Effectiveness of myocarditis therapy depending on the diagnosis approach (with or without myocardial biopsy)

Aim . To evaluate the effectiveness of myocarditis therapy depending on the diagnosis approach (with or without myocardial biopsy). Material and methods . The study included 83 patients ≥18 years old with severe and moderate myocarditis (25 women and 58 men; mean age, 45,7±11,7 years), established by myocardial biopsy (group 1, n=36) or by a non-invasive diagnostic algorithm (group 2, n=47), for which immunosuppressive therapy (IST) was carried out. Inclusion criteria were left ventricular (LV) end-diastolic dimension >5,5 cm and ejection fraction (EF) <50%. An endomyocardial (n=31) or intraoperative (n=5) biopsy with a study of the viral genome and level of anticardiac antibodies were performed. Coronary angiography (29%), cardiac multislice computed tomography (75%), cardiac magnetic resonance imaging (41%), and 99m Tc-MIBI scintigraphy (35%) were also carried out. The mean follow-up period was 3 years (36 [12; 65] months). The study was approved by the Intercollegiate Ethics Committee. Results . The groups were completely comparable in age, baseline parameters (class III [2,25; 3] and III [2; 3] heart failure (HF); end-diastolic LV dimension, 6,7±0,7 and 6,4±0,7 cm; EF, 29,9±8,7 and 31,4±9,3%), the extent of cardiac therapy (excluding the administration rate of в-blockers — 94,4 and 78,7%, p<0,05) and 1ST (methylprednisolone in 91,7 and 89,4% of patients at a mean dose of 24 [16; 32] and 20 [15; 32] mg/day, azathioprine in 50,0 and 46,8% of patients at a mean dose of 150 mg/day or mycophenolate mofetil 2,0 g/day in 30,6% in group 1, hydroxychloroquine 0,2 g/day in 27,8 and 23,4%). Biopsy in group 1 revealed active/borderline (61/39%) myocarditis, in 8 patients — viral genome in the myocardium, including parvovirus B19 in 7 of them. Both groups showed a comparable significant increase in EF after 6 months up to 37,6±8,1 and 42,6±11,5% (p<0,001) and after 27 [12; 54] months up to 43,4±9,6 and 45,5±12,3% (p<0,001), as well as a significant decrease in HF class to 2 [1; 2] in both groups. An increase in EF by ≥10% was recorded in 70 and 72% of patients, respectively. The mortality rate was 13,9 and 12,8%. Taking into account the only transplantation in group 2, the death+transplantation endpoints reached 13,9 and 14,9% of patients (without significant differences between the groups). Conclusion . In patients with severe and moderate myocarditis diagnosed with and without myocardial biopsy, the effectiveness of combined therapy, including IST, was comparable. If it is impossible to perform a biopsy, complex non-invasive strategy makes it possible to diagnose myocarditis with different probability rate and conduct an effective IST, the refusal of which mostly is not justified.