were to review currently available treatment strategies, define unmet clinical needs, explore clinical trial design issues, and identify promising novel therapeutic targets and approaches for patients with chronic ischemia. The Working Group brought together medical experts in the management of refractory angina with representatives from regulatory agencies, Centers for Medicare and Medicaid Services, and industry. The meeting began with presentations reviewing the limitations of the current medical therapies and revascularization strategies and focused on lessons learned from past therapeutic attempts to optimize outcomes and on what are considered to be the most promising new approaches. Perspectives from clinical experts and from regulatory agencies were juxtaposed against needs and concerns of industry regarding development of new therapeutic strategies. This report presents the considerations and conclusions of the meeting on December 4-5, 2006. This document has been developed as a 2-part article, with contemporary and emerging therapies for advanced coronary artery disease reviewed first. Trial design, end points, and regulatory issues will be discussed in the second part of the article.

Skin-derived microorgan autotransplantation as a novel approach for therapeutic angiogenesis

Despite promising preclinical results, transient single-factor-based therapeutic angiogenesis has shown no definitive benefits in clinical trials. The use of skin-derived microorgans (SMOs), capable of sustained expression of angiogenic factors and sustained viability with their cellular and extracellular elements, constitutes an attractive alternative. We sought to evaluate the efficacy of SMO implantation in a porcine model of chronic myocardial ischemia. Eighteen pigs underwent placement of an ameroid constrictor on the proximal circumflex artery. Three weeks later, split-thickness skin biopsies were harvested and pigs were randomized to lateral wall implantation of either 8 or 16 SMOs or blank injections. The procedure was safe and resulted in no adverse events. Three weeks after treatment, SMO implantation resulted in significant improvement of lateral wall perfusion during pacing, assessed by isotope-labeled microspheres [post- vs. pretreatment ratios of lateral/anterior wall blood flow were 1.31 ± 0.09 (SMOs) and 1.04 ± 0.06 (controls); P = 0.03]. No significant difference in angiographic scores was observed. Microvascular relaxation in response to VEGF was impaired in the ischemic territory of the control group but returned to normal after SMO implantation, indicating restoration of endothelial function. Molecular studies showed significant increases in VEGF and CD31 expression in the ischemic area of treated animals. Morphometric analysis showed increased neovascularization with SMO treatment. Autotransplantation of SMOs constitutes a novel approach for safe and effective therapeutic angiogenesis with improvement in perfusion, normalization of microvascular reactivity, and increased expression of VEGF and CD31.

Therapeutic potential of adult progenitor cells in the management of chronic myocardial ischemia

Refractory angina as a result of chronic myocardial ischemia is a common and disabling condition. Adult progenitor cells have emerged as a potential revolutionary treatment for cardiovascular disease. Locally administered adult progenitor cells with particular vasculogenic potential may offer treatment hope for those with chronic ischemia; however, the optimal cell type, dose, delivery mode, and target patient population has not been defined. Preclinical cell therapy studies have shown safety and efficacy sufficient to warrant human trials. Early, small-scale human trials exploring various cell types and delivery modes have shown that most approaches are safe, with modest early efficacy. This overview discusses the rationale and early results for ongoing larger cardiovascular disease trials, with a special emphasis on refractory angina and chronic myocardial ischemia.

Ranolazine in patients with coronary artery disease

Traditional anti-anginal agents such as beta-blockers and nitrates improve symptoms of cardiac ischemia by affecting either blood pressure or heart rates. Despite aggressive therapy, many patients suffer persistent angina, and optimal therapy is limited by intolerance to traditional agents. Ranolazine, a novel anti-anginal agent that is approved for use in the US, is felt to improve ischemic symptoms by reducing myocardial cellular sodium and calcium overload via inhibition of the late sodium current (I(Na)) of the cardiac action potential. Several Phase-III trials in patients with chronic angina have demonstrated that ranolazine improves exercise tolerance and reduces ischemic symptoms as compared with placebo. In the largest evaluation of ranolazine, the MERLIN-TIMI 36 trial (Metabolic Efficiency with Ranolazine for Less Ischemia in non ST elevation acute coronary syndrome), ranolazine did not reduce the risk of death or recurrent myocardial infarction in patients with non-ST-elevation acute coronary syndromes, but it did improve ischemic symptoms over the subsequent year of therapy. Thus, ranolazine offers clinicians a new therapy in the long-term treatment of patients with chronic angina.

