Age and gender effects on the extent of myocardial involvement in acute myocarditis: a cardiovascular magnetic resonance study

Objective: Based upon epidemiological studies, male gender and younger age are risk factors for developing fatal myocarditis. The impact of age and gender on myocardial injury pattern in acute myocarditis, however, is not well understood. In patients with clinically acute myocarditis, this study sought to characterise the relation between patient age and gender and the extent of myocardial involvement using cardiovascular magnetic resonance (CMR) imaging. CMR markers for oedema, inflammation and fibrosis defined myocardial involvement. Design, Setting and Patients: 65 patients (42 years old (SD 15), 41 male) with clinically acute myocarditis were assessed. Using standard methods, T2-weighted and contrast-enhanced T1-weighted (early and late enhancement) CMR images were acquired. T2 images were visually and quantitatively assessed for oedema. Early enhancement images were quantified for inflammation, as was regional fibrosis in late enhancement images. Data were analysed for groups of age (>40, <40 years) and gender. Results: 62% of all patients had evidence of regional oedema, which was more prevalent in patients below 40 years of age (80.7% vs 51.3%, p<0.05), as was myocardial fibrosis (76.9% vs 48.7%, p<0.05). However, early enhancement was more frequently found in patients above 40 years (84.2% vs 61.5%, p<0.05). Men were twice as likely as women to demonstrate myocardial fibrosis (73.2 vs 37.5%, p<0.01). Conclusion: In patients with clinically acute myocarditis, myocardial fibrosis was more frequent in men and in patients younger than 40 years. Injury sustained in younger patients appears to be more regional and more severe, as indicated by a higher incidence of irreversible injury.