Background : The aetiology of dilated cardiomyopathy (DCM) is highly heterogeneous including genetic and/or acquired (infective, toxic, immune, endocrine, and nutritional) factors. The major part of acquired DCM in developed countries is caused by either viral or autoimmune myocarditis. It is believed that the activation of the T-lymphocyte cell system is the major pathomechanism underlying autoimmune myocarditis and inflammatory DCM (DCMi). However, in the hearts of a subset of patients, a significant number of CD20+ B-lymphocytes can be detected too. Limited information exists on the role of B-cell-dependent mechanisms in the progression of DCMi. Particularly CD20+ B-lymphocytes, which can be targeted by anti-CD20+ B-lymphocytes antibodies or inhibitors, might contribute to the pathogenesis of myocardial damage beyond antibody production. Case summary : Here, we present a case series of six patients with subacute and chronic endomyocardial biopsy-proven CD20+ B-lymphocyte-associated DCMi, where symptomatic heart failure therapy, with or without combined immunosuppressive therapy with steroid-based treatment regime, was insufficient to improve cardiac function. Five patients improved clinically several weeks after a standard infusion protocol with rituximab, a chimeric monoclonal antibody against the pan-B-cell surface molecule CD20. Discussion : Our case series shows that CD20+ B-lymphocyte persistence can play a pathophysiologic role in a subset of DCMi patients and highlights the potential of targeting CD20+ B cells in patients with prominent CD20+ B-lymphocyte persistence.

Background: Cardiac amyloidosis (CA) is an infiltrative disease characterised by accumulation of amyloid deposits in the extracellular space of the myocardium—comprising transthyretin (ATTR) and light chain (AL) amyloidosis as the most frequent subtypes. Histopathological proof of amyloid deposits by endomyocardial biopsy (EMB) is the gold standard for diagnosis of CA. Cardiovascular magnetic resonance (CMR) allows non-invasive workup of suspected CA. We conducted a multi-centre study to assess the diagnostic value of CMR in comparison to EMB for the diagnosis of CA. Methods: We studied N = 160 patients characterised by symptoms of heart failure and presence of left ventricular (LV) hypertrophy of unknown origin who presented to specialised cardiomyopathy centres in Germany and underwent further diagnostic workup by both CMR and EMB. If CA was diagnosed, additional subtyping based on EMB specimens and monoclonal protein studies in serum was performed. The CMR protocol comprised cine- and late-gadolinium-enhancement (LGE)-imaging as well as native and post-contrast T1-mapping (in a subgroup)—allowing to measure extracellular volume fraction (ECV) of the myocardium. Results: An EMB-based diagnosis of CA was made in N = 120 patients (CA group) whereas N = 40 patients demonstrated other diagnoses (CONTROL group). In the CA group, N = 114 (95%) patients showed a characteristic pattern of LGE indicative of CA. In the CONTROL group, only 1/40 (2%) patient showed a “false-positive” LGE pattern suggestive of CA. In the CA group, there was no patient with elevated T1-/ECV-values without a characteristic pattern of LGE indicative of CA. LGE-CMR showed a sensitivity of 95% and a specificity of 98% for the diagnosis of CA. The combination of a characteristic LGE pattern indicating CA with unremarkable monoclonal protein studies resulted in the diagnosis of ATTR-CA (confirmed by EMB) with a specificity of 98% [95%-confidence interval (CI) 92–100%] and a positive predictive value (PPV) of 99% (95%-CI 92–100%), respectively. The EMB-associated risk of complications was 3.13% in this study—without any detrimental or persistent complications. Conclusion: Non-invasive CMR shows an excellent diagnostic accuracy and yield regarding CA. When combined with monoclonal protein studies, CMR can differentiate ATTR from AL with high accuracy and predictive value. However, invasive EMB remains a safe invasive gold-standard and allows to differentiate CA from other cardiomyopathies that can also cause LV hypertrophy.

