An Alternative Mechanism of Subcellular Iron Uptake Deficiency in Cardiomyocytes.

BACKGROUND: Systemic defects in intestinal iron absorption, circulation, and retention cause iron deficiency in 50% of patients with heart failure. Defective subcellular iron uptake mechanisms that are independent of systemic absorption are incompletely understood. The main intracellular route for iron uptake in cardiomyocytes is clathrin-mediated endocytosis. METHODS: We investigated subcellular iron uptake mechanisms in patient-derived and CRISPR/Cas-edited induced pluripotent stem cell-derived cardiomyocytes as well as patient-derived heart tissue. We used an integrated platform of DIA-MA (mass spectrometry data-independent acquisition)-based proteomics and signaling pathway interrogation. We employed a genetic induced pluripotent stem cell model of 2 inherited mutations (TnT [troponin T]-R141W and TPM1 [tropomyosin 1]-L185F) that lead to dilated cardiomyopathy (DCM), a frequent cause of heart failure, to study the underlying molecular dysfunctions of DCM mutations. RESULTS: We identified a druggable molecular pathomechanism of impaired subcellular iron deficiency that is independent of systemic iron metabolism. Clathrin-mediated endocytosis defects as well as impaired endosome distribution and cargo transfer were identified as a basis for subcellular iron deficiency in DCM-induced pluripotent stem cell-derived cardiomyocytes. The clathrin-mediated endocytosis defects were also confirmed in the hearts of patients with DCM with end-stage heart failure. Correction of the TPM1-L185F mutation in DCM patient-derived induced pluripotent stem cells, treatment with a peptide, Rho activator II, or iron supplementation rescued the molecular disease pathway and recovered contractility. Phenocopying the effects of the TPM1-L185F mutation into WT induced pluripotent stem cell-derived cardiomyocytes could be ameliorated by iron supplementation. CONCLUSIONS: Our findings suggest that impaired endocytosis and cargo transport resulting in subcellular iron deficiency could be a relevant pathomechanism for patients with DCM carrying inherited mutations. Insight into this molecular mechanism may contribute to the development of treatment strategies and risk management in heart failure.

Natural History of MYH7-Related Dilated Cardiomyopathy.

BACKGROUND: Variants in myosin heavy chain 7 (MYH7) are responsible for disease in 1% to 5% of patients with dilated cardiomyopathy (DCM); however, the clinical characteristics and natural history of MYH7-related DCM are poorly described. OBJECTIVES: We sought to determine the phenotype and prognosis of MYH7-related DCM. We also evaluated the influence of variant location on phenotypic expression. METHODS: We studied clinical data from 147 individuals with DCM-causing MYH7 variants (47.6% female; 35.6 ± 19.2 years) recruited from 29 international centers. RESULTS: At initial evaluation, 106 (72.1%) patients had DCM (left ventricular ejection fraction: 34.5% ± 11.7%). Median follow-up was 4.5 years (IQR: 1.7-8.0 years), and 23.7% of carriers who were initially phenotype-negative developed DCM. Phenotypic expression by 40 and 60 years was 46% and 88%, respectively, with 18 patients (16%) first diagnosed at <18 years of age. Thirty-six percent of patients with DCM met imaging criteria for LV noncompaction. During follow-up, 28% showed left ventricular reverse remodeling. Incidence of adverse cardiac events among patients with DCM at 5 years was 11.6%, with 5 (4.6%) deaths caused by end-stage heart failure (ESHF) and 5 patients (4.6%) requiring heart transplantation. The major ventricular arrhythmia rate was low (1.0% and 2.1% at 5 years in patients with DCM and in those with LVEF of ≤35%, respectively). ESHF and major ventricular arrhythmia were significantly lower compared with LMNA-related DCM and similar to DCM caused by TTN truncating variants. CONCLUSIONS: MYH7-related DCM is characterized by early age of onset, high phenotypic expression, low left ventricular reverse remodeling, and frequent progression to ESHF. Heart failure complications predominate over ventricular arrhythmias, which are rare.

Incidence and predictors of worsening heart failure in patients with wild-type transthyretin cardiac amyloidosis.