Ranolazine in patients with angina and coronary artery disease

The optimal management of coronary artery disease is based on achieving two parallel objectives: 1) prevention of major cardiovascular events, and 2) resolution of symptoms. Traditional antianginal agents improve ischemic symptoms by reducing myocardial oxygen demand through modulation of heart rate, preload, and/or afterload. Ranolazine is a novel antianginal agent believed to relieve ischemia by reducing myocardial cellular sodium and calcium overload via inhibition of the late sodium current of the cardiac action potential. In three randomized double-blind trials in selected patients with chronic angina, ranolazine prolonged exercise duration and reduced symptoms when compared with placebo when given as either monotherapy or in combination with traditional antianginal pharmacotherapy. When evaluated in patients with non-ST-elevation acute coronary syndromes, ranolazine reduced recurrent ischemia but did not significantly reduce the risk of death or myocardial infarction at 1 year. Ranolazine complements traditional antianginal agents and offers clinicians a new option in the long-term treatment of patients with angina.

Spinal cord stimulation for refractory chronic angina pectoris: influence on quality of life

Percutaneous coronary revascularization, coronary artery bypass graft surgery and medical management are nowadays very effective in treating coronary artery disease. Nevertheless, the number of patients affected by refractory chronic angina pectoris is increasing. Epidemiological estimates for refractory angina pectoris predict the diagnosis of more than 100,000 patients each year in the USA and approximately 50,000 in Europe. Spinal cord stimulation is a valuable therapeutic option for patients who have failed multiple percutaneous and surgical revascularizations and who are not eligible for further revascularization procedures. The aim of this study is to assess the benefits, in terms of quality of life, of spinal cord stimulation in no-option patients affected by refractory angina pectoris.

Transmyocardial laser revascularization plus cell therapy for refractory angina

We report that the use of transmyocardial laser revascularization combined with intramyocardial injection is a therapeutic option for patients with severe ischemic heart disease (IHD) not amenable to conventional myocardial revascularization. Recently, cell therapy with autologous bone marrow cells (BMC) has been tested in clinical trials for severe IHD. We tested the hypothesis that TMLR combined with intramyocardial injection of BMC is safe, and may help increase the functional capacity and myocardial perfusion in patients with refractory angina. We enrolled 8 patients (7 men), 64+/-4 years old, with refractory angina, non-candidates for another procedure. TMLR (8+/-2 laser drills) was performed via a limited thoracotomy. BMC were obtained prior to surgery, and the lymphomonocytic fraction was separated by density gradient centrifugation. During surgery, 5 mL containing approximately 1.6+/-0.2 x 10(8) BMC (CD34+=1.7+/-0.4%) was delivered by multiple injections in the ischemic myocardium. We observed a reduction in the ischemic score as assessed by MRI from 1.56+/-0.09 (B) to 0.93+/-0.10 (6M) (P=0.01), as well as a reduction in functional class of angina from 3.6+/-0.2 (B) to 1.4+/-0.2 (6M) (P<0.0001). We concluded that, in this early experience, the combined strategy of TMLR plus cell therapy appeared to be safe, and may have synergistically acted to reduce myocardial ischemia, with clinically relevant improvement in functional capacity.

Intramyocardial Transplantation of Autologous CD34 + Stem Cells for Intractable Angina

BACKGROUND

A growing population of patients with coronary artery disease experiences angina that is not amenable to revascularization and is refractory to medical therapy. Preclinical studies have indicated that human CD34+ stem cells induce neovascularization in ischemic myocardium, which enhances perfusion and function.

METHODS AND RESULTS

Twenty-four patients (19 men and 5 women aged 48 to 84 years) with Canadian Cardiovascular Society class 3 or 4 angina who were undergoing optimal medical treatment and who were not candidates for mechanical revascularization were enrolled in a double-blind, randomized (3:1), placebo-controlled dose-escalating study. Patients received granulocyte colony-stimulating factor 5 microg x kg(-1) x d(-1) for 5 days with leukapheresis on the fifth day. Selection of CD34+ cells was performed with a Food and Drug Administration-approved device. Electromechanical mapping was performed to identify ischemic but viable regions of myocardium for injection of cells (versus saline). The total dose of cells was distributed in 10 intramyocardial, transendocardial injections. Patients were required to have an implantable cardioverter-defibrillator or to temporarily wear a LifeVest wearable defibrillator. No incidence was observed of myocardial infarction induced by mobilization or intramyocardial injection. The intramyocardial injection of cells or saline did not result in cardiac enzyme elevation, perforation, or pericardial effusion. No incidence of ventricular tachycardia or ventricular fibrillation occurred during the administration of granulocyte colony-stimulating factor or intramyocardial injections. One patient with a history of sudden cardiac death/ventricular tachycardia/ventricular fibrillation had catheter-induced ventricular tachycardia during mapping that required cardioversion. Serious adverse events were evenly distributed. Efficacy parameters including angina frequency, nitroglycerine usage, exercise time, and Canadian Cardiovascular Society class showed trends that favored CD34+ cell-treated patients versus control subjects given placebo.

