Cardiac sarcoidosis and sudden death. The heart may look normal or mimic other cardiomyopathies.

Cardiac sarcoidosis has been known to give rise to heart failure, arrhythmias and sudden cardiac death. We have a large database of sudden cardiac death cases at the CRY Centre for Cardiac Pathology at Imperial College, London, UK in which we found 17 of 1,720 cases with a diagnosis of cardiac sarcoid. Macroscopic examination showed a variety of findings including left ventricular hypertrophy, a dilated thin-walled left ventricle, areas of fibrosis, changes resembling arrhythmogenic right ventricular cardiomyopathy and in some cases, no gross abnormalities. Histological examination revealed large areas of fibrosis and focal lymphocytic inflammation mimicking infarction/myocarditis. Careful search had to be made for non-necrotizing granulomata, since the lymphocytic foci, fibrosis and granulation tissue often predominated throughout the heart. The conduction tissue is often not sampled at autopsy despite the history of heart block. The heterogeneous nature of the macroscopic appearance and histological findings means that widespread sampling of the heart and the conduction system is essential in cases of sudden death in order that a diagnosis of myocardial sarcoidosis is not missed.