Anthony Mathur

Autologous bone marrow stem cells to treat acute myocardial infarction: a systematic review.

AIMS To provide systematic assessment of the safety and efficacy of autologous bone marrow-derived stem cell (BMSC) transplantation in acute myocardial infarction (AMI) based on clinical evidence. METHODS AND RESULTS The search strategy included MEDLINE, EMBASE, the Cochrane Library, and Current Controlled Trials Register through to August 2007 for randomized controlled trials of BMSC treatment for AMI. Thirteen trials (14 comparisons) with a total of 811 participants were included. Data were analysed using a random effects model. Overall, stem cell therapy improved left ventricular ejection fraction (LVEF) by 2.99% [95% confidence interval (CI), 1.26-4.72%, P = 0.0007], significantly reduced left ventricular end-systolic volume (LVESV) by 4.74 mL (95% CI, -7.84 to -1.64 mL, P = 0.003), and myocardial lesion area by 3.51% (95% CI, -5.91 to -1.11%, P = 0.004) compared with controls. Subgroup analysis revealed that there was statistical significant difference in LEVF in favour of BMSCs when cells were infused within 7 days following AMI and when the BMSC dose administered was higher than 10(8) BMSCs. In addition, there were trends in favour of benefit for most clinical outcomes examined, although it should be acknowledged that the 95%CI included no significant difference. CONCLUSION Stem cell treatment for AMI still holds promise. Clinically, these data suggest that improvement over conventional therapy can be achieved. Further, adequately powered trials using optimal dosing, longer term outcome assessments, more reliable, and more patient-centred outcomes are required.

Stem cells and repair of the heart

Stem-cell therapy provides the prospect of an exciting and powerful treatment to repair the heart. Although research has been undertaken in animals to analyse the safety and efficacy of this new approach, results have been inconclusive. The mechanism by which stem cells could improve cardiac function remains unclear. We describe the background to the concept of natural repair and the work that has been done to establish the role of stem cells in cardiac repair. Controversies have arisen in interpretation of experimental data. The important issues surrounding the application of stem-cell therapy to man are discussed critically. We discuss the future of this pioneering work in the setting of growing concerns about clinical studies in man without understanding the biological mechanisms involved, with the difficulties in funding this type of research.

Evaluation of fluorescent dyes for the detection of mitochondrial membrane potential changes in cultured cardiomyocytes

OBJECTIVE Maintenance of the mitochondrial membrane potential (Deltapsim) is fundamental for the normal performance and survival of cells such as cardiomyocytes, that have a high energy requirement. Measurement of Deltapsim is therefore essential in order to develop an understanding of the molecular mechanisms controlling cardiomyocyte function. Here we have evaluated various potentiometric dyes for their ability to detect alterations of Deltapsim, using flow cytometry and confocal microscopy. METHODS Primary cultures of cardiomyocytes from neonate rats were treated with mitochondrial uncouplers before or after loading with Rho123, DiOC(6)(3), CMXRos or JC-1, and then analysed by flow cytometry. Apoptotic cells were identified by light scatter and Annexin V staining. RESULTS The four potentiometric dyes tested were able to discriminate between viable and apoptotic cells. However, only JC-1 was able to detect the collapse of Deltapsim induced by uncouplers of mitochondrial respiration. Confocal microscopic analysis confirmed that JC-1 stained mitochondria in a potential-dependent manner. In contrast, CMXRos stained cardiomyocytes irrespective of alterations in Deltapsim. CONCLUSIONS We conclude that JC-1 is the optimal dye to use when measuring Deltapsim in cardiomyocytes.