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a progressively debilitating, rare disease associated with high mortality. ATTR-CM occurs when TTR amyloid protein builds up in the myocardium along with different organs, most commonly the peripheral and the autonomic nervous systems. Managing the cardiac complications with standard heart failure medications is difficult due to the challenge to maintain a balance between the high filling pressure associated with restricted ventricular volume and the low cardiac output. To date, tafamidis is the only agent approved for ATTR-CM treatment. Besides, several agents, including green tea, tolcapone, and diflunisal, are used off-label in ATTR-CM patients. Novel therapies using RNA interference also offer clinical promise. Patisiran and inotersen are currently approved for ATTR-polyneuropathy of hereditary origin and are under investigation for ATTR-CM. Monoclonal antibodies in the early development phases carry hope for amyloid deposit clearance. Despite several drug candidates in the clinical development pipeline, the small ATTR-CM patient population raises several challenges. This review describes current and future therapies for ATTR-CM and sheds light on the clinical development hurdles facing them.

Introduction: This study investigated the spontaneous clinical course of patients with endomyocardial biopsy (EMB)-proven lymphocytic myocarditis and cardiac human herpesvirus 6 (HHV6) DNA presence, and the effectiveness of steroid-based intervention in HHV6-positive patients. Results: 756 heart failure (HF) patients underwent an EMB procedure to determine the underlying cause of unexplained HF. Low levels of HHV6 DNA, detectable by nested PCR only, were found in 10.4% of the cases (n = 79) of which 62% (n = 49) showed myocardial inflammation. The spontaneous course of patients with EMB-proven HHV6 DNA-associated lymphocytic myocarditis (n = 26) showed significant improvements in the left ventricular ejection fraction (LVEF) and clinical symptoms, respectively, in 15/26 (60%) patients, 3–12 months after disease onset. EMB mRNA expression of components of the NLRP3 inflammasome pathway and protein analysis of cardiac remodeling markers, analyzed by real-time PCR and MALDI mass spectrometry, respectively, did not differ between HHV6-positive and -negative patients. In another cohort of patients with ongoing symptoms related to lymphocytic myocarditis associated with cardiac levels of HHV6-DNA copy numbers <500 copies/µg cardiac DNA, quantified by real-time PCR, the efficacy and safety of steroid-based immunosuppression for six months was investigated. Steroid-based immunosuppression improved the LVEF (≥5%) in 8/10 patients and reduced cardiac inflammation in 7/10 patients, without an increase in cardiac HHV6 DNA levels in follow-up EMBs. Conclusion: Low HHV6 DNA levels are frequently detected in the myocardium, independent of inflammation. In patients with lymphocytic myocarditis with low levels of HHV6 DNA, the spontaneous clinical improvement is nearby 60%. In selected symptomatic patients with cardiac HHV6 DNA copy numbers less than 500 copies/µg cardiac DNA and without signs of an active systemic HHV6 infection, steroid-based therapy was found to be effective and safe. This finding needs to be further confirmed in large, randomized trials.

BACKGROUND: No large registries of patients with acute eosinophilic myocarditis (EM) are available. However, EM is perceived as a cardiac disease with high mortality, affecting mainly young and middle-aged adults according to small series and case reports. Awareness of the clinical presentation, associated systemic conditions, treatments, and outcomes of this uncommon condition is an unmet need. METHODS: In this international, multicenter, retrospective cohort study, 53 centers screened 193 patients with histologically proven acute EM between 1992 and 2023. After the exclusion of patients with insufficient data (n=10), symptoms lasting >30 days (n=19), or histological diagnosis not confirmed after review (n=8), 156 patients were included. RESULTS: Median age at presentation was 48 years (first to third quartile, 34–59 years) with male predominance (67.3%), and only 2 were pediatric cases (≤16 years of age; 1.3%). The main signs and symptoms at presentation were dyspnea (75.6%), fever (61.3%), and chest pain (53.2%). Unexpectedly, peripheral eosinophilia was reported in only 57.4% of cases, with a median cell count of 630 eosinophils/μL. The median left ventricular ejection fraction at presentation was 32% (first to third quartile, 25%–48%). The disorders most frequently associated with EM were eosinophilic granulomatosis with polyangiitis (22.4% of cases) and hypersensitivity forms (14.1%). Idiopathic/undefined forms accounted for 44.9% of cases, and miscellaneous causes accounted for 18.6%. In-hospital death or need for heart transplantation (HTx) occurred in 23 patients (14.7%; 22 deaths and 1 HTx), despite 43.6% being treated with temporary mechanical circulatory support and 92.9% being treated with immunosuppressive agents. Estimated rates of death or HTx at 1 and 3 years were 19.0% and 23.8%. Increased age, decreased left ventricular ejection fraction on admission, and no immunosuppressive therapy during hospitalization were independent predictors of death or HTx. A nonsignificant higher occurrence of deaths or HTx was observed in the hypersensitivity form (46.1%) compared with the eosinophilic granulomatosis with polyangiitis–associated form (13.1%) at 3 years ( P =0.15). CONCLUSIONS: Acute EM can often present without peripheral eosinophilia, and rates of in-hospital and midterm mortality or HTx are high. Endomyocardial biopsy is required to reach the final diagnosis of EM because relying on peripheral eosinophilia can lead to missing diagnosis. In-hospital immunosuppression is associated with HTx-free survival, although tailored immunosuppressive therapies are needed to improve outcomes. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT06447935.

