Study objective: To examine the diagnostic and prognostic value of myocardial scintigraphy using thallium-201 and gallium-67 in cardiac sarcoidosis.
Patients: Twenty-five patients with sarcoidosis.
Methods: All patients underwent myocardial thallium-201 scintigraphy. Six patients with myocardial thallium-201 defects were classified into group A and another 19 without defects were classified into group B. Between group A and B, we compared the results of other noninvasive examinations, including standard 12-lead ECG, 24 h ambulatory ECG, chest radiography, measurements of serum angiotensin-converting enzyme (ACE) and lysozyme levels, and gallium-67 scintigraphy.
Results: Proportions of subjects who had varying degrees of heart block, severe ventricular arrhythmias (more than or equal to third grade of Lown's classification), and high levels of serum ACE and lysozyme levels were not different between these two groups (p > 0.05). Although an enlarged cardiothoracic ratio was more frequent in group A (p < 0.05), bilateral hilar lymphadenopathy was more frequent in group B (p < 0.01). Four patients of group A and 15 of group B underwent gallium-67 scintigraphy. Although no subjects of group B had myocardial uptake of gallium-67, two of four group A patients showed cardiac uptake. These four group A patients were treated with corticosteroids. The therapy provided clinical and scintigraphic improvement in two patients with myocardial gallium-67 uptake, although it did no improvement in the other two patients without gallium-67 uptake.
Conclusions: When cardiac sarcoidosis was diagnosed according to myocardial thallium-201 defects, other noninvasive examinations were not useful to detect this disease. However, gallium-67 uptake may predict the efficacy of corticosteroids. Thus, the combination of thallium-201 and gallium-67 scintigraphy may be useful not only in diagnosis of cardiac sarcoidosis but also in prediction of effects of corticosteroids.