Successful Recanalization of Chronic Total Occlusions Is Associated With Improved Long-Term Survival

OBJECTIVES This study investigated the impact of procedural success on mortality following chronic total occlusion (CTO) percutaneous coronary intervention (PCI) in a large cohort of patients in the drug-eluting stent era. BACKGROUND Despite advances in expertise and technologies, many patients with CTO are not offered PCI. METHODS A total of 6,996 patients underwent elective PCI for stable angina at a single center (2003 to 2010), 836 (11.9%) for CTO. All-cause mortality was obtained to 5 years (median: 3.8 years; interquartile range: 2.0 to 5.4 years) and stratified according to successful chronic total occlusion (sCTO) or unsuccessful chronic total occlusion (uCTO) recanalization. Major adverse cardiac events (MACE) included myocardial infarction (MI), urgent revascularization, stroke, or death. RESULTS A total of 582 (69.6%) procedures were successful. Stents were implanted in 97.0% of successful procedures (mean: 2.3 ± 0.1 stents per patient, 73% drug-eluting). Prior revascularization was more frequent among uCTO patients: coronary artery bypass grafting (CABG) (16.5% vs. 7.4%; p < 0.0001), PCI (36.0% vs. 21.2%; p < 0.0001). Baseline characteristics were otherwise similar. Intraprocedural complications, including coronary dissection, were more frequent in unsuccessful cases (20.5% vs. 4.9%; p < 0.0001), but did not affect in-hospital MACE (3% vs. 2.1%; p = NS). All-cause mortality was 17.2% for uCTO and 4.5% for sCTO at 5 years (p < 0.0001). The need for CABG was reduced following sCTO (3.1% vs. 22.1%; p < 0.0001). Multivariate analysis demonstrated that procedural success was independently predictive of mortality (hazard ratio [HR]: 0.32 [95% confidence interval (CI): 0.18 to 0.58]), which persisted when incorporating a propensity score (HR: 0.28 [95% CI: 0.15 to 0.52]). CONCLUSIONS Successful CTO PCI is associated with improved survival out to 5 years. Adoption of techniques and technologies to improve procedural success may have an impact on prognosis.

Meta-Analysis of Cell Therapy Trials for Patients With Heart Failure

RATIONALE Cell-based therapies are a promising intervention for the treatment of heart failure (HF) secondary to ischemic and nonischemic cardiomyopathy. However, the clinical efficacy of such new treatment requires further evaluation. OBJECTIVE To assess available clinical evidence on the safety and efficacy of cell-based therapies for HF. METHODS AND RESULTS Electronic databases (CENTRAL, DARE, NHSEED & HTA, PubMed, MEDLINE, EMBASE, CINAHL, LILACS, KoreaMed, PakMediNet, IndMed, and the Transfusion Evidence Library) were searched for relevant randomized controlled trials to June 2014. Trials of participants with HF and where the administration of any dose of autologous cells by any delivery route was compared with no intervention or placebo were eligible for inclusion. Primary outcomes were defined as mortality and rehospitalization as a result of HF. Secondary outcomes included performance status, quality of life, incidence of arrhythmias, brain natriuretic peptide levels, left ventricular ejection fraction, myocardial perfusion, and adverse events. Thirty-one independent trials (1521 participants) were included. The treatment significantly reduced the risk of mortality and rehospitalization caused by HF. There was a significant improvement in favor of stem cell treatment in performance status and exercise capacity, left ventricular ejection fraction, and quality of life. The treatment was also associated with a reduction of brain natriuretic peptide levels and no increase in the incidence of arrhythmias. However, there was considerable risk of performance, selection, and reporting bias among the included trials. CONCLUSIONS This study shows evidence that autologous cell therapy may be beneficial for patients having HF, but further evidence is required.

