Repeated Intramyocardial Bone Marrow Cell Injection in Previously Responding Patients With Refractory Angina Again Improves Myocardial Perfusion, Anginal Complaints, and Quality of Life

Nonpharmacological interventions for 'no-option' refractory angina patients

Refractory angina pectoris (RAP) defined as chronic anginal chest pain because of coronary artery disease (CAD) is a major problem. The increase in the number of patients with RAP in recent years is because of the increasing aging population and improved survival rates among patients with CAD. Management of patients with RAP is often extremely challenging. In this review, we present several interventional approaches for RAP, including device therapies, lifestyle intervention, and cell therapies. Some of these treatments are currently used in the management of RAP, whereas other treatments are under investigation.

Cell Therapy in the Treatment of Coronary Heart Disease

Heart failure is a leading cause of death in patients who have suffered a myocardial infarction. Despite the timely use of modern reperfusion therapies such as thrombolysis, surgical revascularization and balloon angioplasty, they are sometimes unable to prevent the development of significant areas of myocardial damage and subsequent heart failure. Research efforts have focused on developing strategies to improve the functional status of myocardial injury areas. Consequently, the restoration of cardiac function using cell therapy is an exciting prospect. This review describes the characteristics of various cell types relevant to cellular cardiomyoplasty and presents findings from experimental and clinical studies investigating cell therapy for coronary heart disease. Cell delivery methods, optimal dosage and potential treatment mechanisms are discussed.

Cell Therapy in Patients with Heart Failure: A Comprehensive Review and Emerging Concepts

This review summarizes the results of clinical trials of cell therapy in patients with heart failure (HF). In contrast to acute myocardial infarction (where results have been consistently negative for more than a decade), in the setting of HF the results of Phase I–II trials are encouraging, both in ischaemic and non-ischaemic cardiomyopathy. Several well-designed Phase II studies have met their primary endpoint and demonstrated an efficacy signal, which is remarkable considering that only one dose of cells was used. That an efficacy signal was seen 6–12 months after a single treatment provides a rationale for larger, rigorous trials. Importantly, no safety concerns have emerged. Amongst the various cell types tested, mesenchymal stromal cells derived from bone marrow (BM), umbilical cord, or adipose tissue show the greatest promise. In contrast, embryonic stem cells are not likely to become a clinical therapy. Unfractionated BM cells and cardiosphere-derived cells have been abandoned. The cell products used for HF will most likely be allogeneic. New approaches, such as repeated cell treatment and intravenous delivery, may revolutionize the field. As is the case for most new therapies, the development of cell therapies for HF has been slow, plagued by multifarious problems, and punctuated by many setbacks; at present, the utility of cell therapy in HF remains to be determined. What the field needs is rigorous, well-designed Phase III trials. The most important things to move forward are to keep an open mind, avoid preconceived notions, and let ourselves be guided by the evidence.

Stem Cells in Cardiovascular Diseases: 30,000-Foot View

Stem cell and regenerative approaches that might rejuvenate the heart have immense intuitive appeal for the public and scientific communities. Hopes were fueled by initial findings from preclinical models that suggested that easily obtained bone marrow cells might have significant reparative capabilities; however, after initial encouraging pre-clinical and early clinical findings, the realities of clinical development have placed a damper on the field. Clinical trials were often designed to detect exceptionally large treatment effects with modest patient numbers with subsequent disappointing results. First generation approaches were likely overly simplistic and relied on a relatively primitive understanding of regenerative mechanisms and capabilities. Nonetheless, the field continues to move forward and novel cell derivatives, platforms, and cell/device combinations, coupled with a better understanding of the mechanisms that lead to regenerative capabilities in more primitive models and modifications in clinical trial design suggest a brighter future.

