Assessing the effect of repeat positron emission tomography imaging on treatment response and cardiovascular outcomes among a homogenously treated cohort of patients with suspected cardiac sarcoidosis

Background: Serial positron emission tomography (PET) imaging is routinely used to monitor treatment response in patients with suspected cardiac sarcoidosis (CS). Corticosteroids remain the mainstay of therapy in CS. However, there are no data available on the cardiovascular outcomes and optimal timing interval to obtain repeat PET while factoring in the influence of corticosteroid taper in relation to surveillance imaging.

Methods: We identified 81 patients with suspected CS (age: 56.3 ± 1.9, 67% male, left ventricle ejection fraction: 46.5 ± 3) who were not on immunosuppression treatment and demonstrated inflammation on baseline PET, subsequently started on moderate-dose prednisone monotherapy (i.e., 30-40 mg/day), and had a diagnostic follow-up PET. Treatment response was graded as complete treatment response (CTR) or partial treatment response (PTR) vs no response. Patients were divided into tertiles based on follow-up time between PET scans; tertile-1 (<3.2 months; median: 3.1 months), tertile-2 (3.2-6.8 months; median: 5.9 months), and tertile-3 (>6.8 months; median: 9.8 months). Corticosteroid taper was captured by measuring weekly changes in prednisone from the start of treatment to up to one-year follow-up. Major adverse cardiovascular events (MACEs), defined as sustained ventricular arrhythmias, were documented during the first year post baseline PET.

Results: Treatment response CTR/PTR rates were similar across tertiles: (tertile-1 [92%] vs tertile-2 [86.2%] vs tertile-3 [85.2%]; P = .76). Taper rates and one-year cumulative prednisone dose were similar between the three groups (P = .9). No significant difference was found in short-term MACEs between the tertile groups (P = .89). Similarly, MACEs did not differ significantly according to treatment response status (P = .39).

Conclusions: Surveillance time and taper rates do not seem to influence treatment response on PET scans among patients initiated on moderate-dose prednisone only. Similar MACE rates were observed despite variations in follow-up time and treatment response status.