Diagnostic Utility of Signal-Averaged Electrocardiography for Detection of Cardiac Sarcoidosis

INTRODUCTION: Cardiac sarcoidosis (CS) occurs in up to 25% of patients with pulmonary involvement. Early diagnosis is critical because sudden death from ventricular arrhythmias can be the initial presentation. We sought to evaluate the diagnostic utility of signal-averaged ECG (SAECG) for detection of cardiac involvement of sarcoidosis. METHODS: Subjects with biopsy proven sarcoidosis and symptoms suggestive of possible cardiac involvement were included in the cohort. Standard criteria for SAECG were used. Subjects were considered to have CS if they met criteria established by the Japanese Ministry of Health and Welfare modified to include cardiac MRI. RESULTS: Of the 88 patients in the cohort 27 had evidence of CS independent of the SAECG results. The SAECG was abnormal in 14 of these 27 patients and 11 of the 61 of the subjects without cardiac involvement (P < 0.01). The sensitivity of SAECG detection of CS was 52% with a specificity of 82%. For the entire cohort, SAECG had a positive predictive value (PPV) of 0.56 and a negative predictive value (NPV) of 0.79. Within a subgroup of 67 patients with an unfiltered QRS duration of <100 ms, the specificity for diagnosing cardiac sarcoidosis improves to 100% with a reduced sensitivity of 36.8. Of the SAECG parameters, LAS40 was significantly associated with the diagnosis of cardiac sarcoidosis for the entire cohort (P < 0.01) and among the subgroup of patients with an unfiltered QRS duration of <100 ms (P < 0.01). CONCLUSIONS: SAECG is a useful screening tool in the evaluation of sarcoidosis for detection of cardiac involvement.