An evidence-based review of neuromodulation for the treatment and management of refractory angina

Angina pectoris is defined as substernal chest pain that is typically exacerbated by exertion, stress, or other exposures. There are various methods of treatment for angina. Lifestyle modification and pharmacological management are considered as conservative treatments. If these medications do not result in the resolution of pain, more invasive approaches are an option, like coronary revascularization. Refractory angina (RA) is differentiated from acute or chronic angina based on the persistence of symptoms despite conventional therapies. Overall, the prevalence of RA is estimated to be 5%-15% in patients with coronary artery disease, which can account for up to 1,500,000 current cases and 100,000 new cases in the United States per year. Spinal cord stimulation treatment is a viable option for patients who are suffering from RA pain and are either not candidates for revascularization surgery or are currently not being well managed on more traditional treatments. Many studies show a positive result.

A Path Forward for Regenerative Medicine

Although clinical trials of cell-based approaches to cardiovascular disease have yielded some promising results, no cell-based therapy has achieved regulatory approval for a cardiovascular indication. To broadly assess the challenges to regulatory approval and identify strategies to facilitate this goal, the Cardiac Safety Research Consortium sponsored a session during the Texas Heart Institute International Symposium on Cardiovascular Regenerative Medicine in September 2017. This session convened leaders in cardiovascular regenerative medicine, including participants from academia, the pharmaceutical industry, the US Food and Drug Administration, and the Cardiac Safety Research Consortium, with particular focus on treatments closest to regulatory approval. A goal of the session was to identify barriers to regulatory approval and potential pathways to overcome them. Barriers identified include manufacturing and therapeutic complexity, difficulties identifying an optimal comparator group, limited industry capacity for funding pivotal clinical trials, and challenges to demonstrating efficacy on clinical end points required for regulatory decisions. Strategies to overcome these barriers include precompetitive development of a cell therapy registry network to enable dual-purposing of clinical data as part of pragmatic clinical trial design, development of standardized terminology for product activity and end points to facilitate this registry, use of innovative statistical methods and quality of life or functional end points to supplement outcomes such as death or heart failure hospitalization and reduce sample size, involvement of patients in determining the research agenda, and use of the Food and Drug Administration's new Regenerative Medicine Advanced Therapy designation to facilitate early discussion with regulatory authorities when planning development pathways.

Therapeutic potential of menstrual blood-derived endometrial stem cells in cardiac diseases

Despite significant developments in medical and surgical strategies, cardiac diseases remain the leading causes of morbidity and mortality worldwide. Numerous studies involving preclinical and clinical trials have confirmed that stem cell transplantation can help improve cardiac function and regenerate damaged cardiac tissue, and stem cells isolated from bone marrow, heart tissue, adipose tissue and umbilical cord are the primary candidates for transplantation. During the past decade, menstrual blood-derived endometrial stem cells (MenSCs) have gradually become a promising alternative for stem cell-based therapy due to their comprehensive advantages, which include their ability to be periodically and non-invasively collected, their abundant source material, their ability to be regularly donated, their superior proliferative capacity and their ability to be used for autologous transplantation. MenSCs have shown positive therapeutic potential for the treatment of various diseases. Therefore, aside from a brief introduction of the biological characteristics of MenSCs, this review focuses on the progress being made in evaluating the functional improvement of damaged cardiac tissue after MenSC transplantation through preclinical and clinical studies. Based on published reports, we conclude that the paracrine effect, transdifferentiation and immunomodulation by MenSC promote both regeneration of damaged myocardium and improvement of cardiac function.

The Impact of Cell Therapy on Cardiovascular Outcomes in Patients With Refractory Angina

RATIONALE

Cell-based therapies are a novel potential treatment for refractory angina and have been found to improve markers of angina. However, the effects on mortality and major adverse cardiac events (MACE) have not been definitively investigated.

OBJECTIVE

To investigate the efficacy and safety of stem cell treatment compared with optimal medical treatment for refractory angina by conducting an updated meta-analysis, looking at clinical outcomes.

