Improvement in prognosis of dilated cardiomyopathy in the elderly over the past 20 years

The Aging Heart: A Molecular and Clinical Challenge

Aging is associated with an increasing burden of morbidity, especially for cardiovascular diseases (CVDs). General cardiovascular risk factors, ischemic heart diseases, heart failure, arrhythmias, and cardiomyopathies present a significant prevalence in older people, and are characterized by peculiar clinical manifestations that have distinct features compared with the same conditions in a younger population. Remarkably, the aging heart phenotype in both healthy individuals and patients with CVD reflects modifications at the cellular level. An improvement in the knowledge of the physiological and pathological molecular mechanisms underlying cardiac aging could improve clinical management of older patients and offer new therapeutic targets.

Biosensor-based profiling to track cellular signalling in patient-derived models of dilated cardiomyopathy

Dilated cardiomyopathies (DCM) represent a diverse group of cardiovascular diseases impacting the structure and function of the myocardium. To better treat these diseases, we need to understand the impact of such cardiomyopathies on critical signalling pathways that drive disease progression downstream of receptors we often target therapeutically. Our understanding of cellular signalling events has progressed substantially in the last few years, in large part due to the design, validation and use of biosensor-based approaches to studying such events in cells, tissues and in some cases, living animals. Another transformative development has been the use of human induced pluripotent stem cells (hiPSCs) to generate disease-relevant models from individual patients. We highlight the importance of going beyond monocellular cultures to incorporate the influence of paracrine signalling mediators. Finally, we discuss the recent coalition of these approaches in the context of DCM. We discuss recent work in generating patient-derived models of cardiomyopathies and the utility of using signalling biosensors to track disease progression and test potential therapeutic strategies that can be later used to inform treatment options in patients.

Sex Differences, Genetic and Environmental Influences on Dilated Cardiomyopathy

Dilated cardiomyopathy (DCM) is characterized by dilatation of the left ventricle and impaired systolic function and is the second most common cause of heart failure after coronary heart disease. The etiology of DCM is diverse including genetic pathogenic variants, infection, inflammation, autoimmune diseases, exposure to chemicals/toxins as well as endocrine and neuromuscular causes. DCM is inherited in 20–50% of cases where more than 30 genes have been implicated in the development of DCM with pathogenic variants in TTN (Titin) most frequently associated with disease. Even though male sex is a risk factor for heart failure, few studies have examined sex differences in the pathogenesis of DCM. We searched the literature for studies examining idiopathic or familial/genetic DCM that reported data by sex in order to determine the sex ratio of disease. We found 31 studies that reported data by sex for non-genetic DCM with an average overall sex ratio of 2.5:1 male to female and 7 studies for familial/genetic DCM with an overall average sex ratio of 1.7:1 male to female. No manuscripts that we found had more females than males in their studies. We describe basic and clinical research findings that may explain the increase in DCM in males over females based on sex differences in basic physiology and the immune and fibrotic response to damage caused by mutations, infections, chemotherapy agents and autoimmune responses.

Dilated cardiomyopathy

Dilated cardiomyopathy (DCM) is a clinical diagnosis characterized by left ventricular or biventricular dilation and impaired contraction that is not explained by abnormal loading conditions (for example, hypertension and valvular heart disease) or coronary artery disease. Mutations in several genes can cause DCM, including genes encoding structural components of the sarcomere and desmosome. Nongenetic forms of DCM can result from different aetiologies, including inflammation of the myocardium due to an infection (mostly viral); exposure to drugs, toxins or allergens; and systemic endocrine or autoimmune diseases. The heterogeneous aetiology and clinical presentation of DCM make a correct and timely diagnosis challenging. Echocardiography and other imaging techniques are required to assess ventricular dysfunction and adverse myocardial remodelling, and immunological and histological analyses of an endomyocardial biopsy sample are indicated when inflammation or infection is suspected. As DCM eventually leads to impaired contractility, standard approaches to prevent or treat heart failure are the first-line treatment for patients with DCM. Cardiac resynchronization therapy and implantable cardioverter-defibrillators may be required to prevent life-threatening arrhythmias. In addition, identifying the probable cause of DCM helps tailor specific therapies to improve prognosis. An improved aetiology-driven personalized approach to clinical care will benefit patients with DCM, as will new diagnostic tools, such as serum biomarkers, that enable early diagnosis and treatment.

Proteasome dysfunction in cardiomyopathies

The ubiquitin-proteasome system (UPS) plays a critical role in removing unwanted intracellular proteins and is involved in protein quality control, signalling and cell death. Because the heart is subject to continuous metabolic and mechanical stress, the proteasome plays a particularly important role in the heart, and proteasome dysfunction has been suggested as a causative factor in cardiac dysfunction. Proteasome impairment has been detected in cardiomyopathies, heart failure, myocardial ischaemia, and hypertrophy. Proteasome inhibition is also sufficient to cause cardiac dysfunction in healthy pigs, and patients using a proteasome inhibitor for cancer therapy have a higher incidence of heart failure. In this Topical Review we discuss the experimental data which suggest UPS dysfunction is a common feature of cardiomyopathies, with an emphasis on hypertrophic cardiomyopathy caused by sarcomeric mutations. We also propose potential mechanisms by which cardiomyopathy-causing mutations may lead to proteasome impairment, such as altered calcium handling and increased oxidative stress due to mitochondrial dysfunction.

