Diagnosis, therapeutic response assessment, and detection of disease recurrence in cardiac sarcoidosis: Integral role of cardiac PET.

Sarcoidosis is a systemic disease and recognition of cardiac involvement remains challenging. We report a case and illustrate the integral role of cardiac PET perfusion-metabolic imaging in evaluating various stages of cardiac sarcoidosis. A 61-year-old African-American male presented with a 6-month history of progressive exertional dyspnea, cough, palpitations, and atypical chest pain. Physical exam was consistent with acute heart failure and his baseline EKG showed sinus rhythm with frequent premature ventricular contractions. Chest x-ray showed bilateral hilar adenopathy and telemetry monitoring was significant for multiple runs of nonsustained ventricular tachycardia. Echocardiography showed ejection fraction of 30% with global biventricular hypokinesis. Patient underwent coronary angiogram revealing minimal coronary atherosclerosis. A gadolinium-enhanced cardiac MRI was obtained (Figure 1), and a diagnosis of pulmonary and cardiac sarcoidosis was made following which a dual chamber defibrillator was implanted. Prednisone 20 mg daily and methotrexate 12.5 mg weekly was planned. However, given that treatment response and disease progression assessment could not be achieved with serial cardiac MRI (ICD placed), a baseline rest Rubidium 82/F-18 flourodeoxyglucose (Rb-82/18-FDG) cardiac PET was obtained prior to treatment to be used to then assess treatment response with serial scans as indicated showing pattern consistent with active cardiac sarcoidosis (Figure 2). Treatment was initiated and methotrexate titrated up to 15 mg weekly. He was seen in the clinic five months after medical therapy was initiated. Subjectively reported minimal to no symptoms. A repeat cardiac PET was done (Figure 3) using same protocol to assess response to therapy showed marked improvement. His dose of prednisone was decreased to 10 mg daily and then discontinued. Few months later, amiodarone and methotrexate were discontinued due to early development of interstitial lung disease. Seven months after discontinuation of medical therapy, he developed recurrent heart failure symptoms. Echocardiogram EF was 30%-35%. Repeat cardiac PET was done (Figure 4) showing recurrence of active cardiac sarcoidosis. He was reinitiated on prednisone at 50 mg but refused to take it due to weight gain and did not return for follow-up appointments. This case highlights the role of cardiac PET not only in situations where MRI cannot be used but also following treatment response and disease reactivation which is challenging to assess with cardiac MRI. The emerging importance of cardiac PET in cardiac sarcoidosis is now acknowledged in the recent consensus documents and nuclear societies recommendations 1,2 as an indicator of cardiac sarcoidosis in contrast to prior older imaging criteria for CS which included on SPECT or MRI abnormalities. 3 Whole body imaging to evaluate sarcoid activity in other extra cardiac organs apart from the heart and quantitation of standardized uptake values (SUVmax) to enhance diagnosis of disease activity and response to therapy were not available in our study but are key methods to better evaluate and assess sarcoidosis as shown in recent studies. 4