BACKGROUND: Prognostic markers of survival have been identified in wild-type transthyretin amyloidosis (ATTRwt), but limited data exist with respect to hospitalizations with worsening heart failure (WHF). Predictive markers of WHF have yet to be identified. METHODS: From April 2017 to February 2021, 104 patients with ATTRwt were diagnosed and prospectively followed from the time of diagnosis to the time of death or the censoring date of 1 February 2021. Baseline patient characteristics, biomarkers, and advanced echocardiography were used to predict hospitalization with WHF. RESULTS: During the median follow-up period of 23 months, 51% of patients were hospitalized due to WHF. Seventy-three per cent of patients with WHF were admitted at least twice. Patients with WHF during the first year had significantly poorer survival (P < 0.001). Independent predictors of WHF during follow-up were pacemaker implantation prior to diagnosis (PMI, P = 0.037) and right atrial volume index (RAVi, P = 0.008). Patients with PMI had a higher left ventricular mass index and poorer left ventricular and right ventricular systolic function indicating a more advanced stage of amyloid disease. CONCLUSIONS: A high incidence and recurrence of hospital admissions with WHF were demonstrated in contemporary patients with ATTRwt, which was associated with reduced survival. Patients with pacemaker devices prior to ATTRwt diagnosis experienced more frequent hospitalizations with WHF. PMI and right atrial enlargement were identified as independent predictors of WHF during follow-up.

Carriers of COL3A1 pathogenic variants in Denmark: Interfamilial variability in severity and outcome of elective surgical procedures.

The study describes all patients in Denmark with vascular Ehlers-Danlos syndrome (vEDS). Carriers of pathogenic or likely pathogenic COL3A1 variants were retrospectively identified through registries and specialized clinics. Medical records were reviewed for vascular- or organ ruptures and invasive procedures performed. Identified families were divided by variant type (null, splice, and missense) and familial phenotypes (severe or attenuated). Families in which at least one carrier has suffered a major event before the age of 30 were classified as severe, whereas families in which at least three carriers had reached the age of 40 without a major event were classified as attenuated. Eighty-seven persons (59 still alive) from 25 families were included with a mean observation time of 44 years. Sixty-seven percent of patients could be subclassified in a familial phenotype. Thirty-one major events were observed. Eleven complications in 172 invasive procedures were recorded. No fatal complications to elective surgery were observed. The type of COL3A1 variant did not reliably predict phenotype, but a pattern of intrafamilial consistency emerged with some families showing an attenuated form of vEDS. Elective medical procedures appear to be safer than previously thought, although data only allow for conclusions regarding individuals from families with the attenuated form of vEDS.

Reversible Complete Heart Block in a Pregnant Woman Related to Sertraline Treatment.

Complete heart block (CHB) is a serious condition, usually affecting older patients. We report a case of CHB in a 31-year-old pregnant woman treated with sertraline in whom atrioventricular (AV) conduction normalized after discontinuation of sertraline. Results of subsequent genetic investigations for inherited cardiomyopathy and ion-channel disease and a pharmacogenetic study of sertraline pharmacokinetics were negative. Reversible CHB in this younger pregnant patient was temporally related to sertraline. This case underlines the importance of identifying reversible causes when a young patient presents with AV block with unknown trajectory and prognosis, as well as regular recording of electrocardiograms in pregnant patients on psychotropic medications.

Le bloc cardiaque complet (BCC) est une affection sérieuse, qui touche généralement les patients âgés. Nous présentons un cas de BCC chez une femme enceinte de 31 ans traitée par sertraline chez qui la normalisation de la conduction atrioventriculaire (AV) a été constatée après l'arrêt de la sertraline. Les résultats des examens génétiques subséquents de cardiomyopathie héréditaire et de maladies des canaux ioniques, et d'une étude pharmacogénétique de la pharmacocinétique de la sertraline étaient négatifs. LE BCC réversible chez cette jeune patiente enceinte était temporairement lié à la sertraline. Ce cas montre l'importance de cerner les causes réversibles lorsqu'un jeune patient présente un bloc AV à la trajectoire et au pronostic inconnus, et de faire régulièrement des électrocardiogrammes chez les patientes enceintes qui prennent des psychotropes.

Association of Left Ventricular Systolic Dysfunction Among Carriers of Truncating Variants in Filamin C With Frequent Ventricular Arrhythmia and End-stage Heart Failure.

