Unusual form of Cardiomyopathy

Youn, Ho Joong

Abstract

The cardiomyopathies constitute a group of diseases in which the dominant feature is direct involvement of the heart muscle itself. They are distinctive because they are not the result of pericardial, hypertensive, congenital, valvular, or ischemic diseases. Although the diagnosis of cardiomyopathy requires the exclusion of these etiological factors, the features of cardiomyopathy are often sufficiently distinctive-both clinically and hemodynamically-to allow a definitive diagnosis to be made. With increasing awareness of this condition, along with improvements in diagnostic techniques, cardiomyopathy is being recognized as a significant cause of morbidity and mortality. Whether the result of improved recognition or of other factors, the incidence and prevalence of cardiomyopathy appear to be increasing. A variety of schemes have been proposed for classifying the cardiomyopathies. The most widely recognized classification is that promulgated jointly by the World Health Organization (WHO) and the International Society and Federation of Cardiology (ISFC). In the WHO/ISFC classification, the cardiomyopathies are classified based on their predominant pathophysiological features; other diseases that affect the myocardium that are associated with a specific cardiac disorder or are part of a generalized systemic disorder are termed specific cardiomyopathies. Three basic types of functional impairment have been described: 1) dilated (DCM, formerly called congestive), the most common form, accounting for 60 percent of all cardiomyopathies and characterized by ventricular dilatation, contractile dysfunction, and often symptoms of congestive heart failure; 2) hypertrophic (HCM), recognized by inappropriate left ventricular hypertrophy, often with asymmetrical involvement of the interventricular septum, with preserved or enhanced contractile function until late in the course; and 3) restrictive (RCM), the least common form in western countries, marked by impaired diastolic filling and in some cases with endocardial scarring of the ventricle. Two other forms of cardiomyopathy are recognized: arrhythmogenic right ventricular cardiomyopathy and unclassified; the latter includes fibroelastosis, systolic dysfunction with minimal dilatation, and mitochondrial involvement. The distinction between the three major functional categories is not absolute, and often there is overlap; in particular, patients with HCM also have increased wall stiffness as a consequence of the myocardial hypertrophy and thus present some of the features of an RCM. Late in their course, ventricular dilation and systolic heart failure, bearing some resemblance to DCM, may occur. The aim of this review is to introduce the unusual forms of cardiomyopathy with the current literatures in this field.