Myocarditis as a Legitimate Phenomenon in Non-Compaction Myocardium: Diagnostics, Management and Influence on Outcomes

Aim. To evaluate the prevalence of myocarditis in adult patients with non-compaction myocardium (NCM) of the left ventricle (LV), and its influence on the disease course, results of treatment and outcomes. Material and methods. To the study, 103 adult patients included, with NCM, 61 males, mean age 45,6±14,9 y. o. (from 18 to 78). Mean end diastolic LV size was 6,0±0,8 сm, EF LV 38,8±14,5%. Diagnosis of NCM had been done by echocardiography, multispiral computed tomography (n=81) and magnetic resonance tomography (n=39). DNA-diagnostics was performed by NGS method with further Senger sequencing. Pathogenic mutations were found in 9% of patients in the genes MYH7, MyBPC3, LAMP2, DES, DSP, TTN. The investigation also included anticardiac antibodies, genome of cardiotropic viruses by PCR, coronary arteriography (n=26), scintigraphy (n=25). Morphological assessment of the myocardium was done in 19 patients (12 endomyocardial biopsies), 1 intraoperation biopsy, 3 explanted hearts, incl. 2 after biopsy, and 5 autopsies. Mean follow-up 12 [2; 32] months. Results. Myocarditis was found in 53,4%, incl. virus-positive in 32,7% of those, with morphology done for 19 patients (active myocarditis in 10, borderline in 6; with minimal signs of activeness in 3). Viral genome in myocardium found in 8 patients (42,1%). The prevalence of myocarditis 44,4% in an arrhythmic variant of NCM, 12,5% in chronic ischemic, 57,5% in dilation cardiomyopathy, 50,0% in NCM patients with other cardiomyopathies. Special cases were acute/subacute myocarditis in NCM (10,7% of all), acute necrosis (infarction) in 4,9%. Comorbidity with myocarditis in NCM led to significantly more severe LV dysfunction (CHF FC 2 [1; 3] v 1,75 [0; 2], p<0,01, EF 33,8±13,5 v 44,7±13,6%, p<0,001), more prevalent non-sustained ventricular tachycardia (67,3% v 29,3%, p<0,01), proper shocks (38,9% v 0, p<0,05), deaths (16,4 and 4,2%, OR 5,75, 95% CI 1,21-27,43, p<0,05) and transplantation (7,3% v 2,1%, p>0,05). Only in myocarditis patients, as a result of basis (antiviral, immune suppression) and cardiotropic therapy there was significant increase of EF (in acute myocarditis from 25,4±7,9 to 38,6±9,5%, p<0,01), decrease of LV size and pulmonary systolic pressure. Conclusion. Myocarditis is typical phenomenon developing in patients with the primary, i. e. genetically verified NCM. The nature of myocarditis in NCM varies (primary infectious-autoimmune, secondary as a response on genetic/ischemic damage of cardiomyocytes), however regardless of this, it leads to significant worsening of structural and functional parameters, increase of the life-threatening arrhythmias rate, and outcomes (death + transplantation, proper shocks), demanding for active basic therapy.