METHODS AND RESULTS

We performed a systematic review and meta-analysis of randomized controlled trials using the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. A comprehensive search was performed of PubMed, EMBASE (Excerpta Medica database), Cochrane, ClinicalTrials.gov , Google Scholar databases of randomized controlled trials, and scientific session abstracts. Studies were deemed eligible if they met the following criteria: (1) full-length publications in peer-reviewed journals; (2) evaluated cell therapy use in patients with no further revascularisation options while on optimal medical treatment; (3) patients had ongoing angina, Canadian Cardiovascular Society class II-IV; and (4) included a placebo/control arm. We calculated risk ratios for all-cause mortality, combined MACE events. We assessed heterogeneity using χ² and I² tests. We identified 1191 citations with 8 randomized controlled trials meeting inclusion criteria involving 526 patients. Outcomes pooled were MACE, mortality, and indices of angina (angina episodes, Canadian Cardiovascular Society angina class, exercise tolerance, and antianginal medications). Our analysis showed a decreased risk of both MACE (odds ratio, 0.41; CI, 0.25-0.70) and mortality (odds ratio, 0.24; 95% CI, 0.10-0.60) in cell-treated patients compared with patients on maximal medical therapy. This was supported by improvements in surrogate end points of anginal episodes, use of antianginal medications, Canadian Cardiovascular Society class, and exercise tolerance.

CONCLUSIONS

In addition to improvements in indices of angina, cell-based therapies improve cardiovascular outcomes (mortality/MACE) in patients with refractory angina. Given the premature termination of the phase III study, this supports the need for further definitive trials. Prospero Registration : URL: https://www.crd.york.ac.uk/prospero/ . Unique identifier: CRD42018084257.

Biological therapies in otology

Hearing loss is present in millions of people worldwide. Current treatment for patients with severe to profound hearing loss consists of cochlear implantation. Providing the cochlear nerve is intact, patients generally benefit greatly from this intervention, frequently achieving significant improvements in speech comprehension. There are, however, some cases where current technology does not provide patients with adequate benefit. Ongoing research in cell transplantation and gene therapy promises to lead to new developments that will improve the function of cochlear implants. Translation of these experimental approaches is presently at an early stage. This review focuses on the application of biological therapies in severe hearing loss and discusses some of the barriers to translating basic scientific research into clinical reality. We emphasize the application of these novel therapies to cochlear implantation.

Intramyocardial bone marrow cell injection does not lead to functional improvement in patients with chronic ischaemic heart failure without considerable ischaemia

Background

It has been suggested that bone marrow cell injection may have beneficial effects in patients with chronic ischaemic heart disease. However, previous trials have led to discrepant results of cell-based therapy in patients with chronic heart failure. The aim of this study was to evaluate the efficacy of intramyocardial injection of mononuclear bone marrow cells in patients with chronic ischaemic heart failure with limited stress-inducible myocardial ischaemia.

Methods and results

This multicentre, randomised, placebo-controlled trial included 39 patients with no-option chronic ischaemic heart failure with a follow-up of 12 months. A total of 19 patients were randomised to autologous intramyocardial bone marrow cell injection (cell group) and 20 patients received a placebo injection (placebo group). The primary endpoint was the group difference in change of left ventricular ejection fraction, as determined by single-photon emission tomography. On follow-up at 3 and 12 months, change of left ventricular ejection fraction in the cell group was comparable with change in the placebo group (P = 0.47 and P = 0.08, respectively). Also secondary endpoints, including left ventricle volumes, myocardial perfusion, functional and clinical parameters did not significantly change in the cell group as compared to placebo. Neither improvement was demonstrated in a subgroup of patients with stress-inducible ischaemia (P = 0.54 at 3‑month and P = 0.15 at 12-month follow-up).

Conclusion

Intramyocardial bone marrow cell injection does not improve cardiac function, nor functional and clinical parameters in patients with severe chronic ischaemic heart failure with limited stress-inducible ischaemia.

Clinical Trial Registration: NTR2516

Electronic supplementary material

The online version of this article (10.1007/s12471-018-1213-2) contains supplementary material, which is available to authorized users.

