Background: Electrocardiographic conduction abnormalities including development of atrioventricular block, bundle branch block or ventricular arrhythmias are characteristic manifestations of cardiac sarcoidosis (CS). The present study seeks to show the minute conduction abnormality by detection of late potentials (LP) on signal averaged electrocardiogram (SAECG).
Methods and results: Ten patients with CS, 52 patients with pulmonary sarcoidosis (PS) but no obvious cardiac manifestations and 52 normal controls were studied. All participants underwent SAECG to detect LP. In patients with CS (the CS group), LP were detected in 8 patients (80%). In 52 patients with PS, LP were detected in 25 patients (46.2%, PS-LP(+) group), comparing only 3 (5.8%) of normal controls (p<0.0001). The remaining 27 patients with PS with negative LP were classified in the PS-LP(-) group. In the CS group, premature ventricular contraction frequency on Holter's monitoring and plasma B-type natriuretic peptide concentrations were significantly higher than those in the PS group. However, no significant difference in these parameters between PS-LP(+) and PS-LP(-) groups were found.
Conclusions: In the PS patients without obvious cardiac manifestations, LP were detected as high as 46.2%, suggesting latent minute conduction abnormality. The higher incidence of LP in PS might be considered as an expression of latent myocardial fibrosis. Close follow-up is needed in these patients.