Development of new approaches to the diagnosis of myocarditis and dilated cardiomyopathy

Abstract

Aim. To develop new approaches to the diagnosis of diffuse myocarditis and dilated cardiomyopathy based on the study of immune state as well as structural and functional heart condition. Materials and Methods. The 94 studied patients were divided into 2 groups: the 1st group - 52 patients with chronic diffuse myocarditis and the 2nd group - 42 patients with dilated cardiomyopathy. All patients presented with left ventricular systolic dysfunction - ejection fraction Ј40% and heart failure functional class II or worse. We studied serum levels of mean myocardial antibody titer, immunoglobuline M and G concentrations, blasttransformation lymphocyte activity, and concentrations of СD8+, СD16+ and СD19+ lymphocytes. The heart failure functional class was determined by the 6-minute walk test. By the use of 2D-echocardiography and speckle-tracking we measured left ventricular end-diastolic, end-systolic volume index and ejection fraction as well as the global longitudinal, circumferential, radial systolic strain. Cardiac magnetic resonance imaging with late enhancement was performed in all patients. Results and Discussion. Both study groups were comparable according to the severity of clinical manifestations of heart failure on the results of a 6-minute walk test and left ventricular ejection fraction, which was on average (34,6±2,5)% in the 1st and (32,8±2,7)% in the 2nd group (P>0.05). However, the frequency of myocardial antibodies detection in the 1st group was 53,1%, while in the 2nd group it was 23,3%, the average titer of myocardial antibodies and the activity of the lymphocyte blasttransformation reaction in the group of patients with myocarditis were higher by 21,4% (P<0.05) and 43,3% (P<0.01) respectively, compared with those in dilated cardiomyopathy. The analysis of speckle-tracking echocardiography results showed that in patients with dilated cardiomyopathy parameters of longitudinal and circumferential global systolic strain of the left ventricle were significantly lower compared with those in patients with myocarditis, on average, 45,2% (P<0.01) and 40,2% (P<0.05) respectively. According to the results of magnetic resonance imaging, it was found that myocarditis is characterized by active inflammatory changes in the myocardium, while in dilated cardiomyopathy we did not observe inflammatory changes and 94,2% of patients presented with diffuse fibrosis of the heart muscle. Conclusions. In patients with myocarditis, dilatation and systolic dysfunction of the left ventricle were induced by an active inflammatory process in the myocardium, which according to the correlation analysis was associated with the activation of immunopathological reactions of cellular and humoral immunity and confirmed by the results of cardiac magnetic resonance imaging. Dilated cardiomyopathy is characterized by the low activity of immunopathological reactions of cellular and humoral immunity; diffuse fibrotic changes in the myocardium, which cause dilatation and systolic left ventricular dysfunction; and by a significant decrease in the parameters of longitudinal and circumferential global systolic strain of the left ventricle compared to those in patients with myocarditis.

Keywords

• myocarditis, dilated cardiomyopathy, diagnosis, immune state, speckle-tracking echocardiography