New Advances in the Management of Refractory Angina Pectoris

Refractory angina is a significant clinical problem and its successful management is often extremely challenging. Defined as chronic angina-type chest pain in the presence of myocardial ischaemia that persists despite optimal medical, interventional and surgical treatment, current therapies are limited and new approaches to treatment are needed. With an ageing population and increased survival from coronary artery disease, clinicians will increasingly encounter this complex condition in routine clinical practice. Novel therapies to target myocardial ischaemia in patients with refractory angina are at the forefront of research and in this review we discuss those in clinical translation and assess the evidence behind their efficacy.

Cell Therapy for Refractory Angina: A Reappraisal

Cardiac cell-based therapy has emerged as a novel therapeutic option for patients dealing with untreatable refractory angina (RA). However, after more than a decade of controlled studies, no definitive consensus has been reached regarding clinical efficacy. Although positive results in terms of surrogate endpoints have been suggested by early and phase II clinical studies as well as by meta-analyses, the more recent reports lacked the provision of definitive response in terms of hard clinical endpoints. Regrettably, pivotal trials designed to conclusively determine the efficacy of cell-based therapeutics in such a challenging clinical condition are therefore still missing. Considering this, a comprehensive reappraisal of cardiac cell-based therapy role in RA seems warranted and timely, since a number of crucial cell- and patient-related aspects need to be systematically analysed. As an example, the large variability in efficacy endpoint selection appears to be a limiting factor for the advancement of cardiac cell-based therapy in the field. This review will provide an overview of the key elements that may have influenced the results of cell-based trials in the context of RA, focusing in particular on the understanding at which the extent of angina-related endpoints may predict cell-based therapeutic efficacy.

Safety and efficacy of percutaneous intramyocardial bone marrow cell injection for chronic myocardial ischemia: Long-term results

BACKGROUND

Intramyocardial injection of bone marrow cells (BMC) in refractory angina patients with chronic myocardial ischemia has shown to be safe and improve clinical status during short-term follow-up. However, scarce data are available on long-term (>12 months) safety and efficacy. Therefore, the occurrence of clinical events and the long-term clinical effects of intramyocardial BMC injection were evaluated in patients with chronic myocardial ischemia up to 10 years after treatment.

METHODS AND RESULTS

Patients (n = 100, age 64 ± 9 years, male 88%) with chronic myocardial ischemia who underwent intramyocardial BMC injection between 2004 and 2010 were evaluated. During yearly outpatient clinic visits, the occurrence of clinical events was documented. In addition, clinical status was assessed according to the Canadian Cardiovascular Society (CCS) score and quality of life was measured using the Seattle Angina Questionnaire. These parameters were evaluated at baseline and during the first year, followed by cross-sectional long-term follow-up which was performed in 2011 and 2014. No adverse events considered related to the procedure occurred during 10 years of follow-up. Observed annual mortality rate and annual myocardial infarction rate were 3.8% and 1.9% per year, respectively. When compared to baseline, CCS class and quality of life remained significantly better during 5-year follow-up after BMC treatment (both P < 0.05).

CONCLUSIONS

The present long-term follow-up study shows that intramyocardial BMC injection in patients with chronic myocardial ischemia is safe and improves both angina complaints and quality of life up to 5 years after BMC treatment.

Advances in translational inner ear stem cell research

Stem cell research is expanding our understanding of developmental biology as well as promising the development of new therapies for a range of different diseases. Within hearing research, the use of stem cells has focused mainly on cell replacement. Stem cells however have a broad range of other potential applications that are just beginning to be explored in the ear. Mesenchymal stem cells are an adult derived stem cell population that have been shown to produce growth factors, modulate the immune system and can differentiate into a wide variety of tissue types. Potential advantages of mesenchymal/adult stem cells are that they have no ethical constraints on their use. However, appropriate regulatory oversight seems necessary in order to protect patients from side effects. Disadvantages may be the lack of efficacy in many preclinical studies. But if proven safe and efficacious, they are easily translatable to clinical trials. The current review will focus on the potential application on mesenchymal stem cells for the treatment of inner ear disorders.

