Schreiber, Fabian

Introduction: Studying the clinical nature of myocarditis on a broad scale across age and sex groups is required to investigate risk factors and patterns of disease. This study aimed to examine patient- and hospital-centered characteristics of patients being hospitalized for myocarditis. Hypothesis: Sex differences in myocarditis prevalence are dependent on age. Methods and Results: We included all patients being hospitalized in three tertiary care centers between 1999 and 2021 with a diagnosis of acute or chronic myocarditis. We utilized Chi-square, T-test, Fisher exact or Wilcoxon-Mann-Whitney U tests. 7,031 patients with acute or chronic myocarditis were included in total. 231 (3.3%) were of pre-pubescent age (<13 years if male, <11 years if female), 410 (5.8%) were adolescent patients (<18 years), 2,089 (29.7%) young adults (18-35 years), 2,535 (36.1%) middle-aged adults (35-54 years) and 1,766 (25.1%) patients were over 54 years (post-menopausal age). The diagnosis of myocarditis was confirmed by endomyocardial biopsy in 1,337 patients (19%), while it was based on clinical parameters and/or magnetic resonance imaging in the remaining patients. Adolescent patients had the highest levels of procalcitonin (6.98 ±44.6 μg/l), troponin T (450 ±1,550 ng/l) and creatine kinase (360 ±677U/l), while pre-pubescent patients had the highest levels of anti-streptolysin antibody (320 ±470 kU/l) and NT-proBNP (14,000 ±20,800ng/l) compared to all other age groups. Left-ventricular ejection fraction decreased over age groups from 60 ±4% in adolescent patients to 44.0 ±16% in senior patients. The strongest sex difference in myocarditis frequency was observed in young (608 female vs. 1,481 male; P<0.001) and middle-aged adults (1,025 female vs. 1,510 male; P<0.001) (see Figure 1). Conclusion: Strong sex differences in myocarditis prevalence were particularly observed in young and middle-aged patients. Sex hormones may determine the risk of developing myocarditis.