Inflammatory cardiomyopathy is defined as myocarditis in association with cardiac dysfunction and ventricular remodelling 1,2. Despite extensive research and improved diagnosis and understanding of the pathogenesis of inflammatory cardiomyopathy, this disorder is still associated with a poor prognosis when complicated by left ventricular (LV) dysfunction, heart failure (HF) or arrhythmia 3. Furthermore, fulminant myocarditis, a rare, sudden and severe cardiac inflammation, is one of the main causes of cardiogenic shock in young adults 4,5. Prompt diagnosis and specific treatment strategies are needed to reduce mortality and the need for heart transplantation in these patients 4,5. Many questions remain unanswered regarding the pathogenesis of inflammatory cardiomyopathy and the role of the viral infection, the immune system, the host genetic background and the environment in disease progression and prognosis. These gaps in knowledge highlight the need for advanced experimental systems that can better model the human immune system and the need to improve the characterization and classification of the patients, for example, with the use of phenomapping and phenomics, which involve detailed evaluation of immune status, viral presence and/or other biomarkers. In this Review, we discuss the available evidence and identify the gaps in our understanding of the pathogenesis, diagnosis, treatment and prognosis of myocarditis and inflammatory cardiomyopathy, appraise the available animal and cell models of these conditions and propose future directions for the field. We discuss the role

Background-Increased left ventricular stiffness is a distinct finding in patients who have heart failure with normal ejection fraction (HFNEF). To elucidate how diastolic dysfunction contributes to heart failure symptomatology during exercise, we conducted a study using an invasive pressure-volume loop approach and measured cardiac function at rest and during atrial pacing and handgrip exercise. Methods and Results-Patients with HFNEF (nϭ70) and patients without heart failure symptoms (nϭ20) were enrolled.Pressure-volume loops were measured with a conductance catheter during basal conditions, handgrip exercise, and atrial pacing with 120 bpm to analyze diastolic and systolic left ventricular function. During transient preload reduction, the diastolic stiffness constant was measured directly. Diastolic function with increased stiffness was significantly impaired in patients with HFNEF during basal conditions. This was associated with increased end-diastolic pressures during handgrip exercise and with decreased stroke volume and a leftward shift of pressure-volume loops during atrial pacing. Conclusions-Increased left ventricular stiffness contributed to increased end-diastolic pressure during handgrip exercise and decreased stroke volume during atrial pacing in patients with HFNEF. These data suggest that left ventricular stiffness modulates cardiac function in HFNEF patients and suggests that diastolic dysfunction with increased stiffness is a target for treating HFNEF.