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A 47-year-old black woman with no relevant medical history was brought to the emergency room after a syncopal episode. The electrocardiogram obtained at admission showed an ectopic atrial rhythm with trifascicular block (Fig. 1). Transthoracic echocardiography revealed a normal left ventricular ejection fraction with mild left ventricular hypertrophy and regional wall motion abnormalities in the basal septum and anterolateral wall. Myocardial perfusion scanning with technetium 99m sestamibi showed multiple fixed perfusion defects in the noncoronary distribution (Fig. 2), but subsequent selective coronary angiography showed no evidence of significant coronary artery disease. Cardiac magnetic resonance imaging revealed delayed hyperenhancement (myocardial fibrosis) in the lateral wall of the left ventricle (Fig. 3) and in the basal interventricular septum (Fig. 4), which was similar to the findings on the myocardial perfusion scan. At this point, we strongly suspected the presence of cardiac sarcoidosis, so a computed tomographic scan of the chest was performed. It showed multiple mediastinal lymph nodes. Therefore, a guided biopsy of these abnormal mediastinal lymph nodes was performed by means of mini-video-assisted thoracic surgery. Histopathologic examination of the specimen revealed noncaseating granulomas (Fig. 5). The diagnosis of cardiac sarcoidosis was confirmed.
Sarcoidosis, an inflammatory disorder of unknown origin and characterized by noncaseating granulomas, can affect the lungs, lymph nodes, heart, liver, spleen, skin, eyes, phalangeal bones, parotid glands, and other organs and tissues.1 The annual incidence of sarcoidosis in the United States is higher in the black population (35.5 per 100,000) than in the white population (10.9 per 100,000).2 Another U.S. study has found on autopsy that cardiac sarcoidosis occurs in up to 25% of patients with sarcoidosis,3 and it accounts for 13% to 25% of deaths from the disease.4 Cardiac sarcoidosis usually occurs in young adults. Sarcoid granulomas can be located anywhere in the heart, including the pericardium, endocardium, and, most frequently, the myocardium.1
Conduction abnormalities have been reported in 12% to 62% of patients with cardiac sarcoidosis.1,5–7 Infiltration of the conduction system by sarcoidosis can cause various abnormalities, such as left or right bundle branch block, atrioventricular conduction block,1,5 and, rarely, sinus arrest.8 Complete heart block is the most common presenting conduction abnormality (in 23%–30% of patients), and most frequently presents as syncope,1 but it can also occur without any notable evidence of cardiomyopathy. Syncope in this population can also be due to ventricular arrhythmias, which are usually caused by direct granulomatous involvement of the myocardium.1 The most feared complication—and often the initial presentation of sarcoidosis—is sudden death due to ventricular arrhythmia or complete heart block. In the U.S., sudden death occurs in 24% to 65% of all patients whose deaths are related to cardiac sarcoidosis,1,5 and in 17% of patients, sudden death is the initial presentation of cardiac sarcoidosis.5
Address for reprints: Mahboob Alam, MD, Section of Cardiology, Department of Medicine, BCM 620, 1709 Dryden St., Suite 9.90, Houston, TX 77030 E-mail: ude.cmt.mcb@malam