A systematic review of randomised controlled trials examining the therapeutic effects of adult bone marrow-derived stem cells for non-ischaemic dilated cardiomyopathy

BACKGROUND

Certain early-phase clinical trials have suggested that bone marrow-derived stem cell transplantation might improve left ventricular function in patients with non-ischaemic dilated cardiomyopathy (NIDCM), whereas others trials have revealed no benefit from this approach. We sought to evaluate the therapeutic effects of bone marrow-derived stem cell therapy on NIDCM.

METHODS

We searched the PubMed, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases (through February 2016) for randomised controlled clinical trials that reported on bone marrow-derived stem cell transplantation for patients with NIDCM with a follow-up period ≥12 months. The co-primary endpoints were changes in mortality rate and left ventricular ejection fraction (LVEF); the secondary endpoints were changes in the 6-minute-walk test (6MWT) and left ventricular chamber size. Seven trials involving bone marrow-derived stem cell therapy that included 482 patients satisfied the inclusion and exclusion criteria.

RESULTS

Subjects who received bone marrow-derived stem cell therapy exhibited a significant reduction in mortality rate (19.7% in the cell group vs. 27.1% in the control group; 95% confidence interval (CI) -0.16 to -0.00, I 2 = 52%, p = 0.04). Bone marrow-derived stem cell therapy tended to produce LVEF improvement within 6 months (1.83% increase; 95% CI -0.27 to 3.94, I 2 = 74%, p = 0.09) and significantly improved LVEF after mid-term (6-12 months) follow-up (3.53% increase; 95% CI 0.76 to 6.29, I 2 = 88%, p = 0.01). However, this therapy produced no significant benefit in the 6MWT (p = 0.18). Finally, the transplantation of increased numbers of stem cells resulted in no observable additional benefit with respect to LVEF.

CONCLUSIONS

Bone marrow-derived stem cell therapy might have improved prognoses and appeared to provide moderate benefits in cardiac systolic function at mid-term follow-up. However, this therapy produced no observed improvement in exercise tolerance.

Direct intramyocardial transthoracic transplantation of bone marrow mononuclear cells for non-ischemic dilated cardiomyopathy: INTRACELL, a prospective randomized controlled trial

Objective

We tested the hypothesis that direct intramyocardial injection of bone marrow mononuclear cells in patients with non-ischemic dilated cardiomyopathy can improve left ventricular function and physical capacity.

Methods

Thirty non-ischemic dilated cardiomyopathy patients with left ventricular ejection fraction <35% were randomized at a 1:2 ratio into two groups, control and treated. The bone marrow mononuclear cells group received 1.06±108 bone marrow mononuclear cells through mini-thoracotomy. There was no intervention in the control group. Assessment was carried out through clinical evaluations as well as a 6-min walk test, nuclear magnectic resonance imaging and echocardiogram.

Results

The bone marrow mononuclear cells group showed a trend toward left ventricular ejection fraction improvement, with magnectic resonance imaging - at 3 months, showing an increase from 27.80±6.86% to 30.13±9.06% (P=0.08) and returning to baseline at 9 months (28.78%, P=0.77). Magnectic resonance imaging showed no changes in left ventricular ejection fraction during follow-up of the control group (28.00±4.32%, 27.42±7.41%, and 29.57±4.50%). Echocardiogram showed left ventricular ejection fraction improved in the bone marrow mononuclear cells group at 3 months, 25.09±3.98 to 30.94±9.16 (P=0.01), and one year, 30.07±7.25% (P=0.001). The control group showed no change (26.1±4.4 vs 26.5±4.7 and 30.2±7.39%, P=0.25 and 0.10, respectively). Bone marrow mononuclear cells group showed improvement in New York Heart Association functional class, from 3.40±0.50 to 2.41±0.79 (P=0.002); patients in the control group showed no change (3.37±0.51 to 2.71±0.95; P=0.17). Six-minute walk test improved in the bone marrow mononuclear cells group (348.00±93.51m at baseline to 370.41±91.56m at 12 months, P=0.66) and there was a non-significant decline in the control group (361.25±90.78m to 330.00±123.42m after 12 months, P=0.66). Group comparisons were non-significant.

Conclusion

The trend of intragroup functional and subjective improvement was not confirmed when compared to the control group. Direct intramyocardial application of bone marrow mononuclear cells in non-ischemic dilated cardiomyopathy was not associated with significant changes in left ventricular function. Differences observed within the bone marrow mononuclear cells group could be due to placebo effect or low statistical power.

