Metabolic Profiling Associates with Disease Severity in Nonischemic Dilated Cardiomyopathy.

BACKGROUND: Metabolomic profiling may have diagnostic and prognostic value in heart failure. This study investigated whether targeted blood and urine metabolomics reflects disease severity in patients with nonischemic dilated cardiomyopathy (DCM) and compared its incremental value on top of N-terminal prohormone of brain natriuretic peptide (NT-proBNP). METHODS AND RESULTS: A total of 149 metabolites were measured in plasma and urine samples of 273 patients with DCM and with varying stages of disease (patients with DCM and normal left ventricular reverse remodeling, n = 70; asymptomatic DCM, n = 72; and symptomatic DCM, n = 131). Acylcarnitines, sialic acid and glutamic acid are the most distinctive metabolites associated with disease severity, as repeatedly revealed by unibiomarker linear regression, sparse partial least squares discriminant analysis, random forest, and conditional random forest analyses. However, the absolute difference in the metabolic profile among groups was marginal. A decision-tree model based on the top metabolites did not surpass NT-proBNP in classifying stages. However, a combination of NT-proBNP and the top metabolites improved the decision tree to distinguish patients with DCM and left ventricular reverse remodeling from symptomatic DCM (area under the curve 0.813 ± 0.138 vs 0.739 ± 0.114; P = 0.02). CONCLUSION: Functional cardiac recovery is reflected in metabolomics. These alterations reveal potential alternative treatment targets in advanced symptomatic DCM. The metabolic profile can complement NT-proBNP in determining disease severity in nonischemic DCM.

Balance of Active, Passive, and Anatomical Cardiac Properties in Doxorubicin-Induced Heart Failure.

Late-onset heart failure (HF) is a known side effect of doxorubicin chemotherapy. Typically, patients are diagnosed when already at an irreversible stage of HF, which allows few or no treatment options. Identifying the causes of compromised cardiac function in this patient group may improve early patient diagnosis and support treatment selection. To link doxorubicin-induced changes in cardiac cellular and tissue mechanical properties to overall cardiac function, we apply a multiscale biophysical biomechanics model of the heart to measure the plausibility of changes in model parameters representing the passive, active, or anatomical properties of the left ventricle for reproducing measured patient phenotypes. We create representative models of healthy controls (N = 10) and patients with HF induced by (N = 22) or unrelated to (N = 25) doxorubicin therapy. The model predicts that HF in the absence of doxorubicin is characterized by a 2- to 3-fold stiffness increase, decreased tension (0-20%), and ventricular dilation (of order 10-30%). HF due to doxorubicin was similar but showed stronger bias toward reduced active contraction (10-30%) and less dilation (0-20%). We find that changes in active, passive, and anatomical properties all play a role in doxorubicin-induced cardiotoxicity phenotypes. Differences in parameter changes between patient groups are consistent with doxorubicin cardiotoxicity having a greater dependence on reduced cellular contraction and less anatomical remodeling than HF not caused by doxorubicin.

Titin cardiomyopathy leads to altered mitochondrial energetics, increased fibrosis and long-term life-threatening arrhythmias.

Aims: Truncating titin variants (TTNtv) are the most prevalent genetic cause of dilated cardiomyopathy (DCM). We aim to study clinical parameters and long-term outcomes related to the TTNtv genotype and determine the related molecular changes at tissue level in TTNtv DCM patients. Methods and results: A total of 303 consecutive and extensively phenotyped DCM patients (including cardiac imaging, Holter monitoring, and endomyocardial biopsy) underwent DNA sequencing of 47 cardiomyopathy-associated genes including TTN, yielding 38 TTNtv positive (13%) patients. At long-term follow-up (median of 45 months, up to 12 years), TTNtv DCM patients had increased ventricular arrhythmias compared to other DCM, but a similar survival. Arrhythmias are especially prominent in TTNtv patients with an additional environmental trigger (i.e. virus infection, cardiac inflammation, systemic disease, toxic exposure). Importantly, cardiac mass is reduced in TTNtv patients, despite similar cardiac function and dimensions at cardiac magnetic resonance. These enhanced life-threatening arrhythmias and decreased cardiac mass in TTNtv DCM patients go along with significant cardiac energetic and matrix alterations. All components of the mitochondrial electron transport chain are significantly upregulated in TTNtv hearts at RNA-sequencing. Also, interstitial fibrosis was augmented in TTNtv patients at histological and transcript level. Conclusion: Truncating titin variants lead to pronounced cardiac alterations in mitochondrial function, with increased interstitial fibrosis and reduced hypertrophy. Those structural and metabolic alterations in TTNtv hearts go along with increased ventricular arrhythmias at long-term follow-up, with a similar survival and overall cardiac function.

