Background: There is scarce data about the long‐term mortality as well as the prognostic value of cardiovascular magnetic resonance and late gadolinium enhancement (LGE) in patients with biopsy‐proven viral myocarditis. We sought to investigate: (1) mortality and (2) prognostic value of LGEcardiovascular magnetic resonance (location, pattern, extent, and distribution) in a >10‐year follow‐up in patients with biopsy‐proven myocarditis. Methods and Results: Two‐hundred three consecutive patients with biopsy‐proven viral myocarditis and cardiovascular magnetic resonance were enrolled; 183 patients were eligible for standardized follow‐up. The median follow‐up was 10.1 years. End points were all‐cause death, cardiac death, and sudden cardiac death (SCD). We found substantial long‐term mortality in patients with biopsy‐proven myocarditis (39.3% all cause, 27.3% cardiac, and 10.9% SCD); 101 patients (55.2%) demonstrated LGE. The presence of LGE was associated with a more than a doubled risk of death (hazard ratio [HR], 2.40; 95% CI], 1.30–4.43), escalating to a HR of 3.00 (95% CI, 1.41–6.42) for cardiac death, and a HR of 14.79 (95% CI, 1.95–112.00) for SCD; all P ≤0.009. Specifically, midwall, (antero‐) septal LGE, and extent of LGE were highly associated with death, all P <0.001. Septal LGE was the best independent predictor for SCD (HR, 4.59; 95% CI, 1.38–15.24; P =0.01). Conclusions: In patients with biopsy‐proven viral myocarditis, the presence of midwall LGE in the (antero‐) septal segments is associated with a higher rate of mortality (including SCD) compared with absent LGE or other LGE patterns, underlining the prognostic benefit of a distinct LGE analysis in these patients.

Background: Platelets can infiltrate ischemic myocardium and are increasingly recognized as critical regulators of inflammatory processes during myocardial ischemia and reperfusion (I/R). Platelets contain a broad repertoire of microRNAs (miRNAs), which, under certain conditions such as myocardial ischemia, may be transferred to surrounding cells or released into the microenvironment. Recent studies could demonstrate that platelets contribute substantially to the circulating miRNA pool holding the potential for so far undiscovered regulatory functions. The present study aimed to determine the role of platelet-derived miRNAs in myocardial injury and repair following myocardial I/R. Methods: In vivo model of myocardial I/R, multimodal in vivo and ex vivo imaging approaches (light-sheet fluorescence microscopy, positron emission tomography and magnetic resonance imaging, speckle-tracking echocardiography) of myocardial inflammation and remodeling, and next-generation deep sequencing analysis of platelet miRNA expression. Results: In mice with a megakaryocyte/platelet-specific knockout of pre-miRNA processing ribonuclease Dicer , the present study discloses a key role of platelet-derived miRNAs in the tightly regulated cellular processes orchestrating left ventricular remodeling after myocardial I/R following transient left coronary artery ligation. Disruption of the miRNA processing machinery in platelets by deletion of Dicer resulted in increased myocardial inflammation, impaired angiogenesis, and accelerated development of cardiac fibrosis, culminating in an increased infarct size by d7 that persisted through d28 of myocardial I/R. Worsened cardiac remodeling after myocardial infarction in mice with a platelet-specific Dicer deletion resulted in an increased fibrotic scar formation and distinguishably increased perfusion defect of the apical and anterolateral wall at day 28 post-myocardial infarction. Altogether, these observations culminated in an impaired left ventricular function and hampered long-term cardiac recovery after experimental myocardial infarction and reperfusion therapy. Treatment with the P2Y ₁₂ (P2Y purinoceptor 12) antagonist ticagrelor completely reversed increased myocardial damage and adverse cardiac remodeling observed in Dicer ^{Pf4∆/Pf4∆} mice. Conclusions: The present study discloses a critical role of platelet-derived miRNA in myocardial inflammation and structural remodeling processes following myocardial I/R.

Platelets play a significant role in atherothrombosis. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is critically involved in the regulation of LDL metabolism and interacts with platelet function. The effect of PCSK9 in platelet function is poorly understood. The authors of this article sought to characterize platelets as a major source of PCSK9 and PCSK9’s role in atherothrombosis. In a large cohort of patients with coronary artery disease (CAD), platelet count, platelet reactivity, and platelet-derived PCSK9 release were analyzed. The role of platelet PCSK9 on platelet and monocyte function was investigated in vitro. Platelet count and hyper-reactivity correlated with plasma LDL in CAD. The circulating platelets express on their surface and release substantial amounts of PCSK9. Release of PCSK9 augmented platelet-dependent thrombosis, monocyte migration, and differentiation into macrophages/foam cells. Platelets and PCSK9 accumulated in tissue derived from atherosclerotic carotid arteries in areas of macrophages. PCSK9 inhibition reduced platelet activation and platelet-dependent thrombo-inflammation. The authors identified platelets as a source of PCSK9 in CAD, which may have an impact on LDL metabolism. Furthermore, platelet-derived PCSK9 contributes to atherothrombosis, and inhibition of PCSK9 attenuates thrombo-inflammation, which may contribute to the reported beneficial clinical effects.