Meta-Analysis of Cell Therapy Trials for Patients with Heart Failure - An Update

RATIONALE Cell-based therapies are a promising intervention for the treatment of heart failure (HF) secondary to ischemic and nonischemic cardiomyopathy. However, the clinical efficacy of such new treatment requires further evaluation. OBJECTIVE To assess available clinical evidence on the safety and efficacy of cell-based therapies for HF. METHODS AND RESULTS Electronic databases (CENTRAL, DARE, NHSEED & HTA, PubMed, MEDLINE, EMBASE, CINAHL, LILACS, KoreaMed, PakMediNet, IndMed, and the Transfusion Evidence Library) were searched for relevant randomized controlled trials to June 2014. Trials of participants with HF and where the administration of any dose of autologous cells by any delivery route was compared with no intervention or placebo were eligible for inclusion. Primary outcomes were defined as mortality and rehospitalization as a result of HF. Secondary outcomes included performance status, quality of life, incidence of arrhythmias, brain natriuretic peptide levels, left ventricular ejection fraction, myocardial perfusion, and adverse events. Thirty-one independent trials (1521 participants) were included. The treatment significantly reduced the risk of mortality and rehospitalization caused by HF. There was a significant improvement in favor of stem cell treatment in performance status and exercise capacity, left ventricular ejection fraction, and quality of life. The treatment was also associated with a reduction of brain natriuretic peptide levels and no increase in the incidence of arrhythmias. However, there was considerable risk of performance, selection, and reporting bias among the included trials. CONCLUSIONS This study shows evidence that autologous cell therapy may be beneficial for patients having HF, but further evidence is required.

Diagnostic performance of hyperaemic myocardial blood flow index obtained by dynamic computed tomography: does it predict functionally significant coronary lesions?

AIMS The severity of coronary artery narrowing is a poor predictor of functional significance, in particular in intermediate coronary lesions (30-70% diameter narrowing). The aim of this work was to compare the performance of a quantitative hyperaemic myocardial blood flow (MBF) index derived from adenosine dynamic computed tomography perfusion (CTP) imaging with that of visual CT coronary angiography (CTCA) and semi-automatic quantitative CT (QCT) in the detection of functionally significant coronary lesions in patients with stable chest pain. METHODS AND RESULTS CTCA and CTP were performed in 80 patients (210 analysable coronary vessels) referred to invasive coronary angiography (ICA). The MBF index (mL/100 mL/min) was computed using a model-based parametric deconvolution method. The diagnostic performance of the MBF index in detecting functionally significant coronary lesions was compared with visual CTCA and QCT. Coronary lesions with invasive fractional flow reserve of ≤0.75 were defined as functionally significant. The optimal cut-off value of the MBF index to detect functionally significant coronary lesions was 78 mL/100 mL/min. On a vessel-territory level, the MBF index had a larger area under the curve (0.95; 95% confidence interval [95% CI]: 0.92-0.98) compared with visual CTCA (0.85; 95% CI: 0.79-0.91) and QCT (0.89; 95% CI: 0.84-0.93) (both P-values <0.001). In the analysis restricted to intermediate coronary lesions, the specificity of visual CTCA (69%) and QCT (77%) could be improved by the subsequent use of the MBF index (89%). CONCLUSION In this proof-of-principle study, the MBF index performed better than visual CTCA and QCT in the identification of functionally significant coronary lesions. The MBF index had additional value beyond CTCA anatomy in intermediate coronary lesions. This may have a potential to support patient management.

Acute myocarditis presenting as acute coronary syndrome: role of early cardiac magnetic resonance in its diagnosis

