Underdiagnosis of cardiac sarcoidosis by ECG and echocardiography in cases of extracardiac sarcoidosis

Abstract

Background: Although screening with 12-lead electrocardiography and transthoracic echocardiography for cardiac involvement has been recommended for patients with biopsy-proven extracardiac sarcoidosis, cardiac sarcoidosis has been reported even in patients with normal electrocardiography and echocardiography findings. We investigated the prevalence and characteristics of these patient cohorts.

Methods: We studied 112 consecutive patients (age, 55±17 years, 64% females) with biopsy-proven extracardiac sarcoidosis who had undergone ¹⁸F-fluorodeoxyglucose positron emission tomography and cardiac magnetic resonance imaging for cardiac sarcoidosis evaluation. The patients were categorised as those showing normal findings both in electrocardiography and transthoracic echocardiography (normal group) and those showing abnormal findings in one or both examinations (abnormal group).

Results: 33 (29%) and 79 (71%) patients were categorised into the normal and abnormal groups, respectively, of which 6 (18%) and 43 (54%) patients, respectively, were diagnosed with cardiac sarcoidosis (p<0.01). Of these six patients in the normal group, two with multiple-organ sarcoidosis showed clinical deterioration of cardiac involvement and required steroid therapy; three with small cardiac involvement showed natural remission over follow-up assessments; and one underwent steroid therapy and showed an improvement in the left ventricular ejection fraction to within normal limits.

Conclusions: The prevalence of cardiac sarcoidosis in patients with biopsy-proven extracardiac sarcoidosis and normal electrocardiography and transthoracic echocardiography findings was ∼20%. Electrocardiography and transthoracic echocardiography may not detect cardiac sarcoidosis in patients without conduction and morphological abnormalities. However, some of these patients may subsequently show clinically manifested cardiac sarcoidosis. Physicians should be mindful of this population.

FIGURE 1

Frequency of positive scans. a) Positive ¹⁸F-fluoro-deoxyglucose positron emission tomography (¹⁸F-FDG PET) findings consistent with cardiac sarcoidosis (CS) were recorded in 27% of the patients in the normal group and 53% of those in the abnormal group, with the frequency of positive findings being significantly higher in the abnormal group (p=0.012). b) Positive cardiac MRI (CMR) findings consistent with CS were recorded in 42% of the patients in the normal group and 71% of those in the abnormal group, with the frequency of positive findings being significantly higher in the abnormal group (p=0.005). ECG: electrocardiography; TTE: transthoracic echocardiography.

FIGURE 2

Study flow and prevalence of cardiac sarcoidosis. A flow diagram illustrating the classification of normal and abnormal groups based on the ECG and TTE results. Six of the 33 patients (18%) in the normal group and 43 of the 79 patients (59%) in the abnormal group were diagnosed with CS on the basis of Japanese guidelines, with a significantly higher frequency in the abnormal group (p=0.0004). CS: cardiac sarcoidosis; ECG: electrocardiography; TTE: transthoracic echocardiography.

FIGURE 3

Representative images (small cardiac lesion) (patient 1 in table 2). a). Maximum intensity projection ¹⁸F-fluoro-deoxyglucose positron emission tomography (¹⁸F-FDG PET) image shows ¹⁸F-FDG uptake in the mediastinal, bilateral hilar and abdominal lymph nodes and heart. b) ¹⁸F-FDG PET image shows focal myocardial ¹⁸F-FDG uptake in the right ventricular papillary muscle (arrow). c) Late gadolinium-enhanced magnitude inversion recovery image in the short axis shows hyperenhancement in the right ventricular papillary muscle (arrow).

FIGURE 4

Representative images (multiorgan involvement) (patient 5 in table 2). a) Maximum intensity projection ¹⁸F-fluoro-deoxyglucose positron emission tomography (¹⁸F-FDG PET) image shows ¹⁸F-FDG uptake in the mediastinal, bilateral hilar and abdominal lymph nodes, spleen and heart. b) ¹⁸F-FDG PET image shows focal myocardial ¹⁸F-FDG uptake in the mid-segments of the anteroseptal and inferior walls (arrows). c) Late gadolinium-enhanced magnitude inversion recovery image in the short axis shows hyperenhancements in the mid-segments of the anteroseptal and inferior walls (arrows).

FIGURE 5

A case with reduced LV ejection fraction (LVEF) (patient 6 in table 2). a) Maximum intensity projection ¹⁸F-fluoro-deoxyglucose positron emission tomography (¹⁸F-FDG PET) image shows ¹⁸F-FDG uptake in the mediastinal lymph nodes and heart. b) ¹⁸F-FDG PET image shows focal myocardial ¹⁸F-FDG uptake in the basal segment of the anteroseptal wall (arrow). c) Late gadolinium-enhanced magnitude inversion recovery image in the short axis shows hyperenhancements in the basal segment of the anteroseptal wall (arrow).