To determine morphological and functional cardiovascular magnetic resonance (CMR) patterns in histopathologically confirmed myocardial involvement in patients with systemic sclerosis (SSc). Twenty patients (6 females; mean age 41 ± 11 years) with histopathologically proven cardiac involvement in SSc in the years 2008–2016 were retrospectively evaluated. Morphological, functional and late gadolinium enhancement (LGE) images were acquired in standard angulations at 1.5 T CMR. Pathologies were categorized: 1) Pericardial effusion; 2) pathologic left (LV) or right ventricular (RV) contractility (hypokinesia, dyssynchrony, and diastolic restriction); 3) reduced left (LV-EF) and right ventricular ejection fraction (RV-EF); 4) fibrosis and/or inflammation (positive LGE); 5) RV dilatation. 95 % confidence intervals (CI) were calculated for appearance of pathologic EF and RV dilatation. Seven patients (35 %) had positive CMR findings in three categories, 9 patients (45 %) in four categories and 4 patients (20 %) in five categories. The distribution of pathologic findings was: minimal pericardial effusion in 7 patients (35 %), moderate pericardial effusion >5 mm in nine patients (45 %); abnormal LV or RV contractility in 19 patients (95 %), reduced LV or RV function in 14 patients (70 %; 95 % CI: 51–88 %), pathologic LGE in all patients, RV dilatation in 6 patients (30 %; 95 % CI: 15–54 %). CMR diagnosis of myocardial involvement in SSc requires increased attention to subtle findings. Pathologic findings in at least three of five categories indicate myocardial involvement in SSc.

Objective: Patients with coronary artery disease (CAD) are at increased risk for cardiac death and respiratory failure following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Platelets are crucially involved in pathogenesis of CAD and might also contribute to pathophysiology of SARS-CoV-2 infection. Approach and Results: We enrolled a cohort of 122 participants from February 2020 to July 2020 including 55 patients with preexisting CAD and acute SARS-CoV-2 infection (CAD-SARS-CoV-2 ^positive ), 28 patients with CAD and without SARS-CoV-2 (CAD-SARS-CoV-2 ^negative ), and 39 healthy controls. Clinical and cardiac examination of the CAD-SARS-CoV-2 ^positive group included blood sampling, echocardiography, and electrocardiography within 24 hours after hospital admission. Phenotyping of platelets was performed by flow cytometry; plasma levels of chemokines were analyzed by ELISA. Respiratory failure of patients was stratified by the Horovitz index as moderately/severely impaired when Horovitz index <200 mm Hg. The clinical end point was defined as Horovitz index <200 mm Hg with subsequent mechanical ventilation within a follow-up of 60 days. CAD-SARS-CoV-2 ^positive patients display a significant enhanced platelet activation and hyper-inflammation early at time of hospital admission. Circulating platelet/leukocyte co-aggregates correlate with plasma levels of cytokines/chemokines like IL (interleukin)-6, CCL2, and CXCL10 (chemokine [C-X-C motif] ligand) as well as activation of platelets is associated with CCL5 and elevation of pulmonary artery pressure. Furthermore, furin is stored and released from activated platelets. High furin plasma levels are associated with poor clinical prognosis in CAD-SARS-CoV-2 ^positive patients. Conclusions: Patients with CAD and SARS-CoV-2 infection exhibit elevated systemic platelet activation and enhanced plasma levels of the subtilisin-like proprotein convertase furin, which may contribute to an unfavorable clinical prognosis.

To provide clinically relevant criteria for differentiation between the athlete’s heart and similar appearing hypertrophic (HCM), dilated (DCM), and arrhythmogenic right-ventricular cardiomyopathy (ARVC) in MRI. 40 top-level athletes were prospectively examined with cardiac MR (CMR) in two university centres and compared to retrospectively recruited patients diagnosed with HCM (n = 14), ARVC (n = 18), and DCM (n = 48). Analysed MR imaging parameters in the whole study cohort included morphology, functional parameters and late gadolinium enhancement (LGE). Mean left-ventricular enddiastolic volume index (LVEDVI) was high in athletes (105 ml/m²) but significantly lower compared to DCM (132 ml/m²; p = 0.001). Mean LV ejection fraction (EF) was 61% in athletes, below normal in 7 (18%) athletes vs. EF 29% in DCM, below normal in 46 (96%) patients (p < 0.0001). Mean RV-EF was 54% in athletes vs. 60% in HCM, 46% in ARVC, and 41% in DCM (p < 0.0001). Mean interventricular myocardial thickness was 10 mm in athletes vs. 12 mm in HCM (p = 0.0005), 9 mm in ARVC, and 9 mm in DCM. LGE was present in 1 (5%) athlete, 8 (57%) HCM, 10 (56%) ARVC, and 21 (44%) DCM patients (p < 0.0001). Healthy athletes’ hearts are characterized by both hypertrophy and dilation, low EF of both ventricles at rest, and increased interventricular septal thickness with a low prevalence of LGE. Differentiation of athlete’s heart from other non-ischemic cardiomyopathies in MRI can be challenging due to a significant overlap of characteristics also seen in HCM, ARVC, and DCM.