[Biological therapies in otology. German version]

Millions of people worldwide suffer from hearing loss. Current treatment for patients with severe to profound hearing loss consists of cochlear implants. Providing the cochlear nerve is intact, patients generally benefit enormously from this intervention, frequently achieving significant improvements in speech comprehension. There are, however, some cases where current technology does not provide patients with adequate benefit. New therapeutic concepts based on cell transplantation and gene therapy are developing rapidly, at least in the research sector. Compared to the wealth of basic research available in this area, translation of these new experimental approaches into clinical application is presently at a very early stage. The current review focuses on translatable treatment concepts and discusses the barriers that need to be overcome in order to translate basic scientific research into clinical reality. Furthermore, the first examples of clinical application of biological therapies in severe hearing loss are presented, particularly in connection with cochlear implants.

Stem cell therapy for chronic ischaemic heart disease and congestive heart failure

BACKGROUND

A promising approach to the treatment of chronic ischaemic heart disease and congestive heart failure is the use of stem cells. The last decade has seen a plethora of randomised controlled trials developed worldwide, which have generated conflicting results.

OBJECTIVES

The critical evaluation of clinical evidence on the safety and efficacy of autologous adult bone marrow-derived stem/progenitor cells as a treatment for chronic ischaemic heart disease and congestive heart failure.

SEARCH METHODS

We searched CENTRAL in the Cochrane Library, MEDLINE, Embase, CINAHL, LILACS, and four ongoing trial databases for relevant trials up to 14 December 2015.

SELECTION CRITERIA

Eligible studies were randomised controlled trials comparing autologous adult stem/progenitor cells with no cells in people with chronic ischaemic heart disease and congestive heart failure. We included co-interventions, such as primary angioplasty, surgery, or administration of stem cell mobilising agents, when administered to treatment and control arms equally.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened all references for eligibility, assessed trial quality, and extracted data. We undertook a quantitative evaluation of data using random-effects meta-analyses. We evaluated heterogeneity using the I2 statistic and explored substantial heterogeneity (I2 greater than 50%) through subgroup analyses. We assessed the quality of the evidence using the GRADE approach. We created a 'Summary of findings' table using GRADEprofiler (GRADEpro), excluding studies with a high or unclear risk of selection bias. We focused our summary of findings on long-term follow-up of mortality, morbidity outcomes, and left ventricular ejection fraction measured by magnetic resonance imaging.

MAIN RESULTS

We included 38 randomised controlled trials involving 1907 participants (1114 cell therapy, 793 controls) in this review update. Twenty-three trials were at high or unclear risk of selection bias. Other sources of potential bias included lack of blinding of participants (12 trials) and full or partial commercial sponsorship (13 trials).Cell therapy reduced the incidence of long-term mortality (≥ 12 months) (risk ratio (RR) 0.42, 95% confidence interval (CI) 0.21 to 0.87; participants = 491; studies = 9; I2 = 0%; low-quality evidence). Periprocedural adverse events associated with the mapping or cell/placebo injection procedure were infrequent. Cell therapy was also associated with a long-term reduction in the incidence of non-fatal myocardial infarction (RR 0.38, 95% CI 0.15 to 0.97; participants = 345; studies = 5; I2 = 0%; low-quality evidence) and incidence of arrhythmias (RR 0.42, 95% CI 0.18 to 0.99; participants = 82; studies = 1; low-quality evidence). However, we found no evidence that cell therapy affects the risk of rehospitalisation for heart failure (RR 0.63, 95% CI 0.36 to 1.09; participants = 375; studies = 6; I2 = 0%; low-quality evidence) or composite incidence of mortality, non-fatal myocardial infarction, and/or rehospitalisation for heart failure (RR 0.64, 95% CI 0.38 to 1.08; participants = 141; studies = 3; I2 = 0%; low-quality evidence), or long-term left ventricular ejection fraction when measured by magnetic resonance imaging (mean difference -1.60, 95% CI -8.70 to 5.50; participants = 25; studies = 1; low-quality evidence).

