[Diagnostic strategy in acute myocarditis].

Myocarditis is a focalised or diffuse disease of the myocardium. The principal causal agents are viruses in Europe and North America and a parasite in South America (Chagas' disease). The prevalence of acute myocarditis is variable, related to the periodic cycle of viral epidemics. The diagnosis is difficult to establish because the clinical presentation is variable, ranging from asymptomatic forms to rapidly fatal acute congestive heart failure. The diagnostic tools suffer from lack of sensitivity or specificity. Endomyocardial biopsy, despite its low sensitivity, remains the reference investigation as it provides histological proof of the myocarditis. Myocardial scintigraphy with antimyosin antibodies has the advantage of very good sensitivity but with less specificity. The authors discuss the critical indications and limitations of each investigation.