Purpose: perform a comparative analysis of myocardial biopsy in patients with "idiopathic" arrhythmias and dilated cardiomyopathy (DCM).
Methods: in 74 patients (42 men, 43.6±12,2 years) with "idiopathic" arrhythmias (n = 20) and syndrome of DCM (n = 54) were performed 46 endomyocardial, 14 intraoperative myocardial biopsy, 5 study of explanted hearts, 9 autopsy with virus investigation (real-time PCR). Among "idiopathic" arrhythmias prevailed atrial fibrillation (n = 16). In patients with DCM the average left ventricle diastolic diameter was 6.8±1.1 cm, EF 26.1±11.0%. The control group included 32 patients (16 men, 51.7±12.7 years) with coronary and valvular heart disease, hypertrophic cardiomyopathy, who underwent open-heart surgery.
Results: In group of "idiopathic" arrhythmias myocarditis was detected in 15 patients (75.0%), incl. myocarditis with prevalence of vasculitis (n = 4), endocarditis (n = 2), and also unverified genetic cardiomyopathy in 3 patients, arrhythmogenic right ventricular dysplasia in 1 and Fabry disease in 1. In group of DCM isolated myocarditis was detected in 33 patients (56.9%), with vasculitis (n = 16), endocarditis (n = 6), and also association of myocarditis and cardiomyopathy (arrhythmogenic right ventricular dysplasia, myocardial noncompaction, desminopathy) in 10 patients (18.5%) and postinflammatory sclerosis in 2. In DCM also were diagnosed postradiation cardiomyopathy (n =2), amyloidosis (n =1), Emery-Dreifuss dystrophy (n =1) and unverified genetic cardiomyopathy (n = 5). In control group myocarditis was found only in 25.0% of patients (p < 0.001). Morphological marker of patients with arrhythmias was subendocardial lipomatosis (in 65.0%). In DCM degeneration, hypertrophy of cardiomyocytes and focal fibrosis (16.7%) were typical. Viral genome in the myocardium was detected in 16.7% patients with arrhythmias (parvovirus B19 in 2 cases, herpes virus type 6 in 1), in 55.3% patients with DCM (parvovirus B19 in 16 cases, herpes virus type 6 in 11, cytomegalovirus in 4, Epstein-Barr virus in 7, herpes simplex virus in 5, incl. mixed infection in 10) and in 64.7% patients of control group (p < 0.001 with group of arrhythmias).
Conclusions: The etiologic structure of "idiopathic" arrhythmias and syndrome of DCM is very similar and represented mainly by myocarditis, different forms of genetic cardiomyopathias and its associations. The frequency of virus detection in the "idiopathic" arrhythmias significantly lower than in DCM and control group. Cytomegalovirus, Epstein-Barr virus and mixed infection were significantly more frequent in DCM.