Preface

Heart failure places a considerable burden on both patients and healthcare systems. It causes increased morbidity and mortality and is a risk factor for arrhythmia and sudden cardiac death. Heart failure is commonly caused by ischemic heart disease, abnormal loading, or cardiomyopathies. Cardiomyopathies are diseases of the heart muscle with diverse etiologies ranging from myocarditis to gene mutations. Definitions of cardiomyopathies differ over time and between clinical traditions. While in the future cardiomyopathies might be classified after causative mutations, they have traditionally been classified by phenotype and cardiac morphology. This system of classification has the advantage that the phenotype is most often known prior to the genotype. Originally, cardiomyopathies were considered distinct primary myocardial disorders of unknown etiology, whereas heart muscle disorders of known etiology or caused by systemic disease were classified as secondary or specific heart muscle disease. In 2006, the American Heart Association proposed a classification that defined cardiomyopathies as either primary or secondary, referring either to a disease where the heart is the sole or primarily affected organ or where myocardial involvement is part of a systemic disease. In 2008, the European Society of Cardiology proposed an alternate classification in which cardiomyopathy is defined as "a myocardial disorder in which the heart muscle is structurally and functionally abnormal in the absence of coronary artery disease, hypertension, valvular disease, and congenital heart disease sufficient to cause the observed myocardial abnormality." Furthermore, the European Society of Cardiology subdivides cardiomyopathies depending on morphology and function, that is, dilated cardiomyopathy, hypertrophic cardiomyopathy, arrhythmogenic cardiomyopathy, restrictive cardiomyopathy, and unclassified cardiomyopathies (e.g., left-ventricular non-compaction cardiomyopathy). They are then further categorized based on inheritance pattern, distinguishing between familial or genetic forms versus non-familial or non-genetic forms of cardiomyopathy and based on specific etiologies.

This book is divided into seven sections. The "Overview" section introduces the topic, and the "Genetics" section provides information on the genetic basis of many of the cardiomyopathies. "Arrhythmogenic Cardiomyopathy," "Hypertrophic Cardiomyopathy," and "Dilated Cardiomyopathy" include chapters sorted by category of cardiomyopathy. The book ends with sections on "Miscellaneous Cardiomyopathies" and "Treatment and Future Perspectives."

We wish to thank the chapter authors, all of whom are expert clinicians and researchers in the fields of cardiology, cardiomyopathies, and cardiogenetics.

**Gustav Mattsson and Peter Magnusson** Centre for Research and Development Region Gävleborg/Uppsala University, Gävle, Sweden

Section 1 Overview

#### **Chapter 1**
