Serum Levels of IgG4 in Patients Elevated in Acute Idiopathic Myocarditis

Background: IgG4 is a subgroup of immunoglobulin superfamily of serum proteins, which is involved in IgG4-related disease. Recently elevated IgG4 levels were observed in coronary artery disease. Its role in pathophysiology of acute idiopathic myocarditis has not yet been investigated.

Aim: To investigate the potential role of IgG4 in acute myocarditis

Methods and Patients: Patients with acute idiopathic myocarditis admitted to our institution were included in this study. Clinical, laboratory and echocardiographic data were collected. Serum concentrations levels of IgG4 were measured in patients with myocarditis and compared with those of healthy volunteers.

Results: Thirty patients with acute myocarditis comprised (mean age 32±8.45 years, 93.3% male) were included in this study. The mean IgG4 concentration was 113±90.3 mg/dL, mean troponin was 10±9 ng/dL and mean LVEF 48.0±6.2%. The mean serum levels of IgG4 were significantly higher in patients with myocarditis compared to healthy controls (50.28±28.76 mg/dL, p<0.001). The serum concentrations of IgG4 inversely correlated with LVEF (r =-0.33) and there was a strong association between serum IgG4 levels and serum troponin (r=0.64).

Conclusions: Increased IgG4 levels were found in patients with acute myocarditis. In addition, they were associated with higher levels of troponin and lower LVEF suggesting the possible role of IgG4-related immune-inflammation in myocarditis.