CONCLUSIONS

A randomized trial of intramyocardial injection of autologous CD34+ cells in patients with intractable angina was completed that provides evidence for feasibility, safety, and bioactivity. A larger phase IIb study is currently under way to further evaluate this therapy.

Neurostimulation technology for the treatment of chronic pain: a focus on spinal cord stimulation

Over the past 40 years we have seen how electrical stimulation for the relief of pain has progressed from an experimental treatment based upon a clinical theory to being on the threshold of becoming a standard of medical practice. While tens of thousands of devices are implanted every year, the mechanism of action still evades complete understanding. Nevertheless, technological improvements have been considerable and the current neuromodulation devices are both extremely sophisticated and reliable. Unlike most conventional treatments, neurostimulation cannot be restricted to one speciality as its clinical applications ignore the boundaries of medical specialities. Conditions such as neuropathic pain in the back and the leg, complex regional pain syndrome, ischemic pain due to peripheral vascular disease and coronary artery disease are likely to respond to spinal cord stimulation. Even though the evidence for efficacy remains unsatisfactory, the stimulation of the dorsal column has been remarkably successful in relieving pain and improving function in patients who have failed conventional management. The development, the technicalities and the most important clinical applications of spinal cord stimulation are reviewed here.

Catheter-based stem cell and gene therapy for refractory myocardial ischemia

Intramyocardial delivery of genes and cells derived from bone marrow has been evaluated in several small studies of 'no-option' symptomatic patients with chronic ischemic coronary artery disease. Clinical experience with intramyocardial gene delivery is limited to genes encoding isoforms of vascular endothelial cell growth factor. In the largest study (Euroinject One), 80 patients were randomized to receive a plasmid encoding vascular endothelial cell growth factor 165 or placebo. The results of this study suggested no beneficial therapeutic effect of this strategy. The experience with stem cells is limited to use of autologous, nonexpanded, nonmanipulated bone-marrow-derived cells; thus, the number of injected stem cells reflects their natural proportion within the bone marrow. The results of these preliminary studies suggest this approach is feasible and has a high safety profile. Although no conclusion can yet be made regarding efficacy, the improved myocardial perfusion in all four studies described in this Review is encouraging. Data from assessments of individual patients, however, suggests a wide variability in response, underscoring the need for further bench and clinical investigations.

Long-term results following percutaneous myocardial laser therapy

OBJECTIVES

The usefulness and safety of percutaneous myocardial laser therapy in selected patients have been identified in previous 1-year randomized trial reports, including that from a double-blind, sham-controlled trial we independently conducted. We aimed to determine whether the 1-year effects are maintained through a long-term, longitudinal follow-up.

METHODS

Patients (n=77) with chronic, stable, medically refractory angina (class III or IV) not amenable to conventional revascularization and with evidence of reversible ischemia, ejection fraction > or =25%, and myocardial wall thickness > or =8 mm were treated with percutaneous myocardial laser. After the 1-year follow-up and disclosure of all randomized assignments as prespecified in the respective study protocol, patients were followed up longitudinally for a mean of 3 years for angina class, left ventricular ejection fraction, medication usage, and adverse events.

RESULTS

No procedural mortality, myocardial infarction, or cerebral embolism occurred. Pericardiocentesis was required in two patients (2.6%). Cardiac event-free survival was 88% at 1 year and 66% at late follow-up. Mean Canadian Cardiovascular Society angina class was significantly improved from baseline (3.2+/-0.4) at 1 year (2.2+/-1.1, P<0.001) and at a mean of 3 years (1.9+/-1.2, P<0.001). Nitrate usage was significantly reduced at late follow-up; however, ejection fraction did not change over time. In a multivariate analysis, angina improvement at 1 year was found to be a significant independent predictor of both survival and angina improvement at late follow-up.

