Prospects and Predictions for the Cardiomyopathies

IN THIS LECTURE I shall attempt to survey the current important problems in the commonest forms of cardiomyopathies and suggest avenues along which research may profitably proceed in the future. The classification of the cardiomyopathies into hypertrophic, congestive, obliterative, and restrictive has the advantage of allowing a study in depth to be made of the pathological, functional, and clinical features of these types without prior knowledge of their etiology. The classification also assists the identification of various forms of cardiomyopathy in circumstances where causal factors are being sought.' Figure 1 shows the four types in diagrammatic form. The general characteristics of each type are well known. In the hypertrophic form there is massive ventricular muscle hypertrophy with reduction in endsystolic volume and often a concentration of hypertrophy in the region of the septum forming the asymmetrical bulge that inspired Teare2 to name the condition "Asymmetrical hypertrophy of the heart." With this concentration of the disease in the region of the septum there is commonly a gradient in systole across the outflow tract and the condition is then usually known as Hypertrophic Obstructive Cardiomyopathy or Idiopathic Hypertrophic Subaortic Stenosis (IHSS). In about 10 to 20% of patients, however, no gradient is discernible either at rest or on