AUTHORS' CONCLUSIONS

This systematic review and meta-analysis found low-quality evidence that treatment with bone marrow-derived stem/progenitor cells reduces mortality and improves left ventricular ejection fraction over short- and long-term follow-up and may reduce the incidence of non-fatal myocardial infarction and improve New York Heart Association (NYHA) Functional Classification in people with chronic ischaemic heart disease and congestive heart failure. These findings should be interpreted with caution, as event rates were generally low, leading to a lack of precision.

Current State of Stem Cell Therapy for Ischemic Heart Disease

Improvements in the care of patients with ischemic cardiovascular disease have led to improved survival but also a burgeoning population of patients with advanced ischemic heart disease. Cell therapies offer a novel approach toward cardiac "rejuvenation" via stimulation of new blood vessel growth, enhancing tissue perfusion, and via preservation or even regeneration of myocardial tissue, leading to improvements in cardiac performance after myocardial infarction and in patients with advanced heart failure. Here, we summarize and offer some thoughts on the state of the field of cell therapy for ischemic heart disease, targeting three separate conditions that have been the subject of significant clinical research: enhancing left ventricular recovery after MI, improving outcomes and symptoms in patients with congestive heart failure (CHF), and treatment of patients with refractory angina, despite maximal medical therapy.

Effects of Transendocardial Delivery of Bone Marrow-Derived CD133+ Cells on Left Ventricle Perfusion and Function in Patients With Refractory Angina: Final Results of Randomized, Double-Blinded, Placebo-Controlled REGENT-VSEL Trial

RATIONALE

New therapies for refractory angina are needed.

OBJECTIVE

Assessment of transendocardial delivery of bone marrow CD133⁺ cells in patients with refractory angina.

METHODS AND RESULTS

Randomized, double-blinded, placebo-controlled trial enrolled 31 patients with recurrent Canadian Cardiovascular Society II-IV angina, despite optimal medical therapy, ≥1 myocardial segment with inducible ischemia in Tc-99m SPECT who underwent bone marrow biopsy and were allocated to cells (n=16) or placebo (n=15). Primary end point was absolute change in myocardial ischemia by SPECT. Secondary end points were left ventricular function and volumes by magnetic resonance imaging and angina severity. After 4 months, there were no significant differences in extent of inducible ischemia between groups (summed difference score mean [±SD]: 2.60 [2.6] versus 3.63 [3.6], P=0.52; total perfusion deficit: 3.60 [3.6] versus 5.01 [4.3], P=0.32; absolute changes of summed difference score: -1.38 [5.2] versus -0.73 [1.9], P=0.65; and total perfusion deficit: -1.33 [3.3] versus -2.19 [6.6], P=0.65). There was a significant reduction of left ventricular volumes (end-systolic volume: -4.3 [11.3] versus 7.4 [11.8], P=0.02; end-diastolic volume: -9.1 [14.9] versus 7.4 [15.8], P=0.02) and no significant change of left ventricular ejection fraction in the cell group. There was no difference in number of patients showing improvement of ≥1 Canadian Cardiovascular Society class after 1 (41.7% versus 58.3%; P=0.68), 4 (50% versus 33.3%; P=0.63), 6 (70% versus 50.0%; P=0.42), and 12 months (55.6% versus 81.8%; P=0.33) and use of nitrates after 12 months.

CONCLUSION

Transendocardial CD133⁺ cell therapy was safe. Study was underpowered to conclusively validate the efficacy, but it did not show a significant reduction of myocardial ischemia and angina versus placebo.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01660581.

Repeated Administrations of Cardiac Progenitor Cells Are Markedly More Effective Than a Single Administration: A New Paradigm in Cell Therapy

RATIONALE

The effects of c-kit(POS) cardiac progenitor cells (CPCs, and adult cell therapy in general) on left ventricular (LV) function have been regarded as modest or inconsistent.

