fumarates and Cardiomyopathy--Dilated

Succinate dehydrogenase, which is known as mitochondrial complex II, has proven to be a fascinating machinery, attracting renewed and increased interest in its involvement in human diseases. Herein, we find that succinate dehydrogenase assembly factor 4 (SDHAF4) is downregulated in cardiac muscle in response to pathological stresses and in diseased hearts from human patients. Cardiac loss of Sdhaf4 suppresses complex II assembly and results in subunit degradation and complex II deficiency in fetal mice. These defects are exacerbated in young adults with globally impaired metabolic capacity and activation of dynamin-related protein 1, which induces excess mitochondrial fission and mitophagy, thereby causing progressive dilated cardiomyopathy and lethal heart failure in animals. Targeting mitochondria via supplementation with fumarate or inhibiting mitochondrial fission improves mitochondrial dynamics, partially restores cardiac function and prolongs the lifespan of mutant mice. Moreover, the addition of fumarate is found to dramatically improve cardiac function in myocardial infarction mice. These findings reveal a vital role for complex II assembly in the development of dilated cardiomyopathy and provide additional insights into therapeutic interventions for heart diseases.

Topics: Animals; Cardiomyopathy, Dilated; Fumarates; Mice; Mitochondrial Dynamics; Mitophagy; Myocytes, Cardiac; Succinate Dehydrogenase

We report a case of acute kidney injury (AKI) caused by a novel direct renin inhibitor, aliskiren. A 43-year-old Japanese man with dilated cardiomyopathy on cardiac resynchronization therapy with defibrillator and chronic kidney disease (CKD) was started on aliskiren in addition to enalapril, carvedilol, furosemide, and spironolactone for worsening cardiac function suggested by the elevation of serum brain natriuretic peptide. After 1 month, he noticed general malaise, loss of appetite and his serum creatinine level increased from 2.0 to 7.24 mg/dL. He had no evidence of exacerbation of hemodynamic instability (heart failure or hypotension) or post-renal cause of AKI. Although a cessation of aliskiren did not ameliorate AKI, renal function returned to baseline after withholding enalapril. Careful monitoring is necessary when aliskiren is used in patients with CKD and/or significant systolic dysfunction since it can cause normotensive ischemic AKI, especially when there is a concomitant use of other renin-angiotensin-aldosterone system inhibitors.

Topics: Acute Kidney Injury; Adult; Amides; Antihypertensive Agents; Cardiomyopathy, Dilated; Fumarates; Humans; Kidney Failure, Chronic; Male; Natriuretic Peptide, Brain

Chronic activation of the renin-angiotensin-aldosterone system is a major contributing factor to the pathogenesis and progression of cardiovascular and renal diseases.. To evaluate the role of renin-angiotensin-aldosterone system blockade with aliskiren, a direct renin inhibitor, in the development and progression of dilated cardiomyopathy in the Syrian cardiomyopathic hamster (SCH) model, we treated 1-month-old SCH with aliskiren (10 mg·kg·d) over a 4-month period. For comparative purposes, we also evaluated the effects of the angiotensin receptor blocker valsartan (10 mg·kg·d) and the combination of both drugs. Age-matched golden hamsters were used as controls. Left ventricular end-diastolic volume and end-systolic volume, ejection fraction, and diastolic function were determined by echocardiography. Systolic blood pressure (SBP) was also measured in the left femoral artery by sphygmomanometry.. Results indicate that at 2 months of age, SBP is higher in SCH than in controls, and administration for 1 month of aliskiren, valsartan, or the combination of these drugs normalized SBP in SCH to a similar extent. In 5-month-old SCH, aliskiren improved ejection fraction (from 48.6% ± 5.8% to 69.4% ± 3.2%, n = 5, P < 0.05), left ventricular end-systolic volume (from 0.28 ± 0.06 to 0.10 ± 0.01 mL/100 g body weight), left ventricular end-diastolic volume (from 0.61 ± 0.05 to 0.34 ± 0.02 mL/100 g body weight), and normalized diastolic function (E:A ratio increases from 0.93 ± 0.13 to 1.70 ± 0.03, n = 5, P < 0.05). Similar results were observed with valsartan or the combination of aliskiren and valsartan.. Our results indicate that in this animal model, aliskiren is as effective as valsartan, or the combination of both drugs, in improving diastolic function and in preventing the development of dilated cardiomyopathy. These findings suggest that aliskiren may be used as a monotherapy in heart failure management. Clinical studies, however, are needed to assess the effectiveness of this drug in patients with heart failure.

Topics: Amides; Angiotensin II Type 1 Receptor Blockers; Animals; Blood Pressure; Cardiomyopathy, Dilated; Cricetinae; Disease Models, Animal; Disease Progression; Drug Therapy, Combination; Fumarates; Male; Renin; Renin-Angiotensin System; Tetrazoles; Valine; Valsartan; Ventricular Dysfunction, Left

Seven boys with an apparently X-linked syndrome of dilated cardiomyopathy, growth retardation, neutropenia, and persistently elevated urinary levels of 3-methylglutaconate, 3-methylglutarate, and 2-ethylhydracrylate were studied. The natural history of the disorder was characterized by severe or lethal cardiac disease and recurrent infections during infancy and early childhood but relative improvement in later childhood. The initial presentation of the syndrome varied from congenital dilated cardiomyopathy to infantile congestive heart failure to isolated neutropenia without clinical evidence of heart disease. The excretion of 3-methylglutaconate and 3-methylglutarate appeared to be independent of the metabolism of leucine, the presumed precursor of these organic acids in humans. Although the cause of the organic aciduria remains obscure, the constellation of biochemical and clinical abnormalities forms a distinct syndrome that may be a relatively common cause of dilated cardiomyopathy or neutropenia in boys during infancy and childhood.

Topics: Adult; Cardiomyopathy, Dilated; Child; Child, Preschool; Chromatography, High Pressure Liquid; Fumarates; Glutarates; Growth Disorders; Heart Failure; Humans; Male; Meglutol; Muscular Diseases; Neutropenia; Pedigree; Syndrome; X Chromosome