Prediction of left ventricular reverse remodeling after therapy with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers and β blockers in patients with idiopathic dilated cardiomyopathy

Background

Predictors of left ventricular reverse remodeling (LVRR) after therapy with angiotensin converting enzyme inhibitors or angiotensin-receptor blockers and β blockers in patients with idiopathic dilated cardiomyopathy (IDC) remains unclear.

Methods

We studied 44 patients with IDC who had been treated with the therapy. LVRR was defined as LV end-diastolic dimension ≤ 55 mm and fractional shortening ≥ 25% at the last echocardiogram.

Results

During a mean follow-up period of 4.7 ± 3.3 years, LVRR occurred in 34% (15/44) of the patients. We divided the patients into 2 groups: (1) patients with LVRR (n = 15); (2) patients without LVRR (n = 29). The presence of atrial fibrillation was 40% in patients with LVRR and 14% in those without (p = 0.067). Initial LV end-diastolic dimension was significantly smaller (62 ± 6 vs. 67 ± 6 mm, p = 0.033) in patients with LVRR than in those without. Initial LV end-diastolic dimension of 63.5 mm was an optimal cutoff value for predicting LVRR (sensitivity: 67%, specificity: 59%, area under the curve: 0.70, p = 0.030). When patients were further allocated according to initial LV end-diastolic dimension ≤ 63.5 mm with atrial fibrillation, the combined parameter was a significant predictor of LVRR by univariate logistic regression analysis (odds ratio, 5.78, p = 0.030) (sensitivity: 33%, specificity: 97%, p = 0.013).

Conclusions

Combined information on LV end-diastolic dimension and heart rhythm at diagnosis is useful in predicting future LVRR in patients with IDC.

Genetic association of IL-21 polymorphisms with dilated cardiomyopathy in a Han Chinese population

BACKGROUND

Autoimmune abnormalities appear to be major predisposing factors for dilated cardiomyopathy (DCM). Interleukin-21 (IL-21) gene polymorphisms have been previously found to be associated with autoimmune diseases. This study aimed to assess the role of IL-21 in DCM in a Han Chinese population.

PATIENTS AND METHODS

A total of 364 independent DCM patients and 384 unrelated healthy controls were recruited for this case-control association study. rs2055979 and rs12508721 were genotyped by PCR-RFLP. IL-21 plasma levels in samples from DCM and control individuals were evaluated by ELISA. The association between the SNPs and overall survival (OS) was evaluated by Kaplan-Meier analysis. Hazard ratios and 95 % confidence intervals (CIs) were assessed in a Cox regression analysis with adjustment for sex and age.

RESULTS

The T allele frequencies of both SNPs were higher in DCM patients than in controls (p < 0.001). The genotypic frequencies of rs2055979 G > T and rs12508721 C > T were associated with DCM in the codominant, dominant, and recessive models (p < 0.05). IL-21 plasma levels in patients were higher than those of the control subjects (p = 0.009). The TT genotypes of both SNPs were associated with significantly higher plasma levels (prs2055979 = 0.03, prs12508721 < 0.001). Kaplan-Meier analysis showed that the genotypic frequencies of both SNPs were associated with OS in the dominant and the recessive models (p < 0.001). The TT genotypes of both SNPs were associated with the worst OS (p < 0.001).

CONCLUSION

Our findings suggest that theIL-21 gene plays an important role in susceptibility to DCM as well as in the clinical outcome of this ailment in the Han Chinese population.

Effect of left ventricular reverse remodeling on long-term prognosis after therapy with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers and β blockers in patients with idiopathic dilated cardiomyopathy

It remains unknown whether left ventricular (LV) reverse remodeling (LVRR) after therapy with angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers and β blockers is correlated with prognosis in patients with idiopathic dilated cardiomyopathy. Forty-two patients with idiopathic dilated cardiomyopathy treated with the therapy were studied. Complete left ventricular reverse remodeling was defined as LV end-diastolic dimension ≤ 55 mm and fractional shortening ≥ 25% at the last echocardiographic assessment. The incidence of complete LVRR was significantly higher in patients who survived than in those who died or underwent heart transplantation. Patients were divided into 3 groups: death or transplantation, alive with complete LVRR, and alive without complete LVRR. Although patients who died or underwent transplantation did not show any LV improvements, those with complete LVRR showed significant improvements at 1 to 6 months after starting the therapy. Patients without complete LVRR also showed small but significant improvements at 1 to 6 months. The decrease in LV end-systolic dimension from the initial value to that at 1 to 6 months was an independent determinant of future cardiac death or transplantation. In conclusion, complete LVRR is related to favorable prognosis in patients with idiopathic dilated cardiomyopathy. The extent of left ventricular reverse remodeling at 1 to 6 months after starting the therapy is predictive of long-term prognosis.