Cardiovascular outcomes among giant cell myocarditis compared with cardiac sarcoidosis: A propensity score-matched analysis.

Background: Giant cell myocarditis (GCM) and cardiac sarcoidosis (CS) are rare inflammatory diseases of the myocardium with poor prognosis. Cardiovascular disease outcomes among both diseases have not been well studied with limited literature.

Objective: This study aims to investigate the cardiovascular outcomes among patients with GCM and CS.

Method: We queried the TriNeTX Global Collaborative Network for adult patients with giant cell myocarditis and cardiac sarcoidosis between January 2000 to May 2023 and created two groups: one with giant cell myocarditis and second with cardiac sarcoidosis. Both the groups were followed for 6 months and 12 months.

Result: After propensity score matched analysis (PSM), among the 4804 patients (2402 patients in each group), the mean age of patients was 57.1 and 57.6 years in GCM and CS groups, respectively. PSM analysis showed that primary outcome i.e., all-cause mortality was significantly higher in GCM group both after 6 months [relative risk (RR) 2.33, 95 % confidence interval (CI): 1.64-3.30, p < 0.01] and 1 year follow up [RR, 1.54 (95 % CI: 1.20-1.98), p < 0.01] as compared with CS group. However, secondary outcomes i.e., heart failure (HF) at 6 month (RR 0.66, 95 % CI: 0.52-0.85, p < 0.01), and at 1 year (RR 0.60, 95 % CI: 0.49-0.73, p < 0.01), ventricular tachycardia (VT) at 6 months (RR 0.34, 95 % CI: 0.25-0.46, p < 0.01), and at 1 year (RR 0.32, 95 % CI: 0.25-0.41, p < 0.01), atrioventricular (AV) node block at 6 month (RR 0.45, 95 % CI: 0.33-0.61, p < 0.01), and at 1 year (RR 0.43, 95 % CI: 0.34-0.55, p < 0.01), and atrial flutter and fibrillation (AF) at 6 months (RR 0.67, 95 % CI: 0.48-0.94, p = 0.02), and at 1 year (RR 0.59, 95 % CI: 0.45-0.76, p < 0.01) were found significantly lower in GCM group as compared to CS group. On the other hand, heart transplant incidence was comparable between both the groups.

Conclusion: These findings suggest that GCM patients have high risk of mortality and lower risk of HF, VT, AV node block, and AF when compared with CS.