Modern critical approach to the diagnosis of acute viral myocarditis and inflammatory cardiomyopathies in clinical practice: Focus on the roles of echocardiography and antivirus antibodies
Authors: Bastać Dušan , Tirmenštajn-Janković Biserka , Marušić Predrag , Joksimović Zoran , Čvorović Vojkan , Bastać Mila , Raščanin Anastasija , Jelenković Bratimirka , Vasić Brankica 
Published: November 2021

SIGNIFICANCE OF THE PROBLEM: The diagnosis of acute viral myocarditis is one of the diagnoses most difficult to make in cardiology and medicine in general. Echocardiography and cardiomagnetic resonance play a crucial role in the clinical diagnosis and the serum titer of antiviral antibodies to cardiotropic viruses is still unjustifiably used for the diagnosis of myocarditis in everyday practice. RESEARCH OBJECTIVES: To analyze the frequency and significance of echocardiographic parameters in the diagnosis of clinically suspected acute viral myocarditis, to determine the role of antiviral antibody titer (AVA) dynamics for the diagnosis of myocarditis and to compare viral serology and echocardiographic function versus echocardiographic function. METHODOLOGY: A retrograde transverse study was performed in the ten-year period from 2006. to 2015, where 126 consecutive patients from the database of the Office of Internal medicine ''Dr. Bastać'' were analyzed, with a working diagnosis of clinically suspected viral myocarditis. They were clinically, ECG, echocardiographically and serologically monitored for 4 to 8 weeks due to the dynamics of AVA titer. The examined group (A) was divided into subgroups: A1 with elevated AVA class IgM titer in 43 (32%) subjects and subgroup A2 without elevated IgM titer in 83 (68%) patients. The control group of healthy (B) of 103 subjects was comparable.Statistical processing was done in the EXCELL database via descriptive statistics, Student's-T test and Chi2 test. RESULTS: 126 patients had clinically suspected myocarditis (≥2 ESC criteria). Diastolic left ventricular dysfunction in 39/126 (31%) patients was the dominant echocardiographic criterion for clinically suspected myocarditis. Reduced ejection fraction (EF <50%) was measured at 19/126 (15%), followed by left ventricular dilatation. Regional systolic dysfunction was found in 21/126 (17%) and changes in myocardial texture in 17 (13%) subjects. The clinical probability of viral etiology was diagnostically supported by elevated titer of IgM antibodies in 43 (32%) subjects (subgroup A1) where IgM antibodies to Parvo B 19 virus predominate in 36/43 patients (84%). Most were without elevated titer of IgM antibodysubgroup A2 83 (68%). Clear dynamics of IgM antibody titer was observed in 23 persons, a decrease in IgM titer with an increase in IgG titer (seroconversion) in 13 patients. Determination of anti-heart autoantibodies (AHA) was done in 17 severe cases, of which 9 had positive AHA. A comparison of subgroups A1 and A2 did not reveal a statistically significant difference in echocardiographic parameters. The whole group A of clinically suspected myocarditis compared to control group B has statistically highly significantly lower parameters of global systolic (EF=8,7±4,6 vs. 63±7,9; p<0,001), longitudinal systolic (S'=6,9±1,3 vs. 9,9±2,1) and diastolic function (E/e'11,9±4,8 vs. 8,7±4,6; p<0,001), and a highly statistically significant increase in left ventricular telediastolic dimension, myocardial mass index, and left atrial size. CONCLUSION: The diagnosis of acute viral myocarditis in clinical practice is made on the basis of the clinical picture, ECG and echocardiography that indicate myocarditis with the exclusion of cardiac comorbidities, based on the ESC criteria for suspected clinical myocarditis. The whole group A had highly statistically significantly lower parameters of systolic and diastolic function compared to control group B. Normal ECG and echocardiography cannot serve to exclude the diagnosis of myocarditis. Comparison of subgroups A1 and A2 did not reveal a statistically significant difference in echocardiographic parameters.