Background: Parvovirus B19 (B19V) and Human Herpesvirus 6 (HHV6) are commonly detected in endomyocardial biopsy (EMB) specimens of patients with myocarditis symptoms. Whether B19V- and HHV6-DNA belong to the cardiac bio-portfolio remains unclear [1,2]. Until today, the role of B19V-/HHV6-DNA presence in myocarditis is doubtful. Both viruses have been detected in the myocardium, even independent of cardiac inflammation. Yet, their contribution to myocarditis remains controversial. The European Society of Cardiology guidelines exclude the use of immunosuppression in patients with virus-associated myocarditis [3]. Whether myocarditis patients with the presence of B19V-DNA alone or with HHV6-DNA in EMB findings can be treated using immunosuppression, remains a delicate question for clinicians. Methods: 931 patients with unexplained heart failure symptoms underwent EMB investigation to determine the underlying cause. Patients with low-levels (<1000 copies/μg DNA) of B19V-DNA and HHV6-DNA were identified. A sub-cohort of 28 patients who suffered from chronic-persistent lymphocytic myocarditis with ongoing symptoms was treated with azathioprine 100 mg once daily and prednisolone 1 mg/kg/day tapered down by 10 mg every two weeks followed by a second EMB. Twenty out of 28 patients had B19V-DNA only (mean LVEF=38%, age=47±15) and eight patients had B19V-/HHV6-DNA copresence (mean LVEF=39%, age=42±10). Patients with systemic infections were excluded. Both cohorts received standard heart failure medications. Continuous variables are expressed as mean±SD. Results: B19V-DNA alone and in the presence of HHV6-DNA was detectable in the EMB of 377 and 63 patients, respectively. Following the immunosuppression course, the patients with B19V-DNA only and those with B19V-/HHV6-DNA showed complete resolution of inflammation in 12/20 and 5/8 patients, New York Heart Association (NYHA) functional class improvement in 9/20 and 4/8 patients, LVEF improvement by 8.0±13.8% (p<0.05) and 8.4±9.6% (p<0.05), and a reduction of LVEDD by 3.8±6.1mm (p0.05), respectively. Importantly, following immunosuppression B19V and HHV6-DNA copy numbers went down from 186±266 to 130±186 copies/μg DNA and from 71±141 to 58±143 copies/μg DNA, respectively. Conclusion: Chronic lymphocytic myocarditis patients with persistent B19V-DNA even in co-presence of HHV6-DNA may benefit from combined immunosuppression therapy. The therapy is clinically effective and safe to reduce cardiac inflammation independent of B19V- and HHV6-DNA copy numbers. In conclusion, we show for the first time that cases with chronic lymphocytic myocarditis can be principally treated with immunosuppression, despite B19V-/HHV6-DNA EMB presence. Funding Acknowledgement: Type of funding sources: Public Institution(s). Main funding source(s): Berlin Institute of Health-Center for Regenerative Therapies