In biology, classification systems are used to promote understanding and systematic discussion through the use of logical groups and hierarchies. In clinical medicine, similar principles are used to standardise the nomenclature of disease. For more than three decades, heart muscle diseases have been classified into primary or idiopathic myocardial diseases (cardiomyopathies) and secondary disorders that have similar morphological appearances, but which are caused by an identifiable pathology such as coronary artery disease or myocardial infiltration (specific heart muscle diseases). In this document, The European Society of Cardiology Working Group on Myocardial and Pericardial Diseases presents an update of the existing classification scheme. The aim is to help clinicians look beyond generic diagnostic labels in order to reach more specific diagnoses.

Blots were performed against DDR (p53 pSer15, histone 2AX pSer139), cell survival/ cell death (AKT pThr308, cleaved PARP), and cell signaling (ERK1/2 pThr202/Tyr204) markers and controls. Actin and GAPDH served as loading controls.

All experts involved in the development of these guidelines have submitted declarations of interest. These have been compiled in a report and published in a supplementary document simultaneously to the guidelines. The report is also available on the ESC website www.escardio.org/Guidelines See the European Heart Journal online for supplementary data that includes background information and detailed discussion of the data that have provided the basis of the guidelines.Click here to access the corresponding ESC CardioMed chapters.

Background Cardiac muscle hypercontractility is a key pathophysiological abnormality in hypertrophic cardiomyopathy, and a major determinant of dynamic left ventricular outflow tract (LVOT) obstruction. Available pharmacological options for hypertrophic cardiomyopathy are inadequate or poorly tolerated and are not disease-specific. We aimed to assess the efficacy and safety of mavacamten, a first-in-class cardiac myosin inhibitor, in symptomatic obstructive hypertrophic cardiomyopathy. Methods In this phase 3, randomised, double-blind, placebo-controlled trial (EXPLORER-HCM) in 68 clinical cardiovascular centres in 13 countries, patients with hypertrophic cardiomyopathy with an LVOT gradient of 50 mm Hg or greater and New York Heart Association (NYHA) class II-III symptoms were assigned (1:1) to receive mavacamten (starting at 5 mg) or placebo for 30 weeks. Visits for assessment of patient status occurred every 2-4 weeks. Serial evaluations included echocardiogram, electrocardiogram, and blood collection for laboratory tests and mavacamten plasma concentration. The primary endpoint was a 1•5 mL/kg per min or greater increase in peak oxygen consumption (pVO 2) and at least one NYHA class reduction or a 3•0 mL/kg per min or greater pVO 2 increase without NYHA class worsening. Secondary endpoints assessed changes in post-exercise LVOT gradient, pVO 2 , NYHA class, Kansas City Cardiomyopathy Questionnaire-Clinical Summary Score (KCCQ-CSS), and Hypertrophic Cardiomyopathy Symptom Questionnaire Shortness-of-Breath subscore (HCMSQ-SoB). This study is registered with ClinicalTrials.gov, NCT03470545.