P5564The myocarditis as a regular phenomenon in primary noncompact myocardium: clinical and morphological diagnostics, significance and treatment

Abstract

Abstract Purpose To estimate the frequency of myocarditis in adult patients with noncompact myocardium (NCM) of the left ventricle (LV), its influence on the disease, the outcome and results of treatment. Methods We included 103 adult patients with NCM (61 males, 45.6±14.9 years). The average EDD LV was 6.0±0.8 cm, LV EF 38.8±14.5%. To diagnose NCM were performed Echo-CG, CT (n=81) and MRI (n=39). We performed NGS sequencing, followed by Sanger sequencing of detected variants (revealed in 9% of patients in the genes MYH7, MyBPC3, LAMP2, DES, DSP, TTN). The examination also included anti-heart antibodies and viruses (PCR) study and morphological study in 19 patients (endomyocardial biopsy in 14, intraoperative biopsy in 1, explanted heart study in 1 and autopsy in 3). The mean follow-up was 12 [2; 32] months. Results The myocarditis was diagnosed in 55 (53.4%) patients with NCM: in 19 patients by morphological study (active in 10 and borderline in 9 patients) and in 36 patients on the basis of a complex examination (the relationship with a respiratory infection, a 3–4-fold increase in the anti-heart antibodies, the viral genome in the blood, pericardial effusion, subepicardial LGE). The myocarditis was virus-positive in 17 patients (36.1%). The parvovirus B19, human herpes virus type 6, cytomegalovirus, herpes simplex virus and Epstein-Barr virus were detected in the myocardium in 8 patients (42.1%), and in 14 patients (25.5%) in the blood. Pathogenic genetic variants were revealed in four patients with morphologically verified myocarditis. The rate of myocarditis depended on the clinical form of NCM: 44.4% in arrhythmic form, 12.5% in chronic ischemic form, 57.5% in dilated pattern and 50.0% in association of NCM with other cardiomyopathies. In 10% of all patients, acute myocarditis was the first manifestation of the disease. In 5% the myocardial necrosis was the main manifestation of the myocarditis. The association of NCM with myocarditis led to more severe myocardial dysfunction (NYHA class 2 [1; 3] v 1.75 [0; 2], p<0.01, EF 33.8±13.5 v 44.7±13.6%, p<0.001), higher rate of the nonsustained ventricular tachycardia (67.3% v 29.3%, p<0.01), appropriate shocks of defibrillators (38.9% v 0, p<0.05), death (16.4 and 4.2%, OR 5.75, 95% CI 1.21–27.43, p<0.05), and heart transplantation (7.3% v 2.1%, p>0.05). Only in patients with myocarditis, there was a significant increase in EF (in acute myocarditis from 25.4±7.9 to 38.6±9.5%, p<0.01), decrease sizes of the LV and systolic pulmonary artery pressure as a result of basic therapy. Morphological verification of myocarditis Conclusion Myocarditis is a regular phenomenon that develops in half of patients with primary NCM. The nature of myocarditis in NCM may be different (primary infectious and immune, secondary in response to genetic/ischemic damage to cardiomyocytes). However, it leads to a significant deterioration of structural and functional parameters, an increase in life-threatening arrhythmias, unfavorable outcomes and requires basic therapy.