Elevated 18F-fluorodeoxyglucose uptake in the interventricular septum is associated with atrioventricular block in patients with suspected cardiac involvement sarcoidosis

Cardiac involvement in sarcoidosis is one of the leading causes of death associated with abnormalities of the conduction system. F-18-FDG PET is useful for detecting inflammatory lesions in cardiac sarcoidosis. However, the relationship between ECG abnormalities and focal F-18-FDG uptake has not been studied. The aim of this study was to evaluate the relationship between electrocardiogram (ECG) abnormalities and the location of elevated myocardial F-18-FDG uptake in patients with sarcoidosis. Included in the study were 50 patients (56.3 +/- 14.9 years old) with histologically proven sarcoidosis with suspected cardiac involvement based on ECG or echocardiography. All patients had fasted for at least 6 h and were given unfractionated heparin (50 IU/kg) intravenously to reduce the physiological F-18-FDG uptake in the myocardium. The left ventricle (LV) wall was divided into 17 segments by visual analysis. Obvious accumulation in each segment was defined as positive. Of the 50 patients, 33 showed some ECG abnormalities, including atrioventricular (AV) block in 13. Patients with abnormal ECG findings had a higher number of regions with F-18-FDG uptake than patients without ECG abnormality (3.48 +/- 2.73 vs. 1.41 +/- 2.09 regions, p=0.0051). Among ECG abnormalities, the predictor for interventricular septum wall F-18-FDG involvement was AV block (p=0.0025). Patients with ECG abnormalities showed a higher number of abnormal F-18-FDG myocardial uptake regions than patients without ECG abnormalities. In particular, focal F-18-FDG uptake in the interventricular septum in cardiac sarcoidosis was associated with AV block. Therefore, determination of regional F-18-FDG distribution might contribute to patient management in cardiac sarcoidosis.