CONCLUSION

We conclude that percutaneous myocardial laser therapy in selected patients with severe, medically refractory angina not treatable with conventional revascularization induces significant and sustained symptomatic benefit.

Spinal Cord Stimulation for Patients With Refractory Angina and Previous Coronary Surgery

BACKGROUND

Refractory angina pectoris is an exceptionally debilitating condition affecting patients who have typically failed multiple percutaneous and surgical revascularizations and optimal medical therapy and who are not amenable for further revascularization procedures. Spinal cord stimulation (SCS) has been adopted in this context at our institution and midterm mortality, anginal status, and quality of life have been evaluated.

METHODS

From 1998 to 2004, 51 patients with refractory class III-IV angina, who were not considered candidates for revascularization procedures, underwent SCS. All patients had already undergone previous surgical revascularization and a median of two percutaneous procedures. Transmyocardial laser revascularization had been previously performed in 8 cases (15.6%). Most of the patients (70.5%) had experienced a myocardial infarction. Mean ejection fraction was 0.42 +/- 0.121, Canadian Cardiovascular Society class 3.5 +/- 0.5, quality of life (Spitzer index) 4.5 +/- 1.2, and the median frequency of weekly angina episodes was 10.

RESULTS

There were no SCS implantation-related complications. At follow-up (100% complete, mean 24 +/- 18 months), a significant improvement of anginal symptoms (>50% reduction of weekly anginal episodes) occurred in 45 patients (88.2%). In those patients (Responders), the quality of life improved significantly (6.8 +/- 1.5; p < 0.0001), CCS class decreased to 2 +/- 0.7 (p < 0.0001), and the median frequency of weekly angina episodes to 3 (p < 0.0001). At 3 years, Responders' survival was 91.8 +/- 4.6% and the freedom from cardiac events 72.6 +/- 8.42%.

CONCLUSIONS

Spinal cord stimulation is a safe and effective procedure in truly no-option patients affected by refractory angina. A midterm sustained improvement of symptoms and quality of life have been documented with a satisfactory 3-year survival rate.

Regenerative medicine for cardiovascular disorders-new milestones: adult stem cells

Cardiovascular disorders are the leading causes of mortality and morbidity in the developed world. Cell-based modalities have received considerable scientific attention over the last decade for their potential use in this clinical arena. This review was intended as a brief overview on the subject of therapeutic potential of adult stem cells in cardiovascular medicine with basic science findings and the current status of clinical applications. The historical perspective and basic concepts are reviewed and a description of current applications and potential adverse effects in cardiovascular medicine is given. Future improvements on cell-based therapies will likely provide remarkable improvement in survival and quality of life for millions of patients with cardiovascular disorders.

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.

Direct left ventricle-to-coronary artery stent restores perfusion to chronic ischemic swine myocardium

BACKGROUND

Direct left ventricle (LV)-to-coronary artery shunts (VSTENT) have been proposed as an alternative means of myocardial revascularization. The goal of this study was to examine quantitative changes in myocardial perfusion and possible mechanisms of revascularization with an LV-to-coronary shunt.

METHODS

Ameroid occluders were implanted on the proximal left anterior descending coronary artery (LAD) of 6 pigs to create chronic ischemia. Four weeks later, a VSTENT was placed to directly connect the distal LAD with the LV chamber. Animals survived for an additional 3 weeks and received periodic bromodeoxyuridine (BrdU) injections to identify dividing cells to identify and quantify angiogenesis. Regional myocardial perfusion (RMP) was measured with color microspheres under adenosine vasodilatory stress before and 3 weeks after VSTENT implantation. Vascularity was assessed histologically by an overall vascularity index and a growth index reflecting the density of BrdU-positive vascular cells.

RESULTS

Three weeks after VSTENT placement, RMP improved from 38.4% +/- 19.6% of non-ischemic flow to 86.8% +/- 13.7% in treated animals (P < .05). This benefit was accompanied by histological evidence of increased vascularity and vascular proliferation. Four of 5 animals had patent and functional devices at the end of the study.

CONCLUSION

Chronic VSTENT placement improves RMP and may promote arterial remodeling in chronically ischemic porcine myocardium.

