Idiopathic dilated cardiomyopathy (IDC) is the primary indication for cardiac transplantation,
with associated costs of approximately $177 million per year. Recognizing the economic
implications of IDC, the increasing incidence, and the limited information on pathogenesis
and prognosis, the National Heart, Lung, and Blood Institute convened a workshop on
the Prevalence and Etiology of Idiopathic Dilated Cardiomyopathy on June 13 to 14,
1991. The difficulties of studying the disease were reviewed, including its relatively
low prevalence, its potentially pluricausal nature, and the fact that it is often
a diagnosis of exclusion. Still, it presents significant challenges to the cardiovascular
scientific community, since the mechanism of myocardial damage and related etiologic
and prognostic factors are virtually unknown. The development of more reliable measures
of immune-mediated damage and noninvasive measures of impaired cardiac function present
new research opportunities in this disorder. Standardized diagnostic criteria for
use in observational and interventional trials were developed, and priorities for
future research were proposed. Population-based registries and nested case-control
studies, where feasible, are appropriate study designs for tracking incidence and
prevalence, and for identifying risk factors, respectively. Interventional studies
should focus on secondary prevention, through modifying immune-mediated damage in
clinically evident dilated cardiomyopathy, and through prevention of sudden death
in patients with the disorder. Primary prevention trials must await the identification
of modifiable risk factors and of appropriate and effective interventions.