Cardiac sarcoidosis can be a benign, incidentally discovered condition or a life-threatening disorder causing sudden death. Small observational registries and studies have described clinical evidence of myocardial involvement in 5 percent of patients with systemic sarcoidosis, yet autopsy studies indicate that subclinical cardiac involvement is present in up to 70 percent of cases. These observations suggest that the diagnosis of cardiac sarcoidosis is difficult to establish, especially in patients without evidence of sarcoid in other organs and thus cardiac sarcoidosis is often underdiagnosed in every day clinical practice. Furthermore, there is neither a clear-cut understanding of the underlying pathophysiology and progression of this disease, nor a consensus on the optimal methods for disease detection, monitoring, and treatment.
There appear to be differences in the presentation of cardiac sarcoidosis among various countries, although comparison among studies is limited by differing methodologies. In the United States, 13 to 25 percent of deaths from sarcoidosis have been attributed to cardiac sarcoidosis while in Japan, 47 to 85 percent of deaths from sarcoidosis have been attributed to cardiac involvement. In contrast, a retrospective study from Haifa, Israel reported that only 2 of 120 patients with sarcoidosis died of cardiac involvement .
This report reviews the latest understanding of cardiac sarcoidosis, providing details on the pertinent clinical features, methods used in the diagnosis and monitoring of disease progression and in the management of this condition. General issues related to systemic sarcoidosis are discussed separately. The American Thoracic Society (ATS) statement on sarcoidosis  can be accessed through the ATS web site. (See "Clinical manifestations and diagnosis of pulmonary sarcoidosis" and "Pathogenesis of sarcoidosis".)
Sarcoidosis is a heterogeneous, non-caseating, granulomatous disorder of unknown etiology that can involve any organ within the body. Cardiac involvement may be detected alone and may precede, follow, or occur concurrently with other organ (eg, lung) involvement. As an example, a German study of 52 patients with evidence of sarcoid heart disease found that one-third had normalized lung changes .
There are geographic variations in the epidemiology and presentation of cardiac sarcoidosis. Japanese pathologists report cardiac involvement in as many as 50 to 78 percent, whereas in the United States, 13 to 50 percent of all deaths are related to cardiac involvement [4-10]. A retrospective study from Israel interestingly demonstrated that only 2 of 120 patients (2 percent) with sarcoidosis died from cardiac involvement .