INTRODUCTION:Occasionally myocarditis has been associated with influenza virus infection. Old literature, based on non-specific markers, suggested myocarditis as a common occurrence with influenza infection (1). However, a recent large series examining 152 patients with influenza identified no patients with elevated troponins suggesting that the prevalence of Influenza associated myocarditis is very rare (2). Here we report a patient with influenza infection, biopsy-proven myocarditis, and associated QT prolongation.
CASE PRESENTATION:A 52-year-old white female presented with a one-day history of fever, headache, and mental status change. Several hours prior to presentation she also had a single episode of left-sided chest pain that was associated with emesis. Her past medical history included hypothyroidism and depression. Lumbar puncture yielded no evidence of meningitis. An electrocardiogram showed sinus tachycardia, no ischemic changes, and a normal corrected QT interval (QTc). Initial cardiac enzymes were elevated with a troponin of 0.59ng/mL. Over the next 24 hours, the troponin level peaked at 1.07ng/mL and then trended down towards normal. A rapid flu test was positive for influenza B, eventhough the patient had taken influenza vaccine last fall. On day 2 of hospitalization, an electrocardiogram was repeated and demonstrated a prolonged QTc interval of 600 msec. The patient’s venlafaxine and mirtazapine which she has been taking chronically were discontinued. The QTc prolongation resolved over the next 2 days. A transthoracic echocardiogram revealed a normal ejection fraction and no wall motion abnormalities. Left heart catheterization revealed normal coronaries prompting an endomyocardial biopsy which later confirmed myocarditis. The patient recovered well without any identifiable cardiac dysfunction.
DISCUSSIONS:Our case is unique for two reasons. First, elevations in cardiac enzymes are detected uncommonly in influenza myocarditis. A large series examining 152 patients with influenza identified no patients with elevated troponins2. Second, our literature review revealed no previous reports of QTc prolongation in patients afflicted with influenza myocarditis. Previous electrocardiograms from our patient had normal QT intervals while she was taking the same medication regimen. It is doubtful that medications alone were the cause of QT prolongation. We hypothesize that conduction system involvement, represented in our patient by QT prolongation, may be an important sequela of influenza myocarditis.
CONCLUSION:Although rare, influenza can cause myocarditis and life threatening electrocardiogram changes. We suggest that if cardiac involvement is suspected or patients are taking QT prolonging medications, continuous cardiac monitoring and testing with cardiac enzymes should be implemented.
DISCLOSURE:Beau Hawkins, No Financial Disclosure Information; No Product/Research Disclosure Information