Intravenous immunoglobulin therapy in adult patients with idiopathic chronic cardiomyopathy and cardiac parvovirus B19 persistence: a prospective, double-blind, randomized, placebo-controlled clinical trial.

AIMS: Previous uncontrolled studies suggested a possible benefit of intravenous immunoglobulin (IVIg) in parvovirus B19 (B19V)-related dilated cardiomyopathy (DCM). This randomized, double-blind, placebo-controlled, single-centre trial investigated the benefits of IVIg beyond conventional therapy in idiopathic chronic DCM patients with B19V persistence. METHODS AND RESULTS: Fifty patients (39 men; mean age 54 ± 11 years) with idiopathic chronic (>6 months) DCM on optimal medical therapy, left ventricular ejection fraction (LVEF) <45%, and endomyocardial biopsy (EMB) B19V load of >200 copies/µg DNA were blindly randomized to either IVIg (n = 26, 2 g/kg over 4 days) or placebo (n = 24). The primary outcome was change in LVEF at 6 months after randomization. Secondary outcomes were change in functional capacity assessed by 6-min walk test (6MWT), quality of life [Minnesota Living with Heart Failure Questionnaire (MLHFQ)], left ventricular end-diastolic volume (LVEDV), and EMB B19V load at 6 months after randomization. LVEF significantly improved in both IVIg and placebo groups (absolute mean increase 5 ± 9%, P = 0.011 and 6 ± 10%, P = 0.008, respectively), without a significant difference between groups (P = 0.609). Additionally, change in 6MWT [median (interquartile range) IVIg 36 (13;82) vs. placebo 32 (5;80) m; P = 0.573], MLHFQ [IVIg 0 (-7;5) vs. placebo -2 (-6;6), P = 0.904] and LVEDV (IVIg -16 ± 49 mL/m2 vs. placebo -29 ± 40 mL/m2 ; P = 0.334) did not significantly differ between groups. Moreover, despite increased circulating B19V antibodies upon IVIg administration, reduction in cardiac B19V did not significantly differ between groups. CONCLUSION: Intravenous immunoglobulin therapy does not significantly improve cardiac systolic function or functional capacity beyond standard medical therapy in patients with idiopathic chronic DCM and cardiac B19V persistence. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov ID NCT00892112.

Implications of Genetic Testing in Dilated Cardiomyopathy.

BACKGROUND: Genetic analysis is a first-tier test in dilated cardiomyopathy (DCM). Electrical phenotypes are common in genetic DCM, but their exact contribution to the clinical course and outcome is unknown. We determined the prevalence of pathogenic gene variants in a large unselected DCM population and determined the role of electrical phenotypes in association with outcome. METHODS: This study included 689 patients with DCM from the Maastricht Cardiomyopathy Registry, undergoing genetic evaluation using a 48 cardiomyopathy-associated gene-panel, echocardiography, endomyocardial biopsies, and Holter monitoring. Upon detection of a pathogenic variant in a patient with DCM, familial segregation was performed. Outcome was defined as cardiovascular death, heart transplantation, heart failure hospitalization, and/or occurrence of life-threatening arrhythmias. RESULTS: A (likely) pathogenic gene variant was found in 19% of patients, varying from 36% in familial to 13% in nonfamilial DCM. Family segregation analysis showed familial disease in 46% of patients with DCM who were initially deemed nonfamilial by history. Overall, 18% of patients with a nongenetic risk factor had a pathogenic gene variant. Almost all pathogenic gene variants occurred in just 12 genes previously shown to have robust disease association with DCM. Genetic DCM was independently associated with electrical phenotypes such as atrial fibrillation, nonsustained ventricular tachycardia, and atrioventricular block and inversely correlated with the presence of a left bundle branch block (P<0.01). After a median follow-up of 4 years, event-free survival was reduced in genetic versus patients with nongenetic DCM (P=0.01). This effect on outcome was mediated by the associated electrical phenotypes of genetic DCM (P<0.001). CONCLUSIONS: One in 5 patients with an established nongenetic risk factor or a nonfamilial disease still carries a pathogenic gene variant. Genetic DCM is characterized by a profile of electrical phenotypes (atrial fibrillation, nonsustained ventricular tachycardia, and atrioventricular block), which carries increased risk for adverse outcomes. Based on these findings, we envisage a broader role for genetic testing in DCM.

Value of Speckle Tracking-Based Deformation Analysis in Screening Relatives of Patients With Asymptomatic Dilated Cardiomyopathy.

