Clinical history of acute myocarditis in patients with preserved left ventricular ejection fraction

Abstract

The aim – to investigate the dynamic changes of the structural and functional state of the heart and the persistence of cardiac rhythm disorders in patients with acute myocarditis with preserved left ventricular ejection fraction (LV EF) during 6 months of follow-up.Materials and methods. 54 patients with acute myocarditis and preserved LV EF (> 40 %) of the left ventricle (LV) were screened. The examination was performed twice: in the first month from the debut of myocarditis and in 6 months of follow-up. Results and discussion. According to data obtained by CMR, in the 1st month from the disease onset, the early contrast on T1-weighted images and/or the high intensity of the signal on T2 images were detected in all patients, with their percentage being 66.6 % and 62.9 % respectively, and late enhancement was observed in 14.8 % of cases. After 6 months of observation, edema and myocardial hyperemia were detected only in 7.4 and 9.2 % of cases, and fibrotic changes were in 37.0 % of patients, while 59.2 % of patients had no pathological changes on CMR at all. The average number of affected by inflammatory changes LV segments in the 1st month was 2.33±0.23, and after 6 months it decreased to 1.43±0.17 segments (р<0.01). The value of LV EF increased from 47.3±2.3 % in the 1st month to 56.2±2.5 % after 6 months (р<0.05) of follow-up, and detection of non-sustained ventricular tachycardia (NSVT) episodes decreased from 20.4 % cases in the 1st month to 7.4 % of cases after 6 months. According to the results of the correlation analysis, a strong direct correlation was established between the number of LV segments involved in the inflammatory process in the 1st month from the myocarditis onset (r=0.81, р<0.01) as also after 6 months (r=0.72; р<0.01) and the presence of NSVT episodes, that was also confirmed by determining the exact Fisher criterion (p=0.019), statistically reliable correlations of the same direction were also established between the presence of NSVT episodes and fibrotic changes on cardiac MRI.Conclusions. For patients with acute myocarditis with a preserved LV EF, the absence of severe violations of the LV contractile function is characterized by a small amount of inflammatory lesions of myocardium. Clinically significant cardiac rhythm disorders, in particular episodes of non-sustained ventricular tachycardia, can be observed in these patients in the absence of significant violations of the structural and functional heart state and are associated with a greater number of LV segments affected by inflammatory and fibrotic changes.