Importance: Truncating variants in the gene encoding filamin C (FLNCtv) are associated with arrhythmogenic and dilated cardiomyopathies with a reportedly high risk of ventricular arrhythmia. Objective: To determine the frequency of and risk factors associated with adverse events among FLNCtv carriers compared with individuals carrying TTN truncating variants (TTNtv). Design, Setting, and Participants: This cohort study recruited 167 consecutive FLNCtv carriers and a control cohort of 244 patients with TTNtv matched for left ventricular ejection fraction (LVEF) from 19 European cardiomyopathy referral units between 1990 and 2018. Data analyses were conducted between June and October, 2020. Main Outcomes and Measures: The primary end point was a composite of malignant ventricular arrhythmia (MVA) (sudden cardiac death, aborted sudden cardiac death, appropriate implantable cardioverter-defibrillator shock, and sustained ventricular tachycardia) and end-stage heart failure (heart transplant or mortality associated with end-stage heart failure). The secondary end point comprised MVA events only. Results: In total, 167 patients with FLNCtv were studied (55 probands [33%]; 89 men [53%]; mean [SD] age at baseline evaluation, 43 [18] years). For a median follow-up of 20 months (interquartile range, 7-60 months), 29 patients (17.4%) reached the primary end point (19 patients with MVA and 10 patients with end-stage heart failure). Eight (44%) arrhythmic events occurred among individuals with baseline mild to moderate left ventricular systolic dysfunction (LVSD) (LVEF = 36%-49%). Univariable risk factors associated with the primary end point included proband status, LVEF decrement per 10%, ventricular ectopy (≥500 in 24 hours) and myocardial fibrosis detected on cardiac magnetic resonance imaging. The LVEF decrement (hazard ratio [HR] per 10%, 1.83 [95% CI, 1.30-2.57]; P < .001) and proband status (HR, 3.18 [95% CI, 1.12-9.04]; P = .03) remained independent risk factors on multivariable analysis (excluding myocardial fibrosis and ventricular ectopy owing to case censoring). There was no difference in freedom from MVA between FLNCtv carriers with mild to moderate or severe (LVEF ≤35%) LVSD (HR, 1.29 [95% CI, 0.45-3.72]; P = .64). Carriers of FLNCtv with impaired LVEF at baseline evaluation (n = 69) had reduced freedom from MVA compared with 244 TTNtv carriers with similar baseline LVEF (for mild to moderate LVSD: HR, 16.41 [95% CI, 3.45-78.11]; P < .001; for severe LVSD: HR, 2.47 [95% CI, 1.04-5.87]; P = .03). Conclusions and Relevance: The high frequency of MVA among patients with FLNCtv with mild to moderate LVSD suggests that higher LVEF values than those currently recommended should be considered for prophylactic implantable cardioverter-defibrillator therapy in FLNCtv carriers.

Dilated cardiomyopathy caused by truncating titin variants: long-term outcomes, arrhythmias, response to treatment and sex differences.

BACKGROUND: Truncating variants in titin (TTNtv) are the most common cause of dilated cardiomyopathy (DCM). We evaluated the genotype-phenotype correlation in TTNtv-DCM, with a special focus on long-term outcomes, arrhythmias, response to treatment and sex-related presentation. METHODS: Data on patient characteristics and outcomes were collected retrospectively from electronic health records of patients genotyped at two Danish heart transplantation centres. RESULTS: We included 115 patients (66% men). At diagnosis of DCM, mean age was 46±13 years and left ventricular ejection fraction (LVEF) was 28%±13%. During a median follow-up of 7.9 years, 26% reached a composite outcome of left ventricular assist device implantation, heart transplantation or death. In 20% an arrhythmia preceded the DCM diagnosis. In total, 43% had atrial fibrillation (AF) and 23% had ventricular arrhythmias. Long-term left ventricular reverse remodelling (LVRR; LVEF increase ≥10% points or normalisation) was achieved in 58% and occurred more frequently in women (72% vs 51%, p=0.042).In multivariable proportional hazards analyses, occurrence of LVRR was a strong independent negative predictor of the composite outcome (HR: 0.05 (95% CI 0.02 to 0.14); p<0.001). Female sex independently predicted lower rates of ventricular arrhythmias (HR: 0.33 (95% CI 0.11 to 0.99); p=0.05), while the location of the TTNtv was not associated with cardiovascular outcomes. CONCLUSION: DCM caused by TTNtv presented in midlife and was associated with a high burden of AF and ventricular arrhythmias, which often preceded DCM diagnosis. Furthermore, LVRR occurred in a high proportion of patients and was a strong negative predictor of the composite outcome. Female sex was positively associated with occurrence of LVRR and longer event-free survival.

Human pluripotent stem cell line (HDZi001-A) derived from a patient carrying the ARVC-5 associated mutation TMEM43-p.S358L.

Arrhythmogenic right ventricular cardiomyopathy type 5 (ARVC-5) is a dominantly inherited cardiomyopathy caused by the mutation TMEM43-p.S358L. An induced pluripotent stem cell (iPSC) line (HDZi001-A) from an adult male mutation carrier was generated, using the CytoTune Sendai Kit. The resulting iPSCs carried the mutation TMEM43-p.S358L, had a normal morphology, a stable karyotype and were positive for the expression of pluripotency markers. This iPSC line can be differentiated into the three germ layers and might be a useful model for the characterization of ARVC-5 associated pathomechanism.

Statin-associated rhabdomyolysis triggered by drug-drug interaction with itraconazole.

