Additive Value of Cardiac Dyssynchrony Parameters using Rest Myocardial Perfusion SPECT in the Diagnosis of Cardiac Sarcoidosis: A Cross-sectional Analytical Study.

Background: Cardiac sarcoidosis is a challenging condition to diagnose with potentially severe consequences. Early diagnosis is crucial, but existing criteria help in diagnosis, not without limitations. This study explores the status of cardiac dyssynchrony parameters measured through gated myocardial perfusion single-photon emission computed tomography (SPECT) in diagnosing cardiac sarcoidosis.

Methods: We conducted a retrospective analytical study using data from patients who underwent cardiac inflammation imaging study (which includes myocardial perfusion SPECT and fluorodeoxyglucose positron emission tomography (FDG PET) under cardiac inflammatory protocol) between September 2018 and September 2021. The images were analyzed independently by two experienced nuclear medicine physicians. The patients were categorized as sarcoidosis positive or negative based on the Japanese Circulation Society (JCS) 2016 guidelines. Cardiac dyssynchrony parameters were assessed using phase analysis of the gated SPECT study.

Results: Among the 22 patients (11 males, 11 females), 9 were positive for cardiac sarcoidosis according to JCS 2016 criteria. Data from 9 normal control subjects were analyzed separately. The dyssynchrony parameters assessed on gated SPECT studies were significantly higher in sarcoidosis-positive patients (mean phase standard deviation [PSD] =43.05 and phase histogram bandwidth [PHB] =108.11) compared to normal control subjects (mean PSD = 19.68 and PHB = 56.22, = 0.01). However, these parameters did not show a significant difference compared to sarcoidosis-negative patients (mean PSD = 51.13, mean PHB = 143.23, = 0.293).

Conclusion: Cardiac dyssynchrony parameters from gated myocardial perfusion SPECT are higher in sarcoidosis patients when compared to the normal control subjects. The potential role in aiding the diagnosis of early cardiac sarcoidosis should be further investigated. To validate these findings and assess their clinical utility, further research is needed with larger sample sizes, early-stage disease, and elimination of confounding factors.