Antimicrobial agents for myocarditis: target the pathway, not the pathogen

Myocarditis is a serious and potentially life-threatening disorder that may lead to acute and/or chronic dilated cardiomyopathy and heart failure. Viruses are the most common pathogens associated with myocarditis and may cause cardiac injury by direct damage or through the immune and autoimmune reaction that follows viral infection. Antiviral agents, including pleconaril and interferon beta, have been used to treat acute and chronic viral myocarditis in small case series. Most therapeutic strategies that have targeted postviral and autoimmune inflammation have sought to inhibit adaptive immune components, including anti-heart antibodies and T lymphocytes, in the setting of lymphocytic or giant cell myocarditis. Rarely, bacteria may cause acute myocarditis. Fournier et al 1 described eight patients with acute Q fever ( Coxiella burnetii ) who developed myocarditis. All eight patients were treated with doxycycline for a minimum of 14 days. Five patients fully recovered, two died and one was listed for heart transplantation. Vogiatzis et al 2 reported a 30-year-old man with Coxiella burnetii who presented with chest pain, ECG changes and elevated serum cardiac biomarkers. He remained symptom free for at least 2 years after 21 days of doxycycline. Murcia et al 3 reported a similar case of a 40-year-old man with Coxiella burnetii who presented with fever and rapidly developed symptoms of heart failure. The patient was treated with clarithromycin, as well as losartan and furosemide, and his cardiac function completely normalised by 6 months. Myocarditis from Chlamydia and Mycoplasma pneumoniae …