Angiogenic gene therapy in patients with nonrevascularizable ischemic heart disease: a phase 2 randomized, controlled trial of AdVEGF121 (AdVEGF121) versus maximum medical treatment

The demonstration that angiogenic growth factors can stimulate new blood vessel growth and restore perfusion in animal models of myocardial ischemia has led to the development of strategies designed for the local production of angiogenic growth factors in patients who are not candidates for conventional revascularization. The results of recent clinical trials of proangiogenesis gene therapy have been disappointing; however, significant limitations in experimental design, in particular in gene transfer strategies, preclude drawing definitive conclusions. In the REVASC study cardiac gene transfer was optimized by direct intramyocardial delivery of a replication-deficient adenovirus-containing vascular endothelial growth factor (AdVEGF121, 4 x 10(10) particle units (p.u.)). Sixty-seven patients with severe angina due to coronary artery disease and no conventional options for revascularization were randomized to AdVEGF121 gene transfer via mini-thoracotomy or continuation of maximal medical treatment. Exercise time to 1 mm ST-segment depression, the predefined primary end-point analysis, was significantly increased in the AdVEGF121 group compared to control at 26 weeks (P=0.026), but not at 12 weeks. As well, total exercise duration and time to moderate angina at weeks 12 and 26, and in angina symptoms as measured by the Canadian Cardiovascular Society Angina Class and Seattle Angina Questionnaire were all improved by VEGF gene transfer (all P-values at 12 and 26 weeks < or =0.001). However, if anything the results of nuclear perfusion imaging favored the control group, although the AdVEGF121 group achieved higher workloads. Overall there was no significant difference in adverse events between the two groups, despite the fact that procedure-related events were seen only in the thoracotomy group. Therefore, administration of AdVEGF121 by direct intramyocardial injections resulted in objective improvement in exercise-induced ischemia in patients with refractory ischemic heart disease.

Spinal cord stimulation for the management of refractory angina pectoris

Despite sophisticated medical and surgical procedures, including percutaneous endovascular methods, a large number of patients suffer from chronic refractory angina pectoris. Improvement of pain relief in this category of patients requires the use of adjuvant therapies, of which spinal cord stimulation (SCS) seems to be the most promising. Controlled studies suggest that in patients with chronic refractory angina, SCS provides symptomatic relief that is equivalent to that provided by surgical or endovascular reperfusion procedures, but with a lower rate of complications and rehospitalization. Similarly, SCS proved cost effective compared to medical as well as surgical or endovascular approaches in a comparable group of patients. This technique is still met with reluctance by the medical community. Reasons for this disinclination may be related to incomplete understanding of the mechanism of action of SCS and the fact that SCS refers to the modulation of neuroendocrine parameters rather than to revascularization, which is currently the dominant treatment paradigm in coronary artery disease.

The immediate and long-term outcome of enhanced external counterpulsation in treatment of chronic stable refractory angina

BACKGROUND

Treatment of angina recalcitrant to conventional pharmacological therapy and revascularization remains problematic. Safe, effective and affordable treatments with high patient acceptability are desirable. Enhanced external counterpulsation (EECP) may fulfil these criteria better than many other proposed interventions.

OBJECTIVE

To examine the immediate and long-term effect of EECP in treatment of chronic stable refractory angina.

DESIGN

Prospective observational study of consecutive patients treated with EECP and follow-up for 1 year.

SETTING

Teaching hospital.

MAIN OUTCOME MEASURES

Canadian Cardiovascular Society (CCS) angina grading, weekly angina frequency and glyceryl trinitrate (GTN) use.

RESULTS

Sixty-one patients were treated with EECP and 58 completed a course of treatment. Further analysis is confined to those who completed EECP. About 52% of patients suffered from CCS III and IV angina prior to EECP. Immediately post-EECP, angina improved by at least one CCS class in 86% and by two classes in 59%. At 1-year follow-up, sustained improvement in CCS was observed in 78% of the patients. The median weekly angina frequency and GTN use were significantly reduced immediately after EECP [7 (4-14) vs. 1 (0-4) episodes per week and 7 (2-16) vs. 0 (0-2) times per week respectively, P < 0.0001; data in median (interquartile range)]. The reduction was sustained at 1-year follow-up. In 48 patients, their mean exercise time improved significantly after EECP [301 +/- 130 s vs. 379 +/- 147 s, P < 0.0001]. Major adverse treatment-related events were rare.

CONCLUSION

This study shows that for patients who fail to respond to conventional measures, a high proportion gain symptomatic benefit from EECP.