New Guidelines for Cardiac Sarcoidosis in Japan Yield Higher Number of Diagnoses

New diagnostic guidelines for cardiac sarcoidosis yield a higher number of diagnoses and identify more cases of isolated cardiac sarcoidosis (iCS), according to a study in Japan.

In cardiac sarcoidosis, inflammatory clusters of white blood cells — called granulomas — affect the heart but can also affect other organs. In contrast, the heart is the only affected organ in cases of iCS.

The study, “Diagnosis of isolated cardiac sarcoidosis based on new guidelines,” was published in the journal ESC Heart Failure.

The Japanese Circulation Society (JCS) recently updated its guidelines for diagnosing iCS. One of the updates sets as a major diagnostic criteria the presence of abnormally high accumulation of the diagnostic tracer 18F‐fluorodeoxyglucose (FDG) in the heart. FDG is used in positron emission tomography/computed tomography (FDG‐PET/CT). Another new criterion is late‐gadolinium enhancement of the myocardium (heart muscle) in gadolinium‐enhanced MRI scans.

These tracers allow physicians to better visualize the tissue damage that sarcoidosis can incur.

The issuance of these new guidelines prompted researchers in Japan to evaluate past records using the two sets of diagnostic criteria — the previous conventional criteria and the new ones — to see how the new guidelines might affect diagnosis.

The study analyzed 94 records of suspected cardiac sarcoidosis patients (mean age of 61 years) who underwent whole-body or cardiac FDG-PET/CT scanning between January 2013 and August 2019. None of the patients had taken corticosteroids before the study.

Among the cohort analyzed, 22 patients were diagnosed with cardiac sarcoidosis based on conventional international criteria. When the new JCS guidelines were applied to this cohort, this number rose to 34 — 27 with systemic sarcoidosis and seven with definitive iCS.

Of the remaining 60 patients not diagnosed with cardiac sarcoidosis under the new guidelines, four were judged to have suspected iCS, 13 had systemic sarcoidosis without cardiac involvement, and the remaining 43 were deemed to have no sarcoidosis.

Of the 72 patients not diagnosed with cardiac sarcoidosis under the conventional guidelines, 16 met the new criteria for diagnosis of the disease. In contrast, four of the 22 who met the conventional criteria did not meet the new JCS criteria for a positive diagnosis of cardiac sarcoidosis.

The team also assessed corticosteroid administration, as these treatments are often used to help manage sarcoidosis symptoms.

Twenty-six of the 34 cases identified by the new guidelines, and six of the 60 identified without cardiac sarcoidosis received corticosteroids.

In comparison, 18 of 22 patients who met the conventional criteria for cardiac sarcoidosis and 14 of the 72 who did not met the criteria received corticosteroids, translating to a higher percentage of corticosteroid prescription.

Although this study had some limitations, including its retrospective nature of a relatively small patient sample from a single center, the researchers suggested that the new JCS guidelines appear to result in higher cardiac sarcoidosis and iCS diagnoses compared to the conventional international criteria.

“Diagnostic yield with the new JCS guidelines was higher, with approximately 1.5‐fold of the patients diagnosed with CS compared with the previous international criteria and definitive iCS accounting for approximately 20% of the whole CS cohort,” the researchers wrote.

In some cases, the initial FDG-PET/CT scan was negative, although subsequent scans turned up positive. Because of this, the researchers argue that any patient suspected of having cardiac sarcoidosis should be carefully observed, even when the first scan is negative.