The Utility of BMIPP SPECT and Late Gadolinium Enhancement MRI: Prognostic Value in Patients with Cardiac Sarcoidosis

Introduction: Sarcoidosis is a systemic chronic inflammatory disease characterized by the presence of noncaseating granulomas. Cardiac involvement is one of the major causes of disease-related death. Steroid therapy is the mainstay of treating cardiac sarcoidosis (CS). Previous studies reported that late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) could predict prognosis in patients with CS. However, the evaluation of LGE was limited due to implant of cardiac device or renal dysfunction. ¹²³I-betamethyl-p-iodophenyl-pentadecanoic acid single-photon emission computed tomography (BMIPP) was developed to evaluate fatty acid metabolism and effective in detecting myocardial damage in CS. Present study aimed to investigate the relationship between LGE and myocardial damage obtained from BMIPP SPECT, and to explore the potential of BMIPP SPECT as prognostic factors in CS patients undergoing steroid therapy.

Methods: Forty-five CS patients who underwent BMIPP SPECT and LGE-CMR within 2 months were enrolled. The left ventricle was divided into 17 myocardial segments on BMIPP and LGE-CMR. BMIPP defects were assessed in each segment using a scoring system from 0 to 4 (0 normal; 1 mild; 2 moderate; 3 severe; 4 absent), and total BMIPP defect score (BDS) in the entire left ventricle were calculated. LGE in each segment was assessed using a scoring system from 0 to 2 (0 none; 1 partially positive; 2 homogeneously positive), and total LGE extent score (LES) in the entire left ventricle was also calculated. The relationship between BDS and LES was examined using Pearson’s correlation coefficient. The predictability of the BDS and LES for major adverse cardiac events (MACE), consisting of all-cause death, hospitalization due to heart failure, and recurrence or onset of sustained ventricular tachycardia and ventricular fibrillation, was analyzed using Kaplan–Meier analysis.

Results: BDS of the group with MACE was significantly higher than that of the group without MACE (25±14 vs. 11±10, p = 0.0008). LGE of patients with MACE was also significantly higher than that of patients without MACE (12.2±5.4 vs. 6.9±4.9, p = 0.0045). BDS showed a significant correlation with LES (r = 0.88, p < 0.0001). Patients with LES ≥9 had a significantly higher MACE rate than patients with BDS <9 (log-rank test, p = 0.0098). Patients with BDS ≥16 also had a significantly higher MACE rate than patients with BDS <16 (log-rank test, p = 0.0029).

Conclusions: Myocardial damage assessed by BMIPP SPECT correlated with LGE extent. Both BDS and LES have the predictive values of MACE in CS.In CS, many patients have cardiac devices implanted, including defibrillation, which limits the evaluation of CMR. In comparison, BMIIPP has the advantage of being performed without the influence of cardiac devices.

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