Prevalence of myocarditis and its contribution to the course of primary myocardial hypertrophy

Aim. To assess the incidence of myocarditis in patients with primary myocardial hypertrophy and to study its contribution to the disease course.Material and methods. The study included 100 patients with primary left ventricular myocardial hypertrophy, 52 men and 48 women (mean age, 51,5±15,7 years; followup period 10,4 [2,1; 36,1] months). All patients underwent electrocardiography, 24-hour electrocardiographic monitoring, echocardiography, as well as DNA analysis (n=96), myocardium pathological study (n=29), cardiac magnetic resonance imaging (n=31), cardiac multislice computed tomography (n=26), assessment of anti-cardiac antibodies (n=43), free light chain level in serum and urine by immunofixation method (n=10); 99mTc-pyrophosphate myocardial scintigraphy (n=5); biopsy of the rectal mucosa and/or subcutaneous fat for amyloid (n=9).Results. In 68%, true (sarcomeric) hypertrophic cardiomyopathy (HCM) was diagnosed, in 16% — amyloidosis with cardiac involvement, in 10% — storage diseases, in 3% — neuromuscular diseases, in 2% — myocardial hypertrophy was combined with severe restriction (mixed phenotype), and in 1% — LEOPARD syndrome. Concomitant myocarditis was diagnosed in 30% of patients. In HCM, myocarditis was detected in 31% of cases. These patients had a significantly higher heart failure class (heart failure class 3 [2; 3] vs 2 [1; 3], p=0,026) and mortality (33,3% vs 6,4%, p=0,01). In amyloidosis, the incidence of myocarditis was 31,3%. In these patients, ventricular tachycardia was observed significantly more often: 80,0% vs 18,2% (p=0,036). The prevalence of concomitant myocarditis in the subgroup of storage diseases was 30%: 2 patients with Fabry disease and 1 patient with Danon disease. Of the three patients with neuromuscular diseases, myocarditis was diagnosed in 1. In the subgroups with the restrictive phenotype and LEOPARD syndrome, no cases of myocarditis were recorded. Treatment of myocarditis made it possible to stabilize the patients' condition.Conclusion. Concomitant myocarditis led to heart failure progression, worsening ventricular arrhythmias and, as a consequence, an increased risk of sudden cardiac death. It is necessary to actively diagnose and treat myocarditis in patients with primary myocardial hypertrophy.