Background In patients presenting with acute cardiac symptoms, abnormal ECG and raised troponin, myocarditis may be suspected after normal angiography. Aims To analyse cardiac magnetic resonance (CMR) findings in patients with a provisional diagnosis of acute coronary syndrome (ACS) in whom acute myocarditis was subsequently considered more likely. Methods and results 79 patients referred for CMR following an admission with presumed ACS and raised serum troponin in whom no culprit lesion was detected were studied. 13% had unrecognised myocardial infarction and 6% takotsubo cardiomyopathy. The remainder (81%) were diagnosed with myocarditis. Mean age was 45±15 years and 70% were male. Left ventricular ejection fraction (EF) was 58±10%; myocardial oedema was detected in 58%. A myocarditic pattern of late gadolinium enhancement (LGE) was detected in 92%. Abnormalities were detected more frequently in scans performed within 2 weeks of symptom onset: oedema in 81% vs 11% (p<0.0005), and LGE in 100% vs 76% (p<0.005). In 20 patients with both an acute (<2 weeks) and convalescent scan (>3 weeks), oedema decreased from 84% to 39% (p<0.01) and LGE from 5.6 to 3.0 segments (p=0.005). Three patients presented with sustained ventricular tachycardia, another died suddenly 4 days after admission and one resuscitated 7 weeks following presentation. All 5 patients had preserved EF. Conclusions Our study emphasises the importance of access to CMR for heart attack centres. If myocarditis is suspected, CMR scanning should be performed within 14 days. Myocarditis should not be regarded as benign, even when EF is preserved.

The causal role of megakaryocyte–platelet hyperactivity in acute coronary syndromes.

Platelets are causally involved in coronary artery obstruction in acute coronary syndromes (ACS). This cell type is unique to mammals and its production, which is unlike that of any other mammalian cell, involves polyploid nuclear change in the mother cell (megakaryocyte) and the production of anucleate cells with a log Gaussian distribution of volume. Platelets vary more in cellular volume than any other circulating blood element in mammals. Larger platelets are denser, contain more secretory granules, and are more reactive than their smaller counterparts. A causal relationship between the presence of large, dense, reactive platelets in the circulation and ACS is supported by many clinical studies. Furthermore, the results of two large, prospective, epidemiological studies have demonstrated that mean platelet volume was the strongest independent predictor of outcome in patients with acute myocardial infarction. Notably, evidence indicates that an increase in mean platelet volume in the pathogenesis of ACS can potentially overwhelm current therapeutics. The control system for the physiological and pathophysiological production of large platelets should, therefore, be researched. An understanding of this system might give rise to new therapeutics that could control platelet reactivity and thereby comprehensively prevent ACS.

Bone Marrow Stem Cell Treatment for Ischemic Heart Disease in Patients with No Option of Revascularization: A Systematic Review and Meta-Analysis.

Objective To evaluate bone marrow stem cell treatment (BMSC) in patients with ischemic heart disease (IHD) and no option of revascularization. Background Autologous BMSC therapy has emerged as a novel approach to treat patients with acute myocardial infarction or chronic ischemia and heart failure following percutaneous or surgical revascularization, respectively. However, the effect of the treatment has not been systematic evaluated in patients who are not eligible for revascularization. Methods MEDLINE (1950–2012), EMBASE (1980–2012), CENTRAL (The Cochrane Library 2012, Issue 8) and ongoing trial databases were searched for relevant randomized controlled trials. Trials where participants were diagnosed with IHD, with no option for revascularization and who received any dose of stem cells by any delivery route were selected for inclusion. Study and participant characteristics, details of the intervention and comparator, and outcomes measured were recorded by two reviewers independently. Primary outcome measures were defined as mortality and measures of angina; secondary outcomes were heart failure, quality of life measures, exercise/performance and left ventricular ejection fraction (LVEF). Results Nine trials were eligible for inclusion. BMSC treatment significantly reduced the risk of mortality (Relative Risk 0.33; 95% Confidence Interval 0.17 to 0.65; P = 0.001). Patients who received BMSC showed a significantly greater improvement in CCS angina class (Mean Difference −0.55; 95% Confidence Interval −1.00 to −0.10; P = 0.02) and significantly fewer angina episodes per week at the end of the trial (Mean Difference −5.21; 95% Confidence Interval −7.35 to −3.07; P<0.00001) than those who received no BMSC. In addition, the treatment significantly improved quality of life, exercise/performance and LVEF in these patients. Conclusions BMSC treatment has significant clinical benefit as stand-alone treatment in patients with IHD and no other treatment option. These results require confirmation in large well-powered trials with long-term follow-up to fully evaluate the clinical efficacy of this treatment.