Diagnosis of viral myocarditis by cardiac magnetic resonance and viral genome detection in peripheral blood

In patients with acute myocarditis, viral genome can be detected in plasma and peripheral leukocytes. Its relationship with active myocardial inflammation, however, is not well understood. Myocardial edema as a feature of inflammation and myocardial necrosis or fibrosis can be frequently observed in patients with acute myocarditis by cardiovascular magnetic resonance (CMR). We assessed the association of viral genome presence in peripheral blood samples with myocardial edema and irreversible injury. We examined consecutive patients with clinically suspected myocarditis after an episode of viral illness. State-of-the-art methods were used for detecting myocardial edema and irreversible injury using CMR and viral genome applying reverse transcribed, nested polymerase chain reaction in peripheral blood samples. The specificity of viral amplification products was confirmed by automatic DNA sequencing. Of a total of 55 patients (53.5 ± 15.6 years), 21 were positive for viral genome in peripheral leukocytes. Interestingly, 18 (86 %) of these patients also showed global myocardial edema, as compared to only 7/34 (21 %) without PCR evidence for viral genome. The overall agreement between CMR criteria for edema and viral PCR was 84 %. In contrast, there was no significant relationship of viral genome presence with myocardial necrosis or scars. In patients with clinically suspected myocarditis, myocardial edema but not irreversible myocardial injury is associated with the presence of viral genome in peripheral blood.