OBJECTIVE

To determine whether 3 CPC infusions have greater efficacy than 1 infusion.

METHODS AND RESULTS

Rats with a 30-day-old myocardial infarction received 1 or 3 CPC infusions into the LV cavity, 35 days apart. Compared with vehicle-treated rats, the single-dose group exhibited improved LV function after the first infusion (consisting of CPCs) but not after the second and third (vehicle). In contrast, in the multiple-dose group, regional and global LV function improved by a similar degree after each CPC infusion, resulting in greater cumulative effects. For example, the total increase in LV ejection fraction was approximately triple in the multiple-dose group versus the single-dose group (P<0.01). The multiple-dose group also exhibited more viable tissue and less scar, less collagen in the risk and noninfarcted regions, and greater myocyte density in the risk region.

CONCLUSIONS

This is the first demonstration that repeated CPC administrations are markedly more effective than a single administration. The concept that the full effects of CPCs require repeated doses has significant implications for both preclinical and clinical studies; it suggests that the benefits of cell therapy may be underestimated or even overlooked if they are measured after a single dose, and that repeated administrations are necessary to evaluate the effectiveness of a cell product properly. In addition, we describe a new method that enables studies of repeated cell administrations in rodents.

Autologous CD34+ Cell Therapy for Refractory Angina: 2-Year Outcomes From the ACT34-CMI Study

An increasing number of patients have refractory angina despite optimal medical therapy and are without further revascularization options. Preclinical studies indicate that human CD34⁺ stem cells can stimulate new blood vessel formation in ischemic myocardium, improving perfusion and function. In ACT34-CMI (N = 167), patients treated with autologous CD34⁺ stem cells had improvements in angina and exercise time at 6 and 12 months compared to placebo; however, the longer-term effects of this treatment are unknown. ACT34 was a phase II randomized, double-blind, placebo-controlled clinical trial comparing placebo, low dose (1 × 10⁵ CD34/kg body weight), and high dose (5 × 10⁵ CD34/kg) using intramyocardial delivery into the ischemic zone following NOGA^® mapping. To obtain longer-term safety and efficacy in these patients, we compiled data of major adverse cardiac events (MACE; death, myocardial infarction, acute coronary syndrome, or heart failure hospitalization) up to 24 months as well as angina and quality of life assessments in patients who consented for 24-month follow-up. A total of 167 patients with class III-IV refractory angina were randomized and completed the injection procedure. The low-dose-treated patients had a significant reduction in angina frequency (p = 0.02, 0.035) and improvements in exercise tolerance testing (ETT) time (p = 0.014, 0.017) compared to the placebo group at 6 and 12 months. At 24 months, patients treated with both low-and high-dose CD34⁺ cells had significant reduction in angina frequency (p = 0.03). At 24 months, there were a total of seven deaths (12.5%) in the control group versus one (1.8%) in the low-dose and two (3.6%) in the high-dose (p = 0.08) groups. At 2 years, MACE occurred at a rate of 33.9%, 21.8%, and 16.2% in control, low-, and high-dose patients, respectively (p = 0.08). Autologous CD34⁺ cell therapy was associated with persistent improvement in angina at 2 years and a trend for reduction in mortality in no-option patients with refractory angina.

Management of Refractory Angina Pectoris

With improvements in survival from coronary artery disease (CAD) and an ageing population, refractory angina (RA) is becoming an increasingly common clinical problem facing clinicians in routine clinical practice. These patients experience chronic symptoms in the context of CAD, characterised by angina-type pain, which is uncontrolled despite optimal pharmacological, interventional and surgical therapy. Although mortality rates are no worse in this cohort, patients experience a significantly impaired quality of life with disproportionately high utilisation of healthcare services. It has been increasingly recognised that the needs of RA patients are multifactorial and best provided by specialist multi-disciplinary units. In this review, we consider the variety of therapies available to clinicians in the management of RA and discuss the promise of novel treatments.