To: Fulminant myocarditis associated with the H1N1 influenza virus: case report and literature review

To the Editor,

We would like to discuss the recent publication titled “Fulminant myocarditis associated with the H1N1 influenza virus: case report and literature review.”⁽¹⁾ In this report, Lobo et al. noted that “the H1N1 influenza virus should be considered an etiologic agent of myocarditis”⁽¹⁾ and concluded that “the use of extracorporeal membrane oxygenation therapy appears promising but has not yet been routinely implemented in underdeveloped countries.”⁽¹⁾ Indeed, myocarditis is sporadically reported in the course of H1N1 influenza infection. In our experience, the use of extracorporeal membrane oxygenation therapy is effective.⁽²⁾ Nevertheless, complications can also occur after using extracorporeal membrane oxygenation therapy. Oda et al. reported spinal infarction as an important complication.⁽³⁾ Focusing on other alternative treatments, Busani et al. recently reported the effectiveness of levosimendan.⁽⁴⁾ The efficacy of this new alternative treatment should be further assessed. Finally, cardiac pathology due to H1N1 influenza infection can be reversible.⁽⁵⁾ Hence, aggressive management and supportive care is required. The case reported by Lobo et al.⁽¹⁾ was diagnosed with H1N1 influenza virus infection based on a positive PCR test of nasopharyngeal secretions swab. However, this case of fulminant myocarditis could have resulted from either a direct clinical association with H1N1 influenza or a coincidental concomitant illness. To determine whether the H1N1 influenza virus induced myocarditis, an RT-PCR test should be performed to confirm the presence of the virus in the tissue specimen.⁽⁶⁾ In fact, the existence of myocarditis in cases with H1N1 influenza might or might not relate to the clinical presentation of H1N1.⁽⁷⁾ Thus, in the present case, the possibility of pre-existing silent myocarditis due to other causes cannot be ruled out. The histopathological finding of “lymphocyte infiltration with degeneration of some myocytes” in the present case report is also discordant with a previous report that the hallmark histopathological finding is “lymphocyte and macrophage infiltration with surrounding cardiomyocyte necrosis”.⁽⁶⁾

Beuy Joob - Sanitation 1 Medical Academic Center, Bangkok Thailand

Viroj Wiwanitkit - Hainan Medical University, China.