Dynamic changes of heart structural and functional condition in patients with acute myocarditis

Abstract

Diagnosis and prognosis of myocarditis course, which is an inflammatory heart muscle disease, has been and remains one of the most urgent, complex and unresolved problem in modern cardiology. The purpose of the study – to investigate the dynamic changes in the structural and functional heart state in patients with acute myocarditis and reduced left ventricular ejection fraction. Materials and methods. In total, 74 patients with clinically suspected acute myocarditis (AM) with reduced left ventricular (LV) ejection fraction (EF) ≤40 % and NYHA heart failure (HF) functional class II or higher were examined three times: in the first month of myocarditis debut, after 6 and 12 months of observation. All the patients underwent echocardiography and speckle-tracking echocardiography, Holter electrocardiogram monitoring and cardiac magnetic resonance imaging (MRI). Results. It was found that the debut of AM was characterized by the presence of active inflammatory process according to the cardiac MRI - edema and hyperemia of the myocardium were detected in 54.0 % and 70.2 % of cases, respectively, followed by LV dilation and systolic dysfunction as well as by a significant decrease in longitudinal and circumferential LV global systolic strain. After 12 months of observation, there was a significant increase in LV EF, decrease in end-diastolic volume index and an improvement in the parameters of longitudinal and circumferntial LV systolic strain by 30.8 % and 36.8 %, respectively, (P < 0.01), the frequency of active inflammatory changes in the myocardium was significantly reduced, herewith in 41.8 % of cases, delayed enhancement was noted, indicating fibrotic changes in the myocardium. The presence of delayed enhancement in cardiac MRI after 12 months since myocarditis onset was correlated with the presence of unstable ventricular tachycardia episodes (r = 0.62; P < 0.02) and with the frequency of ventricular extrasystoles (r = 0.53; P < 0.05). A significant influence of fibrotic changes in the myocardium on the presence of unstable ventricular tachycardia episodes in 12 months after the disease onset was confirmed by determining Fisher's exact test, its value was: P = 0.016 (P < 0.05). Conclusions. It was established that the debut of myocarditis was characterized by a significant violation of the structural and functional heart state: an active inflammatory process in the myocardium causedLV dilatation and contractile dysfunction. After 12 months, a decrease in detection of active inflammatory myocardial changes followed by regression ofLV dilation and its contractile function improvement was observed. It was proved that the presence of fibrotic changes in the myocardium in patients with myocarditis was associated with the persistence of ventricular rhythm disorders.