A 47-year-old woman had been treated with high-dose simvastatin for several years. After systemic treatment with the antifungal agent itraconazole, she developed muscle pain and highly elevated levels of creatine kinase and myoglobin. Muscle biopsy was compatible with statin-associated rhabdomyolysis, probably caused by a drug-drug interaction between simvastatin and itraconazole. The patient made full recovery. Three commonly used statins-simvastatin, atorvastatin and lovastatin-are metabolised by the liver enzyme CYP3A4. Several potent inhibitors of this enzyme are known, for example, azole antifungal agents such as itraconazole and posaconazole. If antifungal treatment is indicated in a patient using a CYP3A4-metabolised statin, we recommend (1) topical administration of the antifungal agent if possible, (2) the use of a non-CYP3A4-inhibiting antifungal drug such as terbinafine or (3) temporary discontinuation of statin treatment.

The TMEM43 Newfoundland mutation p.S358L causing ARVC-5 was imported from Europe and increases the stiffness of the cell nucleus.

AIMS: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare genetic condition caused predominantly by mutations within desmosomal genes. The mutation leading to ARVC-5 was recently identified on the island of Newfoundland and caused by the fully penetrant missense mutation p.S358L in TMEM43. Although TMEM43-p.S358L mutation carriers were also found in the USA, Germany, and Denmark, the genetic relationship between North American and European patients and the disease mechanism of this mutation remained to be clarified. METHODS AND RESULTS: We screened 22 unrelated ARVC patients without mutations in desmosomal genes and identified the TMEM43-p.S358L mutation in a German ARVC family. We excluded TMEM43-p.S358L in 22 unrelated patients with dilated cardiomyopathy. The German family shares a common haplotype with those from Newfoundland, USA, and Denmark, suggesting that the mutation originated from a common founder. Examination of 40 control chromosomes revealed an estimated age of 1300-1500 years for the mutation, which proves the European origin of the Newfoundland mutation. Skin fibroblasts from a female and two male mutation carriers were analysed in cell culture using atomic force microscopy and revealed that the cell nuclei exhibit an increased stiffness compared with TMEM43 wild-type controls. CONCLUSION: The German family is not affected by a de novo TMEM43 mutation. It is therefore expected that an unknown number of European families may be affected by the TMEM43-p.S358L founder mutation. Due to its deleterious clinical phenotype, this mutation should be checked in any case of ARVC-related genotyping. It appears that the increased stiffness of the cell nucleus might be related to the massive loss of cardiomyocytes, which is typically found in ventricles of ARVC hearts.

Fatal giant cell myocarditis in a patient with multiple autoimmune disorders.

A case of circulatory collapse due to severe heart failure is reported in a 52-year old male with autoimmune disorders in the form of type-1 diabetes, Graves' disease and total alopecia.Upon admission, the patient had severe heart failure with a cardiac index of 0.9 l/min/m(2), a mixed venous saturation of 29% and left ventricular ejection fraction of 5%. The condition was refractory to treatment with inotropic agents and required mechanical cardiopulmonary support. Endomyocardial biopsies revealed extensive giant cell myocarditis (GCM). Immunosuppressant treatment did not alter the condition and urgent orthotopic heart transplantation was performed.Histopathological examination of the explanted heart confirmed the diagnosis and showed widespread vascular deposition of complement C4d suggesting a pathogenic role for the innate immune system in GCM.At 1-year follow-up the patient was in New York Heart Association (NYHA) class I, had episodes of sustained ventricular tachycardia but showed no evidence of GCM recurrence in endomyocardial biopsies.

[Osmotic demyelination syndrome in Addison crisis and severe hyponatremia]. / Osmotisk demyeliniseringssyndrom ved Addisonkrise og svaer hyponatriaemi.

Acute adrenal insufficiency is a life threatening disease with dehydration, hypotension, cerebral dysfunction and gastrointestinal symptoms accompanied by low plasma sodium and high plasma potassium. Osmotic demyelination syndrome (ODS) can occur rarely following correction of plasma sodium. We describe a case with extremely low plasma sodium and subsequent development of ODS. Correction which is too slow may lead to cerebral oedema, brain stem herniation and low sodium encephalopathy. Correction which is too fast may cause ODS. The dilemma is accentuated by concomitant Addison crisis.

[Toxic megacolon secondary to Clostridium difficile-associated pseudomembranous colitis]. / Toksisk megacolon sekundaert til Clostridium difficile-associeret pseudomembranøs kolitis.

A 78-year-old male without pre-existing comorbidity who underwent revision of a hip arthroplasty developed abdominal pain and distension, diarrhoeas, pyrexia and leucocytosis after only 5 days' postoperative treatment with cefuroxime and gentamycine. Abdominal computed tomography demonstrated severe colonic dilation, inflammation and oedema consistent with toxic megacolon. Stool samples were positive for Clostridium difficile. Oral vancomycine treatment and colonic decompression were inefficient. Subtotal colectomy was performed after which the condition improved.