OBJECTIVES: This study sought to investigate the prevalence of systolic dysfunction using global longitudinal strain (GLS) and its prognostic value in relatives of dilated cardiomyopathy (DCM) patients that had normal left ventricular ejection fraction (LVEF). BACKGROUND: DCM relatives are advised to undergo cardiac assessment including echocardiography, irrespective of the genetic status of the index patient. Even though LVEF is normal, the question remains whether this indicates absence of disease or simply normal cardiac volumes. GLS may provide additional information regarding (sub)clinical cardiac abnormalities and thus allow earlier disease detection. METHODS: A total of 251 DCM relatives and 251 control subjects with a normal LVEF (≥55%) were screened. Automated software measured the GLS on echocardiographic 2-, 3-, and 4-chamber views. The cutoff value for abnormal strain was >-21.5. Median follow-up was 40 months (interquartile range: 5 to 80 months). Primary outcome was the combination of death and cardiac hospitalization. RESULTS: A total of 120 relatives and 83 control subjects showed abnormal GLS (48% vs. 33%, respectively; p < 0.001). Abnormal GLS was independently associated with DCM relatives and cardiovascular risk factors, rather than genetic mutations. Subjects with abnormal GLS had more frequent cardiac hospitalizations and a higher mortality as compared with subjects with normal GLS (hazard ratio: 3.29; 95% confidence interval: 1.58 to 6.87; p = 0.001). Additionally, follow-up LVEF was measured in a subset of relatives, and it decreased significantly in those with abnormal as compared with normal GLS (p = 0.006). CONCLUSIONS: Relatives of DCM patients had a significantly higher prevalence of systolic dysfunction detected by GLS despite normal LVEF compared with control subjects, independent of age, sex, comorbidities, and genotype. Abnormal GLS was associated with LVEF deterioration, cardiac hospitalization, and death.

Cardiac Inflammation Impedes Response to Cardiac Resynchronization Therapy in Patients With Idiopathic Dilated Cardiomyopathy.

BACKGROUND: Cardiac resynchronization therapy (CRT) is an established therapy in patients with dilated cardiomyopathy (DCM) and conduction disorders. Still, one-third of the patients with DCM do not respond to CRT. This study aims to depict the underlying cardiac pathophysiological processes of nonresponse to CRT in patients with DCM using endomyocardial biopsies. METHODS: Within the Maastricht and Innsbruck registries of patients with DCM, 99 patients underwent endomyocardial biopsies before CRT implantation, with histological quantification of fibrosis and inflammation, where inflammation was defined as >14 infiltrating cells/mm2. Echocardiographic left ventricular end-systolic volume reduction ≥15% after 6 months was defined as response to CRT. RNA was isolated from cardiac biopsies of a representative subset of responders and nonresponders. RESULTS: Sixty-seven patients responded (68%), whereas 32 (32%) did not respond to CRT. Cardiac inflammation before implantation was negatively associated with response to CRT (25% of responders, 47% of nonresponders; odds ratio 0.3 [0.12-0.76]; P=0.01). Endomyocardial biopsies fibrosis did not relate to CRT response. Cardiac inflammation improved the robustness of prediction beyond well-known clinical predictors of CRT response (likelihood ratio test P<0.001). Cardiac transcriptomic profiling of endomyocardial biopsies reveals a strong proinflammatory and profibrotic signature in the hearts of nonresponders compared with responders. In particular, COL1A1, COL1A2, COL3A1, COL5A1, POSTN, CTGF, LOX, TGFß1, PDGFRA, TNC, BGN, and TSP2 were significantly higher expressed in the hearts of nonresponders. CONCLUSIONS: Cardiac inflammation along with a transcriptomic profile of high expression of combined proinflammatory and profibrotic genes are associated with a poor response to CRT in patients with DCM.

Clinical Phenotype and Genotype Associations With Improvement in Left Ventricular Function in Dilated Cardiomyopathy.

