5 Perimyocarditis

Perimyocarditis is an acute inflammation of the pericardium and the underlying myocardium resulting in myocellular damage. It can simply be considered as acute pericarditis with elevated cardiac biomarkers. The coexistence of acute myocarditis and pericarditis is not uncommon since both are commonly caused by cardiotropic viruses. The 2 terms “perimyocarditis” and “myopericarditis” are used to describe the disease. While perimyocarditis implies predominant myocardial involvement and myopericarditis implies predominant pericardial involvement, both terms are used interchangeably without specific reference to the type of cardiac involvement. There is a wide spectrum of clinical presentations reflecting the extent of myocardial involvement ranging from asymptomatic cases with spontaneous recovery, to mild cases where symptoms are masked by the existing illness, to more severe cases complicated with heart failure necessitating inotropic support or even cardiac transplantation. Due to detrimental complications of acute myocarditis including left ventricular dysfunction and ventricular arrhythmias the diagnosis of myocarditis is more important and should be thoroughly looked for. Monitoring of the cardiac biomarkers is therefore mandatory in every patient presenting with clinical picture and electrocardiographic (EKG) evidence of acute pericarditis to exclude an underlying myocarditis. Acute pericarditis can present with ST segment elevation which can sometimes be focal rather than diffuse. In this scenario, chest pain associated with focal ST segment elevation and elevated cardiac biomarkers (if myocarditis co-existed) can mimic transmural myocardial infarction. Differentiation between both entities is of utmost importance to avert the un-necessary utilization of thrombolytic therapy which can be deleterious in perimyocarditis or to avoid missing a more serious diagnosis of ST segment elevation myocardial infarction (STEMI). After hospital discharge, patients should be followed for several weeks to exclude the development of heart failure or subclinical left ventricular dysfunction.