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Background Pentraxin 3 (PTX3) is an acute phase protein, which regulates the outcomes of inflammation. Currently, there are no myocarditis-typical biomarkers that allow a non-invasive diagnosis, and endomyocardial biopsy (EMB) is still the gold standard. Finally, risk stratification is often challenging in these patients. Aim To investigate whether PTX3 could be expressed in cardiomyocytes and released during myocarditis, serving as a novel and independent diagnostic indicator of myocardial inflammation, and contributing to prognosis prediction. Methods Fifty-five patients with a diagnosis of acute or chronic active myocarditis proven by cardiac magnetic resonance (CMR) and/or endomyocardial biopsy (EMB), were included. First, we evaluated tissue PTX3 expression by immunohistochemistry (IHC). Then, we assessed circulating blood PTX3 by ELISA technique. Results On cardiac tissue, PTX3 at IHC did not localize in the interstitium, and showed an inconstant expression in the vascular endothelium, but a marked staining by cardiomyocytes in all myocarditis patients. The only exception was represented by two patients with systemic COVID-19, with SARS-CoV-2 and PVB-19 intracardiac genomes, respectively, who showed a diffuse cardiac PTX3 expression. Remarkably, at semi-quantitative pixel analysis, viral aetiology showed higher levels of tissue expression, rather than the autoimmune one. Circulating PTX3 levels were significantly higher in myocarditis patients than controls, with pathologic values in 87% of myocarditis patients, and none among controls. Remarkably, plasma PTX3 proved to be more sensitive in myocarditis detection than CRP, ESR, troponin T, and NT-proBNP. As regards of prognosis, we observed that patients with heart failure (HF) presentation all had elevated PTX3 levels, as compared with chest pain or arrhythmia. Remarkably, patients with reduced LVEF ( Conclusions Tissue PTX3 is mostly expressed by cardiomyocytes in patients with active myocarditis on EMB samples. In addition, plasma PTX3 is a sensitive diagnostic and prognostic marker in patients with inflammatory cardiomyopathy.

Background Preclinical data support the rationale for targeting myocardial inflammation in genetic nonischemic cardiomyopathies. However, no consistent clinical reports have been provided so far. Methods We describe a series of patients (n=25) with genetic cardiomyopathy and active myocardial inflammation (AMI) proven by multimodal diagnostic workup. Patient-tailored immunosuppressive therapy was empirically started to target myocardial inflammation whenever feasible. Multiple outcomes were retrospectively assessed by a dedicated multidisciplinary disease unit. Results Patients carrying desmosomal (DGV), cytoskeletal (CGV) and membrane gene variants (MGV), were 12 (48%), 10 (40%), and 3 (12%), respectively. DGV carriers uniformly presented with myocarditis-like chest pain and ventricular arrhythmias, whereas heart failure symptoms were found only in CGV carriers. Dilated cardiomyopathy phenotype and ring-like pattern on cardiac magnetic resonance allowed the best discrimination among genotypes. AMI was proven by endomyocardial biopsy in all cases, and by noninvasive imaging in 21 (83%). IST was started in 17 patients (71%) with no safety issues. By the end of follow-up (median 69 months, range 21-182), signs of AMI were documented in 6/18 IST receivers (33%) and 4/7 untreated cases (57%). For most genotypes, paucity of adverse events was noted while on immunosuppression as compared to the off-treatment period. Conclusion Our preliminary data provide the clinical rationale for the research and targeting of AMI in a spectrum of genetic nonischemic cardiomyopathies.