BACKGROUND: Improvement of left ventricular function (also called left ventricular reverse remodeling [LVRR]) is an important treatment goal in patients with dilated cardiomyopathy (DCM) and hypokinetic non-DCM (HNDC) and is prognostically favorable. We tested whether genetic DCM mutations impact LVRR independent from clinical parameters. METHODS AND RESULTS: Patients with DCM and hypokinetic non-DCM (n=346; mean left ventricular ejection fraction, 30%) underwent genotyping for 47 DCM-associated genes in addition to extensive phenotyping. LVRR was defined as improvement of left ventricular ejection fraction >50% or ≥10% absolute increase, with cardiac dimensions (left ventricular end diastolic diameter) ≤33 mm/m2 or ≥10% relative decrease. LVRR occurred in 180 (52%) patients after a median follow-up of 12-month optimal medical treatment. Low baseline left ventricular ejection fraction, a hypokinetic non-DCM phenotype, high systolic blood pressure, absence of a family history of DCM, female sex, absence of atrioventricular block, and treatment with ß-blockers were all independent positive clinical predictors of LVRR. With the exception of TTN, genetic mutations were strongly associated with a lower rate of LVRR (odds ratio, 0.19 [0.09-0.42]; P<0.0001). TTN and LMNA were independently associated with LVRR (odds ratio, 2.49 [1.09-6.20]; P=0.038 and 0.11 [0.01-0.99]; P=0.049, respectively). Adding mutation status significantly improved discrimination (C statistics) and reclassification (integrated discrimination improvement/net reclassification index) of the clinical model predicting LVRR. Furthermore, the risk for heart failure hospitalization and cardiovascular death is lower in the LVRR patients on the long term (hazard ratio, 0.47 [0.24-0.91]; P=0.009 and 0.18 [0.04-0.82]; P=0.007, respectively), and LVRR is an independent predictor for event-free survival. CONCLUSIONS: The genetic substrate is associated with the clinical course and long-term prognosis of patients with DCM/hypokinetic non-DCM.

Prognostic Relevance of Gene-Environment Interactions in Patients With Dilated Cardiomyopathy: Applying the MOGE(S) Classification.

BACKGROUND: The multifactorial pathogenesis leading to dilated cardiomyopathy (DCM) makes stratification difficult. The recent MOGE(S) (morphofunctional, organ involvement, genetic or familial, etiology, stage) classification addresses this issue. OBJECTIVES: The purpose of this study was to investigate the applicability and prognostic relevance of the MOGE(S) classification in patients with DCM. METHODS: This study used patients from the Maastricht Cardiomyopathy Registry in the Netherlands and excluded patients with ischemic, valvular, hypertensive, and congenital heart disease. All other patients underwent a complete diagnostic work-up, including genetic evaluation and endomyocardial biopsy. RESULTS: A total of 213 consecutive patients with DCM were included: organ involvement was demonstrated in 35 (16%) and genetic or familial DCM in 70 (33%) patients, including 16 (8%) patients with a pathogenic mutation. At least 1 cause was found in 155 (73%) patients, of whom 48 (23%) had more than 1 possible cause. Left ventricular reverse remodeling was more common in patients with nongenetic or nonfamilial DCM than in patients with genetic or familial DCM (40% vs. 25%; p = 0.04). After a median follow-up of 47 months, organ involvement and higher New York Heart Association functional class were associated with adverse outcome (p < 0.001 and p = 0.02, respectively). Genetic or familial DCM per se was of no prognostic significance, but when it was accompanied by additional etiologic-environmental factors such as significant viral load, immune-mediated factors, rhythm disturbances, or toxic triggers, a worse outcome was revealed (p = 0.03). A higher presence of MOGE(S) attributes (≥2 vs. ≤1 attributes) showed an adverse outcome (p = 0.007). CONCLUSIONS: The MOGE(S) classification in DCM is applicable, and each attribute or the gene-environment interaction is associated with outcome. Importantly, the presence of multiple attributes was a strong predictor of adverse outcome. Finally, adaptation of the MOGE(S) involving multiple possible etiologies is recommended.

Ureter smooth muscle cell orientation in rat is predominantly longitudinal.

In ureter peristalsis, the orientation of the contracting smooth muscle cells is essential, yet current descriptions of orientation and composition of the smooth muscle layer in human as well as in rat ureter are inconsistent. The present study aims to improve quantification of smooth muscle orientation in rat ureters as a basis for mechanistic understanding of peristalsis. A crucial step in our approach is to use two-photon laser scanning microscopy and image analysis providing objective, quantitative data on smooth muscle cell orientation in intact ureters, avoiding the usual sectioning artifacts. In 36 rat ureter segments, originating from a proximal, middle or distal site and from a left or right ureter, we found close to the adventitia a well-defined longitudinal smooth muscle orientation. Towards the lamina propria, the orientation gradually became slightly more disperse, yet the main orientation remained longitudinal. We conclude that smooth muscle cell orientation in rat ureter is predominantly longitudinal, though the orientation gradually becomes more disperse towards the proprial side. These findings do not support identification of separate layers. The observed longitudinal orientation suggests that smooth muscle contraction would rather cause local shortening of the ureter, than cause luminal constriction. However, the net-like connective tissue of the ureter wall may translate local longitudinal shortening into co-local luminal constriction, facilitating peristalsis. Our quantitative, minimally invasive approach is a crucial step towards more mechanistic insight into ureter peristalsis, and may also be used to study smooth muscle cell orientation in other tube-like structures like gut and blood vessels.