This large retrospective study found that an abnormal electrocardiogram and cardiac-related symptoms are powerful early predictors of cardiac involvement in patients with sarcoidosis.
In contrast, cardiac sarcoidosis is very rare in subjects without symptoms and with a normal electrocardiogram. This knowledge is important and may be used in a clinical algorithm for identifying patients who should be followed and investigated extensively for the presence of cardiac sarcoidosis.
Sarcoidosis is a systemic inflammatory disease of unknown etiology that most often affects the lungs, eyes and skin. Cardiac involvement is an uncommon clinical manifestation with a high mortality rate. One large study in the United States reported clinically evident cardiac involvement in only 2.3% of patients with biopsy-confirmed sarcoidosis, although many specialists believe that the rate of occult disease is much higher. Autopsy studies support rates of over 20%, and Japanese patients appear be at greater risk than Caucasians.
Physicians who treat patients with noncardiac sarcoidosis may find these statistics anxiety provoking. Currently, no clear guidelines exist on appropriate diagnostic testing to identify these high-risk patients.
The authors reviewed the charts of 1,017 consecutive Caucasian patients with systemic sarcoidosis who underwent screening examinations and electrocardiograms at a single center.
An abnormal electrocardiogram was documented in 166 patients (16.3%). This cohort of patients was more likely to be male (relative risk [RR] 1.4, P < 0.05) and had more deaths (RR 2.3, P < 0.05) than those with normal electrocardiograms. In addition, patients with cardiac-related symptoms, such as palpitations, pre-syncope and syncope, were more likely to have cardiac sarcoidosis.
None of the patients with an absence of cardiac symptoms and a normal electrocardiogram were ultimately diagnosed with cardiac sarcoidosis. Of the 51 patients with cardiac symptoms and a normal electrocardiogram, only one developed cardiac sarcoidosis. In 126 patients with no cardiac symptoms and pathologic electrocardiograms, 11 (9%) were diagnosed with cardiac sarcoidosis. Of the 40 patients with both cardiac symptoms and an abnormal electrocardiogram, 11 (28%) developed cardiac disease. Furthermore, patients with Löfgren syndrome had a reduced risk for cardiac sarcoidosis compared to those without it (P < 0.05).
In addition to a careful history and review of systems, physicians contemplating a diagnosis of noncardiac sarcoidosis may consider adding a baseline electrocardiogram to their diagnostic testing. In patients with cardiac symptoms (palpitations, pre-syncope and syncope), referral to a cardiologist may be warranted. Certainly, any patient with an abnormal electrocardiogram should undergo further testing. Prospective studies with more diverse patient populations are needed to help the sarcoidosis community develop criteria to identify patients who are at risk of cardiac involvement.