Contribution of concomitant myocarditis to the development of various clinical types of arrhythmogenic right ventricular cardiomyopathy

Aim. To assess the contribution of genetic and inflammatory factors to the development of arrhythmogenic right ventricular cardiomyopathy (ARVC).Material and methods. The study involved 54 patients with ARVC (age, 38,7±14,1 years; men, 42,6%; mean follow-up period, 21 [6; 60] months). All patients underwent electrocardiography (ECG), 24-hour ECG monitoring, echocardiography, determination of anticardiac antibodies and DNA of cardiotropic viruses in the blood, molecular genetic ARVC testing, as well as cardiac magnetic resonance imaging (n=49), high-resolution ECG (n=18), right ventricular endomyocardial biopsy (n=2), and autopsy (n=2).Results. Following four clinical types of ARVC were identified: I. Latent arrhythmic form: characterized by frequent premature ventricular contractions and/or nonsustained ventricular tachycardia (VT). II. Manifested arrhythmic form (n=11) — SVT/ventricular fibrillation (VF). III. ARVC with progressive heart failure (HF, n=8). IV. Combination of ARVC with left ventricular noncompaction (LVNC, n=8). Superimposed myocarditis was identified in 74%, 36%, 87,5% and 85,7% of patients in forms I-IV, respectively. Mutations were detected in 11%, 46%, 50%, and 38% of patients in forms I-IV, respectively. Clinical forms were stable: there was no transition from one clinical form to another during follow-up period.Conclusion. The contribution of genetic and inflammatory mechanisms to the clinical picture is different: in the latent arrhythmic form, the leading role belongs to inflammation; in the manifested arrhythmic form, the contribution of pathogenic mutations prevails, and in ARVC with progressive HF and in combination with LVNC, the contribution of genetic and inflammatory factors is equally important.